test: tighten the enrichment-reset fixture (CodeRabbit)

Narrow the import guard to ImportError (not blind Exception, BLE001), and stop
clearing _caa_index_locks — it's guarded by _caa_index_locks_guard, so an
unlocked clear() would race a still-alive worker, and its per-release mutexes
carry no test state.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -52,7 +52,7 @@ jobs:
         run: pytest
 
       - name: Run JS plugin-API tests
-        run: node --test tests/js/*.test.js 'tests/plugins/*/js/*.test.js'
+        run: node --test tests/js/*.test.js 'tests/plugins/*/js/*.test.js' 'plugins/*/tests/*.test.js'
 
   tailwind-fresh:
     # Guard that the committed static/tailwind.min.css is in sync with source.
@@ -123,3 +123,28 @@ jobs:
               sys.exit(1)
           print(f"Validated {len(manifests)} manifest(s) — OK")
           EOF
+
+  lint:
+    # Maintainer/CI-only size + module-hygiene gate (constitution Principle I:
+    # dev tooling, never on the serve/Docker path — same category as
+    # scripts/build-tailwind.sh). max-lines WARNS (the 1,500-line size ratchet;
+    # non-blocking), while import-x/no-unresolved + no-cycle HARD-ERROR on the
+    # ES-module graphs the refactor produces. Exemptions: docs/size-exemptions.md.
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        # npm ci runs third-party postinstall scripts; don't leave the token in
+        # git config for them (this job never pushes).
+        with:
+          persist-credentials: false
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: ESLint (size norm + module hygiene)
+        run: npm run lint

.github/workflows/nightly.yml

@@ -1,41 +1,19 @@
 name: Nightly
 
+# Trunk-based: nightly always builds main — the release-branch discovery
+# from the old release-centric flow is gone (it pinned nightlies to the
+# highest release/v* branch forever, even after it shipped). Stabilization
+# builds from release/** come from rc.yml instead.
 on:
   schedule:
-    - cron: '0 2 * * *'
+    - cron: '0 23 * * *'
   workflow_dispatch:
 
 permissions:
   contents: read
 
 jobs:
-  setup:
-    runs-on: ubuntu-latest
-    outputs:
-      branch: ${{ steps.branch.outputs.branch }}
-      date: ${{ steps.date.outputs.date }}
-
-    steps:
-      - name: Find active release branch
-        id: branch
-        env:
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          branch=$(gh api "repos/${{ github.repository }}/git/matching-refs/heads/release/v" \
-            --jq '[.[].ref | ltrimstr("refs/heads/")] | map(ltrimstr("refs/heads/")) | .[]' \
-            | sort -V | tail -1 || true)
-          if [[ -z "$branch" ]]; then
-            branch="main"
-          fi
-          echo "branch=$branch" >> "$GITHUB_OUTPUT"
-          echo "Active branch: $branch"
-
-      - name: Get date
-        id: date
-        run: echo "date=$(date -u +%Y%m%d)" >> "$GITHUB_OUTPUT"
-
   build-docker:
-    needs: setup
     runs-on: ubuntu-latest
     permissions:
       contents: read
@@ -44,9 +22,12 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ needs.setup.outputs.branch }}
           persist-credentials: false
 
+      - name: Get date
+        id: date
+        run: echo "date=$(date -u +%Y%m%d)" >> "$GITHUB_OUTPUT"
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
@@ -65,6 +46,6 @@ jobs:
           push: true
           tags: |
             ghcr.io/got-feedback/feedback:nightly
-            ghcr.io/got-feedback/feedback:nightly-${{ needs.setup.outputs.date }}
+            ghcr.io/got-feedback/feedback:nightly-${{ steps.date.outputs.date }}
           cache-from: type=gha
           cache-to: type=gha,mode=max

.github/workflows/rc.yml

@@ -0,0 +1,63 @@
+name: rc
+
+# Release-candidate images for stabilization: every push to a release/**
+# branch builds and pushes ghcr.io tags :rc (moving) and
+# :rc-<version>-<date> (pinned). Final versioned images still come from
+# release.yml on tag push.
+on:
+  push:
+    branches: ['release/**']
+
+permissions:
+  contents: read
+
+# One build per branch at a time; a newer push supersedes an in-flight one.
+concurrency:
+  group: rc-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build-docker:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+
+      - name: Derive RC tags
+        id: meta
+        run: |
+          # release/v0.3.0 -> 0.3.0 (tolerate a missing v prefix too)
+          version="${GITHUB_REF_NAME#release/}"
+          version="${version#v}"
+          date="$(date -u +%Y%m%d)"
+          {
+            echo "tags<<TAGS_EOF"
+            echo "ghcr.io/got-feedback/feedback:rc"
+            echo "ghcr.io/got-feedback/feedback:rc-${version}-${date}"
+            echo "TAGS_EOF"
+          } >> "$GITHUB_OUTPUT"
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max

.github/workflows/release.yml

@@ -35,9 +35,9 @@ jobs:
           # stable releases (no pre-release suffix).
           {
             echo "tags<<TAGS_EOF"
-            echo "ghcr.io/${GITHUB_REPOSITORY}:${version}"
+            echo "ghcr.io/${GITHUB_REPOSITORY,,}:${version}"
             if [[ "$version" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
-              echo "ghcr.io/${GITHUB_REPOSITORY}:latest"
+              echo "ghcr.io/${GITHUB_REPOSITORY,,}:latest"
             fi
             echo "TAGS_EOF"
           } >> "$GITHUB_OUTPUT"

.github/workflows/ship-ci.yml

@@ -8,6 +8,11 @@ name: ship-ci
 on:
   pull_request:
     branches: [main, 'release/**']
+  # Trunk-based: post-merge CI on main catches semantic conflicts between
+  # independently-green PRs; push on release/** covers stabilization
+  # cherry-picks that land without a PR.
+  push:
+    branches: [main, 'release/**']
 
 permissions:
   contents: read

.gitignore

@@ -44,6 +44,12 @@ plugins/minigames/__pycache__/
 plugins/tuner/__pycache__/
 !plugins/input_setup/
 !plugins/input_setup/**
+!plugins/drum_highway_3d/
+!plugins/drum_highway_3d/**
+plugins/drum_highway_3d/__pycache__/
+!plugins/keys_highway_3d/
+!plugins/keys_highway_3d/**
+plugins/keys_highway_3d/__pycache__/
 node_modules/
 test-results/
 playwright-report/

.specify/memory/constitution.md

@@ -48,11 +48,30 @@ output is committed, so Docker / desktop / end users never build. New
 features extend `app.js` and the existing globals (`window.playSong`,
 `window.showScreen`, `window.createHighway`, `window.feedBack`).
 
+Native ES modules are a first-class, build-free extension mechanism.
+Because `<script type="module">` and `import` are browser features — not
+a bundler — a large source file MAY be split into an `import`-ed module
+graph of plain source files, with **no build step and no framework**. A
+plugin opts in with `"scriptType": "module"` in `plugin.json`: its
+`screen.js` becomes a one-line `import './src/main.js'`, and the host
+serves the `src/` subtree from the sandboxed `/api/plugins/<id>/src/…`
+route and injects the entry as `<script type="module">`. The classic
+global-scope `screen.js` path remains fully supported; both coexist, and
+module scripts are still source-served — the no-bundler, no-transpiler,
+build-free-at-serve rule is unchanged. Core's own `static/` tree may
+migrate to the same module-graph shape (`static/js/…`) over time under
+this rule.
+
 **Non-negotiable rules**
 
 - Do not introduce a frontend framework, JSX, or a JS build pipeline in
   core. Plugins MAY ship their own bundled assets but core MUST remain
   source-served.
+- ES-module plugins remain source-served: no bundler or transpiler, and
+  their own asset URLs (worklets, WASM, images) resolve via
+  `import.meta.url` — never `document.currentScript`, which is `null`
+  inside a module. `scriptType:"module"` and the optional `minHost`
+  version floor are the only new `plugin.json` keys the module path adds.
 - Because the core Tailwind stylesheet is prebuilt, it contains only the
   classes present in core source at build time. Core's committed
   `static/tailwind.min.css` MUST stay in sync with source — CI enforces
@@ -214,6 +233,15 @@ no `..`, no absolute paths).
   runs first). Plugins MUST tolerate dependent globals being absent
   at load time and check at runtime
   (`typeof window.X === 'function'`).
+- **Module load contract**: a `scriptType:"module"` plugin is injected
+  as `<script type="module">`, whose load event fires only after its
+  whole static-import graph fetches and evaluates — so the loader's
+  completion-by-`onload` guarantee (and the `playSong` wrapper-chain
+  order above) is preserved exactly. The host loads `screen.js` once per
+  version and `showScreen` re-injects nothing, so a plugin's per-visit
+  re-initialization comes from its `screen:changed` handler, not from
+  screen.js re-running; ES-module plugins inherit this unchanged (module
+  top-level code does not re-execute on same-version re-mount).
 
 ## Development Workflow
 
@@ -256,4 +284,4 @@ no `..`, no absolute paths).
   higher-numbered principle's escape hatch is to live in a plugin
   with its own bundled assets.
 
-**Version**: 1.1.0 | **Ratified**: 2026-05-09 | **Last Amended**: 2026-06-01
+**Version**: 1.2.0 | **Ratified**: 2026-05-09 | **Last Amended**: 2026-07-08

CHANGELOG.md

@@ -7,7 +7,151 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- **The packaged desktop app could not start (`ModuleNotFoundError: No module named
+  'appstate'`).** feedback-desktop's `scripts/bundle-slopsmith.sh` copies a *hardcoded
+  list* of core files into the app bundle — `server.py`, `VERSION`, `lib/`, `data/`,
+  `static/`, `plugins/__init__.py`. The root-level `appstate.py` and `routers/` added in
+  R3 shipped correctly in Docker and passed every test, and were then silently dropped
+  from the packaged app, which died at startup. Both now live under **`lib/`** — the one
+  core directory the Dockerfile (`COPY lib/`), `docker-compose.yml`, and the desktop
+  bundler (`cp -r lib`) all copy wholesale, and that all three put on `sys.path` (on
+  Windows via the embeddable-Python `._pth`, where `PYTHONPATH` is ignored). This needs no
+  change in feedback-desktop and no new release to take effect. Placing them there is also
+  correct under Principle V: with the injection seam, `appstate.py` constructs nothing and
+  does no import-time IO, and a route module only builds an `APIRouter`. The
+  `Dockerfile` / `.dockerignore` / `docker-compose.yml` entries added for the root layout
+  are reverted. New `tests/test_packaging.py` walks `server.py`'s module-level imports and
+  fails if any first-party module resolves outside a directory the packagers copy, so the
+  next root-level module can't ship broken.
+
 ### Added
+- **Perf harness now measures 2D-highway frame time (R3c gate).** `scripts/perf-baseline.mjs` gains a `--song` mode that reports per-frame draw-cost p50/p95/p99 (draw-tagged via `highway.addDrawHook`), the metric that gates the `highway.js` split. Maintainer/CI-only; baseline recorded in `docs/perf-baseline.md`.
+- **`routers/` — extracting `server.py`'s route layer, cheapest-first (R3).** Each PR moves a cohesive route group into a `fastapi.APIRouter` under `lib/routers/`, mounted with `app.include_router(...)` at its original site (FastAPI matches in registration order; the full route table stays byte-identical). Bodies are verbatim — only the decorator receiver (`@app` → `@router`) and singleton reads (`meta_db` → `appstate.meta_db`, resolved at call time) change. So far: `audio_effects` (5), `artist_aliases` (5), `loops` (3), `playlists` (12 + covers), `ws_highway` (the 902-line highway chart WebSocket), `chart` (split/unsplit/work/fileinfo — unblocked by the DLC-path substrate), `library_extras`, `wanted`, `shop`, `progression`, `profile`, `stats` (the `/api/stats/{path}` catch-all stays registered last so it can't shadow `/recent` `/best` `/top`), `version` (`/api/version`; VERSION-file lookup adjusted for the router subdir depth), and `diagnostics` (`/api/diagnostics/export|preview|hardware`; the plugins-root lookup adjusted for the router subdir depth, `_running_version` reached through the `appstate` seam, pure payload-cap helpers re-exported for the `server._diag_*` tests), and `tunings` (`/api/tunings`; the pure `config.json` reader moved to `lib/appconfig.py`, the tuning-provider registry read through the `appstate` seam so plugin-contributed tunings still merge). The DLC library-path resolution (`_get_dlc_dir`, pure `_resolve_dlc_path`) moved to `lib/dlc_paths.py`, reading paths through the seam; `config_dir`/`dlc_dir`/`dlc_dir_env` now ride the `appstate` seam (env-derived, so the pop-and-reimport fixtures reconfigure it for free), and the shared request-field sanitizer `_clean_str` moved to `lib/reqfields.py`. The next cut is picked by a dependency-closure scan that ranks groups by how many `monkeypatch.setattr(server, …)` targets they'd drag along.
+- **`routers/` — the first extracted route module (R3).** The five audio-effects mapping
+  endpoints move out of `server.py` into `lib/routers/audio_effects.py` as a
+  `fastapi.APIRouter`, mounted with `app.include_router(...)` **at the point in the file
+  where they used to be defined** — FastAPI matches routes in registration order, so the
+  mount site preserves it. Verified: the full 143-route table (paths, methods, *and*
+  order) is byte-for-byte identical to `main`. Bodies are verbatim; the only edits are
+  the decorator receiver (`@app.get` → `@router.get`) and the singleton read
+  (`audio_effect_mappings` → `appstate.audio_effect_mappings`, a module attribute
+  resolved at call time). This proves the seam from #833 under a real consumer, including
+  the second slot. The `_demo_mode_guard` middleware still blocks all four moved write
+  routes with 403, and `Query(...)` validation still 422s — both checked against a running
+  server. `server.py`: **9,445 → 9,386 lines**.
+- **`lib/enrichment.py` — the metadata-enrichment subsystem leaves `server.py` (R3, move-only).** MusicBrainz / Cover-Art-Archive / AcoustID transport, the match-scorer glue, and the background enrichment worker (~930 lines, 61 defs) move out as one cohesive unit. Bodies are verbatim; the only changes are seam reads — `meta_db`/`config_dir`/`sloppak_cache_dir`/`art_cache_dir` and the two shared art helpers (`song_pack_art_exists`, `art_override_paths`, which stay in `server.py` for the art/delete routes) are reached through `appstate` at call time, and the User-Agent VERSION lookup is corrected for the module's new depth. `server.py` drives the worker through the module (`import enrichment`; the routes + scan lifecycle call `enrichment.X`); tests that faked the network on `server` now patch the same names on `enrichment` (module attribute resolved at call time, so one `setattr` reaches both the routes and the worker's internal callers). Acyclic — `enrichment` imports no `server`. Route table byte-identical; full suite green. `server.py`: 6,917 → 5,988.
+- **`appstate.py` — the router seam (R3).** Route modules moving out of `server.py`
+  need `meta_db` and friends but must not `import server`, or the import graph goes
+  circular the moment `server` imports them back. So `server.py` keeps *constructing*
+  its singletons and now **injects** them once — `appstate.configure(meta_db=…,
+  audio_effect_mappings=…)` — and a router reads them back as module attributes at call
+  time (`import appstate; appstate.meta_db.…`). This is the Python analogue of the
+  frontend refactor's injected `configureX({…})` seams and of the plugin
+  `setup(app, context)` contract: dependencies flow one way, `server → routers →
+  appstate`. Two properties are load-bearing and pinned by `tests/test_appstate.py`:
+  (1) `import appstate` constructs nothing and touches no disk, so the ~49 test fixtures
+  that `sys.modules.pop("server")` + re-import (to rebuild `meta_db` under a patched
+  `CONFIG_DIR`) keep working untouched — a singleton *owned* by `appstate` would survive
+  that pop and go stale; (2) reads must be late-bound (`appstate.meta_db`, never
+  `from appstate import meta_db`), since a `from` import freezes the binding and defeats
+  both a later `configure()` and `monkeypatch.setattr` — the same read-only-binding trap
+  as ES `import`. `configure()` rejects an unknown slot rather than silently creating a
+  global nothing reads, and the suite asserts `server` actually calls it (a seam whose
+  wiring can no-op undetected is worse than no seam). Lives at `lib/appstate.py`.
+
+### Changed
+- **`AudioEffectsMappingDB` moved out of `server.py` into `lib/audio_effects_db.py`
+  (R3, move-only).** The core-owned song/tone → provider routing index follows
+  `MetadataDB` out of the host file, byte-identical apart from the same constructor
+  seam (`__init__` takes `config_dir`; `audio_effect_mappings = AudioEffectsMappingDB(CONFIG_DIR)`),
+  so the module does no IO at import. The singleton stays in `server.py`; no route,
+  no test and no `monkeypatch.setattr(server, …)` target moves. `server.py`:
+  **9,705 → 9,433 lines**.
+- **`MetadataDB` moved out of `server.py` into `lib/metadata_db.py` (R3, move-only).**
+  The library metadata cache — the `MetadataDB` class (4,018 lines) plus the query
+  helpers it owns (keyset paging cursors, the tuning grouping key, smart-arrangement
+  naming, tag normalisation, the startup DB-restore swap) — now lives in its own flat
+  `lib/` module. `server.py` drops from **14,037 → 9,705 lines** and keeps the
+  `meta_db` singleton, so `server.meta_db` and `server.app` resolve exactly as before
+  and every route is untouched. The only non-verbatim change is the seam that lets the
+  class leave `server.py`: `MetadataDB.__init__` now takes `config_dir` explicitly
+  (`meta_db = MetadataDB(CONFIG_DIR)`) instead of reading the module-level `CONFIG_DIR`,
+  which also means `lib/metadata_db.py` performs no IO at import (Principle V). Logging
+  still goes through the `feedBack.server` logger, so existing log filters and `caplog`
+  assertions resolve to the same logger object. `tests/test_settings_export_library_db.py`
+  now imports `_apply_pending_db_restore` from `metadata_db` (the test moved with its
+  subject); no other test changed. Every moved block is byte-identical to its
+  `server.py` original.
+
+### Added
+- **Plugins can ship an ES-module `src/` tree (module-migration rails, R0).** The host gains three things so a plugin can move off a single global-scope `screen.js` IIFE onto native ES modules with **no build step**: (1) a new sandboxed `GET /api/plugins/{id}/src/{path}` route that serves a plugin's `src/` source subtree, containment-checked by the same `safe_join` guard as `assets/` (traversal/absolute/NUL → 404); (2) the live-edit cache contract — `Cache-Control: no-cache` + a weak mtime/size `ETag` + `If-None-Match`→`304` — applied to `src/`, `screen.js`, and `assets/` (previously `screen.js` sent no cache headers and `assets/` emitted an ETag but never revalidated), so an edited module reloads on refresh while unchanged ones `304`; and (3) `scriptType`/`minHost` passthrough from `plugin.json` to `/api/plugins`, with the loader injecting a plugin that declares `"scriptType":"module"` as `<script type="module">` (its screen.js becomes `import './src/main.js'`). A `<script type=module>` fires its load event only after its whole static-import graph evaluates, preserving the loader's completion-by-`onload` + `_loadingPluginId` contract. Classic plugins are unaffected; `minHost` is passthrough-only for now (enforcement deferred). Tests: `tests/test_plugin_src_route.py` (serve/media-type/traversal/304/no-stale-304/screen.js+assets conditional), `tests/js/plugin_loader_script_type.test.js` (guarded module injection).
+- **Module-migration governance & rails (R0).** Constitution amended to **v1.2.0**: Principle II now names native ES modules as a first-class, *build-free* extension mechanism (the `scriptType:"module"` load path, both plugins and — over time — core's `static/js/`), keeping the no-bundler/no-transpiler/source-served rule intact; Operating Constraints gains a "Module load contract" clause (a `<script type=module>` load event awaits the whole static-import graph, so completion-by-`onload` is preserved; per-visit re-init comes from the `screen:changed` event, not screen.js re-execution). Mirrored into `CLAUDE.md`. New `docs/plugin-modules.md` (the migration playbook — layering, import-time purity, `import.meta.url` assets, the ETag live-edit loop) and `docs/size-exemptions.md` (the signed 1,500-line size-norm register; Byron signs core/bundled rows, Christian the authored virtuoso row). Adds a **maintainer/CI-only** ESLint gate (`eslint.config.js` + a `lint` CI job): `max-lines` warns at 1,500 as a non-blocking ratchet (ceilings for exempt files mirror the register), and `import-x/no-unresolved` + `import-x/no-cycle` hard-error on ES-module graphs — dormant until module code lands, never on the serve/Docker path.
+- **Perf-baseline harness (R0).** `scripts/perf-baseline.mjs` (maintainer-only, Playwright-driven) captures server p50/p95/p99 latency, cold boot-to-interactive, JS-heap after an idle soak, and the injected plugin-script shape (how many are `type=module`), so every refactor phase can be checked for "screen-entry and frame-time no worse." Methodology + the R0 baseline live in `docs/perf-baseline.md`; playback frame-time and chart-loaded screen-entry rows need a seeded library and are re-taken per environment.
+- **Sort and filter the library by your personal difficulty rating — now visible at a glance, not just in the edit drawer.** `song_user_meta.user_difficulty` (the 1–5 planning rating, settable manually or seeded by a plugin like the community `difficulty_tagger`) already existed but was only readable by opening a song's per-song details drawer. The library API gains `sort=difficulty` / `sort=difficulty-desc` — a correlated subquery over `song_user_meta`, following the same unrated-rows-sort-to-the-bottom-in-both-directions pattern as the existing `mastery` sort — and library cards now show the rating as a `◆N` badge (v2 grid/tree views and the v3 grid alike), next to the tuning and lyrics badges. The classic tree view's `query_artists` batch-attaches `user_difficulty` the same way `query_page` already did for the grid, so the badge actually renders there too instead of staying dark. Tests: `tests/test_library_filters.py::test_difficulty_sort_pushes_unrated_to_bottom`, `tests/test_library_filters.py::test_tree_view_songs_carry_user_difficulty`.
+- **`lib/midi_import.py`: `convert_midi_tempo_map` — MIDI imports can finally carry
+  their bars.** The keys/drums note converters always computed a tempo-aware
+  tick→seconds map internally (to bake note times to absolute seconds) and then threw
+  it away — and never read `time_signature` meta at all — so every MIDI import landed
+  with no measures and an implied 4/4 regardless of what the file said. The new helper
+  extracts the whole grid: `tempos` (`{time, bpm}`), `time_signatures` (`{time,
+  ts:[num,den]}`, the song-timeline sidecar shape), and a full `beats` grid on the
+  editor's row shape (numbered downbeats with a `den` hint, `-1` interior beats,
+  eighth-note rows in 6/8 etc.). Event scope mirrors the existing tick map — SMF
+  type 0/1 merge meta across tracks, type 2 reads only the chosen track (independent
+  timelines must never share a grid); mid-bar signature events apply at the next bar
+  boundary; times are computed from absolute ticks through the cumulative tempo table
+  and rounded once at emit, so rounding error never accumulates with song length.
+  Consumed by the editor's upcoming multitrack MIDI import (tempo-seed dialog). Tests:
+  `tests/test_midi_tempo_map.py`.
+
+### Fixed
+- **Tuner: opening the player screen no longer throws `NotFoundError` and aborts the player render (feedBack#800).** `injectPlayerButton()` anchored the injected Tuner button with `controls.querySelector('button:last-child')`, which — unlike a `:scope`-scoped query — can match a **nested** button that is not a direct child of `#player-controls`. `controls.insertBefore(btn, nestedButton)` then throws `NotFoundError` (the reference node must be a direct child), and because the injection runs from the tuner's `screen:changed` → player handler, the throw propagated out of the player-screen transition and stalled its render (surfaced by a headless render of a notation arrangement; the v3 path was already safe via the plugin-control slot, only the classic path had the bad anchor). The anchor is now `:scope > button:last-of-type` (a direct child only) with a `parentNode === controls` guard before `insertBefore`, falling back to `appendChild`. `plugins/tuner` → 1.3.4. Tests: `tests/plugins/tuner/js/inject_player_button.test.js` (nested-last-button repro, direct-child insert, no-button append, idempotency, v3 slot path).
+- **Auto-sync: DTW step constraint — riff-based songs no longer produce garbage sync points.** `librosa.sequence.dtw`'s default step pattern allows unbounded horizontal/vertical path runs, and on music with long self-similar chroma stretches (riff-driven stoner/doom, drone sections) the flat cost surface let the warping path collapse — minutes of score mapped onto a single audio frame, so the per-bar warp imported charts wildly out of sync while reporting success (observed on a real 138 BPM tab: effective displayed tempo 159 BPM, three sync points sharing one audio timestamp). `_dtw_align` now uses the standard music-sync slope-constrained step pattern (`[[1,1],[1,2],[2,1]]`, local tempo ratio bounded to 0.5x–2x), which makes the degenerate path impossible, with a fallback to unconstrained steps when the global length ratio makes the constrained pattern infeasible (e.g. a tab aligned against a full-concert video). Validated on the failing song: coarse points track the recording 1:1, refined downbeats land on onset peaks at 3.3x background energy.
+
+### Added
+- **3D Keys Highway: key layout modes, lane-color opacity & octave lines.** A new **Highway layout** settings section rebuilds how sharps/flats and lanes draw on the 3D piano highway. **Sharps & flats layout** (`keys3d_bg_sharpMode`) picks between **floating** (the original raised-sharp look), **flat** (one plane, zero-overlap piano-shaped tiled lanes with the naturals evened out), and **realistic** (one plane, bars sized like the physical keys) — default **realistic**; the geometry lives in pure, unit-tested `laneSpanFlat()`/`laneSpanReal()` helpers. **Lane color opacity** (`keys3d_bg_laneOpacity`, 0–1, default 0) fades the pitch-class lane tint from full vivid color down to a dark floor with guide lines only at the key-block boundaries (E→F and each octave); the lane strips, per-lane separators and block lines crossfade with the value. **Octave separators** (`keys3d_bg_octaveGaps`, default on) and **Octave line contrast** (`keys3d_bg_octaveContrast`, 0–1) control the B→C octave divider, which auto-shifts from a dark to a bright layer as lane opacity fades. Settings re-read on init and apply on the next chart build. `plugins/keys_highway_3d` → 0.2.0. Tests: `plugins/keys_highway_3d/tests/fx_settings.test.js` (new defaults, sharp-mode setting, lane-geometry tiling/evening for flat, uniform/overlap for realistic, and an active-range boundary case where a white key's edge stays untrimmed when its neighboring sharp falls outside the active range).
+- **Unmapped-percussion capture now records velocities alongside times.** Both drum converters' opt-in `out_unmapped` reporting (`lib/midi_import.py` `convert_drum_track_from_midi`, `lib/gp2rs.py` `convert_drum_track_to_drumtab`) gain an index-aligned `velocities` list next to `times`, carrying each dropped note's real dynamics (MIDI velocity verbatim; GP velocity with the same 1–127 gate as mapped hits, falling back to the 100 import default). This lets a hand-mapping UI (the editor's unmapped-notes dialog) restore mapped notes at their source dynamics instead of flattening everything to `v:100`. The GP path's chronological sort now reorders times and velocities in lockstep so multi-voice measures can't silently reassign dynamics. Additive — callers that ignore the new key are unaffected. Tests: `tests/test_midi_import_drums.py`, `tests/test_gp2rs_drums.py`.
+- **Handedness (left-handed) is now a first-class choice in the instrument selector — and surfaced during onboarding.** Left-handed players could already mirror the highway, but only via a buried Settings toggle they had to find *after* setup — so a lefty hit the tour, the tuner and calibration all right-handed first. The v3 instrument badge popover now has a **Handedness: Right / Left** row alongside Instrument / Strings / Tuning (all player-orientation choices), writing the same `lefty` preference (`highway.setLefty` when a live highway exists, else the `lefty` localStorage key it reads on init; the Settings checkbox stays in sync). The first-run tour's "Choose your instrument" step — which runs **before** the tuner/audio-calibration steps — now calls it out so lefties flip it up front. Frontend-only, additive: `static/v3/badges.js`, `static/v3/onboarding-tour.js`. Tests: `tests/js/badges_handedness.test.js`.
+- **"Colorblind (deuteranope)" highway string-color preset.** Adds a one-click preset to the shared "Highway String Colors" picker, sitting next to the existing Okabe–Ito "Colorblind-friendly" preset — contributed by a deuteranopic player who found the Okabe–Ito set still hard to separate. It retunes the six main strings (red / yellow-green / blue / orange / teal / deep-purple) and keeps that set's 7/8-string colors, and applies to **both** the 2D and 3D highways via the shared picker. Frontend-only, additive: `static/app.js` (`HWC_PRESETS`).
+- **`lib/gp_autosync.py`: piecewise time-warp helpers + a working `refine_sync()`.** `auto_sync()` has always computed per-bar sync points (DTW), but consumers could only apply the scalar bar-1 `audio_offset`, so any tempo difference between the recording and the tab's authored tempo accumulated audibly over the song. New librosa-free helpers expose the full mapping: `bar_start_times(gp_path)` (per-bar score times on the same axis as the sync points — GPIF bar-resolution map for `.gp`/`.gpx`, per-tick integration for GP3/4/5), `build_warp_anchors(points, bar_starts)` (strictly-monotonic `(score, audio)` anchor pairs), `warp_time(t, anchors)` (piecewise-linear map with edge-slope extrapolation for count-ins/tails), `warp_song_times(song, warp)` (retimes a `lib.song.Song` in place: notes + sustains, chords, beats, sections, anchors, handshapes, per-phrase difficulty levels, tone changes, tempo overrides), and `gp_has_expandable_repeats(gp_path)` (detects GP3/4/5 repeat/volta/direction markup whose playback expansion the as-written sync points cannot map — callers fall back to offset-only sync). Also implements `refine_sync()`, which the editor plugin's refine-sync endpoint has imported since the snapshot but which never existed in core (the Refine button 500'd): it densifies the coarse DTW points to every Nth bar and re-times each with a local onset phase sweep (sweep radius clamped under half a beat so periodic material can't lock a full beat off; short scoring grid + median residual snap). Synthetic click-track validation: ~13ms mean / ~40ms max error from ±180ms coarse input across 117–123 BPM recordings of a 120 BPM tab. Tests: `tests/test_gp_autosync_warp.py`.
+- **Playlist shuffle.** The v3 playlist detail page gains a crossing-arrows shuffle toggle next to Play all / Play album. When on, `playQueue.start` Fisher-Yates-shuffles the queue once at start (on a copy — the stored playlist order is untouched), swapping any per-slot album arrangements in lockstep so each slot keeps its pinned arrangement. The preference is global and persists in `localStorage` (`v3PlaylistShuffle`). Tests: `tests/js/play_queue_shuffle.test.js`.
+
+### Changed
+- **Player frame-time hotspots removed (trace-backed) + weak-hardware hardening.** A Chrome performance trace of a 3D-highway session surfaced two core per-frame layout-thrash sources, now fixed: the highway's visibility check read `canvas.offsetParent` every rAF frame (forces style/layout recalc — now sampled every 10th frame with a cached value, force-refreshed on init/canvas-replace/resize/override-clear), and the v3 player chrome loop called `matches(':hover')` per frame and unconditionally rewrote the Up-Next pill's `textContent`/bar width at 6 Hz (now hover-tracked via mouseenter/mouseleave, DOM writes only on value change, progress bar moved from `width` to compositor-only `scaleX`). The 3D highway pre-warms shader programs (`ren.compile`) and deterministic label textures at init — and chart-dependent chord/section label textures on first draw — so first-appearance shader-compile/texture-upload frame spikes move into the load spinner. For weaker hardware: the per-frame renderer bundle is now a single reused object instead of a fresh ~35-field allocation per frame (object identity is stable and meaningless; array fields still swap reference on chart changes), custom viz get `bundle.lowerBoundT`/`bundle.lowerBoundTime` binary-search helpers for visible-window culling, the default 2D highway's beat lines no longer scan every beat in the song per frame, and the 3D highway stops reading `localStorage` per frame (1 Hz poll) and caches its lyrics text-measurement layout per displayed line instead of re-measuring every syllable every frame. A second, throttled-CPU trace pass additionally removed: shader-program re-resolution churn from label texture swaps (`material.needsUpdate` is now only set on a null↔texture transition — swapping between two cached label textures never changes the compiled program), the 3D highway's per-frame `getBoundingClientRect` layout read in its canvas-size self-check (now every 10th frame, still immediate on backing-store change), and the core 60 Hz HUD clock rewriting `textContent` on every tick (now write-on-change, ~1/s). The dominant residual — steady `getParameters` shader-program re-resolution (~4% of throttled main thread) — turned out to be Three r158+'s transparent-DoubleSide two-pass rendering, which sets `material.needsUpdate` twice per object per frame; all 18 of the 3D highway's transparent DoubleSide materials are flat unlit quads (labels, rails, chord frames, lanes), so they now declare `forceSinglePass: true`, eliminating the recompile churn and halving those objects' draw calls.
+
+### Fixed
+- **`playback.loop-api` bridge no longer fires dozens of times per second.** Every `window.feedBack.getLoop()` call recorded a full bridge hit — compat-shim bookkeeping, a `playback:bridge-hit` event, and a diagnostics snapshot rebuild + stringify — so a plugin polling loop state from a HUD tick (note_detect at ~30 Hz) flooded the capability inspector and burned main-thread time even with no song playing. `_recordPlaybackBridge` now throttles per bridge/surface (5 s window): bridge hits are a "surface still in use" signal, not a call counter. The manual A/B loop buttons (`setLoopEnd`) also now emit the same `loop-set` transport event as `setLoop()`, so plugins can react to loop changes via `playback:loop-set` / `playback:loop-cleared` events instead of polling `getLoop()`.
+- **3D Highway: recover from a WebGL context loss instead of crashing on alt-tab.** Switching the active window / alt-tabbing away from the app (most often on Windows) can trigger a GPU context reset; the 3D highway's WebGL renderer had **no `webglcontextlost` handler**, so a lost context was left to escalate into a render-process crash — matching the intermittent "randomly crashes when I change windows" desktop reports. The renderer now binds `webglcontextlost`/`webglcontextrestored` on its own WebGL canvas (`ren.domElement`): the loss is `preventDefault()`'d so the browser keeps the context restorable, `draw()` bails while the context is down so no GL work runs on a dead context, and on restore the viewport is re-applied and rendering resumes (Three re-uploads scene resources on the next frame). Listeners are torn down with the renderer. `plugins/highway_3d` → 3.31.3. Tests: `tests/js/highway_3d_context_loss.test.js`. (The sibling `keys_highway_3d` / `drum_highway_3d` renderers share the same gap — tracked as a follow-up in their repos.)
+- **Guitar Pro 6 (`.gpx`) import no longer fails on every real file.** The GPX BCFS container reader (`lib/gp2rs_gpx.py`) rejected any file whose final sector wasn't a full `0x1000` block — but a real `.gpx`'s BCFZ-declared decompressed size isn't sector-aligned, so the last (small) container file always lands in a partial trailing sector. The bounds check *raised* `GPX BCFS sector pointer out of range (malformed file)` instead of clamping the tail read, so `_load_gpif` threw before `score.gpif` could be extracted and **no GP6 file could be imported into the song editor** (both real test files failed identically — this wasn't file-specific). GP7/GP8 `.gp` files were unaffected — they take the ZIP path, not BCFS, which is why prior GP-import work didn't surface it. The reader now **clamps the final sector read to the buffer end** (the per-file size field trims the padding anyway), matching canonical GPX readers (alphaTab / PyGuitarPro); a sector whose *start* is past the end still raises, preserving the malformed-file guard. Verified against two real GP6 files — both now unpack to valid GPIF with all tracks. Tests: `tests/test_gp2rs_gpx.py` (partial-final-sector round-trip, multi-file container, sector-aligned baseline, and the preserved out-of-range guard).
+- **v3 Songs grid: fixed the scroll stutter that "skips every so many scrolls," up or down.** The virtualized grid rebuilt its **entire** visible window (`grid.innerHTML = …` + a full `wireCards` pass) every time it slid by one row, so each row-boundary crossing was a heavy synchronous frame that stalled the main thread and buffered held-arrow key-repeats into a visible lurch (a tester's "super fast for a second then slowed down") at fixed scroll offsets — in **both directions and regardless of whether the page was already loaded** (the cost was DOM teardown, not fetching, which is why scrolling back up over cached songs hitched too). `renderWindow()` now **reconciles the window in place**: it reuses the card nodes that stay on-screen and builds only the row that enters/leaves (~6 nodes per slide instead of ~60), keyed by absolute index with a real-vs-skeleton + select-mode signature so hole-fills (after a page fetch) and select-mode toggles still rebuild exactly the nodes that changed. `wireCards`'s `data-wired` guard then wires only the freshly-built nodes, so per-slide listener churn drops with it. Follow-up to the stage-2 virtualized grid (got-feedback/feedBack#636 item 3). Frontend-only: `static/v3/songs.js`. Tests: `tests/js/v3_songs_window_recycle.test.js` (window stays `[start,end)` contiguous + in-window node identity reused across a down-then-up scroll; select-mode toggle and rail-seek jump rebuild correctly).
+- **Starter content seeds again (and now ships The Adicts' "Ode to Joy").** `_BUILTIN_STARTER_SOURCES` still listed `beethoven-ode_to_joy.feedpak` after that pack was deleted, and never wired up its replacement `the_adicts-ode-to-joy_vst_cover.feedpak` that landed on disk. The listed-but-missing file made the all-present gate never fire, so **no** starter songs seeded on first run. Synced the manifest to what's on disk (Für Elise, Star Spangled Banner, The Adicts' Ode to Joy). Tests: `tests/test_builtin_starter_seed.py` (the present/unlisted guards were red on `main`).
+- **Edit Metadata now writes into `.feedpak` files, not just legacy `.sloppak` ones.** `lib/songmeta.py`'s suffix gate predated the format rename — core reads both suffixes everywhere else (`sloppak.SONG_EXTS`), but the metadata writer only dispatched on `.sloppak`, so editing a zip-form `.feedpak`'s title/artist/album/year silently fell back to a DB-only update. That looked fine until the next **full library rescan** re-derived metadata from the file and reverted the edit (directory-form packages were unaffected — they dispatch on manifest presence, not suffix). The gate now accepts both package suffixes. Tests: `tests/test_songmeta.py` `TestWriteSongMetadata` (both zip suffixes, mixed-case suffix, directory form, unknown-suffix fallback).
+- **3D Drum & Keys highways now re-frame on fullscreen/layout drift under splitscreen.** The guitar/bass `highway_3d` self-detects when its panel canvas changes size and re-runs `applySize()` every frame, because the splitscreen host overrides `hw.resize` and never calls `renderer.resize()`. The drum and keys highways lacked that fallback — they only re-framed when the host explicitly called `resize(w, h)` — so their panels stayed framed for the pre-fullscreen size while the guitar/bass panels adapted (visible as a too-small, off-center highway after maximizing a split-screen session). Both draw loops now port `highway_3d`'s per-frame drift check: they re-apply on backing-store change (`canvas.width/height`) AND on CSS-box drift (`clientWidth/clientHeight` vs the last applied logical size, throttled to every 10th frame), and reset the tracking in `destroy()` so a reused instance re-frames on the next song. `plugins/drum_highway_3d` → 0.3.1, `plugins/keys_highway_3d` → 0.1.1. Tests: `tests/js/drum_keys_highway_3d_resize_reframe.test.js`.
+- **Tuner: finished the "remove unused settings" cleanup and fixed the sidebar panel position.** The Floating Button and Tuning Visibility settings sections were removed, but their config was still live: `disabledTunings` still filtered the tuner menu (with no UI left to re-enable a hidden tuning — a one-way trap) and `showFloatingButton` still gated the floating launcher. Both are now fully retired — the enforcement paths in `plugins/tuner/screen.js`/`utils/ui.js` and the persistence in `plugins/tuner/routes.py` are gone (and `routes.py` strips the retired keys on write, so stale values are purged). The tuner panel opened from the v3 sidebar Plugins rail popover now anchors beside it via the host's stable plugin-control slot API (falling back to the popover id), is **clamped to the viewport** so it can't open off the right/bottom edge on narrow/short windows, and re-anchors on window resize. `plugins/tuner` → 1.3.3.
+
+### Added
+- **Host theme read surface — `window.feedBack.theme` + always-present `--fbv-*` tokens — so a plugin feature can render correctly under any theme instead of binding to whichever one the developer happened to see.** The cosmetics applier (`static/v3/theme-core.js`) previously only *applied* themes and emitted `--fbv-*` vars **only while a theme was equipped** (nothing for a plugin to read in the default, un-themed state) with no read/capability API — so plugins reinvented their own theming and a new visual *device* (a glow, a gradient) silently bound to one look. It now: (1) emits the default `fb` palette as **always-present `--fbv-*` on `:root`** (additive — the un-themed look is unchanged; the `fb-*` utilities still use their compiled defaults; this only hands plugins a stable host token to read + derive surfaces from), plus two keystone ROLES the palette lacked — **`on-accent`** (a foreground legible *on* the accent fill — the missing piece behind white-on-accent contrast bugs) and **`focus-ring`**; (2) adds **`window.feedBack.theme`** — `get()` → `{id, isThemed, tokens}`, **`capabilities()`** → `{glow, gradients, motion}` (the device-affordance signal a feature reads to choose a glow vs. a solid device; recolor-only themes report defaults, a theme may opt out via a `capabilities` block in its payload, and `motion` is additionally reduced-motion-gated), and **`prefersReducedMotion()`** (one central matchMedia wrapper); and (3) emits a normalized **`theme:changed`** event (`{id, isThemed, tokens, capabilities}`) from the single `apply()` chokepoint. All additive + feature-detected (the apply side stays on `window.v3Theme`; the read surface is attached defensively so it survives the `feedBack` bus being (re)built by `capabilities.js` regardless of load order). First slice of the host theme contract (got-feedback/feedBack#644) — the framework fix so a plugin UI feature can't accidentally carve itself into a single theme; see `docs/host-theme-contract.md`. Verified by a headless render (apply/unequip intact, defaults present + restored, capability opt-out honored, event payload correct). Tests: `tests/js/v3_theme_read_api.test.js`.
+- **3D Keys Highway: audio-reactive background ambience + score effects (parity slice 4 — completes the keys side of the visual-parity epic).** The gradient sky behind the highway gains the guitar's **background ambience styles** — drifting **Particles**, pitch-class-colored pulsing **Stage lights**, wireframe **Geometric** shapes, or Off — driven by the shared audio-analyser bridge (stems-first on sloppaks, one-shot `#audio` fallback; bass/mid/treble bands, 5 ms cache) with an **Ambience intensity** slider and an **Audio-reactive** toggle. And the score talks back: a **score-FX overlay** canvas draws rising **“+1” pops** off each scored key, an **expanding ring every 10-combo tier**, **milestone bursts** at 25/50/100 streak, and a brief **red flicker** when a 3+ streak breaks (wrong notes and swept misses both count). All settings-gated and on by default (`keys3d_bg_*`), pooled, cleared when idle, torn down with the scene. Butterchurn/image/video remain out of scope. The `#audio` analyser tap is also **shared across visualizers** now (`window.__feedBackAudioTap` — whoever taps first publishes, everyone else adopts, `highway_3d` included), so switching between or splitting the guitar/drum/keys highways can't strand a permanently non-reactive backdrop, and the tap is never created before the page has user activation (a suspended AudioContext would silence live playback). Tests: bg-style id validation + FX defaults (30 total).
+- **3D Keys Highway: the anti-plastic pass — lacquered note gems, glossy piano-black keys, a studio environment, scene themes and a gradient sky (parity slice 3).** The note gems move to `MeshPhysicalMaterial` with a full **clearcoat** (roughness 0.32, clearcoat 1.0/0.18, envMapIntensity 0.9): a sharp lacquer highlight over the colored body instead of the old dead matte surface — glass, not plastic. What sells it is **image-based lighting**: the same procedural PMREM "studio" environment as the drum highway (dark room + cool overhead / warm+cool side light strips, no addon dependency) feeds `scene.environment`, so the **black keys finally read as glossy piano black** (roughness 0.55 → 0.22, envMapIntensity 1.3) with visible strip reflections, whites keep an ivory sheen (0.42/0.55), and the highway floor gets a stage sheen (roughness 0.9 → 0.55, metalness 0.15). The flat background becomes a **vertical gradient** (lighter above the horizon → theme color → darker toward the keyboard), and the guitar highway's **11 scene themes** arrive (same names/values — your look carries across instruments; `default` preserves the original keys palette; pitch-class note/key colors are never themed — themes own the scene, Synthesia colors own the notes). Plus **Cinematic lighting** (ambient 0.55/key 1.3, on by default) and a **Glow strength** slider multiplying the note glow, key approach-glow and the sustain consume-flash (0.5 = stock). All live-applying from the Graphics settings (`keys3d_bg_theme` + `keys3d_bg_*`); the PMREM target and gradient texture are disposed with the scene. Tests: theme-table id parity + default-look preservation + fallbacks (28 total).
+- **3D Drum Highway: audio-reactive background ambience + score effects (parity slice 4 — completes the drum side of the visual-parity epic).** The empty fog band behind the kit gains the guitar highway's **background ambience styles**: drifting **Particles**, palette-colored pulsing **Stage lights**, and slowly-tumbling wireframe **Geometric** shapes (plus Off) — driven by the same audio-analyser bridge the guitar uses (prefers the stems plugin's per-song analyser on sloppaks, falls back to a one-shot `#audio` tap; bass/mid/treble bands with a 5 ms cache), with an **Ambience intensity** slider and an **Audio-reactive** toggle (off = the styles animate on time only; a permanently-tapped `#audio` in a mixed split degrades the same way). The guitar's butterchurn/image/video styles are deliberately out of scope (vendored megabytes / upload plumbing; the style enum is extensible). And your combo finally talks back: a **score-FX overlay** (2D canvas over the WebGL scene, guitar `drawScoreFx` adapted to this plugin's internal scoring) draws rising **“+1” pops** off each scored lane, an **expanding ring pulse every 10-combo tier**, **milestone particle bursts** at 25/50/100 streak, and a brief **red flicker** when a 3+ streak breaks. Everything is settings-gated (Background ambience dropdown + intensity + reactive, Score effects toggle — all on by default, live-applying, `drum_h3d_bg_*` keys), pooled (zero per-frame allocation), and torn down with the scene across kit changes. Tests: bg-style id validation + FX defaults (15 total).
+- **3D Drum Highway: real materials + scene themes (parity slice 3).** The scene gets **image-based lighting**: a procedural PMREM "studio" environment (dark room + three emissive light strips — cool overhead key, warm/cool side fills; no vendored-addon dependency) feeds `scene.environment`, so the cymbals' metalness **finally reads as metal** (retuned to roughness 0.2 / metalness 0.85 / envMapIntensity 1.2 — the old 0.7-metalness look was matte because there was nothing to reflect), drumheads get a satin sheen, and the floor (roughness 0.95 → 0.7) catches the strips without turning into a mirror. **Scene themes arrive** — the same 11 theme names as the guitar highway (Midnight, Charcoal, Deep Purple, Forest, Warm Slate, Deep Focus, Deep Sea, Cathode, Cathode Green, Hearth) retint the background/fog, floor and lane stripes so your look carries across instruments; `default` preserves the original drum palette byte-for-byte, and piece colours stay with the existing Palette picker (themes own the scene, palettes own the kit). Plus **Cinematic lighting** (dimmer ambient / stronger key, on by default), a **Glow strength** slider (0–1, 0.5 = stock) multiplying every emissive base — notes, hit line, snare wires — and a **Lane vibrancy** slider driving stripe/halo/ghost-ring strength (the hit-FX approach highlight stacks on top). Everything applies live from the plugin settings (`drum_h3d_bg_theme` + `drum_h3d_bg_*` keys); the PMREM render target is rebuilt across kit-change renderer recreation and disposed in both teardown paths — and the floor/hit-bar geometry+materials that previously leaked on every kit change are now tracked and disposed too. Tests: theme-table parity with the guitar ids + default-look preservation + fallbacks (13 total).
+- **3D Drum Highway: hit FX — sparks, timing-colored lane flashes, kick camera pulse, approach glow, and open hi-hat notation (parity slice 2).** Striking a pad now *feels* struck: a pooled additive **spark burst** fires at the lane (ported from the guitar highway's Points-cloud system, pool 160), colored by **timing** — on-time green, early cyan, late amber (same `_timingHex` vocabulary as `highway_3d`, classified against the ±50 ms hit window with the inner 40% reading as on-time); with **Streak feedback** on, bursts grow with your combo. The **lane flash** feedback that was removed when note-recoloring landed is resurrected properly: pooled additive quads with a soft gaussian falloff light up the struck lane at the hit line (timing-colored; red for wrong-pad hits), and a **kick** hit fires triple amber bursts across the bar plus a subtle **camera dip + amber floor wash** that decays exponentially. Lanes also glow ahead of time: each stripe brightens as its next note approaches the hit line, so the eye is led to where the next hit lands. **Open hi-hat finally renders distinctly** — `hh_open` chart hits get a thin warm ring around the cymbal gem (standard notation's "o"), closing the long-standing TODO; the flag is orthogonal to accents/ghosts/flams so combined cues stack. All of it is settings-gated (Graphics → Hit sparks / Timing colours / Streak feedback / a 0–1 **Hit feedback intensity** slider driving flashes, approach glow and the kick pulse; everything on by default, `drum_h3d_bg_*` keys, live-applying) and GPU-frugal: every new visual is pooled or shares geometry/materials — zero per-note allocation on top of the per-frame notes rebuild, all registered in both dispose paths (kit-change renderer recreation included). Tests: timing-classifier boundaries + FX defaults added to `plugins/drum_highway_3d/tests/data_layer.test.js` (10 total).
+- **3D Keys Highway: hit FX — vibrant note gems, timing-colored sparks, and a hit-line that reacts to your playing (parity slice 2).** The washed-out note look is gone: gem opacity is now driven by a **Note vibrancy** slider (default 0.85 → opacity 0.92, up from a fixed 0.8; lane guides scale with it too, live-applying without a chart rebuild) and the resting emissive glow rises 0.08 → 0.22, so the falling notes finally read saturated against the dark floor. Scored key presses fire a pooled additive **spark burst** at the struck key (guitar-highway port, pool 96) **colored by timing** — on-time green, early cyan, late amber, classified against the ±100 ms window with the inner 40% reading as on-time (the timing delta is recovered from the matched note's key, so `judgeHit`'s tested contract is untouched); the per-pitch-class flame sprite keeps its identity color so pitch and timing stay separate signals. With **Streak feedback** on, bursts grow with the combo. The **hit line kicks brighter** for a beat on every scored press (exponential decay, scaled by a 0–1 **Hit feedback intensity** slider). All new controls live in the plugin's Graphics settings (on by default, `keys3d_bg_*` keys, live-applying), and the spark pool is disposed with the scene like every other GPU resource. Tests: timing-classifier boundaries, the noteKey time round-trip that the delta recovery relies on, and the new FX defaults (26 total).
+- **3D Drum Highway: bloom glow + adaptive-resolution support — the first slice of visual parity with the guitar highway.** The drum highway now renders through the same post-processing path as `highway_3d`: an `UnrealBloomPass` (strength 0.65, radius 0.5, threshold 0.82 — high, so only emissive/bright surfaces bleed) on a multisampled HalfFloat target with ACES filmic tone mapping, so the white hit-line bar and proximity-lit notes get a real glow instead of a flat emissive tint. **On by default**, with a new **Graphics → "Glow (bloom)"** toggle in the plugin settings (`drum_h3d_bg_bloom`, applies live, no reload); if the vendored postprocessing addons can't load (older self-hosted core), the plugin silently falls back to the direct render path. The plugin also now honors the host's **adaptive render scale** (`bundle.renderScale` — the Quality/"Min res" controls that the guitar highway already respected), multiplying it into the device pixel ratio, and caps DPR at 1.25 when more than one viz instance is live (splitscreen) so two panels don't double the GPU fill cost. Groundwork for the rest of the parity series: an FX-settings scaffold (`FX_DEFAULTS`/`readFxSettings`/`window.drumH3dSetFx`, `drum_h3d_bg_*` localStorage keys) that the sparks/themes/backgrounds PRs extend, plus a first node test suite for the plugin (`plugins/drum_highway_3d/tests/data_layer.test.js` — vm-loaded like the keys plugin's, covering the hit-variant precedence, the Auto-mode steal-guard predicate, and FX defaults; 8 tests, runs in CI via the `plugins/*/tests/*.test.js` glob).
+- **3D Keys Highway: sharp HiDPI rendering, bloom glow, a live combo HUD, and a graphics settings panel — the first slice of visual parity with the guitar highway.** The biggest single fix is resolution: the plugin never called `setPixelRatio`, so on HiDPI/retina displays (and Windows display scaling) it rendered at CSS resolution and was upscaled — soft and aliased. It now multiplies the device pixel ratio (capped at 2, or 1.25 when two viz panels are live in splitscreen) with the host's **adaptive render scale** (`bundle.renderScale`, the Quality/"Min res" controls), exactly like `highway_3d`. On top of that: the same **bloom** post-processing path as the guitar highway (UnrealBloomPass 0.65/0.5/0.82 on a multisampled HalfFloat target + ACES tone mapping — the cyan hit-line, hit flames and the sustain "consume" glow finally bleed light instead of reading flat), **on by default** with a graceful direct-render fallback when the vendored addons can't load. The plugin gains its first **settings panel** (`settings.html`, Settings → graphics category, `"settings"` block in plugin.json) with a live-applying "Glow (bloom)" toggle (`keys3d_bg_bloom`), plus the FX scaffold (`FX_DEFAULTS`/`readFxSettings`/`window.keys3dSetFx`, `keys3d_bg_*` keys) the later parity PRs extend. And the score state the plugin was already tracking is finally visible: a **combo / accuracy / best-streak HUD** overlay (drum-highway pattern), shown only while a MIDI keyboard session is wired so it never renders a frozen 0× combo. Tests: `plugins/keys_highway_3d/tests/fx_settings.test.js` (defaults, localStorage overrides + type coercion, setter persist/dispatch/unknown-key guard; 3 tests alongside the existing 20).
+- **The 3D Drum Highway and 3D Keys Highway are now bundled core plugins** (`plugins/drum_highway_3d/`, `plugins/keys_highway_3d/`), imported from their former standalone repos (`feedBack-plugin-drum-highway-3d`, `feedBack-plugin-keys-highway-3d`, now archived) via `git subtree` so their history is preserved. They join the other in-tree plugins-as-plugins: the loader treats them identically to user-installed ones, both are marked `"bundled": true` in their manifests, and `.gitignore` gains the matching `!plugins/<id>/` exceptions. This puts all three 3D highways (guitar, drums, keys) in one repo ahead of a visual-parity pass that ports the guitar highway's polish (bloom, sparks, themes, reactive backgrounds) to the other two — shared helper code and theme tables can now be reviewed and kept in sync in a single place. The keys plugin's existing node test suite is wired into CI (the JS test step gains a `plugins/*/tests/*.test.js` glob, +20 tests), and `static/tailwind.min.css` is regenerated since the core Tailwind build scans `plugins/**`. One deliberate behavior change ships with the bundling: the drum highway's Auto-mode predicate is **narrowed** (it used to claim any pack with `has_drum_tab` — a pack-level flag — which, now that the plugin ships to everyone and sorts before `highway_3d` in first-match-wins Auto order, would have stolen full-band packs from the guitar highway even on Lead/Bass arrangements; it now claims only drum arrangements, or packs nothing more specific can render). Picking the drum highway manually from the viz picker is unchanged.
+- **The tuner now tracks what tuning your instrument is *actually* in, so it prompts you to retune in BOTH directions — down to a song's tuning, and back up when the next song needs it.** The coverage check used to compare each song against your fixed instrument-profile tuning, so it only ever prompted you *away* from "home" (e.g. E → Drop C#) and stayed silent coming back (Drop C# → E), even though you'd physically retuned. It now reads the host's live **per-instrument working tuning** (`window.feedBack.workingTuning`) — what your selected instrument is currently in — so coverage is measured against your *actual* tuning and fires both ways. When you clear an auto-opened tuner, the tuner publishes that song's tuning as your instrument's live working tuning (`assumed` — an explicit "I tuned / Skip" refines it in a later PR), so the next song is judged against where you now are. **Per-instrument** — your guitar's and bass's tunings are tracked separately (keyed like the selector), so switching instruments uses the right one. Feature-detected: on a host without the working-tuning capability it falls back to the static `/api/settings` tuning (today's behavior). `plugins/tuner/screen.js` (`_playerTuning` reads `workingTuning` keyed by the selected instrument; `_publishWorkingTuning` writes on clear). Builds on the host `workingTuning` foundation (PR 1 of the series) + the instrument→chart routing (PR 2). Tests: `tests/js/tuner_auto_open.test.js` (both-directions coverage via a live Drop-D working tuning; publish-on-clear targets the right instrument slot) — 29 pass.
+- **`.jsonc` support for feedpak data files** (feedpak-spec §8, FEP #3 / PR #13). Hand-edited packs may now use the `.jsonc` extension (JSON with C-style `//` line and `/* */` block comments) for any data file the manifest points at — arrangements, notation sidecars, `drum_tab`, `song_timeline`, `lyrics`, and `keys`. New shared `lib/jsonc.py` provides `parse_jsonc(text)` + `load_json(path)` (auto-detects `.jsonc` by suffix, string-aware so comment-like text inside JSON string values is preserved) and is now used by every reader in `lib/sloppak.py` (six side-file sites) and `scripts/lift_keys_notation.py` (three arrangement / song_timeline read sites). The strip regex mirrors the reference validator in `feedpak-spec/tools/validate.py`. This is an additive (MINOR) change: `.jsonc` is opt-in, so any pack that keeps its data files as `.json` is unaffected and needs no regeneration. Note that a `.jsonc` file containing real comments only loads on a reader that implements §8 — a pre-this-change reader calls bare `json.loads` and fails on the comments rather than ignoring them, so don't hand out `.jsonc` packs to older hosts. Tests: `tests/test_sloppak_jsonc_load.py` (covers all six side-file types, the lift helper, and the string-boundary preservation rule end-to-end).
+- **The highway now loads the part that matches your selected instrument — a bass player gets the Bass arrangement, not the default Lead/guitar chart.** When you open a song without an explicit arrangement, the WebSocket handler (`server.py` `highway_ws`) reads your selected `instrument` from `config.json` (the same file it already reads for your default-arrangement preference) and routes to the matching part: **bass → the Bass arrangement**; guitar — and any unknown/future instrument (drums, keys) — falls through to the existing preference/most-notes default, which already lands on a guitar part. Previously the instrument selector only fed the tuner, so a bass player was handed a guitar chart (and a tune/coverage check then compared a 4-string bass against a 6-string part). An **explicit arrangement request always wins** (a manual arrangement switch is untouched), and a bass player's saved default-arrangement preference is still honored **within** the bass parts (so a preferred `Bass 2` / `Alt. Bass` wins over the canonical Bass), so this only changes the *default* part chosen on load. Server-only — every launch path already flows through the WS, so there's no client change. This is the instrument↔chart-routing piece the working-tuning series leans on (otherwise coverage compares across instruments). Tests: `tests/test_highway_ws_instrument_routing.py` (bass→Bass, bass-honors-pref, bass-no-bass-part→guitar, guitar→default, explicit-wins).
+- **Host "working tuning" — a live, app-wide record of what tuning your instrument is *actually* in right now (foundation; no behavior change yet).** Introduces `window.feedBack.workingTuning`, a host-owned, session-lived state distinct from any one song's tuning and from a soft opt-in default: the offsets + string-count + reference pitch the player's instrument is currently in, plus an `assumed`/`verified` provenance flag. It's **per-instrument** — your guitar's current tuning and your bass's are kept *separately* (keyed like the instrument selector, e.g. `guitar-6` / `bass-4`), so switching instruments surfaces that instrument's own remembered tuning and you only ever deal with the one you've selected. It exists so a retune — or an instrument swap mid-session — is reflected **everywhere** (the highway, the library/song-picker, and plugins like the tuner, Virtuoso, and the minigames) instead of being re-derived per surface or wrongly assumed from a fixed profile. Modeled on the shipped `tuning` capability + the `feedBack.theme` read-API: a **synchronous `get(instrument?)`** (returns the selected instrument's state, defaulting to the seed until known), a `set(state, {provenance, instrument})` mutator (the tuner becomes the sole writer in the next change), `setCurrentInstrument()` for the selector, `resetToDefault()`, and a `working-tuning-changed` event that fires on every change **and once on hydration** (carrying which instrument changed) so a late-mounting consumer is never stuck on stale state. State is **in-memory, seeded from `/api/settings` on boot and reset on restart** — a stale "you're in drop-A" assumption is worse than re-asking. Registered as a separate `working-tuning` **exclusive-owner** capability (tuner = writer, the rest = requesters). This is the foundation (plumbing only — nothing writes to it yet) of the working-tuning series, which fixes the tuner gate only ever prompting *away from* a fixed "home" tuning (never back) and makes the current tuning a first-class signal the whole app shares. Offsets use the same per-string semitone vocabulary as song tunings, so fully custom/extended tunings (e.g. a drop-A 8-string) are first-class. Frontend-only: new `static/capabilities/working-tuning.js`, loaded from `static/index.html` + `static/v3/index.html`.
+- **The v3 Songs grid is now DOM-virtualized — card-node count stays bounded no matter how big the library is or how far you scroll.** The grid used to append every scrolled page and never let go, so a 2000-song library grew the DOM from 24 → 624 → 2001 card nodes as you scrolled (layout/memory cost scaling with depth). It now renders only the **visible window** of cards (± a small overscan); a sizer element sized to the whole library (`ceil(total/cols) × rowH`) gives the scrollbar its full geometry while the grid is absolutely positioned to the first visible row. `state.songs` is a sparse, absolutely-indexed store fetched a page at a time on demand — using the stage-1 **keyset cursor** for contiguous forward scroll (O(page)) and falling back to `OFFSET page=` for jumps/restore/non-keyset providers (collections, remote). Verified bounded (~60 nodes for a 2001-song library while the count still reads "2001 songs"). The **A–Z rail now seeks directly**: `sort_letters` gives a letter's first-row index (cumulative of prior buckets), converted to a scrollTop in O(1) — no more paging through every intervening row (a bounded forward scan covers the rare legacy provider without `sort_letters`). Select-mode selections, accuracy badges, the ⋮ card menu, plugin card actions, scroll-restore (now scrollTop-based, since geometry is stable), and the tree/folder views all survive cards leaving and re-entering the DOM. Plugins that decorate cards get a stable `window.v3Songs.visibleCards()` accessor + a `v3:library-window-rendered` event instead of assuming every card is present (the highway-stutter lesson). Stage 2 of the virtualized-grid project (got-feedback/feedBack#636 item 3), building on the stage-1 keyset data layer below. Frontend-only: `static/v3/songs.js`, `static/v3/v3.css`. Tests: `tests/browser/v3-grid-virtualization.spec.ts` (bounded-DOM invariant across a 2001-song scroll + direct rail jump), updated `tests/js/v3_az_rail.test.js` + `tests/js/v3_songs_scroll.test.js`.
+- **Keyset (cursor) pagination for the library grid — the data layer for an upcoming virtualized grid, and a latent paging bug fixed along the way.** Every library sort now carries a unique `filename` tiebreak, making the order **total** — which fixes a latent bug where rows sharing a sort key (e.g. two songs by the same artist) could be skipped or duplicated across `OFFSET` pages. `GET /api/library` gains an opaque `after` cursor + a `next_cursor` in the response: passing the cursor back fetches the next page with a **WHERE-seek** instead of `OFFSET`, so deep paging is O(page) regardless of depth. The seek is NULL-aware and exactly `OFFSET`-equivalent (verified across artist/title/recent, ascending + descending, including the legacy `dir=desc` shape and NULL sort keys); unknown/compound sorts and bad cursors fall back to `OFFSET`, and only the local provider is handed a cursor (collections/remote page by `OFFSET`). New composite `(artist NOCASE, filename)` / `(title NOCASE, filename)` / `(mtime, filename)` indexes cover the order. This is stage 1 of the virtualized-grid project (got-feedback/feedBack#636 item 3); the DOM-recycling render window builds on it next. Tests: `tests/test_library_keyset.py` (keyset==OFFSET parity, stable tiebreak, dir=desc, NULL keys, cursor fallback).
+- **Smart collections — save a set of library filters as a live, auto-updating source.** A collection is a saved `/api/library` query (e.g. "Drop-D tunings", "sloppak only", "recently added") that stays live: it's registered as a **library provider**, so it shows up in the v3 Songs source picker and inherits the whole grid UI — paging, stats, the A–Z rail, art — for free, with **no new screen**. Storage reuses the playlist subsystem (a `playlists.rules` JSON blob = a smart collection; membership is the live filter result, not stored songs, and collections are excluded from the manual-playlist list + read-only to playlist mutations). New `GET`/`POST`/`PUT`/`DELETE /api/collections`; a per-collection `SmartCollectionProvider` delegates `query_page`/`query_stats`/`query_artists` to the local DB with the stored rules applied; providers are re-registered from a boot scan so collections survive a restart. Rules mirror the raw `/api/library` query params (unknown keys dropped, never 500). Frontend: a "＋ Save as collection" action in the v3 filter drawer (shown when filters are active) names the current filter set and switches to it. The charrette's "the homelab primitive FeedBack was missing" pick (got-feedback/feedBack#636 item 2); richer rule fields (accuracy, genre, difficulty) follow as the metadata work lands. Tests: `tests/test_collections_api.py`, `tests/js/v3_collections.test.js`.
+- **The settings backup now includes your library database + custom art — your scores, favorites, playlists, and play history are no longer the one thing a backup can't save.** `GET /api/settings/export` gains an additive `core_server_files` section carrying a **consistent snapshot of `web_library.db`** (taken via the SQLite online-backup API, so it's a complete single file even while the server is running) plus any custom **playlist covers** and **avatar** (`CONFIG_DIR/playlist_covers/`, `CONFIG_DIR/avatars/`). On `POST /api/settings/import` the database is **staged** to `web_library.db.restore` rather than written over the live, open DB; it's swapped in at the next startup (`_apply_pending_db_restore`, before the connection opens), which also clears the old WAL sidecars so a stale `-wal` can't be replayed onto the restored file — the import response sets `restart_required: true` and warns accordingly. Custom art is written immediately. The bundle stays backward-compatible (older servers ignore the new section). Came out of the library design charrette (dev-ops lens's top "protect irreplaceable data" pick, got-feedback/feedBack#636). _Known gap:_ custom uploaded **song** art is still commingled with the rebuildable thumbnail cache in `art_cache/`, so it isn't bundled yet (a tracked follow-up). Tests: `tests/test_settings_export_library_db.py` (snapshot consistency, staged-not-live restore, sidecar clearing, traversal rejection, full round-trip).
+- **A persisted wishlist — keep a list of songs you want but don't own yet.** New `wanted` table + `GET`/`POST`/`DELETE /api/wanted` give FeedBack the *arr-style "Wanted/Monitored" primitive it was missing: an entry is a *not-owned* song (artist/title/source/source_ref/note), so it lives in its own table rather than the playlist subsystem (which references owned local files). The API is idempotent on identity (case-insensitive artist+title, plus source+source_ref), so a producer — the `find_more` ownership-diff, or a manual add — can re-post without duplicating. Newest-first. Backend primitive for the charrette's wishlist finding (got-feedback/feedBack#636 item 4); the consuming UI lives in the producing plugin. Tests: `tests/test_wanted_api.py`.
+- **Practice-aware library home — a "Repertoire" meter + a "Keep practicing" shelf on the v3 Songs page.** The library opened cold into a flat sorted grid; now the unfiltered grid front door leads with two practice-aware surfaces built entirely from data already on hand (no new endpoints or stored state). A **Repertoire meter** shows how much of your library you can actually play — *"Repertoire: 12 of 80 songs · 7 in progress"* with a progress bar — counting songs at or above the same mastery threshold the green accuracy badge uses (≥ 90% best accuracy) over the unfiltered library total. A **"Keep practicing" shelf** is a horizontal row of your recently-played-but-not-yet-mastered songs (newest first, click to play) — the practice-accuracy-driven "continue" rail a media server can't do. Both reuse `/api/stats/best` (already loaded for the card badges) + `/api/stats/recent`; they show **only** on the grid view when you aren't searching/filtering/selecting, refresh after a song is scored, and collapse to nothing on an empty library. Soft-gamification only — descriptive encouragement (goal-gradient / endowed-progress), never content-gating, decay, or nagging. Frontend-only: `static/v3/songs.js` (`renderLibraryHome`/`_repertoireCounts`), `static/v3/v3.css`. Came out of the library design charrette (the UX + gamification lenses' top pick). Tests: `tests/js/v3_keep_practicing.test.js`.
+- **A–Z fast-scroll rail on the v3 Songs grid.** A vertical letter rail (Plex/Radarr/iOS-contacts pattern) pinned to the right edge next to the scrollbar lets you jump the library to a starting letter — tap a letter, drag to scrub with a live letter bubble, or arrow-key between letters. It shows **only** for the grid view + alphabetical (artist/title) sorts, and only offers letters actually present in the current sort **and filter set**, so a tap always lands on a real card (absent letters are dimmed + non-interactive). Because the grid is forward-only, server-paged infinite scroll, a jump pages through to the target card and scrolls to it (a newer jump supersedes an in-flight one); a keyset-seek + virtualized window is the noted scaling follow-up for very large libraries. Backend: `/api/library/stats` now accepts `sort` and returns an additive `sort_letters` map (songs-per-first-letter of the active sort column — artist or title), filter-synced; the legacy `letters` (distinct-artist) field is unchanged for the dashboard + classic tree. Frontend: `static/v3/songs.js` (`refreshRail`/`jumpToLetter`, cards tagged with `data-letter`), `static/v3/v3.css` (`.v3-azrail`). The classic (v2) tree already had letter selection; this brings the new grid to parity. Tests: `tests/test_library_filters.py` (sort_letters artist/title + song-vs-artist counting), `tests/test_library_providers.py` (sort forwarded to providers), `tests/js/v3_az_rail.test.js`.
 - **Playlists get content-dependent covers + custom art.** Playlist cards were a tiny `🎵` emoji on an empty square. Now a playlist's cover reflects its contents: **empty → the icon**, **a few songs → the first song's album art**, **4+ songs → a 2×2 art mosaic**. You can also **upload a custom cover** (a "Cover" button in the playlist detail view → image picker; "Remove cover" reverts to the content view). `MetadataDB.list_playlists()` now returns each playlist's first few song `art_urls`; `GET /api/playlists` and `GET /api/playlists/{id}` add `cover_url` when a custom cover exists. New routes `POST` / `GET` / `DELETE /api/playlists/{id}/cover` store a small PNG thumbnail under `CONFIG_DIR/playlist_covers/` (PIL-converted, like song-art upload); the cover is removed with the playlist. Frontend: `playlistCoverHtml(p)` in `static/v3/playlists.js`. Tests: `tests/test_playlists_api.py` (art_urls + cover roundtrip / reject-non-image / delete-cleanup), `tests/js/v3_playlist_cover.test.js`.
 - **v3 Songs: "Add to playlist" is now on each song's ⋮ "More" menu.** Previously a song could only be added to a playlist through select-mode (the checkbox → batch bar). The per-card overflow menu now has an **Add to playlist** row that targets that one song, reusing the same picker (choose a listed number or type a new name to create it). The select-mode batch flow and the single-song menu now share one extracted `addFilenamesToPlaylist(filenames)` helper in `static/v3/songs.js` (both grid and tree rows, since they share `openCardMenu`). Tests: `tests/js/v3_add_to_playlist_menu.test.js`.
 - **Resume where you left off — leaving a song now snapshots your place so an exit is recoverable, not a restart-from-zero.** Exiting the player (`showScreen()` teardown, before audio unload) writes `{song, arrangement, position, speed}` to `localStorage` (`feedBack.resumeSession`), and a non-blocking **"Resume practice"** pill offers it back on the next non-player screen (and on the next app launch). Clicking Resume re-enters the song, restores the arrangement + playback speed, and seeks to the saved position via the existing `_audioSeek` funnel; `playSong()` gains a `{ resume: {position, speed} }` option that arms a `song:ready`-consumed restore instead of the normal autostart, so the two never fight over playback. The snapshot is deliberately conservative — ignored for a song you barely started (< 3s) or had basically finished (within 5s of the end), cleared on natural song-end and once consumed, and expired after 24h. The pill is self-contained (inline-styled, body-appended, works identically in the classic and v3 shells with no Tailwind rebuild), never blocks, and a dismiss forgets the current snapshot for the session. This pairs with the Escape focus fix: now that Escape reliably leaves regardless of focus, an *accidental* exit is one tap to undo. Public surface: `window.resumeLastSession()` / `window.feedBack.resumeLastSession`. (The broader nav-state work — returning to a song after wandering into Settings → Tone Builder — is a separate, larger track; this lands the player-session slice.) Tests: `tests/browser/resume-session.spec.ts` (snapshot guards, staleness, pill show/hide/dismiss, resume consumption).
@@ -40,6 +184,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **v3 library: exact artist/album filters + scroll/page-depth restore** (feedBack#857). The v3 Songs toolbar gains Artist and Album dropdowns (Album populates from the selected artist and stays disabled until one is chosen), backed by new exact, case-insensitive (`COLLATE NOCASE`) `artist` / `album` query params threaded through `MetadataDB._build_where` → `query_page` / `query_artists` / `query_stats` and the `/api/library`, `/api/library/artists`, `/api/library/stats` endpoints (the free-text `q` search stays fuzzy and composes with the exact filters). The artist/album catalog is fetched independently of the active artist/album selection so the dropdowns always list the full set for the current provider/search. The toolbar is now sticky so filter controls stay reachable when browsing deep libraries, and returning from the player restores the previous scroll position **and** the loaded infinite-scroll page depth via a `sessionStorage` snapshot keyed by a filter/sort/view state hash (invalidated whenever those change, so a filter change still resets to the top). Tests: `tests/test_library_filters.py` (backend artist/album filters), `tests/js/v3_songs_scroll.test.js` (state-hash + snapshot helpers).
 
 ### Fixed
+- **GP8 multi-staff (piano/keys) tracks now import both hands — the bass stave was being silently dropped, and hand-splits landed on the wrong hand.** A GP8 grand-staff keyboard part is one `<Track>` with two `<Staff>` entries, and `MasterBar/Bars` lists one bar id per **stave**, not per track (`lib/gp2rs_gpx.py`). Two bugs fell out of assuming one stave per track: (1) the bar-column lookup used a raw `enumerate(Tracks)` index, so every track *after* a multi-stave track read the wrong column; (2) the string-tuning parse scanned all `.//Property` descendants and let the last stave's `<Tuning>` overwrite the first, so a treble note indexed against the 5-entry bass tuning fell out of range in `_note_midi` and was **dropped without a trace**. The importer now advances a bar-column counter by each track's stave count, reads tuning **per stave** (with a per-staff fall-back to the track-level property so an untuned staff never yields empty pitches), and folds **every** extra stave's notes into the arrangement (not just stave 1), keeping the `note_count` import-preview honest. A grand-staff track is now classified as keys end-to-end so the stave-0 and folded stave-1+ notes share one encoding. Separately, `notation_lift.split_hands` no longer forces a hard middle-C split when doing so produces a physically unplayable hand (e.g. a bass note under an Em7-shape voicing dipping below C4 would put a 19-semitone span in one hand) — it uses the middle-C boundary only when both resulting hands are within `HAND_SPLIT_SPAN_SEMITONES`, else falls back to the largest-gap heuristic. The GPX LH/RH pair merge and the GP8 stave fold now share one `_collect_column_notes` / `_merge_lh_notes` pair so the two formats can't drift in tie/timing/dedup handling. Companion editor change: got-feedback/feedBack-plugin-editor#38. Tests: `tests/test_gp2notation.py` (grand-staff fold + bar-column offset), `tests/test_notation_lift.py` (both middle-C split cases). Follow-up: `lib/gp_autosync.py` still carries the pre-fix bar-column + tuning logic (CLI/tests only, no production caller).
+- **Tuner auto-open is now opt-in and persists instead of flashing open-then-shut.** When you entered a song (or switched arrangement) whose tuning differed from the last, the tuner auto-opened and — for some testers — vanished ~1s later (reported macOS+Windows, 0.3.0). Root cause: the tuner closes itself on `song:play` (`plugins/tuner/utils/ui.js` — you don't tune while playing), so a **song switch** fired autoplay → `song:play` → the just-auto-opened tuner closed; an **arrangement switch** (which never arms autoplay) had no `song:play`, so it stayed open — exactly why two testers saw opposite behaviour (it wasn't the mic). Now: (1) the feature is a **new opt-in setting** ("Auto-open on tuning change", in the tuner's Settings panel, persisted as `autoOpenOnTuningChange`, **default OFF**); (2) an **auto**-opened tuner *persists* — it ignores the autoplay `song:play`, stray outside-clicks, and same-screen re-emits, closing only via the new in-panel **`×`** / **"Skip"** buttons or when you leave the song. A *manually* opened tuner keeps its classic click-away / play-to-close behaviour. The panel previously had no in-box close at all; this adds one (`×` + contextual Skip). All in the tuner plugin (`routes.py` config, `screen.js` gate + persist, `utils/ui.js` buttons + `song:play` guard, `settings.html` toggle) — **no core `app.js` changes**. Tests: `tests/js/tuner_auto_open.test.js` (opt-in gate, `{ auto: true }` persist mode, play/click-proofing). **Default (opt-in vs opt-out) is teed up for Byron to decide — flip one boolean.**
+- **Tuner auto-open is now tuning-coverage-aware — extended-range players aren't nagged for songs their instrument already covers.** With the opt-in auto-open on, it now prompts only when your **current physical tuning** (from your instrument selection in Settings) doesn't already cover the song. FeedBack is tune-to-song — the highway draws tab in the song's tuning — so the check aligns the song's open-string tuning string-for-string against your instrument: an **8-string F♯-standard** player gets **no** prompt for a 6- or 7-string standard song (its top strings already match those tunings), while a song needing an open string you don't have (e.g. a **Drop-A 7-string**, whose low A isn't an open string on an F♯ 8-string) **still** prompts. A whole-instrument reference difference also prompts — A440 vs A432, or an octave-down `centOffset` (which the auto-open now accounts for; it was previously ignored). The player's instrument is read from core **`/api/settings`** (the v3 instrument selector — a stable physical reference, not the tuner's song-tracking selection); when nothing's declared or the lookup is unavailable it falls back to a conservative prompt, so a real retune is never silently skipped. **v3-only** (the instrument selector is v3). All in the tuner plugin (`plugins/tuner/screen.js`) — **no core changes**. Tests: `tests/js/tuner_auto_open.test.js` (covered vs uncovered, the Drop-A case, reference-pitch mismatch, contiguous alignment). _Follow-up (E1.6): a passive "different tuning" badge cue that names the string(s) to retune, plus the splitscreen / no-usable-input guards._
+- **The tuner badge now passively flags when a song needs a different tuning — and names the retune.** Building on the coverage check: when you enter a song your current instrument doesn't cover, the topbar tuner badge gets an amber ring and a tooltip that **names the change** — e.g. *"retune B→A"* for a Drop-A song on an F♯ 8-string, or *"the reference pitch"* for an A440-vs-A432 mismatch. It's purely **advisory** (it never auto-opens the panel — tap the badge to tune), recomputed on `song:ready` and cleared when a new song loads or you leave the player. The retune diff comes from the tuner plugin's coverage report (`window._tunerAutoOpen.coverageReport` → `{ covered, retune: [{ from, to }], reference, cantCover }`); the cue is CSS-free (an inline ring + native tooltip — no Tailwind rebuild) and no-ops when the tuner plugin isn't installed. **v3-only.** Touches `static/v3/badges.js` (the cue) + `plugins/tuner/screen.js` (the report). Tests: `tests/js/tuner_auto_open.test.js` (the report names the strings; reference mismatch; the badge wiring). _(The splitscreen-suppress and no-usable-input guards move to the playback-gate stage, where they matter for its no-trap rule.)_
+- **Tuner auto-open can now gate playback until you've tuned — the "tune before you play" model — via a new core `holdAutoplay()` hook.** With the opt-in auto-open on, when a song needs a retune the tuner opens and **playback waits** for your choice — **Skip** (you've tuned → play, and record the song's tuning as your instrument's current working tuning), **Back to library** / **Esc** (leave the song; a gated retune is never a one-way trap), or press **Play** (always wins). For an auto-open the in-panel **×** is dropped — Skip / Back to library / Esc are its dismiss surface. Previously the song played with the tuner overlaid; now it holds — which also definitively kills the original flash, since autoplay's `song:play` can't fire while playback is held. Implemented as a small **core hook** `window.feedBack.holdAutoplay()` (mirrors the existing `holdAutoExit()`): a plugin claims it **synchronously on `song:loading`** (so it beats the `song:ready` autostart), and `release()` — or a **12-second fail-open backstop** — runs the deferred start. **Generation-guarded** (a new song invalidates a stale hold) and **fail-open** (a wedged or crashed plugin can never permanently strand a song); **manual Play always wins** (it doesn't flow through the autostart path). The tuner claims the gate only when the feature is on, and **releases it the instant** it decides not to open (song already covered / tuning unchanged) or when you Skip. Touches core `static/app.js` (the hook + an autostart refactor) and the tuner plugin (`plugins/tuner/screen.js` — the claim/release; `plugins/tuner/utils/ui.js` — the Skip / Back-to-library buttons, × dropped on auto-open); the hook is generic and shell-agnostic (a test asserts `app.js` still doesn't reference the tuner's internals). Tests: `tests/js/tuner_auto_open.test.js` (claim on `song:loading`, release on dismiss, feature-off no-claim, the core hook + fail-open backstop, the Skip / Back-to-library / Esc escape-hatch) + a `speed_reset.test.js` stub. ⚠️ **Needs a manual smoke-test before shipping** — this is a core playback change; verify on desktop that the tuner mic doesn't contend with note_detect's scoring input (ASIO/exclusive mode), per the design charrette.
+- **v3 Songs List View: favoriting a song now turns the heart red immediately (no re-search needed).** In the tree / "List View" (Songs → List → expand an artist), clicking the heart flipped the glyph ♡→♥ but it stayed dim grey until you re-searched the library — reported on macOS + Windows, open since 0.3.0 / 2026-06-25. One shared `wireCards()` `[data-fav]` handler (`static/v3/songs.js`) serves both the grid card and the List-View row, but the two render with different idle colours — grid `text-white`, List View `text-fb-textDim` — and the handler only ever removed the grid's `text-white`. So in List View the row kept `text-fb-textDim` alongside the freshly-added `text-fb-accent`, and the dim class won by CSS source order (glyph changed, colour didn't). Each heart now declares its idle colour via a `data-fav-idle` attribute and the handler swaps exactly that class, so only one colour class is ever present; the handler also writes the new state back onto the in-memory song model so a re-render / virtualized-grid recycle agrees instead of reverting. Tests: `tests/js/v3_favorites_toggle.test.js`.
+- **v3 Songs A–Z rail: taps now land reliably, a drag releases exactly on the let-go letter, and the rail is large enough to hit on hi-res displays.** Follow-up to the rail's debut (#634); three bugs reported on macOS + Windows (0.3.0, 2026-06-29): a tap often did nothing ("clicked O, nothing happened"), a drag "got you kind of there but where you release isn't where you get sent," and the rail was "way too small" at 1440p and didn't scale with resolution. Root causes & fixes, all in `static/v3/songs.js` + `static/v3/v3.css` (`bindRailOnce`/`jumpToLetter`/`.v3-azrail`): (1) **taps** — `pointerdown` calls `setPointerCapture`, after which the browser **retargets the follow-up `click` to the rail container**, so the click handler's `closest('.v3-azrail-letter')` resolved `null` and a plain tap (no `pointermove`) had no other path → no-op. The jump is now driven from `pointerdown` itself (seek on press); the `click` handler is reduced to **keyboard activation only** (`e.detail === 0`, Enter/Space). (2) **drag precision** — every letter crossed fired `jumpToLetter` with `behavior:'smooth'`; stacked smooth-scroll animations over the virtualized grid lagged and settled short of the release. `jumpToLetter(letter, smooth)` now scrolls **instantly while scrubbing** (`'auto'`) and only animates discrete taps/keyboard jumps, so the grid tracks the finger and the release lands on the let-go letter. (3) **size** — the letters were a fixed `.62rem` glued at `right:2px` (~13px-tall target on the screen edge); they now scale with the viewport (`clamp(.72rem, 1.4vh, 1.05rem)`), sit off the edge with taller/wider equal-width hit targets and a hover/active highlight so the scrub target is visible. Keyboard arrow-nav + the present-letter gating are unchanged. Reported by =Scr4tch= and MajorMokoto. Tests: `tests/js/v3_az_rail.test.js` (pointerdown-seek, keyboard-only click guard, instant-vs-smooth scroll).
+- **v3 player: opening another rail popover now closes the Section Practice popover (no more two stacked popovers).** Opening the **Practice** pill's popover and then clicking a different player-rail icon (e.g. **Plugins**) left the Practice popover open underneath the new one — looked broken (reported on macOS, 0.3.0 / 2026-06-28). The rail icons call `e.stopPropagation()` in their click handler (`static/v3/player-chrome.js`), which killed bubbling before it reached the Practice popover's outside-click dismiss bound on `document`. The dismiss (`_installSectionPracticeDismiss` in `static/app.js`) now binds in the **capture phase**, which runs before the target's handler so a descendant's `stopPropagation()` can't swallow it — mirroring how the audio-mixer popover already dismisses. Esc handling stays bubble-phase (the player's Escape-to-exit ordering is unchanged). v2 shares `app.js` and is only hardened (no rail `stopPropagation` there). Tests: `tests/js/section_practice_dismiss.test.js`.
+- **v3 UI no longer lets you accidentally text-select the chrome.** Dragging or double-clicking across the interface used to marquee-highlight buttons, labels, the sidebar, the transport, and the note-highway HUD — which looks broken (reported on Mac + Windows). The v3 shell now defaults to `user-select: none` on `html` (`static/v3/v3.css`), then opts *content* back in — so chrome is non-selectable but the text you actually copy still works. Decided by a 4-lens panel (UX / accessibility / dev-ops / plugin-ecosystem); the guardrails are deliberate: **form fields are always re-enabled** (never break the caret / IME — no `* { user-select:none }`, which trips a WebKit input bug); **plugin screens (`.screen[id^="plugin-"]`) stay selectable by default** so a plugin's copyable text (lyrics, chord names, results) — including community plugins that don't know about this — isn't silently locked; and **core read-only content opts back in by container** via a new hand-authored **`.fb-selectable`** class — applied to the whole **Settings** panel (paths, device names, version, diagnostics, About — answering "is settings still copyable?": yes), the **now-playing song metadata** (with `pointer-events` re-enabled so the HUD text is actually reachable), and the focused **modals / dialogs / toasts / scan banner** that carry copyable errors, IDs, paths, and file names. It's cosmetic only (it protects nothing) and never used to lock copy-worthy text — errors, IDs, paths, versions, and metadata stay selectable per WCAG 2.2 (copy-paste as a permitted mechanism). Dense card lists (library grid, dashboard, profile) stay non-selectable by design — making them selectable would reintroduce the marquee-mess across cards. **v3-only** (v2 unchanged); plain CSS, no Tailwind rebuild; no desktop changes (standard OS-framed window). Plugin authors: `.fb-selectable` is documented in `CLAUDE.md` for re-enabling copyable content rendered outside a plugin screen. Tests: `tests/js/v3_user_select_policy.test.js`.
+- **Input-setup wizard no longer collapses an audio device's driver-type variants into one entry.** On Windows the desktop engine enumerates the same interface once per host API (ASIO / Windows Audio / DirectSound), and the wizard's audio picker (`plugins/input_setup/screen.js`) de-duped the source list by display **label** — so the variants (which share a name) collapsed to a single choice, silently keeping whichever sorted first (often *not* the low-latency ASIO one the player wants). The audio-input capability already collapses true duplicates by `logicalSourceKey` (`_visibleInputSources` in `static/capabilities/audio-session.js`), and the variants each have a **distinct** key, so the wizard's extra label-collapse was redundant for real dupes and destructive for these — it also could drop the variant that was actually `selected`. Removed it; the picker now lists every selectable input. Pairs with feedBack-desktop's change to label each source with its driver type (e.g. "Focusrite (ASIO)") so the now-distinct entries are legible.
+- **3D Highway FPS counter no longer hides behind the v3 "Up Next" pill.** The on-highway FPS readout (Settings → Graphics → 3D Highway → Show FPS counter) is pinned to the top-right of the highway overlay — the same corner the v3 player chrome stacks its persistent **Up Next** pill and live-performance HUD into, on a higher layer that paints over the canvas. So the readout sat *behind* that chrome and couldn't be read — precisely when a tester had turned it on to judge performance (it also made the separate "Up Next won't turn off" complaint worse, since the default-on pill covered the counter regardless). The counter now stays top-right but drops just **below** whichever of that chrome is showing: `highway_3d`'s `screen.js` measures the lowest visible top-right v3 HUD element (`#v3-upnext` / `#v3-live-performance-hud` / `#hud-time`) and floors the FPS box's Y beneath it. Element refs are resolved once and cached (no per-frame `querySelector`, per the plugin perf rules) and only consulted while the counter is actually drawn; gated on `window.feedBack.uiVersion === 'v3'` so the classic (v2) UI is byte-for-byte unaffected. `plugins/highway_3d/plugin.json` version → `3.30.1` (cache-buster). (For reading raw perf numbers unobstructed, the core perf HUD — `localStorage.highwayPerfHud='1'` — still renders above all chrome and additionally shows the adaptive render-scale.)
+- **3D Highway fret-number row no longer clips off the bottom edge when the camera zooms in on a centred span.** The heat-coloured fret-number row is drawn as a band *below* the board (`sY(lowest) − S_GAP*1.4`), but the camera's self-correcting framing only anchors the board **centre** to the lower third of the screen — it reserved no headroom for that row. So a tight zoom on a centred active span (worst around mid-neck; fine when the span sits at either end of the neck, which is why testers saw it "only when centered" and "not every song") dropped the numbers past the bottom edge. Tilt can't fix it there (it would only trade a bottom clip for a top clip), so `camUpdate()` now **dollies the camera back just enough to bring the row back into frame**: it projects the row band with the final camera and, when it falls below a safe NDC line (`FRET_ROW_FIT_NDC_MIN`), raises a capped, hysteretic `_fretRowFitBoost` applied to the `curDist` lerp target (the span-driven zoom still owns zooming *in*). The boost rises promptly (proportional to the deficit), relaxes lazily past a deadband, and is capped (`FRET_ROW_FIT_BOOST_MAX`, +60%) so the zoom can't pop or hunt; it cooperates with the tilt loop (pull-back shrinks the scene, tilt keeps the centre anchored) and yields entirely to the Camera Director free-cam. Surgical: passages where the row is already visible never trigger it, so framing is unchanged everywhere it already worked. `plugins/highway_3d/plugin.json` version → `3.30.2` (cache-buster). Tests: `tests/js/highway_3d_camera_framing.test.js` (guard constants, the boosted `curDist` lerp, the projected-row hysteresis, free-cam yield).
 - **v3 Songs grid now refreshes after a Settings rescan / DLC-folder change — no app restart needed.** On a fresh install, pointing at a DLC folder in Settings and running a scan left the Songs section empty until a restart (the scan *did* populate the library — `_background_scan` re-reads `config.json` fresh — but the v3 grid never reloaded). The Settings **Rescan / Full Rescan** handlers only refreshed the classic (v2) library via `loadLibrary()`; the v3 grid (`static/v3/songs.js`) had no listener for a scan it didn't start itself (only its own upload path self-refreshed via `watchUploadScan`), so its cached, pre-DLC (empty) DOM/snapshot survived a sidebar return until a full reload. The rescan handlers now emit a **`library:changed`** event (`static/app.js`); the v3 grid listens and **reloads if it's the active screen, else marks itself dirty** so the next entry does a full re-fetch instead of restoring the stale snapshot (a `_libraryDirty` short-circuit ahead of every cached-DOM fast-path in `onV3SongsScreenEnter`). Tests: `tests/js/v3_library_refresh.test.js` (the emit + the reload/dirty wiring).
 - **Edit Metadata modal: the Year is now editable.** You could set a year when authoring a pak but the Songs → Edit Metadata modal had no Year field, so it could never be changed afterward. The backend (`POST /api/song/<f>/meta`) already accepted and normalized `year` (writes it into the file via `songmeta`, survives a rescan) — only the UI omitted it. Added a **Year** input to `openEditModal()` (populated from the song's existing year) and included `year` in `saveEditModal()`'s POST body (`static/app.js`). Both the v3 card menu and the legacy edit button already pass the year through, so both surfaces get the field.
 - **Edit Metadata modal no longer closes when a click-drag is released on the backdrop.** Selecting text inside a field and releasing the mouse past the modal's edge dismissed the form without warning (the `click` event's target resolved to the backdrop), discarding the edit. Backdrop dismissal now requires the **mousedown to have started on the backdrop** too — tracked per-modal and decided by a new pure `_editModalShouldClose(clickTarget, modalEl, downOnBackdrop)` helper (`static/app.js`). Cancel / ✕ still close on a normal click. Tests: `tests/js/edit_metadata_modal.test.js` (year in the POST body + the backdrop-close decision table).

CLAUDE.md

@@ -117,6 +117,8 @@ Notes:
 
 **Frontend scripts** — `screen.js` runs in the global scope via a `<script>` tag. It can access `window.playSong`, `window.showScreen`, `window.createHighway`, the `<audio>` element, and the `window.feedBack` event emitter.
 
+**ES-module plugins (`scriptType:"module"`)** — a plugin may instead ship a native ES-module graph with **no build step**: set `"scriptType": "module"` in `plugin.json`, make `screen.js` a one-line `import './src/main.js'`, and put the module tree under `src/` (served by the sandboxed `/api/plugins/<id>/src/{path}` route). The host injects it as `<script type="module">`, whose `onload` fires only after the whole static-import graph evaluates — so the loader's completion-by-`onload` + `_loadingPluginId` + `playSong` wrapper-chain ordering all hold. Resolve your own asset URLs (worklets, WASM) with `import.meta.url` — `document.currentScript` is `null` in a module. Module top-level code does **not** re-run when the user re-enters the screen at the same version (the host loads screen.js once and `showScreen` re-injects nothing), so keep per-visit re-init in a `screen:changed` handler, exactly as classic plugins do. Classic global-scope `screen.js` remains fully supported. See `docs/plugin-modules.md`.
+
 **The playSong wrapper chain** — Plugins commonly wrap `window.playSong` to hook into song playback. Plugins load alphabetically, so the last-loaded (alphabetically later) wrapper runs first, while the alphabetically first plugin runs closest to the original. Be aware that `await` calls in inner wrappers yield to the event loop — WebSocket messages can arrive before outer wrappers finish setup.
 
 ## Plugin Best Practices
@@ -231,6 +233,18 @@ window.feedBackViz_my_viz = function () {
             // toneChanges, toneBase, mastery, hasPhraseData, inverted,
             // lefty, renderScale, lyricsVisible, the 2D coordinate
             // helpers project and fretX, and getNoteState (see below).
+            // The bundle OBJECT is reused across frames (mutated in
+            // place — no per-frame allocation): never cache it or
+            // compare its identity between frames; field values are
+            // only valid for the current draw call. Array FIELDS still
+            // swap reference when chart data changes, so field-identity
+            // caches (`myRef !== bundle.chords`) remain valid.
+            // Windowed-iteration helpers (stable fn refs): bundle
+            // .lowerBoundT(arr, time) is a lower-bound binary search on
+            // `.t` (notes/chords); bundle.lowerBoundTime(arr, time) on
+            // `.time` (beats/anchors/sections). Use these to cull to
+            // the visible window instead of full-scanning chart arrays
+            // per frame.
             // `stringCount` is the active arrangement's string count (4
             // for bass, 6 for guitar, 7+ for extended-range GP imports —
             // size string-indexed geometry against this, not a hardcoded
@@ -552,6 +566,7 @@ a local pointer + code map.
 - **Storage** — `localStorage` for all user preferences
 - **Styling** — Tailwind CSS utility classes, dark theme (`bg-dark-600`, `text-gray-300`, accent `#4080e0`, gold `#e8c040`). Tailwind is served as a **prebuilt** stylesheet (`static/tailwind.min.css`, regenerated by `bash scripts/build-tailwind.sh`), **never** the runtime Play CDN — the CDN's on-the-fly JIT rescanned the DOM on the main thread and dropped ~26% of frames with the 3D highway (feedBack-desktop#110). The committed CSS only contains classes the build scanner saw, so CI (`tailwind-fresh`) rebuilds and diffs it; run the build script and commit when you add new classes. A plugin that uses classes not guaranteed in core (notably arbitrary values like `w-[37px]`) MUST ship its own compiled stylesheet via the `styles` manifest key, built with `corePlugins.preflight = false` (utilities only — core ships the one base reset). Plugins MUST NOT load the Tailwind Play CDN or any runtime CSS JIT. See constitution Principle II.
 - **Naming** — camelCase for JS functions, kebab-case for CSS classes, snake_case for plugin IDs
+- **Text selection (v3)** — the v3 UI defaults to `user-select: none` on `html` (in `static/v3/v3.css`) so accidental drag/double-click selection of chrome never looks broken. Form fields are always re-enabled, and a **plugin's mounted screen subtree (`.screen[id^="plugin-"]`) stays selectable by default**, so a plugin's copy-worthy text (lyrics, chord names, results, diagnostics) is unaffected — *unless your plugin renders copyable content OUTSIDE its `plugin-<id>` screen* (e.g. injected into the player chrome / a HUD overlay), which inherits the non-select default. Opt such content back in with the core-served **`.fb-selectable`** class (it sets `user-select: text` on the element + descendants; works for runtime-installed plugins since it's hand-authored in core CSS, not a scanned Tailwind utility). Never use a `* { user-select: none }` rule (breaks input carets/IME), and never use `user-select: none` to "lock" text — keep errors, IDs, paths, versions, and metadata selectable. (v2 is unchanged.)
 - **Player layout** — `#player` is `display:flex; flex-direction:column; position:fixed; inset:0`. `#highway` is `flex:1`. `#player-controls` sits at the bottom. Hiding the highway collapses the layout — use `margin-top: auto` on controls if you need to hide it.
 
 ## Backend Conventions

Dockerfile

@@ -47,11 +47,11 @@ RUN cmake -S /tmp/vgmstream -B /tmp/vgmstream/build \
 # and update FFMPEG_RELEASE + both SHA256 ARGs below.
 FROM alpine:3.20 AS ffmpeg-fetcher
 ARG TARGETARCH
-ARG FFMPEG_RELEASE=autobuild-2026-06-19-23-17
-ARG FFMPEG_BUILD_AMD64=ffmpeg-n7.1.4-145-g4cbf7a4b3d-linux64-gpl-7.1.tar.xz
-ARG FFMPEG_BUILD_ARM64=ffmpeg-n7.1.4-145-g4cbf7a4b3d-linuxarm64-gpl-7.1.tar.xz
-ARG FFMPEG_SHA256_AMD64=03c0431e0d1aa75cc343d83bda9d2d4cd8eaa37f35b7b93465e9ff6864f5d7f8
-ARG FFMPEG_SHA256_ARM64=74629b88342fd94eea12b7481c8b8560ca6d497744123c0a27b98f39d767fd93
+ARG FFMPEG_RELEASE=autobuild-2026-07-03-13-21
+ARG FFMPEG_BUILD_AMD64=ffmpeg-n7.1.5-1-g7d0e842004-linux64-gpl-7.1.tar.xz
+ARG FFMPEG_BUILD_ARM64=ffmpeg-n7.1.5-1-g7d0e842004-linuxarm64-gpl-7.1.tar.xz
+ARG FFMPEG_SHA256_AMD64=1390e1c320a1e38dae106d6d0b05a6f08eb8b30f732bc1aa0d45a4aa17f13795
+ARG FFMPEG_SHA256_ARM64=53b2e30df04d56932b7782234c9bc97abfe0bb242192ca50346474a41b100ab0
 RUN apk add --no-cache curl xz \
     && arch="${TARGETARCH:-$(apk --print-arch)}" \
     && case "$arch" in \
@@ -94,9 +94,9 @@ FROM python:3.12-slim
 # Re-declare the ffmpeg ARGs so their values are available to LABEL below.
 # ARG values don't cross stage boundaries in multi-stage builds; defaults
 # must be repeated here to take effect when no --build-arg is supplied.
-ARG FFMPEG_RELEASE=autobuild-2026-06-19-23-17
-ARG FFMPEG_BUILD_AMD64=ffmpeg-n7.1.4-145-g4cbf7a4b3d-linux64-gpl-7.1.tar.xz
-ARG FFMPEG_BUILD_ARM64=ffmpeg-n7.1.4-145-g4cbf7a4b3d-linuxarm64-gpl-7.1.tar.xz
+ARG FFMPEG_RELEASE=autobuild-2026-07-03-13-21
+ARG FFMPEG_BUILD_AMD64=ffmpeg-n7.1.5-1-g7d0e842004-linux64-gpl-7.1.tar.xz
+ARG FFMPEG_BUILD_ARM64=ffmpeg-n7.1.5-1-g7d0e842004-linuxarm64-gpl-7.1.tar.xz
 
 # Apply latest security updates to base packages (clears glibc deb13u3 and
 # similar). Done first so any subsequent installs resolve against the

README.md

@@ -1,46 +0,0 @@
-# fee[dB]ack
-
-## Plugins
-
-| Plugin                                                                             | Description                                                                                                                                                                                                                      | Install                                                                 |
-|------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------|
-| [Create from Tab](https://github.com/got-feedback/feedBack-plugin-ug)             | Search Ultimate Guitar for GP tabs and convert to playable songs                                                                                                                                                                 | `git clone ...feedBack-plugin-ug.git ultimate_guitar`                  |
-| [Import Tab](https://github.com/got-feedback/feedBack-plugin-tabimport)           | Drag and drop Guitar Pro files to create songs                                                                                                                                                                                   | `git clone ...feedBack-plugin-tabimport.git tab_import`                |
-| [Practice Journal](https://github.com/got-feedback/feedBack-plugin-practice)      | Auto-track practice time, speed, loops. Dashboard with charts                                                                                                                                                                    | `git clone ...feedBack-plugin-practice.git practice_journal`           |
-| [Setlist Builder](https://github.com/got-feedback/feedBack-plugin-setlist)        | Create ordered playlists with sequential playback                                                                                                                                                                                | `git clone ...feedBack-plugin-setlist.git setlist`                     |
-| [Metronome](https://github.com/got-feedback/feedBack-plugin-metronome)            | Audible click and visual beat flash synced to song tempo                                                                                                                                                                         | `git clone ...feedBack-plugin-metronome.git metronome`                 |
-| [Tone Player](https://github.com/got-feedback/feedBack-plugin-tones)              | View amp/pedal/cab signal chains with gear artwork                                                                                                                                                                               | `git clone ...feedBack-plugin-tones.git tones`                         |
-| [Fretboard View](https://github.com/got-feedback/feedBack-plugin-fretboard)       | Live fretboard overlay showing active notes in real-time                                                                                                                                                                         | `git clone ...feedBack-plugin-fretboard.git fretboard`                 |
-| [Tab View](https://github.com/got-feedback/feedBack-plugin-tabview)               | Scrolling guitar tablature notation via alphaTab                                                                                                                                                                                 | `git clone ...feedBack-plugin-tabview.git tab_view`                    |
-| [MIDI Amp Control](https://github.com/got-feedback/feedBack-plugin-midi)          | Auto-switch amp/modeler presets via MIDI on tone changes                                                                                                                                                                         | `git clone ...feedBack-plugin-midi.git midi_amp`                       |
-| [Section Map](https://github.com/got-feedback/feedBack-plugin-sectionmap)         | Color-coded song structure minimap with clickable navigation                                                                                                                                                                     | `git clone ...feedBack-plugin-sectionmap.git section_map`              |
-| [Arrangement Editor](https://github.com/got-feedback/feedBack-plugin-editor)      | DAW-like visual editor for creating and editing song note charts                                                                                                                                                                 | `git clone ...feedBack-plugin-editor.git editor`                       |
-| [MIDI Capo](https://github.com/masc0t/slopsmith-plugin-midi-capo)                  | MIDI capo control for real-time transposition                                                                                                                                                                                    | `git clone ...slopsmith-plugin-midi-capo.git midi_capo`                 |
-| [Note Detection](https://github.com/got-feedback/feedBack-plugin-notedetect)      | Real-time pitch detection and scoring against highway notes                                                                                                                                                                      | `git clone ...feedBack-plugin-notedetect.git note_detect`              |
-| [Find More](https://github.com/masc0t/slopsmith-plugin-find-more)                  | Search for more songs by the same artist                                                                                                                                                                                         | `git clone ...slopsmith-plugin-find-more.git find_more`                 |
-| [Piano Highway](https://github.com/got-feedback/feedBack-plugin-piano)            | Scrolling piano/keyboard view for Keys arrangements with MIDI input                                                                                                                                                              | `git clone ...feedBack-plugin-piano.git piano`                         |
-| [Studio](https://github.com/got-feedback/feedBack-plugin-studio)                  | Collaborative band recording and multi-track mixing                                                                                                                                                                              | `git clone ...feedBack-plugin-studio.git studio`                       |
-| [Drum Highway](https://github.com/got-feedback/feedBack-plugin-drums)             | Lane-based drum highway with MIDI drum pad input and built-in sounds                                                                                                                                                             | `git clone ...feedBack-plugin-drums.git drums`                         |
-| [Invert Highway](https://github.com/masc0t/slopsmith-plugin-invert-highway)        | Flip the highway note direction                                                                                                                                                                                                  | `git clone ...slopsmith-plugin-invert-highway.git invert_highway`       |
-| [Jumping Tab](https://github.com/renanboni/slopsmith-plugin-jumpingtab)            | Yousician-style 2D horizontal tab with trajectory arcs and hopping ball                                                                                                                                                          | `git clone ...slopsmith-plugin-jumpingtab.git jumpingtab`               |
-| [Step Mode](https://github.com/got-feedback/feedBack-plugin-stepmode)             | Step-by-step practice mode — highway freezes at each note until played (via Note Detection) or Space                                                                                                                             | `git clone ...feedBack-plugin-stepmode.git step_mode`                  |
-| [Lyrics Sync](https://github.com/got-feedback/feedBack-plugin-lyrics-sync)        | Generate synced LRC lyrics from text + vocals stem via Whisper alignment                                                                                                                                                         | `git clone ...feedBack-plugin-lyrics-sync.git lyrics_sync`             |
-| [Lyrics Karaoke](https://github.com/got-feedback/feedBack-plugin-lyrics-karaoke)  | Per-syllable karaoke pitch ribbon for sloppak songs (Whisper alignment + librosa pYIN)                                                                                                                                           | `git clone ...feedBack-plugin-lyrics-karaoke.git lyrics_karaoke`       |
-| [NAM Tone Engine](https://github.com/got-feedback/feedBack-plugin-nam-tone)       | In-browser amp modeling with NAM WASM, cabinet IRs, tone auto-switching                                                                                                                                                          | `git clone ...feedBack-plugin-nam-tone.git nam_tone`                   |
-| [Guitar Theory Lab](https://github.com/topkoa/slopsmith-plugin-guitar-theory)      | Explore scales, chords, intervals, tunings, and voicings on a fully interactive fretboard                                                                                                                                        | `git clone ...slopsmith-plugin-guitar-theory.git guitar-theory-lab`          |
-| [Themes](https://github.com/masc0t/slopsmith-plugin-themes)                        | Offers several basic recolorings of the interface                                                                                                                                                                                | `git clone ...slopsmith-plugin-themes.git themes`                       |
-| [Update Manager](https://github.com/masc0t/slopsmith-update-manager)               | Installs, updates, and uninstalls other plugins and the feedBack core itself                                                                                                                                                    | `git clone ...slopsmith-update-manager.git update_manager`              |
-| [Simplify Chords](https://github.com/bkranendonk/slopsmith-plugin-simplify-chords) | Changes complex chords on the note highway to simpler ones. Inspired by Ultimate Guitar's Simplify button.                                                                                                                       | `git clone ...slopsmith-plugin-simplify-chords.git simplify-chords`     |
-| [Key Bindings](https://github.com/jackipicco/slopsmith-plugin-key-bindings)        | Highway key bindings for keyboard and TV remote                                                                                                                                                                                  | `git clone ...slopsmith-plugin-key-bindings.git key_bindings`           |
-| [Virtuoso](https://github.com/got-feedback/feedBack-plugin-virtuoso)               | Practice studio for guitar & bass — scale, technique, and rhythm drills, timed workouts, and jam backing that teach skills you take off the screen.                                                                              | `git clone ...feedBack-plugin-virtuoso.git virtuoso`                    |
-| [Audio Preview](https://github.com/saleemk/slopsmith-plugin-audio-preview)         | Quick audio previews from library cards with configurable start time, volume, and duration                                                                                                                                       | `git clone ...slopsmith-plugin-audio-preview.git audio_preview`         |
-| [Song Mastery](https://github.com/jamesgaiser/slopsmith-plugin-song-mastery)       | Auto-adjusts difficulty based on your rolling note accuracy and saves the slider position per song                                                                                                                               | `git clone ...slopsmith-plugin-song-mastery.git song_mastery`           |
-| [Mobile Note Highway](https://github.com/saleemk/slopsmith-plugin-mobile-note-highway) | Touch-optimized player with collapsible controls, highway gestures, and device-adaptive layouts for phones and tablets | `git clone ...slopsmith-plugin-mobile-note-highway.git mobile_note_highway` |
-
-Install any plugin by cloning it into your `plugins/` directory and restarting:
-
-```bash
-cd plugins
-git clone https://github.com/got-feedback/feedBack-plugin-ug.git ultimate_guitar
-docker compose restart
-```

VERSION

@@ -1 +1 @@
-0.3.0
+0.3.0-alpha.1

docs/host-theme-contract.md

@@ -55,59 +55,94 @@ The host writes default `--fb-*` role tokens on `:root` **unconditionally** (not
 `[data-fb-theme]`), seeded from the canonical `fb` palette, so `var(--fb-accent, …)` always
 resolves — themed or not. Roles:
 
-`surface · card · border · text · text-dim · accent · accent-2 · good · warn · bad`
-plus two **new keystones**:
+**Namespace (normative).** The public contract lives under one prefix, **`--fb-*`**, written on
+`:root` by a host-owned *contract stylesheet* (see §6 / §8) so it is present **themed or not**.
+The existing `--fbv-*` vars stay **internal plumbing** — `theme-core.js` uses them only to
+recolour the Tailwind `.bg-fb-*/.text-fb-*/.border-fb-*` utilities under `html[data-fb-theme]`;
+they are **not** part of this contract and plugins must not read them. (Implementation may seed
+`--fb-*` from the same source the `--fbv-*` overrides use, so an equipped theme moves both.)
 
-- **`on-accent`** — foreground legible *on* an accent fill. (Rule: any role used as a fill
-  behind text gets a paired `on-*`.) Fixes white-on-amber.
-- **`focus-ring`** — focus indicator independent of accent, so focus stays visible when
-  `accent ≈ surface`.
+**Value grammar (normative).** Colour roles are a **space-separated `r g b` triplet** (matching
+today's `--fbv-*` and the Tailwind utilities), consumed as `rgb(var(--fb-accent))` with optional
+alpha `rgb(var(--fb-accent) / .5)`. Recipe slots (Layer 2) hold **full CSS values** for their
+device (a `box-shadow`, a `border` shorthand, a length, a paint), with `none` legal **except**
+where noted.
 
-`accent-2` is demoted to "just a second hue" — **never** an assumed gradient end.
+**Normative role tokens** (all `--fb-*`, all always present):
+
+| Role | Token | Notes |
+| --- | --- | --- |
+| surface / card / border | `--fb-surface` `--fb-card` `--fb-border` | structural |
+| text / dim | `--fb-text` `--fb-text-dim` | |
+| accent / second hue | `--fb-accent` `--fb-accent-2` | `accent-2` is **just a second hue** — never an assumed gradient end |
+| status | `--fb-good` `--fb-warn` `--fb-bad` | maps onto today's palette `good / mid / low` (mid→warn, low→bad) — implementation aliases both |
+| **on-fill (new)** | `--fb-on-accent` `--fb-on-good` `--fb-on-warn` `--fb-on-bad` | **Rule: every role used as a fill behind text gets a paired `--fb-on-*`** (fixes white-on-amber). Required + contrast-linted (§6). |
+| **focus (new)** | `--fb-focus-ring` | focus indicator independent of `accent`, so focus stays visible when `accent ≈ surface` |
 
 ### Layer 2 — Capability **recipes** (intent-named slots; "off" is legal)
 
-A theme declares its design *language* by filling intent-named slots. A feature applies the
-slot bundle **unconditionally**; it never branches on "is this theme glowy?". Atomic slots
-(renames-by-intent of today's tokens): `corner-radius`, `corner-clip`, `panel-shadow`,
-`text-emph-shadow`, `panel-texture`, `motion-decorative` (reduced-motion-gated).
+A theme declares its design *language* by filling intent-named slots (all `--fb-*`-prefixed,
+same namespace as the roles). A feature applies the slot bundle **unconditionally**; it never
+branches on "is this theme glowy?". Atomic slots (renames-by-intent of today's tokens):
+`--fb-corner-radius`, `--fb-corner-clip`, `--fb-panel-shadow`, `--fb-text-emph-shadow`,
+`--fb-panel-texture`, `--fb-motion-decorative` (reduced-motion-gated). For these, `none` is legal.
 
 Two **composite recipes** carry the load:
 
 - **EMPHASIS** — how this theme makes a primary action special:
-  `--emph-fill / --emph-border / --emph-halo / --emph-on`.
+  `--fb-emph-fill / --fb-emph-border / --fb-emph-halo / --fb-emph-on`.
   neon → halo (glow ring); esports → border (solid accent); metal → fill + drop-shadow.
-  None empty — each emphasises in its own language.
-- **ACCENT-TEXT** — how this theme fills a big accent number: `--acc-text-fill`
+  Any individual slot may be `none` — but a theme **must** emphasise *somehow* (at least one of
+  fill/border/halo non-`none`), so a primary action is never visually flat.
+- **ACCENT-TEXT** — how this theme fills a big accent number: `--fb-acc-text-fill`
   (decoupled from `accent-2`). neon/metal → a gradient; esports → a solid accent.
+  **`--fb-acc-text-fill` is the one slot where `none` is illegal** — it is always a valid paint
+  (solid colour or gradient), defaulting to `rgb(var(--fb-accent))`. Reason: the number is
+  rendered with `background-clip: text` + transparent text-fill, so a `none` paint would make
+  the digits **invisible** (transparent fill, nothing to clip) — which would violate the DoD
+  "a device stays legible when its slot resolves to `none`". The feature also feature-detects
+  `background-clip: text` and keeps a solid `color` base (see §5), so the digits are legible
+  even where clip-text is unsupported.
 
 > These generalize the interim per-skin tokens already shipped in `note_detect`
 > (`--nd-hero-ring-idle/on`, `--nd-hero-border`, `--nd-acc-fill`).
 
 ### Layer 3 — JS read API + reconciliation
 
-On the existing `window.feedBack` bus:
+**The JS API is only for renderers that can't use CSS (canvas / WebGL), never for DOM/CSS
+consumers** — those use the tokens and slots directly (§5). Critically, it exposes *resolved
+token values*, **not** theme-style booleans: a `glow:false` flag can't tell a canvas whether to
+draw a border, a bevel, a drop-shadow, or flat text, so there is **no** `capabilities()` of
+booleans. On the existing `window.feedBack` bus:
 
-- `feedBack.theme.get()` → `{ id, tokens, isThemed }`
-- `feedBack.theme.capabilities()` → `{ glow, gradients, motion }` (the device-affordance signal)
-- `feedBack.theme.prefersReducedMotion()` → boolean (host wraps `matchMedia` once)
-- `theme:changed` event → `{ id, tokens, capabilities }` (emitted at theme-core's existing
-  apply chokepoint; analogous to `note_detect`'s `notedetect:skin`)
+- `feedBack.theme.get()` → `{ id, isThemed, tokens }` where `tokens` is the **resolved** map of
+  every `--fb-*` role + recipe slot (the computed values, so a canvas reads the actual device,
+  e.g. the gradient stops for `--fb-acc-text-fill`, not a boolean).
+- `feedBack.theme.prefersReducedMotion()` → boolean (host wraps `matchMedia` once). **This is the
+  single approved JS reduced-motion gate going forward** — existing direct `matchMedia` callers
+  (`venue-mood-fx.js`, `pedal-cables.js`) migrate to it; `--fb-motion-decorative` covers the
+  CSS-authored decorative motion.
+- `theme:changed` event → `{ id, tokens }`.
 
-**Reconciliation rule (ends the two-disconnected-systems problem) — depends on whether the
-plugin has its own identity:**
+**Lifecycle (normative).** `get()` always returns the **current effective theme synchronously**
+and is valid at any time — before any theme is applied it returns the default/unthemed roles
+(which always exist on `:root`). Theme application is async (it follows a `/api/profile` refresh);
+`theme:changed` fires **only after** the DOM vars/classes are committed, and **once on initial
+hydration** so a late-mounting plugin isn't stuck on stale state. **Plugin rule:** read `get()`
+on mount, then subscribe to `theme:changed` — never assume an order between your mount and the
+first theme apply.
 
-- **A plugin *without* its own skin** should **derive surface/text/border from host tokens**
-  (`background: var(--fbv-card)`, etc.) and **own only its accent + its devices**, selecting the
-  device via the recipe. A host theme then pulls its chrome along — one truth for surfaces — and
-  it never imposes a device the active theme neutralizes. This is the common case.
-- **A plugin *with* deliberate skins** (e.g. `note_detect`'s neon / esports / metal, which are
-  full design languages) **owns its surfaces** — deriving them from the host theme would *erase*
-  the skin's identity (metal's brushed steel becomes a flat host colour). Such a plugin adopts the
-  **role + recipe *pattern*** (per-skin device tokens, `on-accent`, `focus-ring`, "off" is legal)
-  and verifies across **its own** skin matrix, but does not blindly inherit host surfaces.
-  *(Decided 2026-06-29: keep note_detect's skins self-owned + their current button text — so the
-  fix is the per-skin device pattern + the verification gate, not surface-derivation.)*
+**Reconciliation rule (ends the two-disconnected-systems problem):** a plugin skin
+**derives surface/text/border from host tokens** (`--nd-bg: rgb(var(--fb-card))`, etc.) and
+**owns only its accent + its devices**, selecting the device via the recipe. A host theme then
+pulls plugin chrome along (one truth for surfaces), while the plugin layers identity on top and
+never imposes a device the active theme neutralizes.
+
+**Propagation scope (normative).** The contract is **same-document light-DOM**: `:root` `--fb-*`
+inheritance and the central focus/motion rules (§6) reach any normal plugin screen. A plugin that
+renders into a **shadow root or iframe** is responsible for bridging — copy the resolved
+`get().tokens` into its sub-root and re-subscribe to `theme:changed` (host `:root` vars don't
+cross those boundaries).
 
 ## 5. Consumption pattern (the rule for feature authors)
 
@@ -117,28 +152,47 @@ plugin has its own identity:**
 
 ```css
 .hero-cta {
-  background: var(--emph-fill);
-  border:     var(--emph-border);
-  box-shadow: var(--emph-halo);   /* neon→ring · esports→none · metal→drop-shadow */
-  color:      var(--emph-on);     /* never hardcoded #fff again */
-  border-radius: var(--corner-radius);
+  background: var(--fb-emph-fill);
+  border:     var(--fb-emph-border);
+  box-shadow: var(--fb-emph-halo);   /* neon→ring · esports→none · metal→drop-shadow */
+  color:      var(--fb-emph-on);     /* never hardcoded #fff again */
+  border-radius: var(--fb-corner-radius);
 }
 .accuracy-number {
-  color: var(--accent);           /* legible solid fallback FIRST */
-  background: var(--acc-text-fill);
-  background-clip: text; -webkit-background-clip: text; -webkit-text-fill-color: transparent;
+  /* Always-legible solid base; survives no-clip-text support too. */
+  color: rgb(var(--fb-accent));
+}
+/* Apply the clipped paint ONLY where supported — and --fb-acc-text-fill is
+   guaranteed a real paint (never `none`, per Layer 2), so the digits can't go
+   invisible. */
+@supports ((background-clip: text) or (-webkit-background-clip: text)) {
+  .accuracy-number {
+    background: var(--fb-acc-text-fill);
+    -webkit-background-clip: text; background-clip: text;
+    -webkit-text-fill-color: transparent;
+  }
 }
 ```
 
-## 6. Accessibility (baked into the contract, not per-feature)
+**Where the contract physically lives.** A **host-owned static contract stylesheet** (e.g.
+`static/v3/theme-contract.css`, hand-authored, linked from `static/v3/index.html`) holds the
+always-present `:root --fb-*` defaults **plus** the two central a11y rules below. It is **not** a
+Tailwind file, so it never touches the prebuilt `static/tailwind.min.css` artifact the
+`tailwind-fresh` CI check diffs (and it's independent of `theme-core.js`, which keeps
+runtime-injecting only the `--fbv-*` utility overrides under `[data-fb-theme]`).
 
-- **Reduced motion:** `motion-decorative` is the *only* place decorative animation is named;
-  one central rule sets it to `none` under `@media (prefers-reduced-motion: reduce)`, so no
-  theme can forget the gate.
-- **Focus parity:** exactly one contract-level `:focus-visible { outline: 2px solid var(--focus-ring) }`;
-  themes recolour `focus-ring` but may not author their own focus styling.
-- **On-accent contrast:** `on-accent` is required and **lintable** (`contrast(on-accent, accent) ≥ 4.5:1`,
-  3:1 large). Contrast is the theme's job, computed once — not re-judged per feature.
+- **Reduced motion:** `--fb-motion-decorative` is the *only* place CSS decorative animation is
+  named; one central rule in the contract sheet sets it to `none` under
+  `@media (prefers-reduced-motion: reduce)`, so no theme can forget the gate. (JS-driven motion
+  uses `feedBack.theme.prefersReducedMotion()` — §4.3.)
+- **Focus parity:** one contract-level `:focus-visible { outline: 2px solid rgb(var(--fb-focus-ring)) }`
+  for contract consumers; themes recolour `--fb-focus-ring` but may not author their own focus
+  styling. *Migration:* v3 already ships component-specific focus + reduced-motion rules in
+  `v3.css`; those are reconciled onto the contract token (not magically replaced) as a tracked
+  cleanup — "one rule" describes the end state, not day one.
+- **On-fill contrast:** every `--fb-on-*` is required and **lintable**
+  (`contrast(on-X, X) ≥ 4.5:1`, 3:1 large) for each fill role (`accent / good / warn / bad`).
+  Contrast is the theme's job, computed once — not re-judged per feature.
 
 ## 7. Verification gate (prevent recurrence)
 
@@ -157,13 +211,15 @@ stays legible when its slot resolves to `none`** · reduced-motion + focus parit
 
 ## 8. Back-compat & rollout
 
-All additive: new `--fb-*` runtime vars + a new `feedBack.theme` namespace + a new event with no
-current listeners. Existing plugins (those reading `fb-*` utility classes, or shipping their own
-skins) are untouched unless they opt in; two-arg `var(--fb-x, fallback)` + `window.feedBack?.theme?.get`
-feature-detection means older hosts behave exactly as today.
+All additive: the new always-present `--fb-*` tokens (in the contract sheet, §6) + a new
+`feedBack.theme` namespace + a new event with no current listeners. Existing plugins (those
+reading `fb-*` Tailwind utility classes, or shipping their own skins) are untouched unless they
+opt in. On a host too old to ship the contract sheet, a consumer still degrades cleanly: the
+two-arg fallback `rgb(var(--fb-accent, 224 128 32))` resolves to the literal, and
+`window.feedBack?.theme?.get?.()` is feature-detected — so older hosts behave exactly as today.
 
 **Workstream (sub-tasks):**
-1. **Host minimal surface** — always-present default `--fb-*` tokens + `feedBack.theme.{get,capabilities,prefersReducedMotion}` + `theme:changed`. *(the smallest thing that would have prevented the incident)*
+1. **Host minimal surface** — the contract stylesheet's always-present default `--fb-*` tokens + `feedBack.theme.{get, prefersReducedMotion}` (`get().tokens` = resolved values; no boolean `capabilities()`) + `theme:changed`. *(the smallest thing that would have prevented the incident)*
 2. **note_detect refactor** — rename device tokens by intent (EMPHASIS + ACCENT-TEXT recipes), add `on-accent` + `focus-ring`, derive surfaces from host tokens.
 3. **Verification gate** — commit the render-matrix + DoD checklist; add the canvas share-card surface.
 4. **Ecosystem migration guide** — document the contract + the consumption rule for community plugin authors.
@@ -182,5 +238,9 @@ feature-detection means older hosts behave exactly as today.
   plugin-local forever? (This proposal assumes plugin-local + contract-implementing.)
 - Component-recipe **bundles** (per named component) are the richer end-state; intent-named
   slots are the right seed. When/whether to graduate.
-- Where the central reduced-motion + focus rules physically live (core base layer vs a shared
-  plugin import) and how the host injects role tokens into plugin roots.
+
+*(Resolved during review and folded into the sections above: the token namespace + value grammar
+and normative role table (§4.1); the `none`-is-illegal carve-out for `--fb-acc-text-fill` (§4.2);
+JS exposes resolved tokens, not booleans (§4.3); `theme:changed` lifecycle + shadow/iframe
+propagation (§4.3); the physical home of the role tokens + central focus/motion rules — a
+host-owned contract stylesheet outside Tailwind (§6).)*

docs/perf-baseline.md

@@ -0,0 +1,92 @@
+# Perf baseline — module-migration refactor
+
+The refactor promises "measured runtime wins, no hand-waved perf claims" and
+"screen-entry and frame-time no worse." This is the baseline to hold it to.
+Rerun the harness after every phase (R0 → R3c) and compare.
+
+## Running it
+
+```
+# 1. start core against a library with real charts (see caveat below)
+CONFIG_DIR=… DLC_DIR=/path/to/songs PYTHONPATH=lib \
+  python3 -m uvicorn server:app --host 127.0.0.1 --port 8000
+
+# 2. capture (maintainer/CI-only; uses the committed Playwright chromium)
+node scripts/perf-baseline.mjs --base http://127.0.0.1:8000 --n 60 --soak 30
+```
+
+The script prints a markdown block; paste it under "Results" below with the date
+and the commit it was taken at.
+
+## What it measures
+
+- **Server latency** — p50/p95/p99 over N requests for `/api/version`,
+  `/api/plugins`, `/api/library`, `/api/library/artists`.
+- **Cold boot → interactive** — full page load to `networkidle`.
+- **JS heap** — `performance.memory.usedJSHeapSize` after load and after an idle
+  soak (a leak signal across a session).
+- **Plugin-script shape** — how many plugin `<script>`s the loader injected (a
+  "the app booted with its plugins" sanity signal).
+
+**Not yet captured — needs a seeded library with charts** (fill in when run
+against a real environment): playback **frame-time p95** on the 2D and 3D
+highway, and **screen-entry** (plugin inject → interactive) for
+editor / notedetect / highway_3d with a chart loaded. These are the
+perf-sensitive numbers that gate the `highway.js` split (R3c); the harness has
+the hooks, they just need real songs in `DLC_DIR`.
+
+## Results
+
+### R3c pre-lift baseline — 2026-07-10 (2D highway draw cost)
+
+The gate for the `highway.js` split. Captured on a seeded library (the 33 MB
+Arcturus feedpak) with the new `--song` mode, which measures **per-frame draw
+cost** — rAF callbacks are tagged via `highway.addDrawHook`, so only frames the
+highway actually painted count (the other ~half are cheap no-op loops that would
+otherwise mask a regression). Any `highway.js` change must re-run this on the
+same machine and stay within noise of these numbers.
+
+```bash
+node scripts/perf-baseline.mjs --base http://127.0.0.1:8300 \
+    --song "Arcturus - The Sham Mirrors - Kinetic.feedpak"
+```
+
+| run | draw frames | p50 | p95 | p99 | max |
+|---|---|---|---|---|---|
+| 1 | 53/106 | 2.2 | 3.2 | 3.6 | 3.6 |
+| 2 | 50/100 | 2.2 | 2.9 | 3.2 | 3.2 |
+| 3 | 53/106 | 2.1 | 2.7 | 3.5 | 3.5 |
+
+**p50 ≈ 2.2 ms · p95 spread 2.7–3.2 ms** (3 runs × 10 s playback, headless
+chromium on the dev box). The `H`-container lift changes each closure-slot read
+to a `H.<slot>` property load; this is the number that proves it doesn't cost the
+hot loop.
+
+### R0 baseline — 2026-07-08 (branch `feat/r0-plugin-module-rails`)
+
+> ⚠️ A quick capture (`--n 50 --soak 8`) against an **empty** library (no charts
+> in `DLC_DIR`), so the `/api/library*` and boot numbers are floor values —
+> re-take on a seeded environment with the recommended `--n 60 --soak 30` for the
+> real R0 baseline before comparing R1+ against it. Recorded here to prove the
+> harness and lock the methodology.
+
+Server latency (ms), n=50:
+
+| Endpoint | status | p50 | p95 | p99 |
+|---|---|---|---|---|
+| `/api/version` | 200 | 0.9 | 1.8 | 22.3 |
+| `/api/plugins` | 200 | 1.6 | 2.1 | 3.4 |
+| `/api/library?limit=60` | 200 | 1.4 | 1.7 | 2.9 |
+| `/api/library/artists` | 200 | 1.3 | 1.8 | 2.7 |
+
+Client:
+
+| Metric | Value |
+|---|---|
+| Cold boot → networkidle | 1268 ms |
+| JS heap after load | 10.1 MB |
+| JS heap after idle soak | 10.1 MB (no idle growth) |
+| Plugin scripts injected | 12 |
+
+No plugin has migrated yet, so all 12 are classic. When the R1 pilot (stems)
+lands, cold-boot / heap should not regress.

docs/plugin-modules.md

@@ -0,0 +1,103 @@
+# Plugin ES-module migration playbook
+
+How to move a plugin off a single global-scope `screen.js` IIFE onto a native
+ES-module graph — **no build step, no framework, no bundler**. This is the
+mechanism the monolith-killing refactor uses; the host rails for it shipped in
+R0 (see `.specify/memory/constitution.md` Principle II + the "Module load
+contract" in Operating Constraints).
+
+## The shape
+
+```
+my-plugin/
+  plugin.json      +  "scriptType": "module"        ← opt in
+  screen.js           import './src/main.js';        ← the entire file
+  src/
+    state.js          (0) module state + accessors
+    util/…            (1) pure helpers — real-import testable
+    …/…               (2..4) model → render/audio/io → input
+    globals.js        (5) THE ONLY file that writes window.*
+    main.js           (5) boot: wire modules, register screen:changed
+  assets/…            worklets / WASM / images (unchanged, served as today)
+```
+
+`screen.js` becomes a one-line static `import`. The host injects it as
+`<script type="module">`, whose load event fires **only after the whole
+static-import graph fetches and evaluates** — so the loader's
+completion-by-`onload` + `_loadingPluginId` window + `playSong` wrapper-chain
+order are all preserved. (A classic IIFE that fired a fire-and-forget
+`import()` would break that contract — don't do that; use `scriptType:"module"`.)
+
+## Non-negotiable rules
+
+1. **Source-served, no build.** Modules are plain source files fetched from
+   `/api/plugins/<id>/src/<path>`. No bundler, transpiler, or TypeScript.
+2. **Layering points downward** — `state → util → commands/model →
+   render/audio/io → input → globals/main`. A lint check (`import-x/no-cycle`)
+   enforces acyclicity; extract bottom-up so each move only imports
+   already-extracted layers.
+3. **`globals.js` is the only writer of `window.*`.** The deliberate global
+   surface shrinks to one auditable file; everything else is module-scoped.
+4. **Import-time purity.** `node --test` runs a module's top-level code on
+   import, so a module you want to unit-test must be side-effect-free at import:
+   no `document` / `window` / `localStorage` at module top level — lift init
+   into an exported `init()` called by `main.js`. (Constitution Principle V's
+   "no implicit IO at import time", applied to the frontend.) Tests are `.mjs`
+   and use real `import`, retiring the regex/`extractFunction` harness.
+5. **Assets resolve via `import.meta.url`.** `document.currentScript` is `null`
+   inside a module. `assets/` lives at the plugin root, so a `src/` module must
+   climb out of `src/`: from `src/main.js`, `new URL('../assets/x.js',
+   import.meta.url)` (deeper modules need more `../`). Simpler and
+   depth-independent: the absolute route `/api/plugins/<id>/assets/x.js`.
+   Worklets run in a *separate* module graph (`AudioWorkletGlobalScope`) and
+   cannot share modules with `src/`.
+6. **Re-init comes from `screen:changed`, not re-execution.** The host loads
+   `screen.js` once per version and `showScreen` re-injects nothing, so module
+   top-level code does **not** re-run when the user re-enters the screen at the
+   same version. Keep per-visit setup/teardown in a `window.feedBack.on(
+   'screen:changed', …)` handler — exactly as classic plugins (tuner,
+   minigames) already do. Do not rely on the IIFE re-running.
+7. **Inline `onclick=` keeps working** during migration via `globals.js` (which
+   keeps every referenced symbol on `window`); retire inline handlers to
+   module-side `addEventListener` opportunistically, never as a blocking step.
+
+## The live-edit loop
+
+The host serves `screen.js`, `src/**`, and `assets/**` with
+`Cache-Control: no-cache` + a weak `ETag` and honors `If-None-Match` → `304`.
+So: edit a `src/` file → **refresh the browser** → the edited module returns
+`200` and reloads while every unchanged module `304`s. There is no hot-reload;
+the loop is edit → refresh → see change, exactly as before. The `?v=<version>`
+query on `screen.js` is the legacy version buster; it does **not** propagate
+into the `src/` graph and does not need to — ETag/mtime is the correctness
+authority for the whole graph.
+
+## Host-version floor (`minHost`)
+
+A migrated plugin *requires* a host new enough to serve `src/` and inject
+`type=module`. Declare the floor with `"minHost": "X.Y.Z"` in `plugin.json`.
+(R0 plumbs the field through `/api/plugins`; enforcement — refuse-with-message
+on an older host — is deferred, so bundled plugins are unaffected. Community
+plugins should state the floor and not migrate below it.)
+
+## Migration mechanics
+
+- **Move-only PRs.** One slice extracts one module: cut code, add
+  imports/exports, update `globals.js` — zero behavior change. Behavior fixes
+  are separate PRs. (Init-lifts for import purity are the one non-pure move —
+  budget them.)
+- **Bottom-up, layer by layer.** Within a layer, independent modules are
+  independent PRs (a DAG, not a chain); use a git worktree per branch.
+- Tests move with their subject and convert to real `.mjs` imports in the same
+  PR (assertions unchanged).
+- Size norm: no source file over **1,500 lines**; legitimate exceptions
+  (hot renderers, etc.) go in the signed register at `docs/size-exemptions.md`.
+
+## Verifying a migration
+
+`node --test <plugin>/tests/*.mjs`; load the plugin on the `:8000` testbed and
+confirm it boots (`<script type=module>` in DevTools, the `src/` graph in
+Network); edit a `src/` file → refresh → change visible (`200` on the edited
+file, `304` on the rest); leave and re-enter the screen at the same version →
+it re-inits via `screen:changed`. The R1 pilots (stems, then studio) certify
+this end-to-end before the flagship repos migrate.

docs/plugin-theming.md

@@ -1,95 +0,0 @@
-# Theming a plugin so it works in every theme
-
-This is the how-to for plugin authors. It exists because of one recurring bug:
-a plugin's UI is built and eyeballed against the **default** look, ships, and
-then a user switches themes and the feature's *colours adapt but its visual
-devices vanish* — a glow ring, a colour gradient — because the active theme
-doesn't speak that visual language.
-
-**The golden rule:** themes are different **design languages**, not palettes.
-Reference **roles** and **recipe slots**; never hardcode a *device* (a literal
-`box-shadow` glow, a literal `linear-gradient`, a hex colour). Then your feature
-renders correctly in a theme nobody has invented yet — and **verify it across
-the whole theme set before you merge.**
-
-(Design + rationale: [host-theme-contract.md](host-theme-contract.md), got-feedback/feedBack#644.)
-
-## What the host gives you
-
-Always-present CSS role tokens on `:root` (resolve themed *or* un-themed):
-`--fbv-bg / sidebar / card / cardMuted / primary / primaryHi / accent / text /
-textDim / border / good / mid / low / gold`, plus **`--fbv-on-accent`** (a
-foreground legible *on* an accent fill) and **`--fbv-focus-ring`**. Use as
-`color: rgb(var(--fbv-text))`, `background: rgb(var(--fbv-card))`, etc.
-
-A JS read surface on the event bus:
-
-```js
-const t = window.feedBack?.theme;
-t?.get();                  // { id, isThemed, tokens }
-t?.capabilities();         // { glow, gradients, motion } — what devices this theme permits
-t?.prefersReducedMotion(); // boolean (one central matchMedia)
-window.feedBack.on('theme:changed', (e) => { /* e.detail = {id, tokens, capabilities} */ });
-```
-
-Feature-detect everything (`window.feedBack?.theme?.get`) and pass a fallback to
-every `var(--fbv-x, <fallback>)` so you degrade cleanly on an older host.
-
-## Pick your path
-
-### Path A — you do NOT have your own skins (most plugins)
-
-Look like the host. **Derive surfaces from host tokens** and **choose devices
-from capabilities** instead of hardcoding them:
-
-```js
-const caps = window.feedBack?.theme?.capabilities?.() ?? { glow: true, motion: true };
-heroEl.classList.toggle('use-glow', caps.glow && !window.feedBack.theme.prefersReducedMotion());
-```
-```css
-.hero       { background: rgb(var(--fbv-primary)); color: rgb(var(--fbv-on-accent, #fff)); }
-.hero:focus-visible { outline: 2px solid rgb(var(--fbv-focus-ring)); outline-offset: 2px; }
-.hero.use-glow { box-shadow: 0 0 16px -2px rgb(var(--fbv-primary)); } /* only where the theme allows it */
-```
-Re-read on `theme:changed` if you cache anything (e.g. a canvas palette).
-
-### Path B — you HAVE your own deliberate skins (like the scoring UI)
-
-Your skins are an identity (neon vs steel vs clean) — **own your surfaces**;
-don't inherit host surfaces or you'll erase that identity. Adopt only the
-**pattern**: make every visual *device* a **per-skin token whose "off" value is
-legal**, so each skin authors its own version and a glow-less skin simply
-doesn't glow. Example (the "make the hero special" device):
-
-```css
-/* base / neon */         :root      { --hero-ring: .5; --hero-border: transparent; --acc-fill: linear-gradient(135deg, var(--accent), var(--accent2)); }
-/* glow-less skin */      [data-skin="clean"] { --hero-ring: 0; --hero-border: var(--accent); --acc-fill: var(--accent); }
-.hero        { background: var(--acc-fill); border-color: var(--hero-border); }
-.hero::after { opacity: var(--hero-ring); /* the glow ring; 0 = off */ }
-```
-Neon emphasises with the ring, the clean skin with a solid border — **neither is
-empty of emphasis; each speaks its own language.** Same idea for an accent-filled
-number (`--acc-fill` = a gradient in one skin, a solid in another so it doesn't
-wash out to white). Add `on-accent` + `focus-ring` per skin too.
-
-## Accessibility (part of the contract, not an afterthought)
-
-- **Reduced motion:** gate decorative animation on `prefers-reduced-motion`
-  (CSS `@media`, or `theme.prefersReducedMotion()`); functional transitions are fine.
-- **Focus:** always a visible `:focus-visible` outline using `focus-ring` — don't
-  bind focus only to `accent` (it can ≈ the surface in some themes).
-- **On-accent contrast:** text on an accent fill uses `on-accent`; watch light
-  accents (a mid-amber needs dark text, not white).
-
-## Before you merge — verify across the matrix
-
-Render your UI in **every** theme/skin and look at them together. If you ship
-your own skins, do this with a render-matrix in CI/local (reference: the scoring
-UI's `npm run render-skins` + `theme-matrix-checklist.md`). The checklist that
-catches this bug class:
-
-- [ ] colours via tokens, no hardcoded hexes
-- [ ] rendered in **all** themes/skins (not just the default)
-- [ ] every new *device* is per-skin / capability-gated and **legible when its token is `none`**
-- [ ] reduced-motion + visible focus in every theme
-- [ ] text on accent stays legible everywhere

docs/size-exemptions.md

@@ -0,0 +1,66 @@
+# Size-exemption register
+
+The working norm (constitution Principle II; enforced by the `max-lines` lint
+gate) is **no source file over 1,500 lines**. A few files are allowed to exceed
+it because splitting them would do more harm than good — hot per-frame
+renderers, C++, offline generators, cohesive registries. This register is the
+list of those exceptions: each row is a **deliberate, signed** decision with a
+ceiling, a rationale, and a review trigger. Without it, "no file over 1,500
+without a *signed* exemption" is unenforceable.
+
+**Rules**
+- One row per file: a ceiling, a rationale, a signer, a review trigger.
+- The `max-lines` per-file ceilings in `eslint.config.js` mirror this table —
+  keep them in sync (this register is canonical).
+- Files with a scheduled split **plan** are *not* exempt — they live in
+  "Planned, not exempt" at the bottom so nothing falls between the two states.
+- **Signers** (decided 2026-07-08): **Byron** signs core + bundled rows;
+  **Christian** signs the authored-plugin row (virtuoso, its own repo/track).
+
+## Permanent exemptions (structural rationale)
+
+| Repo / file | Lines (7-07) | Ceiling | Rationale | Signer | Review |
+|---|---|---|---|---|---|
+| core `static/highway.js` → residual `renderer-2d.js` (post-split) | ~2,400–2,900 est. | **3,000** | 60 fps hot path; no module boundary inside the per-frame loop | Byron | after the highway.js split |
+| core `plugins/highway_3d/` → residual renderer | sized at split; likely **>3,000** | set at split, flagged now | same hot-path rule; the draw core can't be cut without behavior risk | Byron | after the highway_3d split |
+| core `static/capabilities.js` | 1,538 | 1,600 | cohesive registry + `window.feedBack` bus, 38 lines over; a split spends credibility for nothing | Byron | R4 |
+| tutorials `builtin/reading-the-highway/generate.py` | 1,818 | 2,000 | offline content generator, never imported at runtime, deps not in runtime requirements | Byron | if a 3rd builtin pack appears |
+| desktop `src/audio/NodeAddon.cpp` | 3,542 | as-is | C++, outside the ESM/routes playbooks; under active use-after-free crash work — do not churn | Byron | after crash-class work settles |
+| desktop `src/audio/AudioEngine.cpp` | 2,977 | as-is | same | Byron | same |
+| desktop `src/vst-host/main.cpp` | 1,928 | as-is | same | Byron | same |
+| virtuoso `screen.js` (authored, own track) | 25,741 | as-is until its own split | authored plugin on a separate roadmap; migrates on its own schedule | Christian | virtuoso split kickoff |
+
+## Split-when-touched (no scheduled train; row retires when split)
+
+| Repo / file | Lines | Ceiling | Rationale | Signer | Review |
+|---|---|---|---|---|---|
+| core `lib/gp2rs_gpx.py` | 2,540 | as-is | import converter, off the serve-path hot loop | Byron | when next touched |
+| core `lib/gp2rs.py` | 2,055 | as-is | same | Byron | when next touched |
+| core `lib/song.py` | 1,689 | as-is | data models + wire format; cohesive | Byron | when next touched |
+| core `lib/gp_autosync.py` | 1,572 | as-is | under active dev (#787/#791) — don't collide | Byron | after in-flight work lands |
+| core `plugins/capability_inspector/screen.js` | 1,752 | as-is | bundled diagnostics plugin, low churn | Byron | when next touched |
+| core `plugins/folder_library/screen.js` | 1,672 | as-is | bundled plugin, low churn | Byron | when next touched |
+
+## Temporary rows (cleared by a scheduled PR)
+
+| Repo / file | Lines | Cleared by |
+|---|---|---|
+| core `plugins/__init__.py` | ~2,470 (grew under R0) | the `plugins/_routes.py` + `plugins/_registry.py` split (rides the server.py router work) |
+
+## Watch list (under the norm — no row needed, re-census each phase)
+
+`musicxml-import/mxml2notation.py` (1,456) · core `static/capabilities/audio-effects.js`
+(1,436) · `studio routes.py` (1,399) · `update-manager screen.js` (1,492 — zero headroom).
+
+## Planned, NOT exempt (owned by split plans — listed so nothing falls between states)
+
+core `static/app.js` (11,852) · `static/highway.js` (4,168, whole file) · `server.py`
+(5,988 — was 14,037; ratcheted by the R3 `MetadataDB` + `AudioEffectsMappingDB`
+extractions and fifteen `routers/` modules; the ~930-line metadata-enrichment subsystem — MB/CAA/AcoustID transport, matcher, background worker — now lives in `lib/enrichment.py`) ·
+`lib/metadata_db.py` (4,373 — new in R3; the `MetadataDB` class alone is 4,018 lines
+and is a monolith in its own right, to be split per-table once the router train
+lands) · `static/v3/songs.js` (4,134) · `static/capabilities/audio-session.js`
+(2,974) · `plugins/highway_3d/screen.js` (15,656) · `plugins/keys_highway_3d/screen.js`
+(3,780) · `plugins/drum_highway_3d/screen.js` (3,597) — and every monolith with a PR
+train in the refactor plan. Test files (e.g. `tests/test_plugins.py`) are out of scope
+by policy — the norm governs source files.

docs/working-tuning-on-device-tests.md

@@ -0,0 +1,53 @@
+# Working-tuning — on-device test checklist
+
+The working-tuning series (PRs 1–9) ships with headless unit tests for every state
+machine (`tests/js/working_tuning*.test.js`, `tests/js/tuner_auto_open.test.js`). The
+items below are the parts that **cannot** be covered headlessly — they need a real mic,
+a real instrument, and (for the ASIO item) a specific audio backend. Run these on a
+build before shipping the feature to users.
+
+Prereq: enable the opt-in in **Tuner → settings → "Auto-open on tuning change"** (it's
+off by default). Have a guitar (and a bass, for the per-instrument checks) on hand.
+
+## 1. Auto-open + gate ("tune before you play")
+- [ ] Load a song whose tuning differs from your instrument's current tuning → the tuner
+      **auto-opens** and playback **waits** (does not start underneath it).
+- [ ] Load a song already covered by your tuning → **no** auto-open, playback starts.
+- [ ] **Skip** ("I've tuned") → playback starts, and the tuner badge stops flagging this
+      song's tuning (a working tuning was recorded).
+- [ ] **Back to library** / **Esc** → leaves the song, records **nothing** (re-enter the
+      same song → it still prompts).
+- [ ] Take **longer than 12 s** to tune with the panel open → playback does **not** start
+      underneath you (the fail-open backstop was settled once the panel opened).
+- [ ] Hit **Play** manually while the panel is open → Play wins; no double-start.
+
+## 2. Both-directions retune prompt
+- [ ] From standard, load a Drop-C# song → prompted **down** (E→C#). Tune down, Skip.
+- [ ] Now load a standard song → prompted **back up** (C#→E). (Pre-series, this direction
+      was silent.)
+- [ ] Switch guitar↔bass in the instrument card → each instrument remembers its **own**
+      working tuning; the card label follows the selection (dim = home, amber = retuned).
+
+## 3. Mic-verify (assumed → verified)
+- [ ] With a selected (non-free) tuning, tap **Verify tuning** and play each string in tune.
+      Each string needs ~8 stable in-tune frames (±6 ¢); the per-string progress advances.
+- [ ] Play a string **out of tune** → it never completes; drifting out mid-streak resets it.
+- [ ] Complete all strings → the instrument card's provenance glyph flips to the **filled**
+      (verified) diamond, and the recorded working tuning carries the tuning you verified
+      (not a stale one).
+- [ ] Load the **next** song → the verified state **decays to assumed** (per-session only).
+- [ ] Verify against a **manually-selected** tuning (tuner opened off a song) → the stamped
+      offsets match that tuning, not the last song's.
+
+## 4. Mic contention with note-detection (the ASIO / exclusive-mode risk)
+This is the item flagged in the design charrette: the tuner's mic capture must not starve
+note_detect's scoring input.
+- [ ] Desktop, **ASIO / WASAPI-exclusive** device: auto-open the tuner mid-song, tune, Skip
+      → scoring resumes cleanly; no dropped input, no device-in-use error, no crash.
+- [ ] Shared/`auto` device: same flow → both the tuner and scoring read the mic without a
+      stall.
+- [ ] Leave the tuner's background badge audio running + start a scored song → note_detect
+      still scores (the badge auto-start doesn't hold the device exclusively).
+
+Log the build hash and OS/audio backend with results; file any failure against the
+working-tuning series.

eslint.config.js

@@ -0,0 +1,66 @@
+// Flat ESLint config — MAINTAINER / CI ONLY. Never runs on the serve or Docker
+// path (constitution Principle I: dev-only tooling is exempt, same category as
+// scripts/build-tailwind.sh). It enforces the module-migration guardrails:
+//
+//   * max-lines — the 1,500-line size norm, as a WARNING ratchet. Legacy
+//     monoliths warn (the "this is over the norm, split it" signal) and shrink
+//     as the refactor lands; warnings do not fail CI. Genuinely-large files are
+//     exempted below, mirroring the signed register in docs/size-exemptions.md.
+//   * import-x/no-unresolved + no-cycle — module hygiene, scoped to the real
+//     ES-module graphs the refactor produces (a plugin's src/ tree, .mjs
+//     tests). no-unresolved (a HARD error) catches broken import paths;
+//     no-cycle enforces the downward-only layering rule. Core's classic scripts
+//     have no import graph, so both are dormant today and become live gates the
+//     moment module code appears — validated against the first real module
+//     plugin (R1 pilot).
+
+const importX = require('eslint-plugin-import-x');
+
+// Per-file size ceilings — a mirror of docs/size-exemptions.md (canonical).
+// Keep in sync; each entry corresponds to a signed row in the register.
+const SIZE_EXEMPTIONS = [
+    { files: ['**/static/capabilities.js'], max: 1600 },
+    { files: ['**/plugins/capability_inspector/screen.js'], max: 100000 },
+    { files: ['**/plugins/folder_library/screen.js'], max: 100000 },
+];
+
+const sizeRule = (max) => ['warn', { max, skipBlankLines: false, skipComments: false }];
+
+module.exports = [
+    {
+        ignores: [
+            'node_modules/**',
+            'static/vendor/**',
+            'plugins/**/assets/vendor/**',
+            '**/*.min.js',
+            'static/tailwind.min.css',
+        ],
+    },
+    // Size norm across all first-party JS. Classic scripts are parsed as
+    // scripts (no import/export); module files get their own block below.
+    {
+        files: ['**/*.js', '**/*.cjs'],
+        languageOptions: { ecmaVersion: 'latest', sourceType: 'script' },
+        rules: { 'max-lines': sizeRule(1500) },
+    },
+    // ES-module graphs (a plugin's src/ tree, .mjs tests): module parsing + the
+    // acyclic-imports hard gate + the size norm. A migrated bundled plugin's
+    // entry `import './src/main.js'` screen.js must parse as a module — add its
+    // glob here in that plugin's migration PR (classic screen.js stays a script).
+    {
+        files: ['**/src/**/*.js', '**/*.mjs'],
+        languageOptions: { ecmaVersion: 'latest', sourceType: 'module' },
+        plugins: { 'import-x': importX },
+        // v4 flat-config resolver (resolver-next + createNodeResolver). Without
+        // it the import rules silently skip imports they can't resolve.
+        settings: { 'import-x/resolver-next': [importX.createNodeResolver()] },
+        rules: {
+            'max-lines': sizeRule(1500),
+            'import-x/no-unresolved': 'error',
+            'import-x/no-cycle': 'error',
+        },
+    },
+    // Signed size exemptions (docs/size-exemptions.md) — raise the ceiling so
+    // registered files don't warn below it.
+    ...SIZE_EXEMPTIONS.map(({ files, max }) => ({ files, rules: { 'max-lines': sizeRule(max) } })),
+];

lib/acoustid_match.py

@@ -0,0 +1,152 @@
+"""AcoustID audio-fingerprint identification for MusicBrainz enrichment.
+
+A flat MusicBrainz *text* search ties every take of a song at the same score —
+studio, a dozen live bootlegs, and every compilation — so "AC/DC — Highway to
+Hell" returns junk (see lib/mb_match.py's canonical re-ranking, which mitigates
+it). The definitive fix is content-based: fingerprint the actual audio with
+Chromaprint (`fpcalc`) and look it up on AcoustID, which maps the fingerprint
+straight to the *exact* MusicBrainz recording — the same approach Lidarr uses.
+
+This module is the PURE half (no network, no subprocess): response parsing +
+config gating, so it is unit-testable in isolation. server.py owns the `fpcalc`
+subprocess and the throttled HTTP GET to api.acoustid.org.
+
+Operational requirements (both optional — absent ⇒ this path is a graceful
+no-op and the text matcher still runs):
+  * `fpcalc` (Chromaprint) on PATH or at $FPCALC — generates the fingerprint.
+  * an AcoustID application API key in $ACOUSTID_API_KEY — free from
+    https://acoustid.org/new-application ; AcoustID etiquette limits to ~3 req/s.
+"""
+
+import os
+
+ACOUSTID_API_ROOT = "https://api.acoustid.org/v2"
+
+# The `meta` fields we ask AcoustID to return so a hit resolves to displayable
+# metadata without a second MusicBrainz round-trip. SPACE-separated, not
+# `+`-joined: a literal `+` in the value gets percent-encoded to %2B, which
+# AcoustID does NOT split into flags — it then attaches no recording metadata
+# and every hit comes back empty (verified: `+` → 0 recordings, space → 28).
+# `releases` is what carries the per-release DATE (nested under each
+# releasegroup), which we need to pick the earliest original album + fill year.
+LOOKUP_META = "recordings releasegroups releases compress"
+
+# Mirror mb_match._SECONDARY_SKIP: release-group secondary types that mark a
+# non-canonical (live/comp/remix) release, so we can flag the studio take.
+_SECONDARY_SKIP = {
+    "live", "compilation", "remix", "dj-mix", "mixtape/street",
+    "demo", "interview", "audiobook", "spokenword",
+}
+
+
+def api_key(explicit: str | None = None) -> str:
+    """The AcoustID application API key: an explicit value (e.g. a host setting)
+    wins, else $ACOUSTID_API_KEY, else "" (⇒ fingerprinting disabled)."""
+    return (explicit or os.environ.get("ACOUSTID_API_KEY") or "").strip()
+
+
+def is_configured(explicit_key: str | None = None) -> bool:
+    """True when an API key is available. `fpcalc` presence is checked by
+    server.py (it owns the binary lookup); both are required to actually run."""
+    return bool(api_key(explicit_key))
+
+
+def _rg_is_studio(rg: dict) -> bool:
+    if str(rg.get("type", "")).lower() != "album":
+        return False
+    secs = {str(s).lower() for s in (rg.get("secondarytypes") or [])}
+    return not (secs & _SECONDARY_SKIP)
+
+
+def _rg_earliest_year(rg: dict) -> "int | None":
+    """Earliest release YEAR in a release-group (min over its nested releases'
+    dates). None when no release carries a date. This is what separates the
+    original pressing from later reissues/comps sharing the same group."""
+    years = []
+    for rel in (rg.get("releases") or []):
+        d = (rel or {}).get("date")
+        if isinstance(d, dict) and d.get("year"):
+            try:
+                years.append(int(d["year"]))
+            except (TypeError, ValueError):
+                pass
+    return min(years) if years else None
+
+
+def _best_group(recording: dict) -> dict:
+    """Pick the display album: a clean studio Album first, and among those the
+    EARLIEST-released one — the original, not a later reissue or a compilation
+    that happens to be typed 'Album' (e.g. a soundtrack). This is what pulls
+    "Machine Head" ahead of a later comp for "Smoke on the Water". Falls back to
+    the first group when nothing is a studio album or nothing carries a date."""
+    groups = [g for g in (recording.get("releasegroups") or []) if isinstance(g, dict)]
+    if not groups:
+        return {}
+
+    def sort_key(g):
+        yr = _rg_earliest_year(g)
+        # studio (0) before non-studio (1); then earliest year (undated last).
+        return (0 if _rg_is_studio(g) else 1, yr if yr is not None else 9999)
+
+    return sorted(groups, key=sort_key)[0]
+
+
+def _first_artist(recording: dict) -> str:
+    for a in (recording.get("artists") or []):
+        if isinstance(a, dict) and a.get("name"):
+            return str(a["name"])
+    return ""
+
+
+def parse_lookup_response(body: dict) -> list[dict]:
+    """Normalize an AcoustID /v2/lookup response into the same flat candidate
+    shape as mb_match (recording_id / title / artist / album / year / duration /
+    studio / mb_score / score), so the review UI and the editor's Match popup
+    render fingerprint hits and text hits identically. `mb_score` carries the
+    AcoustID confidence (0-100) — a fingerprint hit is high-signal by nature."""
+    if not isinstance(body, dict) or body.get("status") != "ok":
+        return []
+    out: list[dict] = []
+    seen: set[str] = set()
+    for result in (body.get("results") or []):
+        if not isinstance(result, dict):
+            continue
+        try:
+            score = float(result.get("score") or 0.0)
+        except (TypeError, ValueError):
+            score = 0.0
+        for rec in (result.get("recordings") or []):
+            if not isinstance(rec, dict) or not rec.get("id"):
+                continue
+            rid = str(rec["id"])
+            if rid in seen:
+                continue
+            seen.add(rid)
+            rg = _best_group(rec)
+            _yr = _rg_earliest_year(rg)
+            year = str(_yr) if _yr else ""
+            dur = rec.get("duration")
+            try:
+                duration = int(round(float(dur))) if dur else None
+            except (TypeError, ValueError):
+                duration = None
+            out.append({
+                "recording_id": rid,
+                "title": str(rec.get("title", "") or ""),
+                "artist": _first_artist(rec),
+                "album": str(rg.get("title", "") or ""),
+                "year": year,
+                "duration": duration,
+                "isrc": "",
+                "genres": [],
+                "studio": _rg_is_studio(rg),
+                "acoustid_score": round(score, 4),
+                # Fingerprint hits are content-verified, not text-guessed — carry
+                # the AcoustID confidence as the display score band.
+                "mb_score": int(round(score * 100)),
+                "score": round(score, 4),
+                "source": "acoustid",
+            })
+    # Best AcoustID confidence first; studio take breaks ties.
+    out.sort(key=lambda c: (c["acoustid_score"], 1 if c["studio"] else 0), reverse=True)
+    return out

lib/appconfig.py

@@ -0,0 +1,28 @@
+"""Reading the app's config.json — the one shared, pure helper (R3).
+
+Extracted verbatim from server.py so route modules that need a config value
+(reference pitch, server_config, …) can read it without reaching back into the
+host file. server.py re-imports it, so its ~11 call sites and any
+`server._load_config` test reference keep resolving unchanged.
+"""
+
+import json
+
+
+def _load_config(config_file):
+    """Read and parse config.json. Returns the parsed dict, or None if
+    the file is missing, unreadable, invalid JSON, or parses to a
+    non-dict (e.g. the file contains `[]` or `42`). Callers treat None
+    as "fall back to defaults". Shared between GET and POST so both
+    handle bad files the same way."""
+    if not config_file.exists():
+        return None
+    try:
+        # Explicit UTF-8: save_settings()/import write config.json as
+        # UTF-8 bytes, so the read must not depend on the platform's
+        # default text encoding (cp1252 on Windows would mojibake or
+        # UnicodeDecodeError on a non-ASCII DLC path).
+        parsed = json.loads(config_file.read_text(encoding="utf-8"))
+    except Exception:
+        return None
+    return parsed if isinstance(parsed, dict) else None

lib/appstate.py

@@ -0,0 +1,122 @@
+"""Shared application state — the seam that lets route modules reach core
+singletons without importing ``server``.
+
+``server.py`` is the host: it owns the FastAPI ``app``, constructs the DB
+singletons, and runs the lifecycle. As routes move out into ``routers/`` (R3),
+those modules need ``meta_db`` and friends — but they must not ``import
+server``, or the import graph goes circular the moment ``server`` imports them
+back.
+
+So ``server`` **injects** its singletons here once, at the point it builds them::
+
+    # server.py
+    meta_db = MetadataDB(CONFIG_DIR)
+    appstate.configure(meta_db=meta_db, ...)
+
+and a router reads them back as **module attributes, at call time**::
+
+    # routers/artists.py
+    import appstate
+
+    @router.get("/api/artist/{name}/page")
+    def artist_page(name):
+        return appstate.meta_db.artist_page(name)
+
+This is the Python analogue of the injected `configureX({...})` seams the
+frontend refactor uses (stems' ``configureStreaming``, studio's
+``configureAudioGraph``, the editor's ``src/host.js``), and of the plugin
+``setup(app, context)`` contract in Principle III: dependencies flow one way,
+``server -> routers -> appstate``, and nothing imports back up.
+
+Two properties this shape buys, both load-bearing:
+
+* **``import appstate`` performs no IO and constructs nothing.** ``server``
+  still owns construction, so the ~49 test fixtures that do
+  ``sys.modules.pop("server")`` + re-import (to rebuild ``meta_db`` under a
+  patched ``CONFIG_DIR``) keep working untouched — a singleton *owned* here
+  would survive that pop and go stale.
+* **Reads are late-bound.** Routers must use ``appstate.meta_db``, never
+  ``from appstate import meta_db`` — a ``from`` import freezes the binding at
+  its current value, so a later ``configure()`` (or a
+  ``monkeypatch.setattr(appstate, "meta_db", fake)``) would not reach the
+  router. This is the same read-only-binding trap as ES ``import``.
+
+Defaults are ``None`` on purpose: they are inert but *type-honest*, so a router
+that runs before ``configure()`` fails loudly on ``NoneType`` instead of
+quietly operating on a stand-in.
+
+Slots are added here only when a router actually needs one — this is a seam,
+not a grab-bag for everything in ``server.py``.
+
+**Why this lives in ``lib/`` and not the repo root.** Because it constructs
+nothing and does no import-time IO, it satisfies Principle V's rule for ``lib/``
+modules — and ``lib/`` is the only core directory every packaging path already
+copies: the Dockerfile (``COPY lib/``), ``docker-compose.yml``, and
+feedback-desktop's ``bundle-slopsmith.sh`` (``cp -r lib``). All three also put
+both the bundle root and ``lib/`` on ``sys.path``. A root-level module ships in
+Docker but is silently dropped from the packaged desktop app, whose bundler
+copies a hardcoded file list — that regression is what moved this file here.
+"""
+
+# The singletons routers may read. Every name here must also be a `_SLOTS` key.
+meta_db = None
+audio_effect_mappings = None
+# The tuning-provider registry instance (built-ins + plugin-contributed). A
+# stable object mutated in place via register()/unregister() — injected here by
+# reference so routers read the same registry plugins populate.
+tuning_providers = None
+
+# Config paths. server.py derives these from the environment (fresh on every
+# import, so the ~49 pop-and-reimport fixtures keep working) and injects them
+# here. Routers read them as `appstate.config_dir` etc. — a module attribute at
+# call time. NOTE: config_dir/dlc_dir are env-derived, so a `setenv`+reimport
+# test reconfigures them for free; STATIC_DIR/SLOPPAK_CACHE_DIR are patched via
+# `setattr(server, …)` in a few tests, so those slots (when added) need their
+# tests retargeted to appstate in the same PR.
+config_dir = None
+dlc_dir = None          # the DLC_DIR env value as a Path (Path("") if unset)
+dlc_dir_env = None      # the raw DLC_DIR env string, "" if unset — distinguishes
+                        # "unset" from Path("")→"." (see dlc_paths._get_dlc_dir)
+# Cache/asset dirs. static_dir + sloppak_cache_dir are patched via
+# `setattr(server, …)` in a few tests, so a router reading them here needs those
+# setattr sites retargeted to `setattr(appstate, …)` in the same PR (ws_highway
+# retargets the 3 test_highway_ws_* SLOPPAK sites). config_dir-derived dirs are
+# reconfigured for free on a setenv+reimport.
+static_dir = None
+sloppak_cache_dir = None
+audio_cache_dir = None
+
+# Injected callables (not values): server owns the impl + its state, routers call
+# through the seam. get_progression_content wraps a lazy content cache that stays
+# in server.py (its `setattr(server, "_progression_content")` test is untouched).
+get_progression_content = None
+builtin_diagnostic_filename = None
+running_version = None
+# Art helpers that stay in server.py (shared with the art/delete routes) but are
+# also called by the enrichment worker in lib/enrichment.py — injected as
+# callables to keep enrichment acyclic. art_cache_dir is server's ART_CACHE_DIR.
+art_cache_dir = None
+song_pack_art_exists = None
+art_override_paths = None
+
+_SLOTS = frozenset({
+    "meta_db", "audio_effect_mappings", "tuning_providers",
+    "config_dir", "dlc_dir", "dlc_dir_env",
+    "static_dir", "sloppak_cache_dir", "audio_cache_dir",
+    "get_progression_content", "builtin_diagnostic_filename",
+    "running_version",
+    "art_cache_dir", "song_pack_art_exists", "art_override_paths",
+})
+
+
+def configure(**kwargs) -> None:
+    """Publish `server`'s singletons into this module. Called once per
+    `server` import (and again on re-import), so it must be idempotent."""
+    unknown = set(kwargs) - _SLOTS
+    if unknown:
+        raise TypeError(
+            f"appstate.configure() got unknown slot(s): {sorted(unknown)}. "
+            f"Known slots: {sorted(_SLOTS)}. Add the name to _SLOTS if a router "
+            f"genuinely needs it."
+        )
+    globals().update(kwargs)

lib/audio_effects_db.py

@@ -0,0 +1,287 @@
+"""Core-owned song/tone -> audio-effect-provider mapping index.
+
+Extracted verbatim from ``server.py`` (R3). ``server.py`` still owns the
+``audio_effect_mappings`` singleton; this module only supplies the class, so
+nothing here touches config paths at import time — the caller passes
+``config_dir`` in.
+"""
+
+import json
+import sqlite3
+import threading
+from pathlib import Path
+
+
+class AudioEffectsMappingDB:
+    """Core-owned public song/tone -> provider mapping index.
+
+    Providers own the preset/chain rows addressed by provider_ref. Core owns
+    the cross-provider routing index and the active mapping per song/tone.
+    """
+
+    def __init__(self, config_dir: Path):
+        config_dir.mkdir(parents=True, exist_ok=True)
+        self.db_path = str(config_dir / "audio_effects.db")
+        self.conn = sqlite3.connect(self.db_path, check_same_thread=False)
+        self.conn.execute("PRAGMA journal_mode=WAL")
+        self.conn.execute("PRAGMA foreign_keys=ON")
+        self.conn.execute("""
+            CREATE TABLE IF NOT EXISTS audio_effect_mappings (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                song_key TEXT NOT NULL,
+                filename TEXT NOT NULL DEFAULT '',
+                tone_key TEXT NOT NULL,
+                provider_id TEXT NOT NULL,
+                provider_ref TEXT NOT NULL,
+                label TEXT NOT NULL DEFAULT '',
+                source TEXT NOT NULL DEFAULT 'manual',
+                metadata_json TEXT NOT NULL DEFAULT '{}',
+                created_at TEXT NOT NULL DEFAULT (datetime('now')),
+                updated_at TEXT NOT NULL DEFAULT (datetime('now')),
+                UNIQUE(song_key, tone_key, provider_id)
+            )
+        """)
+        self.conn.execute("""
+            CREATE TABLE IF NOT EXISTS audio_effect_active_mappings (
+                song_key TEXT NOT NULL,
+                tone_key TEXT NOT NULL,
+                mapping_id INTEGER NOT NULL,
+                updated_at TEXT NOT NULL DEFAULT (datetime('now')),
+                PRIMARY KEY (song_key, tone_key),
+                FOREIGN KEY (mapping_id) REFERENCES audio_effect_mappings(id) ON DELETE CASCADE
+            )
+        """)
+        self.conn.execute(
+            "CREATE INDEX IF NOT EXISTS idx_audio_effect_mappings_provider "
+            "ON audio_effect_mappings(provider_id)"
+        )
+        self.conn.execute(
+            "CREATE INDEX IF NOT EXISTS idx_audio_effect_mappings_filename "
+            "ON audio_effect_mappings(filename)"
+        )
+        self.conn.commit()
+        self._lock = threading.Lock()
+
+    @staticmethod
+    def _text(value, *, field: str, limit: int, allow_empty: bool = False) -> str:
+        if value is None:
+            text = ""
+        elif not isinstance(value, str):
+            raise ValueError(f"{field} must be a string")
+        else:
+            text = value.strip()
+        if not text and not allow_empty:
+            raise ValueError(f"{field} is required")
+        if len(text) > limit:
+            raise ValueError(f"{field} is too long")
+        return text
+
+    @staticmethod
+    def _mapping_id(value) -> int | None:
+        # Bind only values SQLite can store as an INTEGER; an out-of-range id is a
+        # clean miss (404), not a 500 at bind time.
+        if isinstance(value, int) and not isinstance(value, bool) and -(2 ** 63) <= value < 2 ** 63:
+            return value
+        return None
+
+    @staticmethod
+    def _field(data: dict, *keys):
+        # Select the first present snake/camel alias by key, not by truthiness, so a
+        # falsey non-string value (false/0) still reaches _text() and is rejected
+        # instead of being silently swallowed by an `or` chain.
+        for key in keys:
+            if key in data:
+                return data[key]
+        return None
+
+    @staticmethod
+    def _metadata(value) -> str:
+        if value is None:
+            return "{}"
+        if not isinstance(value, dict):
+            raise ValueError("metadata must be an object")
+        encoded = json.dumps(value, ensure_ascii=True, sort_keys=True)
+        if len(encoded) > 8192:
+            raise ValueError("metadata is too large")
+        return encoded
+
+    @staticmethod
+    def _row(row) -> dict | None:
+        if row is None:
+            return None
+        metadata = {}
+        try:
+            metadata = json.loads(row[8]) if row[8] else {}
+        except Exception:
+            metadata = {}
+        return {
+            "id": int(row[0]),
+            "song_key": row[1],
+            "filename": row[2] or "",
+            "tone_key": row[3],
+            "provider_id": row[4],
+            "provider_ref": row[5],
+            "label": row[6] or "",
+            "source": row[7] or "manual",
+            "metadata": metadata if isinstance(metadata, dict) else {},
+            "created_at": row[9] or "",
+            "updated_at": row[10] or "",
+            "active": bool(row[11]),
+        }
+
+    def _select_sql(self) -> str:
+        return """
+            SELECT m.id, m.song_key, m.filename, m.tone_key, m.provider_id,
+                   m.provider_ref, m.label, m.source, m.metadata_json,
+                   m.created_at, m.updated_at,
+                   CASE WHEN a.mapping_id IS NULL THEN 0 ELSE 1 END AS active
+            FROM audio_effect_mappings m
+            LEFT JOIN audio_effect_active_mappings a
+              ON a.song_key = m.song_key AND a.tone_key = m.tone_key AND a.mapping_id = m.id
+        """
+
+    def list(self, *, song_key: str = "", filename: str = "", tone_key: str = "", provider_id: str = "") -> list[dict]:
+        clauses: list[str] = []
+        params: list[str] = []
+        song_key = self._text(song_key, field="song_key", limit=240, allow_empty=True)
+        filename = self._text(filename, field="filename", limit=500, allow_empty=True)
+        tone_key = self._text(tone_key, field="tone_key", limit=160, allow_empty=True)
+        provider_id = self._text(provider_id, field="provider_id", limit=96, allow_empty=True)
+        if song_key and filename:
+            clauses.append("(m.song_key = ? OR m.filename = ?)")
+            params.extend([song_key, filename])
+        elif song_key:
+            clauses.append("m.song_key = ?")
+            params.append(song_key)
+        elif filename:
+            clauses.append("(m.song_key = ? OR m.filename = ?)")
+            params.extend([filename, filename])
+        if tone_key:
+            clauses.append("m.tone_key = ?")
+            params.append(tone_key)
+        if provider_id:
+            clauses.append("m.provider_id = ?")
+            params.append(provider_id)
+        sql = self._select_sql()
+        if clauses:
+            sql += " WHERE " + " AND ".join(clauses)
+        sql += " ORDER BY m.song_key COLLATE NOCASE, m.tone_key COLLATE NOCASE, m.provider_id COLLATE NOCASE"
+        with self._lock:
+            rows = self.conn.execute(sql, params).fetchall()
+        return [self._row(row) for row in rows]
+
+    def get(self, mapping_id: int) -> dict | None:
+        mapping_id = self._mapping_id(mapping_id)
+        if mapping_id is None:
+            return None
+        with self._lock:
+            row = self.conn.execute(self._select_sql() + " WHERE m.id = ?", (mapping_id,)).fetchone()
+        return self._row(row)
+
+    def upsert(self, data: dict) -> dict:
+        if not isinstance(data, dict):
+            raise ValueError("mapping body must be an object")
+        filename = self._text(data.get("filename", ""), field="filename", limit=500, allow_empty=True)
+        song_key_raw = self._field(data, "song_key", "songKey")
+        if song_key_raw is None or song_key_raw == "":
+            song_key_raw = filename
+        song_key = self._text(song_key_raw, field="song_key", limit=240)
+        tone_key = self._text(self._field(data, "tone_key", "toneKey"), field="tone_key", limit=160, allow_empty=True)
+        provider_id = self._text(self._field(data, "provider_id", "providerId"), field="provider_id", limit=96)
+        provider_ref = self._text(self._field(data, "provider_ref", "providerRef"), field="provider_ref", limit=240)
+        label = self._text(data.get("label", ""), field="label", limit=160, allow_empty=True)
+        source = self._text(data.get("source", "manual"), field="source", limit=40, allow_empty=True) or "manual"
+        metadata_json = self._metadata(data.get("metadata", {}))
+        with self._lock:
+            self.conn.execute(
+                """
+                INSERT INTO audio_effect_mappings
+                    (song_key, filename, tone_key, provider_id, provider_ref, label, source, metadata_json, updated_at)
+                VALUES (?, ?, ?, ?, ?, ?, ?, ?, datetime('now'))
+                ON CONFLICT(song_key, tone_key, provider_id) DO UPDATE SET
+                    -- Only overwrite filename when a non-empty one was supplied; an
+                    -- omitted/empty filename must preserve the stored value (it's an
+                    -- alternate lookup key for list(..., filename=...)).
+                    filename=CASE WHEN excluded.filename <> '' THEN excluded.filename ELSE audio_effect_mappings.filename END,
+                    provider_ref=excluded.provider_ref,
+                    label=excluded.label,
+                    source=excluded.source,
+                    metadata_json=excluded.metadata_json,
+                    updated_at=datetime('now')
+                """,
+                (song_key, filename, tone_key, provider_id, provider_ref, label, source, metadata_json),
+            )
+            row = self.conn.execute(
+                "SELECT id FROM audio_effect_mappings WHERE song_key = ? AND tone_key = ? AND provider_id = ?",
+                (song_key, tone_key, provider_id),
+            ).fetchone()
+            if row is None:
+                raise ValueError("failed to create audio-effects mapping")
+            mapping_id = int(row[0])
+            if data.get("active") is True:
+                self.conn.execute(
+                    """
+                    INSERT INTO audio_effect_active_mappings (song_key, tone_key, mapping_id, updated_at)
+                    VALUES (?, ?, ?, datetime('now'))
+                    ON CONFLICT(song_key, tone_key) DO UPDATE SET
+                        mapping_id=excluded.mapping_id,
+                        updated_at=datetime('now')
+                    """,
+                    (song_key, tone_key, mapping_id),
+                )
+            self.conn.commit()
+        return self.get(mapping_id)
+
+    def delete(self, mapping_id: int, *, provider_id: str = "") -> bool:
+        mapping_id = self._mapping_id(mapping_id)
+        if mapping_id is None:
+            return False
+        provider_id = self._text(provider_id, field="provider_id", limit=96, allow_empty=True)
+        with self._lock:
+            if provider_id:
+                cur = self.conn.execute(
+                    "DELETE FROM audio_effect_mappings WHERE id = ? AND provider_id = ?",
+                    (mapping_id, provider_id),
+                )
+            else:
+                cur = self.conn.execute("DELETE FROM audio_effect_mappings WHERE id = ?", (mapping_id,))
+            self.conn.commit()
+            return cur.rowcount > 0
+
+    def activate(self, mapping_id: int, *, provider_id: str = "") -> dict | None:
+        mapping_id = self._mapping_id(mapping_id)
+        if mapping_id is None:
+            return None
+        provider_id = self._text(provider_id, field="provider_id", limit=96, allow_empty=True)
+        with self._lock:
+            row = self.conn.execute(
+                self._select_sql() + " WHERE m.id = ?",
+                (mapping_id,),
+            ).fetchone()
+            mapping = self._row(row)
+            if not mapping or (provider_id and mapping["provider_id"] != provider_id):
+                return None
+            self.conn.execute(
+                """
+                INSERT INTO audio_effect_active_mappings (song_key, tone_key, mapping_id, updated_at)
+                VALUES (?, ?, ?, datetime('now'))
+                ON CONFLICT(song_key, tone_key) DO UPDATE SET
+                    mapping_id=excluded.mapping_id,
+                    updated_at=datetime('now')
+                """,
+                (mapping["song_key"], mapping["tone_key"], mapping_id),
+            )
+            self.conn.commit()
+            selected = self.conn.execute(self._select_sql() + " WHERE m.id = ?", (mapping_id,)).fetchone()
+        return self._row(selected)
+
+    def clear_active(self, *, song_key: str, tone_key: str) -> bool:
+        song_key = self._text(song_key, field="song_key", limit=240)
+        tone_key = self._text(tone_key, field="tone_key", limit=160, allow_empty=True)
+        with self._lock:
+            cur = self.conn.execute(
+                "DELETE FROM audio_effect_active_mappings WHERE song_key = ? AND tone_key = ?",
+                (song_key, tone_key),
+            )
+            self.conn.commit()
+            return cur.rowcount > 0

lib/diagnostics_redact.py

@@ -34,7 +34,7 @@ _QSTRING_SECRET_RE = re.compile(
     r"(?i)\b(api[_-]?key|key|token|secret|password|pwd|auth)=([^\s&\"']+)"
 )
 _SONG_FILENAME_RE = re.compile(
-    r"\b[\w()'\-+&,.!?\[\]]+\.(?:psarc|sloppak|wem|ogg|mp3|wav)\b",
+    r"\b[\w()'\-+&,.!?\[\]]+\.(?:psarc|sloppak|feedpak|wem|ogg|mp3|wav)\b",
     re.IGNORECASE,
 )
 

lib/dlc_paths.py

@@ -0,0 +1,99 @@
+"""DLC library path resolution — where the song files live, plus safe containment.
+
+Extracted from ``server.py`` (R3). ``_resolve_dlc_path`` is pure and moved
+verbatim. ``_get_dlc_dir`` reads the env-derived paths through the ``appstate``
+seam (``server.py`` configures ``dlc_dir``/``dlc_dir_env``/``config_dir`` at
+import, fresh on every re-import), so this module does no import-time IO and the
+pop-and-reimport fixtures keep working. ``server.py`` re-exports both names, so
+existing ``server._get_dlc_dir`` / ``server._resolve_dlc_path`` references
+(tests, other handlers) resolve unchanged.
+"""
+
+import json
+import os
+from pathlib import Path
+
+import appstate
+
+
+def _get_dlc_dir(cfg: dict | None = None) -> Path | None:
+    # Only consider DLC_DIR if the env var was non-empty. `Path("")` collapses
+    # to `.` and reports `.is_dir() == True`, which would silently shadow the
+    # config.json fallback. Checking the raw env string preserves
+    # `DLC_DIR=.` as a valid opt-in for cwd while keeping unset/empty out.
+    if appstate.dlc_dir_env and appstate.dlc_dir.is_dir():
+        return appstate.dlc_dir
+    if cfg is None:
+        config_file = appstate.config_dir / "config.json"
+        if config_file.exists():
+            try:
+                cfg = json.loads(config_file.read_text(encoding="utf-8"))
+            except Exception:
+                pass
+    if isinstance(cfg, dict):
+        raw = str(cfg.get("dlc_dir", "")).strip()
+        if raw:
+            p = Path(raw)
+            if p.is_dir():
+                return p
+    return None
+
+
+def _resolve_dlc_path(dlc: Path, filename: str) -> Path | None:
+    """Resolve `filename` under DLC_DIR and refuse anything that escapes.
+
+    `filename` arrives from `:path` route params and can contain `..`
+    segments. The Sloppak and archive paths happen to fail safely later
+    because their loaders raise on missing/invalid files, but loose-
+    folder format detection (`is_loose_song`) globs and parses XML on
+    disk first, which lets a crafted path trigger filesystem reads
+    outside DLC_DIR before any guard fires. Centralise the containment
+    check so every filename-bound handler validates before touching the
+    filesystem.
+
+    Containment here is LEXICAL (normalize `.`/`..` WITHOUT following
+    symlinks), not `safe_join`'s `.resolve()`-based check — because users
+    commonly mount their song library through a directory JUNCTION/symlink
+    (a library shared across app installs; the desktop app's own mounts).
+    `.resolve()` follows that junction to its real target, sees it sits
+    outside DLC_DIR, and wrongly rejects every song reached through it — the
+    scanner's `rglob` indexes those songs, but art/load then 403/404s (broken
+    covers, unplayable songs). Lexical normalization still rejects the only
+    escapes a `:path` filename can express — `..` traversal and absolute
+    paths — which the traversal tests pin. `safe_join` stays strict (it is
+    the zip-slip / plugin-asset guard, where following a symlink out IS the
+    defense); the loose-folder art handler keeps its own per-file symlink
+    re-check for defence-in-depth.
+
+    Returns the validated Path (not necessarily link-resolved), or None if
+    the filename is empty, contains a NUL, or escapes the DLC root.
+    """
+    if not filename:
+        return None
+    # Backslashes → forward slashes so a Windows-style `..\\x` traversal is
+    # rejected identically on POSIX (mirrors safe_join's normalisation).
+    safe = filename.replace("\\", "/")
+    if "\x00" in safe:
+        return None
+    # Reject drive-letter / absolute paths in BOTH conventions. A POSIX "/x" is
+    # caught by the containment check below (the `/` operator discards `root`),
+    # but a Windows drive-absolute "C:/x" is treated as a relative "C:" dir on
+    # POSIX and would otherwise slip in as `<root>/C:/x` — so the contract must
+    # hold cross-platform (a shared library is reached from either OS).
+    from pathlib import PurePosixPath, PureWindowsPath
+    if (PurePosixPath(safe).is_absolute()
+            or PureWindowsPath(safe).is_absolute()
+            or PureWindowsPath(safe).drive):
+        return None
+    try:
+        root = dlc.resolve()
+        # normpath collapses `.`/`..`/duplicate separators purely lexically —
+        # it never touches the filesystem, so an in-library junction component
+        # is preserved (allowed) while `..`/absolute segments still escape and
+        # get caught by the containment check below.
+        candidate = Path(os.path.normpath(root / safe))
+        if not candidate.is_relative_to(root):
+            return None
+    except (ValueError, OSError):
+        return None
+    return candidate

lib/gp2rs.py

@@ -1114,7 +1114,7 @@ def _build_xml(
     ET.SubElement(root, "arrangement").text = arrangement
     ET.SubElement(root, "offset").text = f"{audio_offset:.3f}"
     ET.SubElement(root, "songLength").text = f"{song_length:.3f}"
-    ET.SubElement(root, "startBeat").text = f"{beats[0].time:.3f}" if beats else "0.000"
+    ET.SubElement(root, "startBeat").text = f"{beats[0].time:.6f}" if beats else "0.000000"
     ET.SubElement(root, "averageTempo").text = str(tempo)
     ET.SubElement(root, "artistName").text = artist
     ET.SubElement(root, "albumName").text = album
@@ -1139,10 +1139,17 @@ def _build_xml(
         tuning_el.set(f"string{i}", str(tuning[i] if i < len(tuning) else 0))
     ET.SubElement(root, "capo").text = "0"
 
-    # Ebeats
+    # Ebeats — write beat times at MICROSECOND (6-decimal) precision, not
+    # millisecond (3-decimal). The editor/timeline DERIVES per-bar BPM from beat
+    # spans (bpm = beats·60/span), which amplifies any rounding: at 3 decimals a
+    # constant-tempo GP (e.g. 140) shows a spurious ±0.05–0.7 BPM per-bar drift
+    # (worse for fast/odd meters) because most bar lengths don't land on a ms
+    # boundary. gp2rs computes these times exactly from the GP tempo map, so the
+    # only loss is this format string — 6 decimals makes the derived tempo match
+    # GP's authored value. (Everything else stays at :.3f; only beats drive tempo.)
     ebeats = ET.SubElement(root, "ebeats", count=str(len(beats)))
     for b in beats:
-        ET.SubElement(ebeats, "ebeat", time=f"{b.time:.3f}", measure=str(b.measure))
+        ET.SubElement(ebeats, "ebeat", time=f"{b.time:.6f}", measure=str(b.measure))
 
     # Sections
     sections_el = ET.SubElement(root, "sections", count=str(len(sections)))
@@ -1836,9 +1843,10 @@ def convert_drum_track_to_drumtab(
     drum strings. Unknown percussion sounds (cowbell, tambourine etc.) are
     skipped — round-tripping them would require teaching `lib/drums.py` first.
     Callers can pass an empty dict as ``out_unmapped`` to receive a per-MIDI
-    record of every skipped note (``{midi: {"count": int, "times": [...]}}``,
-    times capped at 100 samples per note) so they can surface a warning or
-    offer a manual mapping UI.
+    record of every skipped note (``{midi: {"count": int, "times": [...],
+    "velocities": [...]}}``, times/velocities index-aligned and capped at
+    100 samples per note — velocities carry the source notes' real dynamics)
+    so they can surface a warning or offer a manual mapping UI.
 
     Honours GP repeat brackets and D.S./D.C./Coda/Fine jumps when
     ``expand_repeats`` is true — same `_build_playback_schedule` machinery
@@ -1894,18 +1902,29 @@ def convert_drum_track_to_drumtab(
                             # NB: do NOT shadow the outer `entry` loop
                             # variable from `for entry in schedule:`.
                             unmapped_rec = out_unmapped.setdefault(
-                                int(midi_note), {"count": 0, "times": []})
+                                int(midi_note),
+                                {"count": 0, "times": [], "velocities": []})
                             unmapped_rec["count"] += 1
                             if len(unmapped_rec["times"]) < 100:
                                 unmapped_rec["times"].append(round(t, 3))
+                                # Index-aligned with times: the note's real
+                                # dynamics (same 1-127 gate as mapped hits,
+                                # falling back to the 100 import default) so
+                                # a hand-mapping UI doesn't flatten them.
+                                _uv = int(getattr(note, "velocity", 0) or 0)
+                                unmapped_rec["velocities"].append(
+                                    _uv if 1 <= _uv <= 127 else 100)
                         continue
 
                     hit: dict = {"t": round(t, 3), "p": piece}
 
-                    # Velocity: GP stores 1-127 MIDI velocity directly; default
-                    # is 95 (Velocities.default). Pass through verbatim,
-                    # clamping defensively so a corrupt file can't poison the
-                    # wire format.
+                    # Velocity: GP stores 1-127 MIDI velocity directly. Note
+                    # this is GP's *authoring* default (95, Velocities.default)
+                    # — unrelated to the drumtab render default of 100
+                    # (DEFAULT_VELOCITY, lib/drums.py:179), which only applies
+                    # when `v` is omitted from a hit. Pass the GP value through
+                    # verbatim, clamping defensively so a corrupt file can't
+                    # poison the wire format.
                     vel = int(getattr(note, "velocity", 0) or 0)
                     if 1 <= vel <= 127:
                         hit["v"] = vel
@@ -1946,9 +1965,21 @@ def convert_drum_track_to_drumtab(
     # Times for unmapped notes were collected in beat-iteration order;
     # multi-voice measures can produce out-of-order beats, so sort each
     # entry's `times` list chronologically before returning to the caller.
+    # Velocities are index-aligned with times, so they must sort in
+    # LOCKSTEP — sorting times alone would silently reassign dynamics.
     if out_unmapped is not None:
         for _rec in out_unmapped.values():
-            _rec["times"].sort()
+            _vels = _rec.get("velocities")
+            if _vels and len(_vels) == len(_rec["times"]):
+                _pairs = sorted(zip(_rec["times"], _vels))
+                _rec["times"] = [p[0] for p in _pairs]
+                _rec["velocities"] = [p[1] for p in _pairs]
+            else:
+                # Belt-and-suspenders: times & velocities are always appended
+                # together under the same `len(times) < 100` guard above, so
+                # in practice the lengths can't diverge. Kept as a defensive
+                # fallback, not a real divergence case.
+                _rec["times"].sort()
 
     return {
         "version": drums_mod.SCHEMA_VERSION,

lib/gp2rs_gpx.py

@@ -121,10 +121,18 @@ def _parse_bcfs(bcfs: bytes) -> dict:
             while sc <= max_sectors:
                 s = _gi(po + 4 * sc); sc += 1
                 if s == 0: break
-                so = s * SECTOR
-                if HDR + so + SECTOR > len(data):
+                start = HDR + s * SECTOR
+                # Real .gpx files' final sector is a few bytes short of a full
+                # 0x1000 block: the BCFZ-declared decompressed size isn't
+                # sector-aligned, so the last (small) container file lands in a
+                # partial trailing sector. Clamp the read to the buffer end —
+                # the per-file size field (`fs`, applied below) trims any
+                # padding — matching canonical GPX readers (alphaTab /
+                # PyGuitarPro slice-and-clamp). Only a sector whose *start* is
+                # past the end is genuinely malformed.
+                if start < 0 or start >= len(data):
                     raise ValueError("GPX BCFS sector pointer out of range (malformed file)")
-                fb.extend(data[HDR + so: HDR + so + SECTOR])
+                fb.extend(data[start: min(start + SECTOR, len(data))])
             else:
                 raise ValueError("GPX BCFS sector chain too long (malformed file)")
             files[fn] = bytes(fb[:fs])
@@ -229,12 +237,29 @@ def _build_tempo_map(root: ET.Element) -> list[tuple[int, float]]:
     return events
 
 
+def _parse_tuning(el: ET.Element) -> list[int]:
+    """Return the string-tuning MIDI pitches from the first ``Tuning`` Property
+    at or below ``el`` (a Track or a single Staff), high string first. ``[]`` if
+    there is no Tuning property or its Pitches text is unparseable."""
+    for prop in el.findall('.//Property'):
+        if prop.get('name') == 'Tuning':
+            pe = prop.find('Pitches')
+            if pe is not None and pe.text:
+                try:
+                    return [int(p) for p in pe.text.split()]
+                except ValueError:
+                    return []
+            break
+    return []
+
+
 def _gpif_tracks(root: ET.Element) -> list[dict]:
     """Return a list of raw track dicts from the GPIF Tracks element."""
     # Lookups for per-track note counting. MasterBar/Bars lists one bar id per
-    # track in raw Tracks order, so the enumerate index below (which counts
-    # skipped pseudo-tracks) is the correct bar-lookup index — same mapping
-    # convert_file uses via filtered_to_raw.
+    # *stave* (not per Track element) in document order. A multi-stave track
+    # (e.g. GP8 piano with treble + bass) occupies N consecutive columns; the
+    # bar_column counter below advances by num_staves per track so every track
+    # gets the correct column regardless of neighbour stave counts.
     _masterbars = list(root.find('MasterBars') or [])
     _bars_by_id = {b.get('id'): b for b in (root.find('Bars') or [])}
     _voices_by_id = {v.get('id'): v for v in (root.find('Voices') or [])}
@@ -279,10 +304,17 @@ def _gpif_tracks(root: ET.Element) -> list[dict]:
         return n
 
     result = []
-    for raw_idx, t in enumerate(root.find('Tracks') or []):
+    bar_column = 0
+    for t in (root.find('Tracks') or []):
+        # Count staves: each Staff occupies one column in MasterBar/Bars.
+        # Default to 1 for tracks with no explicit <Staves> (GP3/4/5, old GPX).
+        num_staves = max(1, len(list(t.findall('Staves/Staff'))))
+        stave_columns = list(range(bar_column, bar_column + num_staves))
+
         name = (t.findtext('Name') or '').strip()
         if name.startswith('@$') and name.endswith('$@'):
-            continue  # GP internal pseudo-tracks (raw_idx still advances)
+            bar_column += num_staves
+            continue  # GP internal pseudo-tracks (bar_column still advances)
 
         gm = t.find('GeneralMidi')
         midi_program = 0
@@ -319,27 +351,37 @@ def _gpif_tracks(root: ET.Element) -> list[dict]:
                 except (ValueError, TypeError):
                     pass
 
-        # String tuning
-        string_pitches: list[int] = []
-        for prop in t.findall('.//Property'):
-            if prop.get('name') == 'Tuning':
-                pe = prop.find('Pitches')
-                if pe is not None and pe.text:
-                    try:
-                        string_pitches = [int(p) for p in pe.text.split()]
-                    except ValueError:
-                        pass
+        # String tuning — one list per stave, in stave order.  Reading all
+        # `.//Property` descendants across every stave meant the last stave's
+        # tuning overwrote the first; for a GP8 piano (treble 6-string +
+        # bass 5-string) that caused stave-0 notes with String=5 to be
+        # out-of-range against the 5-entry bass tuning and silently dropped.
+        # A staff with no Tuning of its own falls back to the track-level
+        # property (never to []) — an empty list silently drops every fretted
+        # note on that stave in `_note_midi`.  The list stays parallel to
+        # `stave_columns` so a per-stave column always has a matching tuning.
+        _track_tuning = _parse_tuning(t)
+        _staff_els = list(t.findall('Staves/Staff'))
+        if _staff_els:
+            stave_pitches = [(_parse_tuning(s) or _track_tuning) for s in _staff_els]
+        else:
+            # No <Staves> (GP3/4/5 or old GPX): single track-level tuning.
+            stave_pitches = [_track_tuning]
 
         result.append({
             '_el': t,
             'id': t.get('id', ''),
             'name': name,
-            'string_pitches': string_pitches,
+            'string_pitches': stave_pitches[0],   # primary stave (existing key)
+            'num_staves': num_staves,
+            'stave_columns': stave_columns,
+            'stave_pitches': stave_pitches,
             'is_drums': is_drums,
             'midi_program': midi_program,
             'midi_channel': midi_channel,
-            'note_count': _note_count_for_raw(raw_idx),
+            'note_count': sum(_note_count_for_raw(c) for c in stave_columns),
         })
+        bar_column += num_staves
     return result
 
 
@@ -367,6 +409,121 @@ def _beat_dur_secs(beat_el: ET.Element, rhythms_dict: dict, tempo_bpm: float) ->
     return dur_qn * (60.0 / tempo_bpm)
 
 
+def _collect_column_notes(
+    col: int,
+    string_pitches: list[int],
+    *,
+    masterbars: list,
+    bars_by_id: dict,
+    voices_dict: dict,
+    beats_dict: dict,
+    notes_dict: dict,
+    rhythms_dict: dict,
+    tempo_map: list,
+    tempo_bpm: float,
+    audio_offset: float,
+) -> list['RsNote']:
+    """Walk one ``MasterBar/Bars`` column (a single stave / hand) and return its
+    notes as keys-encoded ``RsNote`` (``string = midi // 24``, ``fret = midi %
+    24``). Tie destinations extend the matching prior note's sustain (keyed by
+    pitch, so polyphonic parts are handled) rather than emitting a new note —
+    mirroring the main ``convert_file`` builder, including its full-precision
+    timing and the 0.2s sustain threshold.
+
+    Shared by the GPX LH/RH pair merge and the GP8 multi-stave (grand-staff)
+    fold so the two code paths can never drift in tie / timing / dedup handling.
+    """
+    from gp2rs import RsNote  # lazy: gp2rs<->gpx circular import (see convert_file)
+
+    notes: list[RsNote] = []
+    last_per_key: dict[int, RsNote] = {}
+    tempo_iter = iter(tempo_map)
+    next_bar, next_bpm = next(tempo_iter, (999999, tempo_bpm))
+    cur_tempo = tempo_bpm
+    t_cursor = 0.0
+
+    for mb_idx, mb in enumerate(masterbars):
+        while mb_idx >= next_bar:
+            cur_tempo = next_bpm
+            next_bar, next_bpm = next(tempo_iter, (999999, cur_tempo))
+        ts = mb.findtext('Time', '4/4')
+        try:
+            nb, db = [int(x) for x in ts.split('/')]
+        except ValueError:
+            nb, db = 4, 4
+        bar_dur = nb * (4.0 / db) * (60.0 / cur_tempo)
+        bar_ids = mb.findtext('Bars', '').split()
+        bid = bar_ids[col] if col < len(bar_ids) else '-1'
+        if bid != '-1' and bid:
+            bar = bars_by_id.get(bid)
+            if bar is not None:
+                for vid in bar.findtext('Voices', '').split():
+                    if vid == '-1':
+                        continue
+                    voice = voices_dict.get(vid)
+                    if voice is None:
+                        continue
+                    vt = t_cursor
+                    for beat_id in voice.findtext('Beats', '').split():
+                        beat = beats_dict.get(beat_id)
+                        if beat is None:
+                            continue
+                        dur = _beat_dur_secs(beat, rhythms_dict, cur_tempo)
+                        for nid in beat.findtext('Notes', '').strip().split():
+                            note_el = notes_dict.get(nid)
+                            if note_el is None:
+                                continue
+                            if _note_is_tie(note_el):
+                                tie_midi = _note_midi(note_el, string_pitches)
+                                if tie_midi is not None:
+                                    prev = last_per_key.get(tie_midi)
+                                    tie_t = vt + audio_offset
+                                    if prev is not None and prev.time < tie_t:
+                                        prev.sustain = max(
+                                            prev.sustain, (tie_t + dur) - prev.time)
+                                continue
+                            midi = _note_midi(note_el, string_pitches)
+                            if midi is None:
+                                continue
+                            rn = RsNote(
+                                time=vt + audio_offset,
+                                string=midi // 24,
+                                fret=midi % 24,
+                                sustain=dur if dur > 0.2 else 0.0,
+                            )
+                            notes.append(rn)
+                            last_per_key[midi] = rn
+                        vt += dur
+        t_cursor += bar_dur
+    return notes
+
+
+def _merge_lh_notes(rs_notes: list, rs_chords: list, lh_notes: list) -> None:
+    """Fold ``lh_notes`` (a second stave / left hand) into ``rs_notes`` in
+    place, de-duplicating simultaneous same-pitch notes and keeping the LONGER
+    sustain when both hands strike the same key at the same instant. Seeds the
+    dedup set from chord notes too (polyphonic RH beats live in
+    ``rs_chords[*].notes``). No-op for an empty ``lh_notes``."""
+    if not lh_notes:
+        return
+    seen: dict[tuple, RsNote] = {}
+    for n in rs_notes:
+        seen.setdefault((round(n.time, 3), n.string, n.fret), n)
+    for c in rs_chords:
+        for cn in c.notes:
+            seen.setdefault((round(cn.time, 3), cn.string, cn.fret), cn)
+    for rn in lh_notes:
+        k = (round(rn.time, 3), rn.string, rn.fret)
+        existing = seen.get(k)
+        if existing is None:
+            rs_notes.append(rn)
+            seen[k] = rn
+        elif rn.sustain > existing.sustain:
+            # Mutating the RsNote also updates it in place inside any RH chord.
+            existing.sustain = rn.sustain
+    rs_notes.sort(key=lambda n: (n.time, n.string))
+
+
 # ---------------------------------------------------------------------------
 # Drum encoding tables — ported from alphaTab PercussionMapper (MIT licensed)
 # ---------------------------------------------------------------------------
@@ -1349,6 +1506,10 @@ def convert_file(
     # Surface that to the caller rather than only the docstring: if the score
     # actually uses repeats, the produced bar count/timing will differ from the
     # equivalent .gp5. Warn once so plugin code/logs don't silently drift.
+    # NB: lib/gp_autosync.gp_has_expandable_repeats() encodes this single-pass
+    # behaviour (.gp/.gpx never expand). Implementing GPIF expansion here MUST
+    # update that helper in the same change, or the editor's per-bar sync warp
+    # would silently retime repeated sections onto the wrong bars.
     if expand_repeats and any(
         mb.find('Repeat') is not None or mb.find('AlternateEndings') is not None
         for mb in masterbars
@@ -1366,17 +1527,16 @@ def convert_file(
     rhythms_dict = {r.get('id'): r for r in (root.find('Rhythms') or [])}
     _bend_divisor = _gpx_bend_scale(root)   # GPIF bend value -> semitones
 
-    # Map filtered track index -> raw track index (needed for bar lookup)
-    raw_tracks = list(root.find('Tracks') or [])
-    filtered_to_raw: dict[int, int] = {}
-    filtered_pos = 0
-    for raw_idx, t_el in enumerate(raw_tracks):
-        name = (t_el.findtext('Name') or '').strip()
-        if name.startswith('@$') and name.endswith('$@'):
-            continue
-        filtered_to_raw[filtered_pos] = raw_idx
-        filtered_pos += 1
-
+    # Map filtered track index -> bar column (MasterBar/Bars position for
+    # stave 0 of that track). `_gpif_tracks` already computed the per-stave
+    # column layout (advancing by num_staves per track, pseudo-tracks skipped),
+    # so reuse its `stave_columns[0]` rather than re-deriving the counting rule
+    # here — divergence in stave counting *is* the bug class this fix closes.
+    # NB: despite the historical name, the value is a bar *column*, not a raw
+    # Track index — do not index `root.find('Tracks')` with it.
+    filtered_to_raw: dict[int, int] = {
+        i: t['stave_columns'][0] for i, t in enumerate(tracks)
+    }
 
     # Detect and merge Piano LH+RH pairs into single full-keyboard arrangements
     track_indices, _piano_merge_map = _find_piano_pairs(track_indices, tracks, names)
@@ -1468,7 +1628,16 @@ def convert_file(
         is_keys = (
             not is_drum and not is_vocal
             and (
-                any(kw in track['name'].lower() for kw in ('piano', 'keys', 'keyboard', 'organ'))
+                # A multi-stave track is a grand staff (treble + bass) — i.e. a
+                # keyboard-family part. Treating it as keys end-to-end keeps the
+                # stave-0 encoding and the folded stave-1+ encoding consistent
+                # (both midi//24, midi%24) and makes the `note_count` preview
+                # (which sums every stave column) match what actually imports,
+                # even for instruments the name/program heuristics miss (harp,
+                # celesta, marimba). GPIF writes guitars as a single Staff, so
+                # this does not sweep in ordinary fretted tracks.
+                track.get('num_staves', 1) > 1
+                or any(kw in track['name'].lower() for kw in ('piano', 'keys', 'keyboard', 'organ'))
                 or arr_name.lower().startswith('keys')
                 or (
                     not track['string_pitches']
@@ -1534,7 +1703,6 @@ def convert_file(
         pending_slides: list = []         # (RsNote, rs_string, gp_slide_flags) — resolved post-loop
 
         current_time = 0.0
-        num_raw_tracks = len(raw_tracks)
 
         # Resolve current tempo per bar from the tempo map
         _tempo_iter = iter(tempo_map)
@@ -1866,112 +2034,20 @@ def convert_file(
             tuning = _gpx_tuning(track)
 
         # Merge Piano LH notes into this (RH) arrangement if a pair was detected
+        _walk_kwargs = dict(
+            masterbars=masterbars, bars_by_id=bars_by_id,
+            voices_dict=voices_dict, beats_dict=beats_dict,
+            notes_dict=notes_dict, rhythms_dict=rhythms_dict,
+            tempo_map=tempo_map, tempo_bpm=tempo_bpm, audio_offset=audio_offset,
+        )
         if is_keys and track_idx in _piano_merge_map:
+            # GPX LH/RH pair: the left hand is a *separate* Track element. Walk
+            # its column and fold it into this (right-hand) arrangement.
             lh_idx = _piano_merge_map[track_idx]
             lh_track = tracks[lh_idx]
             lh_raw_idx = filtered_to_raw.get(lh_idx, lh_idx)
-
-            _lh_notes: list[RsNote] = []
-            _lh_last_per_key: dict[int, RsNote] = {}
-            _lh_tempo_iter = iter(tempo_map)
-            _lh_next_bar, _lh_next_bpm = next(_lh_tempo_iter, (999999, tempo_bpm))
-            _lh_cur_tempo = tempo_bpm
-            _lh_time = 0.0
-
-            for _lh_mb_idx, _lh_mb in enumerate(masterbars):
-                while _lh_mb_idx >= _lh_next_bar:
-                    _lh_cur_tempo = _lh_next_bpm
-                    _lh_next_bar, _lh_next_bpm = next(_lh_tempo_iter, (999999, _lh_cur_tempo))
-                _lh_ts = _lh_mb.findtext('Time', '4/4')
-                try:
-                    _lh_nb, _lh_db = [int(x) for x in _lh_ts.split('/')]
-                except ValueError:
-                    _lh_nb, _lh_db = 4, 4
-                _lh_bar_dur = _lh_nb * (4.0 / _lh_db) * (60.0 / _lh_cur_tempo)
-                _lh_bar_ids = _lh_mb.findtext('Bars', '').split()
-                _lh_bid = _lh_bar_ids[lh_raw_idx] if lh_raw_idx < len(_lh_bar_ids) else '-1'
-                if _lh_bid != '-1' and _lh_bid:
-                    _lh_bar = bars_by_id.get(_lh_bid)
-                    if _lh_bar is not None:
-                        for _lh_vid in _lh_bar.findtext('Voices', '').split():
-                            if _lh_vid == '-1':
-                                continue
-                            _lh_voice = voices_dict.get(_lh_vid)
-                            if _lh_voice is None:
-                                continue
-                            _lh_vt = _lh_time
-                            for _lh_beat_id in _lh_voice.findtext('Beats', '').split():
-                                _lh_beat = beats_dict.get(_lh_beat_id)
-                                if _lh_beat is None:
-                                    continue
-                                _lh_dur = _beat_dur_secs(_lh_beat, rhythms_dict, _lh_cur_tempo)
-                                for _lh_nid in _lh_beat.findtext('Notes', '').strip().split():
-                                    _lh_note_el = notes_dict.get(_lh_nid)
-                                    if _lh_note_el is None:
-                                        continue
-                                    if _note_is_tie(_lh_note_el):
-                                        # Extend the matching prior note (same
-                                        # pitch), mirroring the main builder's
-                                        # last_note_per_key handling — blindly
-                                        # extending the last-emitted note
-                                        # mishandles polyphonic (chord) LH parts.
-                                        _tie_midi = _note_midi(_lh_note_el, lh_track['string_pitches'])
-                                        if _tie_midi is not None:
-                                            _prev = _lh_last_per_key.get(_tie_midi)
-                                            # Full-precision comparison (matching
-                                            # the main builder); rounding only
-                                            # happens at XML serialization. Rounding
-                                            # here could make a short note appear to
-                                            # start at the tie time and skip the
-                                            # sustain extension.
-                                            _tie_t = _lh_vt + audio_offset
-                                            if _prev is not None and _prev.time < _tie_t:
-                                                _prev.sustain = max(
-                                                    _prev.sustain,
-                                                    (_tie_t + _lh_dur) - _prev.time,
-                                                )
-                                        continue
-                                    _lh_midi = _note_midi(_lh_note_el, lh_track['string_pitches'])
-                                    if _lh_midi is None:
-                                        continue
-                                    # Keep full-precision time (like the main
-                                    # convert_file() builder — rounding happens at
-                                    # serialization); same 0.2s sustain threshold.
-                                    _lh_rn = RsNote(
-                                        time=_lh_vt + audio_offset,
-                                        string=_lh_midi // 24,
-                                        fret=_lh_midi % 24,
-                                        sustain=_lh_dur if _lh_dur > 0.2 else 0.0,
-                                    )
-                                    _lh_notes.append(_lh_rn)
-                                    _lh_last_per_key[_lh_midi] = _lh_rn
-                                _lh_vt += _lh_dur
-                _lh_time += _lh_bar_dur
-
-            # Merge: combine and deduplicate simultaneous same-pitch notes, then
-            # sort by time. Map each (time, string, fret) to its existing RsNote
-            # so that when both hands hit the same key at the same instant we
-            # keep the LONGER sustain instead of arbitrarily discarding the LH
-            # one. Seed from both single notes and chord notes — polyphonic RH
-            # beats live in rs_chords[*].notes, so seeding from rs_notes alone
-            # would let an identical LH note slip in as a duplicate.
-            _seen: dict[tuple, RsNote] = {}
-            for _n in rs_notes:
-                _seen.setdefault((round(_n.time, 3), _n.string, _n.fret), _n)
-            for _c in rs_chords:
-                for _cn in _c.notes:
-                    _seen.setdefault((round(_cn.time, 3), _cn.string, _cn.fret), _cn)
-            for _lh_rn in _lh_notes:
-                _k = (round(_lh_rn.time, 3), _lh_rn.string, _lh_rn.fret)
-                _existing = _seen.get(_k)
-                if _existing is None:
-                    rs_notes.append(_lh_rn)
-                    _seen[_k] = _lh_rn
-                elif _lh_rn.sustain > _existing.sustain:
-                    # Same key both hands — preserve the longer sustain (mutating
-                    # the RsNote also updates it in place inside any RH chord).
-                    _existing.sustain = _lh_rn.sustain
-            rs_notes.sort(key=lambda n: (n.time, n.string))
+            _merge_lh_notes(rs_notes, rs_chords, _collect_column_notes(
+                lh_raw_idx, lh_track['string_pitches'], **_walk_kwargs))
 
             # Collapse "Keys 2" -> "Keys": the merged LH+RH is a single
             # keyboard arrangement. Keep the standard "Keys" name (not "Piano")
@@ -1979,6 +2055,18 @@ def convert_file(
             # auto-select (which keys on arr_name.startswith("keys")) still work.
             arr_name = re.sub(r'\s*\d+$', '', arr_name).strip() or 'Keys'
 
+        elif track.get('num_staves', 1) > 1:
+            # GP8 grand-staff keyboard: staves 1+ (bass clef, and any further
+            # staves) are extra MasterBar/Bars columns for the SAME Track
+            # element. Fold each one in, exactly like the GPX LH merge above.
+            # (num_staves > 1 implies is_keys, set above.) Iterating every
+            # extra column — not just stave_columns[1] — keeps the arrangement
+            # consistent with note_count, which sums all columns.
+            for _col, _sp in zip(track['stave_columns'][1:],
+                                 track['stave_pitches'][1:]):
+                _merge_lh_notes(rs_notes, rs_chords, _collect_column_notes(
+                    _col, _sp, **_walk_kwargs))
+
         # Resolve pending slides now that every note on each string is known.
         # GPIF slide flags: 1=shift, 2=legato (both slide to the NEXT note on the
         # string); 4=slide out downwards, 8=slide out upwards (unpitched).
@@ -2032,19 +2120,24 @@ def convert_file(
             try:
                 import gp2notation as _gp2notation
                 _lh_idx = _piano_merge_map.get(track_idx)
+                if _lh_idx is not None:
+                    # GPX LH/RH pair (two separate Track elements)
+                    _nt_lh_raw = filtered_to_raw.get(_lh_idx, _lh_idx)
+                    _nt_lh_sp  = tracks[_lh_idx]['string_pitches']
+                elif track.get('num_staves', 1) > 1:
+                    # GP8 two-stave piano (one Track with multiple <Staves>)
+                    _nt_lh_raw = track['stave_columns'][1]
+                    _nt_lh_sp  = (track['stave_pitches'][1]
+                                  if len(track.get('stave_pitches', [])) > 1 else [])
+                else:
+                    _nt_lh_raw, _nt_lh_sp = None, []
                 _payload = _gp2notation.convert_track_to_notation(
                     root, raw_idx, track['string_pitches'],
                     instrument='piano',
                     audio_offset=audio_offset,
                     track_name=track['name'],
-                    lh_raw_idx=(
-                        filtered_to_raw.get(_lh_idx, _lh_idx)
-                        if _lh_idx is not None else None
-                    ),
-                    lh_string_pitches=(
-                        tracks[_lh_idx]['string_pitches']
-                        if _lh_idx is not None else None
-                    ),
+                    lh_raw_idx=_nt_lh_raw,
+                    lh_string_pitches=_nt_lh_sp or None,
                 )
                 _gp2notation.write_notation_sidecar(filepath, _payload)
             except Exception:

lib/gp_autosync.py

@@ -18,8 +18,22 @@ plugin is installed; graceful ImportError otherwise with clear message).
 Public API:
     is_available()                          -> bool
     auto_sync(gp_path, audio_path, ...)    -> GpSyncData
+    refine_sync(sync, audio_path, ...)     -> GpSyncData
     estimate_audio_offset(gp_path,
                           audio_path)      -> float
+    bar_start_times(gp_path)               -> list[float]
+    gp_has_expandable_repeats(gp_path)     -> bool
+    build_warp_anchors(sync_points,
+                       bar_starts)         -> list[tuple[float, float]]
+    warp_time(t, anchors)                  -> float
+    warp_song_times(song, warp)            -> None
+
+The warp helpers (bar_start_times / build_warp_anchors / warp_time /
+warp_song_times) are librosa-free: they turn a GpSyncData produced by
+auto_sync (or extracted from a GP8 file) into a piecewise-linear
+score-time -> audio-time mapping and apply it to a lib.song.Song, so
+converted charts follow the recording's actual tempo drift instead of a
+single scalar offset.
 """
 
 from __future__ import annotations
@@ -353,15 +367,22 @@ def _synthesise_score_chroma(
     return chroma
 
 _GP345_TICKS_PER_QUARTER = 960
+# PyGuitarPro absolute ticks start at quarterTime (measure 1 begins at tick
+# 960, not 0). All tick math in this module runs on a 0-based axis (cumulative
+# measure starts), so raw beat.start values must be shifted by this origin —
+# mixing the two axes applied every mid-song tempo change a quarter note late
+# and skewed the synthesised chroma against the bar timeline.
+_GP345_TICK_ORIGIN = 960
 
 
 def _gp345_tempo_events(song) -> list[tuple[int, float]]:
     """Sorted, tick-deduplicated ``[(tick, bpm)]`` tempo events for a GP3/4/5 song.
 
     Seeds with the song's initial tempo at tick 0, then appends every
-    ``mixTableChange`` tempo. Shared by chroma synthesis and bar-time
-    computation so both use one identical tempo model (mirrors
-    ``gp2rs._build_tempo_map``).
+    ``mixTableChange`` tempo. Ticks are normalised to the 0-based axis
+    (raw ``beat.start`` minus ``_GP345_TICK_ORIGIN``). Shared by chroma
+    synthesis and bar-time computation so both use one identical tempo
+    model (mirrors ``gp2rs._build_tempo_map``).
     """
     events: list[tuple[int, float]] = [(0, float(song.tempo))]
     for track in song.tracks:
@@ -371,7 +392,10 @@ def _gp345_tempo_events(song) -> list[tuple[int, float]]:
                     if beat.effect and beat.effect.mixTableChange:
                         mtc = beat.effect.mixTableChange
                         if mtc.tempo and mtc.tempo.value > 0:
-                            events.append((beat.start, float(mtc.tempo.value)))
+                            events.append((
+                                max(0, beat.start - _GP345_TICK_ORIGIN),
+                                float(mtc.tempo.value),
+                            ))
     events.sort(key=lambda e: e[0])
     seen_ticks: set[int] = set()
     unique: list[tuple[int, float]] = []
@@ -459,8 +483,9 @@ def _synthesise_score_chroma_gp345(
                 for beat in voice.beats:
                     if not beat.notes:
                         continue
-                    beat_secs = tick_to_secs(beat.start)
-                    cur_tempo = tempo_at_tick(beat.start)
+                    beat_tick = max(0, beat.start - _GP345_TICK_ORIGIN)
+                    beat_secs = tick_to_secs(beat_tick)
+                    cur_tempo = tempo_at_tick(beat_tick)
                     dur_secs = duration_to_secs(beat.duration, cur_tempo)
 
                     for note in beat.notes:
@@ -513,13 +538,75 @@ def _dtw_align(
     Returns wp where wp[i] = [score_frame_index, audio_frame_index].
     """
     import librosa
+    import numpy as np
     cs = _safe_normalise(chroma_score)
     ca = _safe_normalise(chroma_audio)
-    _D, wp = librosa.sequence.dtw(cs, ca, metric='cosine')
+    # Slope-constrained step pattern ([[1,1],[1,2],[2,1]], Müller's standard
+    # music-sync config): every step advances BOTH axes, bounding the local
+    # tempo ratio to 0.5x-2x. librosa's default steps allow pure
+    # horizontal/vertical runs, and on riff-based music (long self-similar
+    # chroma stretches, e.g. stoner/doom) the flat cost surface let the path
+    # collapse — whole minutes of score mapped onto a single audio frame,
+    # producing garbage sync points. The constrained pattern makes that
+    # degenerate path impossible.
+    steps = np.array([[1, 1], [1, 2], [2, 1]])
+    weights = np.array([1.0, 1.0, 1.0])
+    try:
+        _D, wp = librosa.sequence.dtw(
+            cs, ca, metric='cosine',
+            step_sizes_sigma=steps, weights_mul=weights,
+        )
+    except Exception as exc:
+        # The constrained pattern needs the global length ratio within its
+        # 0.5x-2x slope bounds; a pathological pairing (e.g. a 3-minute tab
+        # against a 20-minute video) is infeasible and librosa raises. Fall
+        # back to the unconstrained path rather than failing the whole sync.
+        _log.warning("gp_autosync: constrained DTW infeasible (%s) — "
+                     "falling back to unconstrained steps", exc)
+        _D, wp = librosa.sequence.dtw(cs, ca, metric='cosine')
     return wp[::-1]  # reverse to forward order
 
 # ── Sync point extraction from DTW path ──────────────────────────────────────
 
+def _gpif_bar_starts(root: ET.Element) -> list[float]:
+    """Score-time (seconds) at the start of each masterbar in a GPIF score.
+
+    Integrates bar durations from the bar-resolution tempo map and each
+    masterbar's time signature — the same time model _synthesise_score_chroma
+    uses, so bar times land where the bars sit in the synthesised chroma.
+    """
+    tempo_map = _get_tempo_map(root)
+    masterbars = _children(root, 'MasterBars')
+    tempo_iter = iter(tempo_map)
+    next_tb, next_bpm = next(tempo_iter, (999999, tempo_map[0][1]))
+    ct = tempo_map[0][1]
+    t_cur = 0.0
+    bar_starts: list[float] = []
+    for mb_idx, mb in enumerate(masterbars):
+        while mb_idx >= next_tb:
+            ct = next_bpm
+            next_tb, next_bpm = next(tempo_iter, (999999, ct))
+        bar_starts.append(t_cur)
+        ts = mb.findtext('Time', '4/4')
+        try:
+            n_b, d_b = [int(x) for x in ts.split('/')]
+        except ValueError:
+            n_b, d_b = 4, 4
+        t_cur += n_b * (4.0 / d_b) * (60.0 / ct)
+    return bar_starts
+
+
+def _gp345_measure_start_ticks(song) -> list[int]:
+    """Cumulative start tick of each measure in a PyGuitarPro song."""
+    starts: list[int] = []
+    cum = 0
+    for mh in song.measureHeaders:
+        starts.append(cum)
+        ts = mh.timeSignature
+        cum += int(ts.numerator * (4.0 / ts.denominator.value) * _GP345_TICKS_PER_QUARTER)
+    return starts
+
+
 def _extract_sync_points(
     wp: 'np.ndarray',
     root: ET.Element,
@@ -565,22 +652,7 @@ def _extract_sync_points(
     if bar_starts_override is not None:
         bar_starts_score = list(bar_starts_override)
     else:
-        tempo_iter = iter(tempo_map)
-        next_tb, next_bpm = next(tempo_iter, (999999, tempo_map[0][1]))
-        ct = tempo_map[0][1]
-        t_cur = 0.0
-        bar_starts_score = []
-        for mb_idx, mb in enumerate(masterbars):
-            while mb_idx >= next_tb:
-                ct = next_bpm
-                next_tb, next_bpm = next(tempo_iter, (999999, ct))
-            bar_starts_score.append(t_cur)
-            ts = mb.findtext('Time', '4/4')
-            try:
-                n_b, d_b = [int(x) for x in ts.split('/')]
-            except ValueError:
-                n_b, d_b = 4, 4
-            t_cur += n_b * (4.0 / d_b) * (60.0 / ct)
+        bar_starts_score = _gpif_bar_starts(root)
 
     # Map each sampled bar to its audio time via the DTW path
     sync_points: list[SyncPoint] = []
@@ -663,6 +735,224 @@ def _tempo_at_bar(tempo_map: list[tuple[int, float]], bar: int) -> float:
 
 # ── Audio offset estimation ───────────────────────────────────────────────────
 
+# ── Piecewise time warp (librosa-free) ───────────────────────────────────────
+#
+# auto_sync's per-bar sync points describe where each sampled bar of the tab
+# falls in the real recording. Applying only the scalar audio_offset (bar 1)
+# assumes the recording holds the authored tempo for the whole song — any
+# drift accumulates. These helpers build the full piecewise-linear
+# score-time -> audio-time mapping and apply it to a converted Song, so the
+# chart follows the recording bar by bar (Songsterr-style sync).
+
+def bar_start_times(gp_path: str) -> list[float]:
+    """Score-time (seconds) at the start of every bar of a GP file.
+
+    Uses the same tempo models as auto_sync's chroma synthesis (GPIF
+    bar-resolution map for .gp/.gpx, per-tick integration for .gp3/4/5), so
+    the returned times share an axis with auto_sync's sync points.
+
+    Raises ValueError if the file cannot be parsed, ImportError if the file
+    is GP3/4/5 and PyGuitarPro is not installed.
+    """
+    try:
+        root = _load_gpif(gp_path)
+    except _Gp345FileError:
+        import guitarpro
+        try:
+            song = guitarpro.parse(gp_path)
+        except Exception as exc:
+            raise ValueError(f"Cannot parse GP3/4/5 file {gp_path!r}: {exc}") from exc
+        tempo_events = _gp345_tempo_events(song)
+        return [
+            _gp345_tick_to_secs(tempo_events, tick)
+            for tick in _gp345_measure_start_ticks(song)
+        ]
+    return _gpif_bar_starts(root)
+
+
+def gp_has_expandable_repeats(gp_path: str) -> bool:
+    """True when converting `gp_path` expands repeats into a longer timeline
+    than the as-written score auto_sync aligned against.
+
+    gp2rs.convert_file walks the GP3/4/5 playback graph (repeat brackets,
+    voltas, D.S./D.C. directions), so a file using any of those produces an
+    as-performed timeline that auto_sync's as-written sync points cannot be
+    mapped onto. GPIF (.gp/.gpx) conversion is single-pass as-written today,
+    so those files always return False — both sides share one bar order.
+
+    Returns False when the file cannot be parsed (callers fall back to
+    offset-only sync on parse failure anyway).
+    """
+    if Path(gp_path).suffix.lower() in ('.gp', '.gpx'):
+        return False
+    try:
+        import guitarpro
+        song = guitarpro.parse(gp_path)
+    except Exception:
+        return False
+    for mh in song.measureHeaders:
+        if mh.isRepeatOpen or mh.repeatClose >= 0 or mh.repeatAlternative:
+            return True
+        # Both jump SOURCES (fromDirection: D.C., D.S., Da Coda) and jump
+        # TARGETS (direction: Segno, Coda, Fine) count — a plain Da Capo
+        # needs no target marker, so checking `direction` alone would miss
+        # it while gp2rs's playback walker still expands the jump.
+        if (getattr(mh, 'direction', None) is not None
+                or getattr(mh, 'fromDirection', None) is not None):
+            return True
+    return False
+
+
+def build_warp_anchors(
+    sync_points: list[SyncPoint],
+    bar_starts: list[float],
+) -> list[tuple[float, float]]:
+    """Turn sync points into (score_secs, audio_secs) anchor pairs.
+
+    Drops points whose bar index is out of range, points that would break
+    strict monotonicity on either axis (DTW can locally fold on noisy audio;
+    a non-monotonic anchor would make the warp non-invertible and reorder
+    notes), and points whose segment slope implies a physically implausible
+    tempo ratio (outside 0.2x-5x authored). Returns [] when fewer than 2
+    usable anchors remain — callers should fall back to scalar-offset sync
+    in that case.
+    """
+    anchors: list[tuple[float, float]] = []
+    for sp in sorted(sync_points, key=lambda p: p.bar):
+        if not 0 <= sp.bar < len(bar_starts):
+            continue
+        score_t = bar_starts[sp.bar]
+        audio_t = float(sp.time_secs)
+        if anchors and (score_t <= anchors[-1][0] + 1e-6
+                        or audio_t <= anchors[-1][1] + 1e-3):
+            continue
+        if anchors:
+            # Slope sanity gate: a segment whose audio/score tempo ratio is
+            # outside [0.2, 5] is not a performance — it's a DTW fold onto a
+            # repeated section, an abridged recording, or a run of
+            # monotonicity-clamped refine points. Keeping it would crush (or
+            # absurdly stretch) every bar in the span, which is far worse
+            # than interpolating through from the neighbouring anchors.
+            slope = (audio_t - anchors[-1][1]) / (score_t - anchors[-1][0])
+            if not 0.2 <= slope <= 5.0:
+                continue
+        anchors.append((score_t, audio_t))
+    return anchors if len(anchors) >= 2 else []
+
+
+def warp_time(t: float, anchors: list[tuple[float, float]]) -> float:
+    """Map a score-time (seconds) to audio-time via piecewise-linear anchors.
+
+    Between anchors: linear interpolation. Outside the anchor range: the
+    nearest segment's slope is extended, so a count-in before bar 1 and the
+    tail after the last sampled bar keep the local tempo ratio.
+
+    `anchors` must be the >=2-point strictly-monotonic list produced by
+    build_warp_anchors.
+    """
+    lo = 0
+    hi = len(anchors) - 1
+    if t <= anchors[0][0]:
+        seg = (anchors[0], anchors[1])
+    elif t >= anchors[hi][0]:
+        seg = (anchors[hi - 1], anchors[hi])
+    else:
+        # Binary search for the segment containing t
+        while hi - lo > 1:
+            mid = (lo + hi) // 2
+            if anchors[mid][0] <= t:
+                lo = mid
+            else:
+                hi = mid
+        seg = (anchors[lo], anchors[hi])
+    (s0, a0), (s1, a1) = seg
+    slope = (a1 - a0) / (s1 - s0)
+    return a0 + (t - s0) * slope
+
+
+def warp_song_times(song, warp) -> None:
+    """Apply a monotonic time-mapping callable to every absolute time in a
+    lib.song.Song, in place.
+
+    Covers beats, sections, song_length, and per-arrangement notes (onset +
+    sustain), chords (incl. chord notes), anchors, hand shapes, per-phrase
+    difficulty levels, tone changes, and tempo overrides. Durations (note
+    sustain, handshape span) are warped as end-start so they stretch with the
+    local tempo ratio; sub-second intra-note envelopes (bend curves, which are
+    relative to the note onset) are left untouched.
+
+    Duck-typed: accepts any object with the lib.song.Song surface.
+
+    Identity-safe: parse_arrangement shares the SAME Note/Chord/Anchor/
+    HandShape objects between the flat arrangement lists and the
+    max-difficulty phrase level, so each object is warped at most once no
+    matter how many containers reference it.
+    """
+    seen: set[int] = set()
+
+    def _once(obj) -> bool:
+        key = id(obj)
+        if key in seen:
+            return False
+        seen.add(key)
+        return True
+
+    def _warp_notes(notes):
+        for n in notes or []:
+            if not _once(n):
+                continue
+            end = warp(n.time + n.sustain)
+            n.time = warp(n.time)
+            n.sustain = max(0.0, end - n.time)
+
+    def _warp_chords(chords):
+        for c in chords or []:
+            if not _once(c):
+                continue
+            c.time = warp(c.time)
+            _warp_notes(c.notes)
+
+    def _warp_anchors(anchors):
+        for a in anchors or []:
+            if _once(a):
+                a.time = warp(a.time)
+
+    def _warp_handshapes(shapes):
+        for h in shapes or []:
+            if not _once(h):
+                continue
+            start = warp(h.start_time)
+            end = warp(h.end_time)
+            h.start_time = start
+            h.end_time = max(start, end)
+
+    song.song_length = max(0.0, warp(song.song_length))
+    for b in song.beats:
+        b.time = warp(b.time)
+    for s in song.sections:
+        s.start_time = warp(s.start_time)
+    for arr in song.arrangements:
+        _warp_notes(arr.notes)
+        _warp_chords(arr.chords)
+        _warp_anchors(arr.anchors)
+        _warp_handshapes(arr.hand_shapes)
+        for ph in arr.phrases or []:
+            ph.start_time = warp(ph.start_time)
+            ph.end_time = warp(ph.end_time)
+            for lvl in ph.levels or []:
+                _warp_notes(lvl.notes)
+                _warp_chords(lvl.chords)
+                _warp_anchors(lvl.anchors)
+                _warp_handshapes(lvl.hand_shapes)
+        if arr.tones and isinstance(arr.tones, dict):
+            for change in arr.tones.get('changes') or []:
+                if isinstance(change, dict) and isinstance(change.get('t'), (int, float)):
+                    change['t'] = warp(float(change['t']))
+        for tempo_ev in arr.tempos or []:
+            if isinstance(tempo_ev, dict) and isinstance(tempo_ev.get('time'), (int, float)):
+                tempo_ev['time'] = warp(float(tempo_ev['time']))
+
+
 def _estimate_audio_offset(
     root: ET.Element,
     audio_path: str,
@@ -932,12 +1222,7 @@ def auto_sync(
         # below line up with the chroma timeline.
         _tempo_events_gp345 = _gp345_tempo_events(_gp345x_song)
         # Convert tick events to bar events using actual measure start ticks
-        _measure_starts = []  # cumulative tick at start of each bar
-        _cum = 0
-        for _mh2 in _gp345x_song.measureHeaders:
-            _measure_starts.append(_cum)
-            _ts = _mh2.timeSignature
-            _cum += int(_ts.numerator * (4.0 / _ts.denominator.value) * _GP345_TICKS_PER_QUARTER)
+        _measure_starts = _gp345_measure_start_ticks(_gp345x_song)
 
         def _tick_to_bar(tick):
             """Return 0-based bar index for a given tick position."""
@@ -1024,6 +1309,216 @@ def auto_sync(
         sync_points=sync_points,
     )
 
+def refine_sync(
+    sync: GpSyncData,
+    audio_path: str,
+    bars_per_point: int = 8,
+    gp_path: str | None = None,
+    sr: int = _SR,
+    search_radius: float = 0.35,
+    phase_step: float = 0.005,
+    onset_tolerance: float = 0.05,
+) -> GpSyncData:
+    """Refine coarse DTW sync points with a per-bar onset phase sweep.
+
+    auto_sync's mid-song points inherit the DTW frame granularity (~186ms at
+    the default hop). This pass re-times a denser grid of bars — every
+    `bars_per_point`-th bar plus the first and last — by sweeping a local
+    beat grid (±`search_radius`s in `phase_step` steps) against detected
+    onsets and keeping the phase that aligns best, narrowing each kept point
+    to roughly the phase-step resolution on percussive material.
+
+    Args:
+        sync:            Coarse sync data from auto_sync (or a prior refine).
+        audio_path:      The same audio file auto_sync aligned against.
+        bars_per_point:  Refined-point density; every Nth bar gets a point.
+        gp_path:         Optional path to the GP file. When given, exact
+                         per-bar score times (bar_start_times) drive the
+                         densified grid; without it the grid is limited to
+                         a 4/4 approximation built from the points' authored
+                         tempos, and accuracy degrades on odd meters.
+        sr:              Analysis sample rate.
+        search_radius:   ±seconds around each coarse estimate to sweep.
+        phase_step:      Sweep resolution in seconds.
+        onset_tolerance: Max onset-to-click distance that counts as aligned.
+
+    Returns:
+        A new GpSyncData with the refined (and usually denser) points and a
+        recomputed audio_offset. Returns `sync` unchanged when it has no
+        usable points. Quiet bars (fewer than 4 onsets nearby) keep their
+        coarse interpolated time rather than locking onto noise.
+    """
+    if not sync.sync_points:
+        return sync
+
+    pts = sorted(sync.sync_points, key=lambda p: p.bar)
+
+    bar_starts: list[float] | None = None
+    if gp_path:
+        try:
+            bar_starts = bar_start_times(gp_path)
+        except Exception as exc:
+            _log.warning("refine_sync: bar_start_times(%s) failed (%s) — "
+                         "falling back to 4/4 tempo model", gp_path, exc)
+    if bar_starts is None:
+        # Approximate score bar starts from the points' authored tempos,
+        # assuming 4 beats per bar (all GpSyncData carries without the file).
+        max_bar = pts[-1].bar
+        bar_starts = [0.0]
+        ti = 0
+        cur_bpm = pts[0].original_tempo or 120.0
+        for b in range(1, max_bar + 1):
+            while ti + 1 < len(pts) and pts[ti + 1].bar <= b - 1:
+                ti += 1
+                cur_bpm = pts[ti].original_tempo or cur_bpm
+            bar_starts.append(bar_starts[-1] + 4 * 60.0 / max(cur_bpm, 1e-3))
+
+    anchors = build_warp_anchors(pts, bar_starts)
+    if len(anchors) < 2:
+        _log.warning("refine_sync: fewer than 2 usable anchors — returning "
+                     "input unchanged")
+        return sync
+
+    # Authored-tempo lookup via the shared bar-map scan (_tempo_at_bar) so
+    # boundary semantics can't drift from the rest of the module.
+    _orig_map = [(p.bar, p.original_tempo or 120.0) for p in pts]
+
+    def _orig_bpm_at(bar: int) -> float:
+        return max(_tempo_at_bar(_orig_map, bar), 1e-3)
+
+    n_bars = len(bar_starts)
+    step = max(1, int(bars_per_point))
+    targets = sorted(set(range(0, n_bars, step)) | {n_bars - 1})
+
+    # Deferred past the pure early-return paths above so degenerate inputs
+    # (no points, <2 anchors) resolve without librosa installed.
+    import librosa
+    import numpy as np
+
+    y, _ = librosa.load(audio_path, sr=sr, mono=True)
+    audio_dur = len(y) / sr
+    hop = 512  # ~23ms at 22050Hz — fine enough for onset timing
+    onset_frames = librosa.onset.onset_detect(
+        y=y, sr=sr, hop_length=hop, backtrack=True
+    )
+    onset_times = np.asarray(
+        librosa.frames_to_time(onset_frames, sr=sr, hop_length=hop)
+    )
+
+    refined: list[tuple[int, float]] = []
+    for b in targets:
+        score_t = bar_starts[b]
+        coarse = warp_time(score_t, anchors)
+        if coarse > audio_dur + 1.0:
+            break  # bar falls past the end of the recording
+        # Local beat period in AUDIO time: authored beat period scaled by the
+        # local warp slope (recording tempo / authored tempo around this bar).
+        slope = warp_time(score_t + 1.0, anchors) - coarse
+        slope = min(max(slope, 0.25), 4.0)
+        beat_period = (60.0 / _orig_bpm_at(b)) * slope
+
+        # Keep the scoring grid short: beat_period is estimated from the
+        # coarse anchors (a few % off), and grid drift grows linearly with
+        # distance — 16 beats at 2% error is already ~150ms of skew at the
+        # far end, which drags the sweep. 8 beats bounds that to ~beat noise.
+        grid_span = 8 * beat_period
+        # Clamp the sweep window below half a beat so the neighbouring beat
+        # is never a candidate — on periodic material (steady drums) a grid
+        # shifted by one whole beat scores identically and the sweep could
+        # lock a full beat off. DTW coarse error is ~1 analysis frame, which
+        # this window still covers at all but extreme tempos.
+        radius = min(search_radius, 0.45 * beat_period)
+        w_lo = coarse - radius - onset_tolerance
+        w_hi = coarse + radius + grid_span + onset_tolerance
+        local = onset_times[(onset_times >= w_lo) & (onset_times <= w_hi)]
+        if len(local) < 4:
+            refined.append((b, coarse))
+            continue
+
+        best_t, best_score, best_dist = coarse, -1, 0.0
+        for phase in np.arange(coarse - radius, coarse + radius + 1e-9,
+                               phase_step):
+            clicks = np.arange(phase, phase + grid_span, beat_period)
+            score = int(sum(
+                1 for t in local
+                if float(np.min(np.abs(clicks - t))) < onset_tolerance
+            ))
+            dist = abs(float(phase) - coarse)
+            # Ties break toward the coarse estimate so a flat score surface
+            # (sustained pads, sparse onsets) can't drag the point sideways.
+            if score > best_score or (score == best_score and dist < best_dist):
+                best_score, best_t, best_dist = score, float(phase), dist
+
+        # A sweep that matched almost nothing found a spurious edge
+        # alignment, not the beat grid — this happens when the true phase
+        # lies outside the (ambiguity-clamped) window, e.g. fast tempos
+        # where the DTW coarse error exceeds half a beat. Keeping the
+        # coarse estimate degrades gracefully instead of locking a
+        # fraction of a beat off.
+        if best_score < 3:
+            refined.append((b, coarse))
+            continue
+
+        # The onset-count score is flat within ±onset_tolerance of the true
+        # phase, so the sweep alone can be off by up to the tolerance. Snap
+        # inside that plateau: shift by the median residual between matched
+        # onsets and their nearest grid click. Only the first few beats
+        # count here — they are nearly insensitive to beat_period error,
+        # while far clicks would leak that error into the residuals.
+        if best_score > 0:
+            clicks = np.arange(best_t, best_t + 4 * beat_period + 1e-9,
+                               beat_period)
+            residuals = []
+            for t in local:
+                d = clicks - float(t)
+                j = int(np.argmin(np.abs(d)))
+                if abs(d[j]) < onset_tolerance:
+                    residuals.append(-float(d[j]))  # onset minus click
+            if residuals:
+                best_t += float(np.median(residuals))
+        refined.append((b, best_t))
+
+    if not refined:
+        return sync
+
+    # Enforce monotonicity: a point refined earlier than its predecessor
+    # would fold the warp. Clamp to a small positive gap.
+    mono: list[tuple[int, float]] = []
+    prev_t: float | None = None
+    for b, t in refined:
+        t = max(t, 0.0)
+        if prev_t is not None and t <= prev_t + 0.02:
+            t = prev_t + 0.02
+        mono.append((b, t))
+        prev_t = t
+
+    # Recompute per-segment modified tempos from the refined times (same
+    # formula _extract_sync_points uses; the last point carries the previous
+    # segment's tempo forward).
+    new_points: list[SyncPoint] = []
+    for i, (b, t) in enumerate(mono):
+        obpm = _orig_bpm_at(b)
+        if i + 1 < len(mono):
+            b2, t2 = mono[i + 1]
+            score_seg = bar_starts[b2] - bar_starts[b]
+            audio_seg = t2 - t
+            mod = obpm * (score_seg / audio_seg) if audio_seg > 1e-3 else obpm
+            mod = max(20.0, min(300.0, mod))
+        else:
+            mod = new_points[-1].modified_tempo if new_points else obpm
+        new_points.append(SyncPoint(
+            bar=b, time_secs=t, modified_tempo=mod, original_tempo=obpm,
+        ))
+
+    _log.info("refine_sync: %d points (was %d), audio_offset=%.3fs",
+              len(new_points), len(pts), -new_points[0].time_secs)
+    return GpSyncData(
+        audio_offset=-new_points[0].time_secs,
+        audio_asset_id=sync.audio_asset_id,
+        sync_points=new_points,
+    )
+
+
 def estimate_audio_offset(gp_path: str, audio_path: str) -> float:
     """
     Estimate the audio_offset for a GP file aligned to an audio file.

lib/jsonc.py

@@ -0,0 +1,56 @@
+"""JSONC support — JSON with C-style comments.
+
+Per feedpak-spec §8: when a manifest pointer resolves to a ``.jsonc`` file, a
+Reader MUST strip ``//`` line comments and ``/* */`` block comments before
+parsing the JSON content. This module implements that stripping in a single
+shared place so every sloppak/feedpak reader in this repo parses ``.jsonc``
+the same way (string-aware so comment-like text inside JSON strings survives).
+
+The regex mirrors the reference implementation in ``feedpak-spec/tools/validate.py``.
+``load_json(path)`` auto-detects ``.jsonc`` by suffix; plain ``.json`` (and any
+other extension) goes straight through ``json.loads``. Use it as a drop-in
+replacement for ``json.loads(path.read_text(encoding="utf-8"))``.
+"""
+
+from __future__ import annotations
+
+import json
+import re
+from pathlib import Path
+
+# Match JSON string literals (preserved), // line comments, and /* block */
+# comments. A single combined alternation processed by `sub` with a callback
+# that keeps strings and replaces comments with the empty string — so
+# comment-like text inside a string literal is never stripped.
+_JSONC_STRIP_RE = re.compile(
+    r'"(?:[^"\\]|\\.)*"|'   # string literal — keep as-is
+    r'//.*|'                 # // line comment — strip
+    r'/\*[\s\S]*?\*/',       # /* block comment */ — strip
+)
+
+
+def parse_jsonc(text: str) -> object:
+    """Parse a JSONC string, stripping C-style comments before JSON parsing.
+
+    Handles ``//`` line comments and ``/* */`` block comments, respecting
+    string boundaries so that comment-like text inside strings is preserved.
+    Raises ``json.JSONDecodeError`` on malformed JSON (after stripping).
+    """
+    stripped = _JSONC_STRIP_RE.sub(
+        lambda m: m.group(0) if m.group(0).startswith('"') else '',
+        text,
+    )
+    return json.loads(stripped)
+
+
+def load_json(path: Path) -> object:
+    """Read and parse a JSON/JSONC file by path.
+
+    Files ending in ``.jsonc`` are stripped of comments via :func:`parse_jsonc`;
+    all other files are parsed as plain JSON. UTF-8 encoded, matching every
+    other reader in this repo.
+    """
+    raw = path.read_text(encoding="utf-8")
+    if path.name.lower().endswith(".jsonc"):
+        return parse_jsonc(raw)
+    return json.loads(raw)

lib/mb_match.py

@@ -0,0 +1,406 @@
+"""Text-matching engine for MusicBrainz metadata enrichment (P8).
+
+Pure functions only — no network, no database, no server imports — so the
+whole matching pipeline is unit-testable in isolation. server.py owns the
+throttled HTTP transport and the song_enrichment writes; this module owns:
+
+* denoise/tokenize: fold community chart-title noise (author suffixes,
+  ``(440Hz)``/``(Live)``/``(No Lead)``/``(v2)`` parentheticals, punctuation,
+  diacritics, ``AC DC``/``ACDC``/``AC/DC`` spelling drift) into a comparable
+  token form,
+* similarity + scoring: token-set similarity on artist+title with year and
+  duration proximity as corroborating bonuses,
+* tier classification: auto (high) / review (medium) / none (low) — the
+  design rule is that a WRONG match is worse than no match, so the auto
+  tier is deliberately strict and medium confidence goes to a human,
+* MusicBrainz JSON parsing: normalize ``/ws/2`` recording documents into
+  the flat candidate dicts the review UI and song_enrichment store.
+"""
+
+import re
+import unicodedata
+
+# ── Tier thresholds ───────────────────────────────────────────────────────────
+# Combined score = 0.5*artist_sim + 0.5*title_sim + corroboration bonuses
+# (capped at 1.0). Wrong-match is worse than slow (design §5), so `auto`
+# additionally requires BOTH fields to individually agree — a perfect title
+# with a mismatched artist (a cover) must never auto-canonicalize, whatever
+# the combined threshold is set to. AUTO_MIN is only the DEFAULT: the host
+# surfaces it as the user-configurable "auto-apply confidence" setting and
+# passes the chosen value into classify(auto_min=…).
+AUTO_MIN = 0.90
+AUTO_ARTIST_MIN = 0.8
+AUTO_TITLE_MIN = 0.6
+REVIEW_MIN = 0.65
+
+YEAR_BONUS = 0.05        # candidate year within ±1 of the chart's year
+DURATION_BONUS = 0.05    # candidate length within 5s of the chart's audio
+DURATION_BONUS_LOOSE = 0.025   # …within 15s
+_DURATION_TIGHT = 5
+_DURATION_LOOSE = 15
+
+# Release-group secondary types that mark a NON-canonical release (a live album,
+# a greatest-hits comp, a remix/DJ set, …). Used both to pick the canonical
+# studio album for display and to reward studio recordings in ranking.
+_SECONDARY_SKIP = {
+    "live", "compilation", "remix", "dj-mix", "mixtape/street",
+    "demo", "interview", "audiobook", "spokenword",
+}
+
+# ── Denoise ───────────────────────────────────────────────────────────────────
+# A parenthetical/bracketed group is dropped when it contains any of these
+# noise terms as a whole word (chart-variant markers, tuning/pitch notes,
+# performance qualifiers) or when it reads as an author credit ("by X",
+# "charted by X"). Both sides of a comparison are denoised symmetrically, so
+# over-stripping a meaningful group costs a little precision but never
+# produces an asymmetric mismatch.
+_NOISE_TERMS = (
+    r"440\s*hz", r"a440", r"432\s*hz",
+    r"live", r"acoustic", r"instrumental",
+    r"no\s+(?:lead|rhythm|bass|vocals?|drums)",
+    r"(?:lead|rhythm|bass)\s+only",
+    r"v\d+", r"ver(?:sion)?\s*\d+",
+    r"remaster(?:ed)?(?:\s*\d{4})?", r"re-?recorded?",
+    r"fix(?:ed)?", r"updated?",
+    r"bonus", r"custom",
+)
+_NOISE_GROUP_RE = re.compile(
+    r"[(\[][^)\]]*\b(?:" + "|".join(_NOISE_TERMS) + r")\b[^)\]]*[)\]]",
+    re.IGNORECASE,
+)
+# Author credits: "(by SomeCharter)", "[charted by X]", "(chart by X)".
+_AUTHOR_GROUP_RE = re.compile(
+    r"[(\[]\s*(?:chart(?:ed)?\s+)?by\s+[^)\]]*[)\]]", re.IGNORECASE)
+# Trailing "- by SomeCharter" outside parens.
+_AUTHOR_TAIL_RE = re.compile(r"\s+-\s+(?:chart(?:ed)?\s+)?by\s+.+$", re.IGNORECASE)
+
+_PUNCT_RE = re.compile(r"[^\w\s]|_")
+_WS_RE = re.compile(r"\s+")
+
+
+def _strip_diacritics(s: str) -> str:
+    return "".join(
+        ch for ch in unicodedata.normalize("NFKD", s)
+        if not unicodedata.combining(ch)
+    )
+
+
+def denoise(s, *, strip_leading_the: bool = False) -> str:
+    """Fold a community metadata string into its comparable form:
+    lowercase, diacritics stripped, noise parentheticals and author credits
+    removed, punctuation collapsed to spaces. ``strip_leading_the`` drops a
+    leading "The " — used for ARTIST comparison only ("The Beatles" ==
+    "Beatles"), never titles ("The Trooper" must keep its "the")."""
+    s = str(s or "")
+    s = _NOISE_GROUP_RE.sub(" ", s)
+    s = _AUTHOR_GROUP_RE.sub(" ", s)
+    s = _AUTHOR_TAIL_RE.sub(" ", s)
+    s = _strip_diacritics(s).casefold()
+    s = s.replace("&", " and ")
+    s = _PUNCT_RE.sub(" ", s)
+    s = _WS_RE.sub(" ", s).strip()
+    if strip_leading_the and s.startswith("the "):
+        s = s[4:]
+    return s
+
+
+def tokens(s, **kw) -> list[str]:
+    d = denoise(s, **kw)
+    return d.split() if d else []
+
+
+def _compact(toks: list[str]) -> str:
+    return "".join(toks)
+
+
+def similarity(a, b, *, artist: bool = False) -> float:
+    """Token-set similarity in [0, 1]. Dice coefficient over the denoised
+    token sets, with a compacted-string equality fold so spelling drift that
+    only moves token boundaries ("ACDC" / "AC DC" / "AC/DC", "Greenday" /
+    "Green Day") counts as identical."""
+    kw = {"strip_leading_the": artist}
+    ta, tb = tokens(a, **kw), tokens(b, **kw)
+    if not ta or not tb:
+        return 0.0
+    if _compact(ta) == _compact(tb):
+        return 1.0
+    sa, sb = set(ta), set(tb)
+    return 2.0 * len(sa & sb) / (len(sa) + len(sb))
+
+
+def _year_int(v):
+    try:
+        y = int(str(v)[:4])
+        return y if y > 0 else None
+    except (TypeError, ValueError):
+        return None
+
+
+def _duration_int(v):
+    try:
+        d = int(round(float(v)))
+        return d if d > 0 else None
+    except (TypeError, ValueError):
+        return None
+
+
+def cand_artist_sim(song: dict, cand: dict) -> float:
+    """Best artist similarity between the song's reference artist and the
+    candidate's PRIMARY name OR any of its `artist_aliases` (romanized/alternate
+    names). MusicBrainz stores many artists under a non-Latin primary name
+    (大橋純子) with the romanized form ("Junko Ohashi") only as an alias, so a
+    reference typed/derived in romaji scores 0 against the primary but 1.0
+    against the alias. The caller (server) attaches `artist_aliases` only for
+    promising near-misses, so this is a plain max when they're present and the
+    original single comparison when they're not."""
+    best = similarity(song.get("artist"), cand.get("artist"), artist=True)
+    for alias in cand.get("artist_aliases") or []:
+        if best >= 1.0:
+            break
+        s = similarity(song.get("artist"), alias, artist=True)
+        if s > best:
+            best = s
+    return best
+
+
+def score_candidate(song: dict, cand: dict) -> float:
+    """Combined confidence that MusicBrainz candidate `cand` is the song the
+    chart transcribes. 0.5*artist + 0.5*title, plus small year/duration
+    corroboration bonuses, capped at 1.0. Missing fields score 0 on their
+    half — classify() separately refuses to auto-match without both."""
+    artist_sim = cand_artist_sim(song, cand)
+    title_sim = similarity(song.get("title"), cand.get("title"))
+    score = 0.5 * artist_sim + 0.5 * title_sim
+    sy, cy = _year_int(song.get("year")), _year_int(cand.get("year"))
+    if sy and cy and abs(sy - cy) <= 1:
+        score += YEAR_BONUS
+    sd, cd = _duration_int(song.get("duration")), _duration_int(cand.get("duration"))
+    if sd and cd:
+        diff = abs(sd - cd)
+        if diff <= _DURATION_TIGHT:
+            score += DURATION_BONUS
+        elif diff <= _DURATION_LOOSE:
+            score += DURATION_BONUS_LOOSE
+    # NB: the studio-vs-live distinction is deliberately NOT scored here — a live
+    # take is still the RIGHT SONG (same title/artist), so it must not change the
+    # auto/review confidence. Canonical-version preference lives in the RANK sort
+    # (rank_candidates) instead, where it only reorders same-song candidates.
+    return min(score, 1.0)
+
+
+def classify(song: dict, cand: dict, score: float, auto_min: float | None = None) -> str:
+    """Tier for a scored candidate: 'auto' | 'review' | 'none'.
+
+    `auto` (tier-2) needs the combined score AND per-field agreement AND
+    both fields present — a perfect-title/wrong-artist cover, or a chart
+    with no artist at all, is at best a review item, never an auto match.
+    `auto_min` overrides the default combined-score threshold (the user's
+    "auto-apply confidence" setting); the per-field floors always apply.
+    """
+    if auto_min is None:
+        auto_min = AUTO_MIN
+    artist_sim = cand_artist_sim(song, cand)
+    title_sim = similarity(song.get("title"), cand.get("title"))
+    if (score >= auto_min and artist_sim >= AUTO_ARTIST_MIN
+            and title_sim >= AUTO_TITLE_MIN):
+        return "auto"
+    if score >= REVIEW_MIN:
+        return "review"
+    return "none"
+
+
+def rank_candidates(song: dict, candidates: list[dict]) -> list[dict]:
+    """Score every candidate against the song and return them sorted best-first.
+    The combined `score` caps at 1.0, so a perfect-text-match query (every "AC/DC
+    Highway to Hell" recording) ties at the top — there the studio flag and, when
+    the caller knows the audio length, the duration match break the tie so the
+    canonical studio take wins over live/promo/extended cuts. Each returned dict
+    is a copy carrying `score` (rounded — it's displayed and stored)."""
+    sd = _duration_int(song.get("duration"))
+    # For a chart that IS a live take (build_recording_query keeps live
+    # recordings for these) the studio take is the WRONG recording, so drop the
+    # studio tiebreak — duration proximity + text/mb score then pick the right
+    # live version instead of auto-matching the studio one.
+    prefer_studio = not _LIVE_GROUP_RE.search(str(song.get("title") or ""))
+
+    def _dur_diff(c):
+        cd = _duration_int(c.get("duration"))
+        return abs(sd - cd) if (sd and cd) else 10 ** 6
+
+    ranked = []
+    for cand in candidates or []:
+        c = dict(cand)
+        c["score"] = round(score_candidate(song, cand), 4)
+        ranked.append(c)
+    ranked.sort(
+        key=lambda c: (c["score"],
+                       (1 if c.get("studio") else 0) if prefer_studio else 0,
+                       -_dur_diff(c),                 # closest to the audio length
+                       c.get("mb_score") or 0),
+        reverse=True)
+    return ranked
+
+
+# ── MusicBrainz query + response parsing ──────────────────────────────────────
+
+def _lucene_escape_phrase(s: str) -> str:
+    """Escape a string for use inside a quoted Lucene phrase."""
+    return s.replace("\\", "\\\\").replace('"', '\\"')
+
+
+# A parenthetical/bracketed "(Live …)" marker — the live signal denoise() strips
+# from the title. Mirrors _NOISE_GROUP_RE but for the `live` term only.
+_LIVE_GROUP_RE = re.compile(r"[(\[][^)\]]*\blive\b[^)\]]*[)\]]", re.IGNORECASE)
+
+
+def build_recording_query(artist, title, *, loose: bool = False) -> str:
+    """Lucene query for /ws/2/recording. Built from the DENOISED fields —
+    the noise we strip (author credits, "(Live)", "(v2)") would otherwise
+    poison the search server's own scoring.
+
+    ``loose=True`` drops the field-scoped quoted PHRASES for plain AND-ed
+    term groups (``(telephone number) AND (junko ohashi)``). The point:
+    a field phrase like ``artist:"Junko Ohashi"`` only matches MusicBrainz's
+    *primary* artist name — it never searches ALIASES — so a recording stored
+    under a non-Latin primary (大橋純子) whose romanized name is only an alias
+    is invisible to the strict query. A loose term query searches the whole
+    document, aliases included, and surfaces it. Lower precision by design: it
+    is a FALLBACK for when the strict query returns nothing, and its results
+    are re-scored by ``rank_candidates`` (and, for auto-match, gated by the
+    per-field floors), so noise never auto-applies."""
+    t = denoise(title)
+    a = denoise(artist)
+    if loose:
+        # denoise() already reduced each field to lowercase [a-z0-9 and] tokens
+        # (punctuation → spaces, diacritics stripped, & → "and"), so no
+        # Lucene-special character survives to need escaping. Group each field's
+        # terms and require both groups.
+        q = " AND ".join("(%s)" % g for g in (t, a) if g)
+        # Keep the SAME live exclusion as the strict path: the loose query is
+        # lower-precision, and score_candidate doesn't penalize a live take, so
+        # without this a studio chart whose strict query missed could fall back
+        # to — and auto-confirm — a live-only recording. Skipped only when the
+        # source title is itself a live take (mirrors the strict path).
+        if q and not _LIVE_GROUP_RE.search(str(title or "")):
+            q += " AND -secondarytype:Live"
+        return q
+    parts = []
+    if t:
+        parts.append('recording:"%s"' % _lucene_escape_phrase(t))
+    if a:
+        parts.append('artist:"%s"' % _lucene_escape_phrase(a))
+    q = " AND ".join(parts)
+    # Drop live-ONLY recordings (bootlegs, live albums) — the canonical studio
+    # take is never tagged Live, and this is the single biggest source of junk in
+    # a flat recording search. Compilations are deliberately NOT excluded: they
+    # REUSE the studio recording, so filtering them would drop the very recording
+    # we want (verified against MusicBrainz — `-secondarytype:Compilation` cut the
+    # AC/DC studio "Highway to Hell" recording entirely).
+    #
+    # EXCEPT when the source chart is itself a live take: denoise() strips the
+    # "(Live at …)" qualifier from the query, so filtering Live would leave the
+    # genuinely-live chart with NO correct recording. Only a parenthetical marker
+    # counts — a bare title word ("Live and Let Die") is a real word, not a live
+    # tag — mirroring what denoise removes.
+    if q and not _LIVE_GROUP_RE.search(str(title or "")):
+        q += " AND -secondarytype:Live"
+    return q
+
+
+def _artist_credit(doc: dict) -> tuple[str, str, str]:
+    """(display name, artist mbid, sort name) from an artist-credit array."""
+    credits = doc.get("artist-credit") or []
+    name = ""
+    for part in credits:
+        if isinstance(part, dict):
+            name += str(part.get("name", "")) + str(part.get("joinphrase", "") or "")
+        else:  # ws/2 can emit bare join strings in older serializations
+            name += str(part)
+    first = next((p for p in credits if isinstance(p, dict)), None) or {}
+    artist = first.get("artist") or {}
+    return name, str(artist.get("id", "") or ""), str(artist.get("sort-name", "") or "")
+
+
+def _is_clean_studio_album(rg: dict) -> bool:
+    """A release-group that is a primary-type Album with NO non-canonical
+    secondary type (Live / Compilation / Remix / …) — i.e. a studio album."""
+    if str(rg.get("primary-type", "")).lower() != "album":
+        return False
+    secs = {str(s).lower() for s in (rg.get("secondary-types") or [])}
+    return not (secs & _SECONDARY_SKIP)
+
+
+def _best_release(doc: dict) -> dict:
+    """Pick the release used for canon album/year: prefer an OFFICIAL studio
+    Album (primary Album with no Live/Compilation/… secondary type), then the
+    earliest date. Falls back to any release when none is clean. {} if none."""
+    releases = [r for r in (doc.get("releases") or []) if isinstance(r, dict)]
+    if not releases:
+        return {}
+
+    def sort_key(r):
+        rg = r.get("release-group") or {}
+        clean = 0 if _is_clean_studio_album(rg) else 1
+        status_ok = 0 if str(r.get("status", "")).lower() == "official" else 1
+        date = str(r.get("date", "") or "9999")
+        # Official FIRST, then prefer a clean studio album: this still surfaces
+        # the studio album over an (official) live/comp album for the display
+        # album/year, but never lets an UNofficial bootleg album outrank an
+        # official single/EP/comp — which `(clean, status_ok, …)` would.
+        return (status_ok, clean, date)
+
+    return sorted(releases, key=sort_key)[0]
+
+
+def _genres(doc: dict, limit: int = 5) -> list[str]:
+    """Genre names from a recording doc. Search results carry folksonomy
+    `tags`; lookups with inc=genres carry curated `genres`. Both are
+    [{name, count}] — take the most-voted few."""
+    raw = doc.get("genres") or doc.get("tags") or []
+    entries = [e for e in raw if isinstance(e, dict) and e.get("name")]
+    entries.sort(key=lambda e: e.get("count") or 0, reverse=True)
+    return [str(e["name"]) for e in entries[:limit]]
+
+
+def parse_recording_doc(doc: dict) -> dict | None:
+    """Normalize one /ws/2 recording document (search hit or direct lookup)
+    into the flat candidate dict stored in song_enrichment.candidates and
+    rendered by the review drawer. Returns None for malformed docs."""
+    if not isinstance(doc, dict) or not doc.get("id") or not doc.get("title"):
+        return None
+    artist_name, artist_id, artist_sort = _artist_credit(doc)
+    release = _best_release(doc)
+    studio = _is_clean_studio_album(release.get("release-group") or {})
+    length = doc.get("length")
+    try:
+        duration = int(round(float(length) / 1000.0)) if length else None
+    except (TypeError, ValueError):
+        duration = None
+    isrcs = doc.get("isrcs") or []
+    isrcs = [str(i) for i in isrcs if isinstance(i, (str,))]
+    return {
+        "recording_id": str(doc["id"]),
+        "title": str(doc.get("title", "")),
+        "artist": artist_name,
+        "artist_id": artist_id,
+        "artist_sort": artist_sort,
+        "release_id": str(release.get("id", "") or ""),
+        "album": str(release.get("title", "") or ""),
+        "year": str(release.get("date", "") or "")[:4],
+        "duration": duration,
+        "isrc": isrcs[0] if isrcs else "",
+        "genres": _genres(doc),
+        "mb_score": int(doc.get("score") or 0),
+        "studio": studio,
+    }
+
+
+def parse_search_response(body: dict) -> list[dict]:
+    """Candidates from a /ws/2/recording search response."""
+    docs = (body or {}).get("recordings") or []
+    out = []
+    for doc in docs:
+        cand = parse_recording_doc(doc)
+        if cand:
+            out.append(cand)
+    return out

lib/midi_import.py

@@ -203,7 +203,13 @@ def convert_midi_track_to_keys_wire(
     #     a foreign track's tempo events do NOT apply to the chosen
     #     track. Merging would mis-time the notes — restrict the tempo
     #     scan to the selected track only.
-    ticks_per_beat = midi.ticks_per_beat
+    # ``ticks_per_beat`` is 0 for a malformed header and NEGATIVE for SMPTE
+    # division (mido returns the signed short as-is). Both feed the two
+    # divisions below (tempo-table build + tick_to_seconds), so guard here:
+    # 0 would raise ZeroDivisionError and a negative value would yield
+    # negative/garbage times. Use ``> 0`` (not ``or``) so the negative SMPTE
+    # case also falls back to the SMF default.
+    ticks_per_beat = midi.ticks_per_beat if midi.ticks_per_beat > 0 else 480
     raw_events: list[tuple[int, int]] = [(0, 500000)]  # default 120 BPM
     midi_type = getattr(midi, "type", 1)
     tempo_source = (
@@ -352,7 +358,14 @@ def _build_tick_to_seconds(midi: mido.MidiFile, track_index: int) -> Callable[[i
       - type 1: parallel tracks share the timeline; merge tempo events.
       - type 2: independent timelines; tempo only from the chosen track.
     """
-    ticks_per_beat = midi.ticks_per_beat
+    # A metrical header carries positive ticks-per-beat. mido reads the SMF
+    # division as a signed short, so an SMPTE-division file surfaces as a
+    # negative value and a malformed header as 0 — both make the two division
+    # sites below divide by a non-positive number (ZeroDivisionError, or
+    # negative seconds that send the bar walk off the rails). Fall back to the
+    # SMF default here, the single place every caller routes ticks through, so
+    # each caller's own fallback is real rather than cosmetic.
+    ticks_per_beat = midi.ticks_per_beat if midi.ticks_per_beat > 0 else 480
     raw_events: list[tuple[int, int]] = [(0, 500000)]  # default 120 BPM
     midi_type = getattr(midi, "type", 1)
     tempo_source = (
@@ -393,6 +406,141 @@ def _build_tick_to_seconds(midi: mido.MidiFile, track_index: int) -> Callable[[i
     return tick_to_seconds
 
 
+# Safety valve for the bar walk below: a malformed SMF (absurd tempo + long
+# trailing meta) could otherwise imply millions of bars. Real charts sit
+# orders of magnitude below this.
+_TEMPO_MAP_MAX_BARS = 20000
+
+
+def convert_midi_tempo_map(midi_path: str, track_index: int = 0) -> dict:
+    """Extract the song-timeline grid a `.mid` file carries: tempos, time
+    signatures, and a full beat grid — the data the note converters here
+    always computed internally (to bake note times) and then threw away,
+    which left every MIDI import with no bars, no measures, and an implied
+    4/4 no matter what the file said.
+
+    Returns ``{"tempos": [...], "time_signatures": [...], "beats": [...]}``:
+
+    - ``tempos``: ``{time, bpm}`` per tempo event (deduped per tick).
+    - ``time_signatures``: ``{time, ts: [num, den]}`` per signature event —
+      the song-timeline sidecar shape (feedpak-spec §7.4).
+    - ``beats``: one row per beat on the editor grid shape — downbeats carry
+      a running ``measure`` (1, 2, 3, …) plus a ``den`` hint (the signature
+      denominator), interior beats carry ``measure: -1``. The beat unit
+      follows the active signature (6/8 ⇒ six eighth-note rows per bar).
+
+    Event scope mirrors ``_build_tick_to_seconds``: SMF type 0/1 merge meta
+    from all tracks (shared timeline); type 2 reads ONLY ``track_index``
+    (independent timelines — callers must never share one grid across
+    type-2 tracks). Signature changes apply at the NEXT bar boundary when a
+    file places one mid-bar (ill-formed but seen in the wild). All times
+    are computed from absolute ticks through the cumulative tempo table and
+    rounded once at emit — rounding error never accumulates with song
+    length. An SMF with no note events yields empty ``beats``.
+    """
+    midi = mido.MidiFile(midi_path)
+    # Positive for metrical files; 0 (malformed) or negative (SMPTE division,
+    # read as a signed short) otherwise — fall back so beat_ticks below stays
+    # sane, mirroring the guard inside _build_tick_to_seconds.
+    ticks_per_beat = midi.ticks_per_beat if midi.ticks_per_beat > 0 else 480
+    midi_type = getattr(midi, "type", 1)
+    # Same scope both converters use: type 2 reads only the chosen track
+    # (independent timelines); type 0/1 merge all tracks (shared timeline).
+    source_tracks = (
+        [midi.tracks[track_index]] if midi_type == 2 else midi.tracks
+    )
+    tick_to_seconds = _build_tick_to_seconds(midi, track_index)
+
+    # ── collect meta + the end of musical content in one pass ────────────
+    sig_events: list[tuple[int, int, int]] = []
+    tempo_events: list[tuple[int, int]] = []
+    end_tick = 0
+    for tr in source_tracks:
+        abs_tick = 0
+        for msg in tr:
+            abs_tick += msg.time
+            if msg.type == "time_signature":
+                num = int(getattr(msg, "numerator", 4) or 4)
+                den = int(getattr(msg, "denominator", 4) or 4)
+                if num > 0 and den > 0:
+                    sig_events.append((abs_tick, num, den))
+            elif msg.type == "set_tempo":
+                tempo_events.append((abs_tick, int(msg.tempo)))
+            elif msg.type in ("note_on", "note_off"):
+                end_tick = max(end_tick, abs_tick)
+
+    # Dedupe at equal ticks (last wins), matching the tempo-table rule.
+    sig_events.sort(key=lambda e: e[0])
+    sigs: list[tuple[int, int, int]] = []
+    for ev in sig_events:
+        if sigs and sigs[-1][0] == ev[0]:
+            sigs[-1] = ev
+        else:
+            sigs.append(ev)
+    if not sigs or sigs[0][0] > 0:
+        sigs.insert(0, (0, 4, 4))
+
+    tempo_events.sort(key=lambda e: e[0])
+    seen_tempo_ticks: dict[int, int] = {}
+    for ev_tick, ev_tempo in tempo_events:
+        seen_tempo_ticks[ev_tick] = ev_tempo
+    sorted_tempo_ticks = sorted(seen_tempo_ticks)
+    tempos_out: list[dict] = []
+    # Seed the MIDI default (120 BPM) at time 0 when the first tempo event
+    # lands after the start (or there are none). The beat grid already runs
+    # at 120 for the head of the song, so the sidecar must say so too —
+    # symmetric with the (0, 4, 4) default seeded into the signatures above.
+    if not sorted_tempo_ticks or sorted_tempo_ticks[0] > 0:
+        tempos_out.append({"time": 0.0, "bpm": 120.0})
+    for ev_tick in sorted_tempo_ticks:
+        tempos_out.append({
+            "time": round(tick_to_seconds(ev_tick), 3),
+            "bpm": round(60_000_000.0 / seen_tempo_ticks[ev_tick], 3),
+        })
+
+    time_signatures_out = [
+        {"time": round(tick_to_seconds(t), 3), "ts": [num, den]}
+        for t, num, den in sigs
+    ]
+
+    # ── walk bars from tick 0 to the end of the notes ────────────────────
+    beats: list[dict] = []
+    if end_tick > 0:
+        cur_tick = 0.0
+        measure = 1
+        sig_idx = 0
+        while cur_tick < end_tick and measure <= _TEMPO_MAP_MAX_BARS:
+            # Active signature: the latest event at or before this bar's
+            # start. Mid-bar events wait for the next boundary by
+            # construction (we only re-read between bars).
+            while (sig_idx + 1 < len(sigs)
+                    and sigs[sig_idx + 1][0] <= cur_tick + 1e-6):
+                sig_idx += 1
+            _, num, den = sigs[sig_idx]
+            beat_ticks = ticks_per_beat * 4.0 / den
+            beats.append({
+                "time": round(tick_to_seconds(int(round(cur_tick))), 3),
+                "measure": measure,
+                "den": den,
+            })
+            for k in range(1, num):
+                sub_tick = cur_tick + k * beat_ticks
+                if sub_tick >= end_tick:
+                    break
+                beats.append({
+                    "time": round(tick_to_seconds(int(round(sub_tick))), 3),
+                    "measure": -1,
+                })
+            cur_tick += num * beat_ticks
+            measure += 1
+
+    return {
+        "tempos": tempos_out,
+        "time_signatures": time_signatures_out,
+        "beats": beats,
+    }
+
+
 # ── Drum track listing (channel-9 only) ──────────────────────────────────────
 
 # Velocity below this is treated as a ghost note. GM doesn't have an explicit
@@ -486,10 +634,12 @@ def convert_drum_track_from_midi(
 
     Callers can pass an empty dict as ``out_unmapped`` to receive a
     per-MIDI record of every channel-9 note_on that didn't resolve to a
-    piece-id (``{midi: {"count": int, "times": [float, ...]}}``, times
-    capped at 100 samples per note). The default path skips this
-    capture entirely so MIDIs heavy with cowbell/tambourine/etc. take
-    no extra work.
+    piece-id (``{midi: {"count": int, "times": [float, ...],
+    "velocities": [int, ...]}}``, times/velocities index-aligned and
+    capped at 100 samples per note — velocities carry the source notes'
+    real dynamics so a hand-mapping UI doesn't have to flatten them to a
+    default). The default path skips this capture entirely so MIDIs
+    heavy with cowbell/tambourine/etc. take no extra work.
     """
     offset = float(audio_offset)
     if not math.isfinite(offset):
@@ -527,10 +677,13 @@ def convert_drum_track_from_midi(
                     continue
                 t = tick_to_seconds(abs_tick) + offset
                 entry = out_unmapped.setdefault(
-                    midi_note, {"count": 0, "times": []})
+                    midi_note, {"count": 0, "times": [], "velocities": []})
                 entry["count"] += 1
                 if len(entry["times"]) < 100:
                     entry["times"].append(round(t, 3))
+                    # Index-aligned with times: the note's real dynamics,
+                    # so hand-mapping doesn't flatten everything to 100.
+                    entry["velocities"].append(int(msg.velocity))
                 continue
             # Mapped note: compute t once for the raw entry.
             t = tick_to_seconds(abs_tick) + offset

lib/notation_lift.py

@@ -114,11 +114,27 @@ def split_hands(notes: list[dict]) -> dict[str, list[dict]]:
         pitches = sorted(n["midi"] for n in group)
         span = pitches[-1] - pitches[0]
         if len(pitches) > 1 and span > HAND_SPLIT_SPAN_SEMITONES:
-            # Largest internal gap; ties resolve to the lowest such gap so the
-            # left hand keeps the tight low cluster.
-            gaps = [pitches[i + 1] - pitches[i] for i in range(len(pitches) - 1)]
-            split_after = gaps.index(max(gaps))
-            threshold = pitches[split_after]  # lh: midi <= threshold
+            # Prefer middle C as the split boundary when notes straddle it —
+            # this correctly handles bass+treble chords from piano imports where
+            # the largest-gap heuristic picks the wrong split point (e.g.
+            # [G2, E3, C4]: largest gap is G2→E3 but the real split is E3|C4).
+            # BUT only when both resulting hands are themselves playable: a bass
+            # note under a treble voicing that merely dips below C4 (e.g.
+            # [E2, B3, D4, G4]) would otherwise land E2+B3 in one hand — a
+            # 19-semitone span that re-violates HAND_SPLIT_SPAN_SEMITONES. When
+            # the middle-C split produces an unplayable hand, fall back to the
+            # largest internal gap (which correctly isolates E2 there).
+            threshold = None
+            if pitches[0] < MIDDLE_C <= pitches[-1]:
+                _lh = [p for p in pitches if p < MIDDLE_C]
+                _rh = [p for p in pitches if p >= MIDDLE_C]
+                if (_lh[-1] - _lh[0] <= HAND_SPLIT_SPAN_SEMITONES
+                        and _rh[-1] - _rh[0] <= HAND_SPLIT_SPAN_SEMITONES):
+                    threshold = MIDDLE_C - 1  # lh: midi < MIDDLE_C
+            if threshold is None:
+                gaps = [pitches[i + 1] - pitches[i] for i in range(len(pitches) - 1)]
+                split_after = gaps.index(max(gaps))
+                threshold = pitches[split_after]
             for n in group:
                 hands["lh" if n["midi"] <= threshold else "rh"].append(n)
         else:

lib/reqfields.py

@@ -0,0 +1,13 @@
+"""Request-field coercion helpers shared by the raw-`dict` POST handlers.
+
+Extracted verbatim from ``server.py`` (R3). Pure — no IO, no globals — so it
+imports cleanly from both ``server`` and any ``routers/`` module.
+"""
+
+
+def _clean_str(value) -> str:
+    """Trim a request field to a string; non-strings (or missing) → ''.
+    Lets the raw-`dict` POST handlers treat wrong-typed JSON (an int/list/etc.
+    where a string was expected) as "empty" and answer 400, instead of raising
+    AttributeError/TypeError → 500 on a later .strip()/`in`."""
+    return value.strip() if isinstance(value, str) else ""

lib/routers/__init__.py

@@ -0,0 +1,31 @@
+"""FastAPI route modules extracted from ``server.py`` (R3).
+
+Each module here exposes a module-level ``router`` (a ``fastapi.APIRouter``)
+that ``server.py`` mounts with ``app.include_router(...)`` at the point in the
+file where those routes used to be defined — FastAPI matches routes in
+registration order, so keeping the mount site preserves it.
+
+**Routers must never ``import server``.** They reach core singletons through
+the injected seam instead::
+
+    import appstate
+
+    @router.get("/api/thing")
+    def get_thing():
+        return appstate.meta_db.thing()
+
+and always as a **module attribute, at call time** — never
+``from appstate import meta_db``, which freezes the binding and defeats both a
+later ``appstate.configure()`` and ``monkeypatch.setattr``. See ``appstate.py``.
+
+Dependencies flow one way: ``server -> routers -> appstate``.
+
+**Why this lives under ``lib/``.** ``lib/`` is the only core directory every
+packaging path already copies wholesale — the Dockerfile (``COPY lib/``),
+``docker-compose.yml``, and feedback-desktop's ``bundle-slopsmith.sh``
+(``cp -r lib``) — and all three put it on ``sys.path``. A root-level package
+ships in Docker but is silently dropped from the packaged desktop app, whose
+bundler copies a hardcoded file list. Route modules import nothing at module
+scope beyond FastAPI and ``appstate``, so they do no import-time IO and satisfy
+Principle V's rule for ``lib/``.
+"""

lib/routers/artist_aliases.py

@@ -0,0 +1,68 @@
+"""Artist aliases / Tidy-up (P4) — canonicalize messy artist tags at DISPLAY
+("ACDC" -> "AC/DC") without touching feedpak files or the scanner-derived
+songs.artist. All DB-only.
+
+Extracted verbatim from ``server.py`` (R3); only the decorator receiver
+(``@app`` -> ``@router``) and the singleton read (``meta_db`` ->
+``appstate.meta_db``) changed. The read stays a module attribute so a re-imported
+``server`` re-publishes a fresh DB into the seam — see ``appstate.py``.
+"""
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+import appstate
+
+router = APIRouter()
+
+
+@router.get("/api/artist-aliases")
+def list_artist_aliases():
+    """Existing raw→canonical overrides (the Tidy-up 'current merges' list)."""
+    return {"aliases": appstate.meta_db.list_artist_aliases()}
+
+
+@router.get("/api/artists/raw")
+def list_raw_artists(limit: int = 2000):
+    """Distinct RAW artist names + song counts + current canonical — the Tidy-up
+    picker (you merge raw variants into one canonical)."""
+    return {"artists": appstate.meta_db.raw_artists(limit)}
+
+
+@router.post("/api/artist-aliases")
+def set_artist_alias(data: dict):
+    """Upsert one override: {raw_name, canonical_name, mb_artist_id?}. A self-alias
+    (raw == canonical) clears the row instead (un-merge)."""
+    raw = (data.get("raw_name") or "").strip()
+    canon = (data.get("canonical_name") or "").strip()
+    if not raw or not canon:
+        return JSONResponse({"error": "raw_name and canonical_name are required"}, 400)
+    result = appstate.meta_db.set_artist_alias(raw, canon, (data.get("mb_artist_id") or None))
+    if not result.get("ok"):
+        # Would form a cycle (raw → … → raw) — refuse rather than corrupt the chain.
+        return JSONResponse(
+            {"error": "alias would create a cycle", "raw_name": raw, "canonical_name": canon},
+            409)
+    return {"ok": True, "raw_name": raw, "canonical_name": result.get("canonical_name", canon)}
+
+
+@router.post("/api/artist-aliases/merge")
+def merge_artist_aliases(data: dict):
+    """Merge several raw artist variants into one canonical:
+    {raw_names: [...], canonical_name}. The canonical's own self-alias is skipped.
+    Returns {merged: N}."""
+    canon = (data.get("canonical_name") or "").strip()
+    raws = data.get("raw_names")
+    if not canon:
+        return JSONResponse({"error": "canonical_name is required"}, 400)
+    if not isinstance(raws, list) or not raws:
+        return JSONResponse({"error": "raw_names must be a non-empty array"}, 400)
+    n = appstate.meta_db.merge_artists(raws, canon)
+    return {"merged": n, "canonical_name": canon}
+
+
+@router.delete("/api/artist-aliases/{raw_name:path}")
+def delete_artist_alias(raw_name: str):
+    """Remove one override so that raw artist stands on its own again."""
+    appstate.meta_db.remove_artist_alias(raw_name)
+    return {"ok": True}

lib/routers/audio_effects.py

@@ -0,0 +1,80 @@
+"""Audio-effects mapping API — the core-owned song/tone -> provider routing index.
+
+Extracted verbatim from ``server.py`` (R3); only the decorator receiver
+(``@app`` -> ``@router``) and the singleton read (``audio_effect_mappings`` ->
+``appstate.audio_effect_mappings``) changed. The read must stay a module
+attribute so a re-imported ``server`` re-publishes a fresh DB into the seam and
+`monkeypatch.setattr` reaches this module — see ``appstate.py``.
+"""
+
+from fastapi import APIRouter, Body, Query
+from fastapi.responses import JSONResponse
+
+import appstate
+
+router = APIRouter()
+
+
+def _audio_effects_error(exc: Exception):
+    return JSONResponse({"error": str(exc)}, status_code=400)
+
+
+@router.get("/api/audio-effects/mappings")
+def list_audio_effect_mappings(
+    song_key: str = Query(""),
+    filename: str = Query(""),
+    tone_key: str = Query(""),
+    provider_id: str = Query(""),
+):
+    try:
+        return {
+            "mappings": appstate.audio_effect_mappings.list(
+                song_key=song_key,
+                filename=filename,
+                tone_key=tone_key,
+                provider_id=provider_id,
+            )
+        }
+    except ValueError as exc:
+        return _audio_effects_error(exc)
+
+
+@router.post("/api/audio-effects/mappings")
+def upsert_audio_effect_mapping(data: dict = Body(...)):
+    try:
+        mapping = appstate.audio_effect_mappings.upsert(data)
+    except ValueError as exc:
+        return _audio_effects_error(exc)
+    return {"ok": True, "mapping": mapping}
+
+
+@router.delete("/api/audio-effects/mappings/{mapping_id}")
+def delete_audio_effect_mapping(mapping_id: int, provider_id: str = Query("")):
+    try:
+        deleted = appstate.audio_effect_mappings.delete(mapping_id, provider_id=provider_id)
+    except ValueError as exc:
+        return _audio_effects_error(exc)
+    if not deleted:
+        return JSONResponse({"error": "mapping not found"}, status_code=404)
+    return {"ok": True}
+
+
+@router.post("/api/audio-effects/mappings/{mapping_id}/activate")
+def activate_audio_effect_mapping(mapping_id: int, data: dict = Body(default_factory=dict)):
+    try:
+        provider_id = data.get("provider_id") if "provider_id" in data else data.get("providerId")
+        mapping = appstate.audio_effect_mappings.activate(mapping_id, provider_id="" if provider_id is None else provider_id)
+    except ValueError as exc:
+        return _audio_effects_error(exc)
+    if not mapping:
+        return JSONResponse({"error": "mapping not found"}, status_code=404)
+    return {"ok": True, "mapping": mapping}
+
+
+@router.delete("/api/audio-effects/active-mapping")
+def clear_audio_effect_active_mapping(song_key: str = Query(...), tone_key: str = Query("")):
+    try:
+        cleared = appstate.audio_effect_mappings.clear_active(song_key=song_key, tone_key=tone_key)
+    except ValueError as exc:
+        return _audio_effects_error(exc)
+    return {"ok": True, "cleared": cleared}

lib/routers/chart.py

@@ -0,0 +1,115 @@
+"""Chart-level endpoints — split/unsplit a chart from its work, resolve work
+membership, and the context-menu "Get info" file inspector.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``. DLC path resolution comes from
+``dlc_paths``; sloppak/loose detection from the shared lib modules.
+"""
+
+from fastapi import APIRouter, HTTPException
+
+import appstate
+from dlc_paths import _get_dlc_dir, _resolve_dlc_path
+import sloppak as sloppak_mod
+import loosefolder as loosefolder_mod
+
+router = APIRouter()
+
+
+@router.post("/api/chart/{filename:path}/split")
+def api_split_chart(filename: str):
+    """'These aren't the same song' — split this chart out as its own singleton
+    work. Under /api/chart (NOT /api/song) so the DELETE /api/song/{path}
+    catch-all can't shadow it."""
+    key = appstate.meta_db._canonical_song_filename(filename)
+    appstate.meta_db.split_chart(key)
+    return {"ok": True, "filename": key}
+
+
+@router.post("/api/chart/{filename:path}/unsplit")
+def api_unsplit_chart(filename: str):
+    """Undo a split — rejoin the chart to its work."""
+    key = appstate.meta_db._canonical_song_filename(filename)
+    appstate.meta_db.unsplit_chart(key)
+    return {"ok": True, "filename": key}
+
+
+@router.get("/api/chart/{filename:path}/work")
+def api_get_chart_work(filename: str):
+    """Resolve a chart's work membership: {work_key, chart_count}. For openers
+    on rows that came from an ungrouped query (the tree view) — grouped grid
+    rows already carry both fields inline."""
+    return appstate.meta_db.chart_work(filename)
+
+
+@router.get("/api/chart/{filename:path}/fileinfo")
+def api_chart_fileinfo(filename: str):
+    """The context menu's "Get info": where the file lives + what the pack
+    contains. Under /api/chart — the GET /api/song/{path} catch-all would
+    swallow a /api/song/…/fileinfo suffix. Read-only; demo-mode blocks it
+    because it exposes filesystem paths."""
+    dlc = _get_dlc_dir()
+    if not dlc:
+        raise HTTPException(status_code=404, detail="not configured")
+    p = _resolve_dlc_path(dlc, filename)
+    if p is None:
+        raise HTTPException(status_code=403, detail="forbidden")
+    if not p.exists():
+        raise HTTPException(status_code=404, detail="not found")
+    # Restrict to actual charts — sloppak or loose song. Without this the route
+    # would stat ANY file the user happens to keep under DLC_DIR (e.g. notes),
+    # leaking its path/size; the app only recognises these two song formats.
+    is_pak = sloppak_mod.is_sloppak(p)
+    is_loose = loosefolder_mod.is_loose_song(p)
+    if not (is_pak or is_loose):
+        raise HTTPException(status_code=404, detail="not a chart")
+    st = p.stat()
+    info = {
+        "filename": filename,
+        "path": str(p),
+        "folder": str(p.parent),
+        "format": "sloppak" if is_pak else "loose",
+        # Directory-form songs report the tree's total (covers loose folders
+        # and dir-form paks); zip-form paks report the archive size. Symlinked
+        # entries are skipped so a link inside the folder can't pull in — or
+        # leak the size of — a file outside it.
+        "size": (st.st_size if p.is_file()
+                 else sum(f.stat().st_size for f in p.rglob("*")
+                          if f.is_file() and not f.is_symlink())),
+        "mtime": st.st_mtime,
+    }
+    if is_pak:
+        try:
+            m = sloppak_mod.load_manifest(p) or {}
+        except Exception:
+            m = {}
+        arrs = [str(a.get("name", a.get("id", ""))) for a in (m.get("arrangements") or [])
+                if isinstance(a, dict)]
+        stems = [str(s.get("id", "")) for s in (m.get("stems") or []) if isinstance(s, dict)]
+        try:
+            has_cover = sloppak_mod.read_cover_bytes(p, m) is not None
+        except Exception:
+            has_cover = False
+        # The optional identity/catalog keys, listed only when present — the
+        # Get-info panel's "what this pack carries vs what's missing" readout.
+        identity = {k: m.get(k) for k in
+                    ("mbid", "isrc", "genres", "track", "disc", "album_artist",
+                     "feedpak_version", "language")
+                    if m.get(k) not in (None, "", [])}
+        info["manifest"] = {
+            "title": str(m.get("title", "")), "artist": str(m.get("artist", "")),
+            "album": str(m.get("album", "")), "year": str(m.get("year", "") or ""),
+            "arrangements": arrs, "stems": stems,
+            "has_cover": has_cover, "has_lyrics": bool(m.get("lyrics")),
+            "authors": [a.get("name", "") if isinstance(a, dict) else str(a)
+                        for a in (m.get("authors") or [])],
+            "identity": identity,
+        }
+    # The enrichment verdict, so Get info can say "Matched (auto, 96%)" /
+    # "Pinned by you" / "Not matched" alongside the file facts.
+    row = appstate.meta_db.get_enrichment(filename)
+    if row:
+        info["match"] = {k: row.get(k) for k in
+                         ("match_state", "match_source", "match_score",
+                          "canon_artist", "canon_title", "canon_album", "canon_year")}
+    return info

lib/routers/diagnostics.py

@@ -0,0 +1,295 @@
+"""Diagnostic bundle export + hardware probe (/api/diagnostics/*).
+
+One-click "Export Diagnostics" in Settings produces a redacted zip combining
+server logs, system info, hardware (CPU/GPU/RAM), plugin inventory, and the
+browser-side console transcript + hardware probe. Bundle format is specified in
+docs/diagnostics-bundle-spec.md.
+
+Extracted verbatim from server.py (R3) except:
+  - the decorators (@app -> @router),
+  - CONFIG_DIR -> appstate.config_dir and _running_version() ->
+    appstate.running_version() (both read through the appstate seam),
+  - the builtin-plugins lookup in _diag_plugins_roots: Path(__file__).parent
+    (the app root when this lived at the top level) ->
+    Path(__file__).resolve().parents[2] (routers -> lib -> app root). The
+    plugins/ dir ships at the app root in every packaging path.
+
+The pure helpers + caps here are re-exported from server.py so the existing
+`server._diag_*` / `server._DIAG_*` tests keep resolving (none monkeypatch them).
+"""
+
+import json
+import logging
+import os
+from pathlib import Path
+
+from fastapi import APIRouter, Body, Response
+
+import appstate
+from dlc_paths import _get_dlc_dir
+from diagnostics_bundle import build_bundle as _diag_build, preview_bundle as _diag_preview
+from diagnostics_hardware import collect as _diag_hardware
+from env_compat import getenv_compat
+
+log = logging.getLogger("feedBack.server")
+router = APIRouter()
+
+
+def _diag_log_file() -> Path | None:
+    raw = os.environ.get("LOG_FILE", "").strip()
+    if not raw:
+        return None
+    return Path(raw)
+
+
+def _diag_plugins_roots() -> list[Path]:
+    """Return all plugin root directories for orphan scanning.
+
+    Includes both the built-in ``plugins/`` directory and
+    ``FEEDBACK_PLUGINS_DIR`` when set, so user-installed plugins and
+    orphans in the external dir are reflected in the bundle.
+    """
+    roots: list[Path] = []
+    user_dir = getenv_compat("FEEDBACK_PLUGINS_DIR", "").strip()
+    if user_dir:
+        p = Path(user_dir)
+        if p.is_dir():
+            roots.append(p)
+    builtin = Path(__file__).resolve().parents[2] / "plugins"  # R3: app root from lib/routers/
+    if builtin not in roots:
+        roots.append(builtin)
+    return roots
+
+
+def _diag_coerce_bool(v, *, default: bool = True) -> bool:
+    """Coerce a request-side value to bool, accepting both JSON booleans and
+    string representations.
+
+    - Falsy strings: ``"false"``, ``"0"``, ``"no"``, ``""`` → ``False``
+    - ``None`` → *default*
+    - Everything else (including ``"true"``, ``"1"``) → ``True``
+    """
+    if v is None:
+        return default
+    if isinstance(v, bool):
+        return v
+    if isinstance(v, str):
+        return v.strip().lower() not in ("false", "0", "no", "")
+    return bool(v)
+
+
+def _diag_normalize_include(include: dict | None) -> dict:
+    """Coerce request-side flags to the booleans build_bundle expects.
+    Missing keys default to True so a bare {} request still produces
+    the full bundle.
+
+    Accepts both JSON booleans (``true``/``false``) and string
+    representations so callers that serialize flags as strings behave
+    consistently with the preview endpoint:
+    - Falsy strings: ``"false"``, ``"0"``, ``"no"``, ``""`` → ``False``
+    - Everything else (including ``"true"``, ``"1"``, ``"yes"``) → ``True``
+    """
+    keys = ("system", "hardware", "logs", "console", "plugins")
+    if not isinstance(include, dict):
+        return {k: True for k in keys}
+
+    return {k: _diag_coerce_bool(include.get(k), default=True) for k in keys}
+
+
+# Server-side caps on client-supplied payload sections.  diagnostics.js
+# enforces a 500-entry / ~250 KB ring buffer on the browser side; these
+# bounds give generous headroom while still preventing a crafted POST from
+# forcing the server to allocate arbitrarily large in-memory bundles.
+_DIAG_MAX_CONSOLE_ENTRIES = 1000          # hard cap: truncate silently
+_DIAG_MAX_CONSOLE_BYTES = 2 * 1024 * 1024  # 2 MB hard cap on total console list
+_DIAG_MAX_CLIENT_PAYLOAD_BYTES = 2 * 1024 * 1024   # 2 MB per dict section
+_DIAG_MAX_CONTRIBUTIONS_BYTES = 4 * 1024 * 1024    # 4 MB aggregate cap for contributions
+
+
+def _diag_cap_console(v) -> list | None:
+    """Return *v* if it is a list, truncated to _DIAG_MAX_CONSOLE_ENTRIES entries
+    and _DIAG_MAX_CONSOLE_BYTES total.  Entries are accumulated until either cap
+    is reached; no partial-entry splitting occurs."""
+    if not isinstance(v, list):
+        return None
+    result = v[:_DIAG_MAX_CONSOLE_ENTRIES]
+    # Also enforce a byte cap — the count cap alone does not bound memory when
+    # entries contain arbitrarily large strings.
+    try:
+        out = []
+        total = 0
+        for entry in result:
+            encoded = json.dumps(entry, separators=(",", ":")).encode("utf-8", errors="replace")
+            if total + len(encoded) > _DIAG_MAX_CONSOLE_BYTES:
+                break
+            out.append(entry)
+            total += len(encoded)
+        return out
+    except (TypeError, ValueError):
+        return None
+
+
+def _diag_cap_dict(v) -> dict | None:
+    """Return *v* if it is a dict whose JSON serialisation fits within
+    _DIAG_MAX_CLIENT_PAYLOAD_BYTES, otherwise return None."""
+    if not isinstance(v, dict):
+        return None
+    try:
+        encoded = json.dumps(v, separators=(",", ":")).encode("utf-8", errors="replace")
+    except (TypeError, ValueError) as e:
+        log.warning("diagnostics client payload is not JSON-serialisable, dropping: %s", e)
+        return None
+    if len(encoded) > _DIAG_MAX_CLIENT_PAYLOAD_BYTES:
+        return None
+    return v
+
+
+def _diag_cap_contributions(v, known_ids=None) -> dict | None:
+    """Apply per-plugin and aggregate size caps on client_contributions.
+
+    Unlike _diag_cap_dict(), which drops the whole dict when any plugin
+    exceeds the limit, this function caps each plugin independently so
+    one noisy plugin does not silence every other plugin's contribution.
+
+    Parameters
+    ----------
+    v:
+        The raw contributions dict from the POST payload.
+    known_ids:
+        When provided, contributions from plugins not in this set are
+        skipped *before* serialisation, preventing a malicious caller
+        from forcing the server to JSON-encode hundreds of near-limit
+        payloads that ``build_bundle()`` would later discard anyway.
+        ``None`` means "accept all plugin ids" (used in tests / preview).
+    """
+    if not isinstance(v, dict):
+        return None
+    result = {}
+    total_bytes = 0
+    for pid, contribution in v.items():
+        if not isinstance(pid, str):
+            continue
+        # Filter unknown plugin ids early — before serialising — so a
+        # crafted request cannot force large allocations for plugins that
+        # build_bundle() would drop.
+        if known_ids is not None and pid not in known_ids:
+            continue
+        try:
+            encoded = json.dumps(contribution, separators=(",", ":")).encode("utf-8", errors="replace")
+        except (TypeError, ValueError) as e:
+            log.warning(
+                "client_contributions[%r] is not JSON-serialisable, dropping: %s", pid, e
+            )
+            continue
+        if len(encoded) > _DIAG_MAX_CLIENT_PAYLOAD_BYTES:
+            log.warning(
+                "client_contributions[%r] exceeds %d bytes, dropping",
+                pid, _DIAG_MAX_CLIENT_PAYLOAD_BYTES,
+            )
+            continue
+        if total_bytes + len(encoded) > _DIAG_MAX_CONTRIBUTIONS_BYTES:
+            log.warning(
+                "client_contributions aggregate size limit (%d bytes) reached, "
+                "dropping remaining entries",
+                _DIAG_MAX_CONTRIBUTIONS_BYTES,
+            )
+            break
+        result[pid] = contribution
+        total_bytes += len(encoded)
+    return result or None
+
+
+@router.post("/api/diagnostics/export")
+def export_diagnostics(payload: dict = Body(default_factory=dict)):
+    """Build a diagnostic bundle and stream it back as a zip download.
+
+    The browser layers in `client_console`, `client_hardware`,
+    `client_ua`, and `local_storage` before posting; the server adds
+    server logs, hardware, plugin inventory, and packages everything
+    into a single zip.
+
+    Errors during plugin diagnostics callables are caught and logged
+    to the bundle's manifest `notes` rather than failing the export.
+    """
+    from plugins import LOADED_PLUGINS, PLUGINS_LOCK
+
+    redact = _diag_coerce_bool(payload.get("redact", True), default=True)
+    include = _diag_normalize_include(payload.get("include"))
+    client_console = _diag_cap_console(payload.get("client_console"))
+    client_hardware = _diag_cap_dict(payload.get("client_hardware"))
+    client_ua = _diag_cap_dict(payload.get("client_ua"))
+    local_storage = _diag_cap_dict(payload.get("local_storage"))
+    # Fetch the plugin list first so we can filter contributions to known
+    # plugin ids before serialising — prevents a crafted request from
+    # forcing large allocations for plugins build_bundle() would drop.
+    with PLUGINS_LOCK:
+        plugins_snapshot = list(LOADED_PLUGINS)
+    known_ids = {p.get("id") for p in plugins_snapshot if isinstance(p.get("id"), str)}
+    client_contributions = _diag_cap_contributions(
+        payload.get("client_contributions"), known_ids=known_ids
+    )
+
+    zip_bytes, filename, _manifest = _diag_build(
+        feedBack_version=appstate.running_version(),
+        config_dir=appstate.config_dir,
+        dlc_dir=_get_dlc_dir(),
+        log_file=_diag_log_file(),
+        loaded_plugins=plugins_snapshot,
+        include=include,
+        redact=redact,
+        client_console=client_console,
+        client_hardware=client_hardware,
+        client_ua=client_ua,
+        local_storage=local_storage,
+        client_contributions=client_contributions,
+        log=log,
+        plugins_root=_diag_plugins_roots(),
+    )
+    return Response(
+        content=zip_bytes,
+        media_type="application/zip",
+        headers={"Content-Disposition": f'attachment; filename="{filename}"'},
+    )
+
+
+@router.get("/api/diagnostics/preview")
+def preview_diagnostics(
+    redact: bool = True,
+    system: bool = True,
+    hardware: bool = True,
+    logs: bool = True,
+    console: bool = True,
+    plugins: bool = True,
+):
+    """Return what `/api/diagnostics/export` would produce, minus the
+    actual file contents — file tree, sizes, schemas, redaction counts.
+    Lets the Settings UI show the user what's about to be sent."""
+    from plugins import LOADED_PLUGINS, PLUGINS_LOCK
+
+    include = {
+        "system": system,
+        "hardware": hardware,
+        "logs": logs,
+        "console": console,
+        "plugins": plugins,
+    }
+    with PLUGINS_LOCK:
+        plugins_snapshot = list(LOADED_PLUGINS)
+    return _diag_preview(
+        feedBack_version=appstate.running_version(),
+        config_dir=appstate.config_dir,
+        dlc_dir=_get_dlc_dir(),
+        log_file=_diag_log_file(),
+        loaded_plugins=plugins_snapshot,
+        include=include,
+        redact=redact,
+        log=log,
+        plugins_root=_diag_plugins_roots(),
+    )
+
+
+@router.get("/api/diagnostics/hardware")
+def diagnostics_hardware():
+    """Backend hardware probe (cross-platform). Reusable independently
+    of the bundle export — handy for "what's my GPU" plugin queries."""
+    return _diag_hardware()

lib/routers/library_extras.py

@@ -0,0 +1,75 @@
+"""Small meta_db-backed library / user-state endpoints — work keeper-chart
+prefs, favorites, personal tags, saved-for-later, and continue-playing.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``_clean_str`` from ``reqfields``. All paths
+are distinct and non-overlapping, so mounting them together (rather than at each
+original scattered site) does not change routing.
+"""
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+import appstate
+from reqfields import _clean_str
+
+router = APIRouter()
+
+
+@router.get("/api/work/{work_key:path}/charts")
+def api_get_work_charts(work_key: str):
+    """All charts in a work + which is the keeper (your pick vs auto-pick)."""
+    return appstate.meta_db.work_charts(work_key)
+
+
+@router.put("/api/work/{work_key:path}/preferred")
+def api_set_work_preferred(work_key: str, data: dict):
+    """Set the keeper chart of a work: body {filename}. The filename must be a
+    current member of the work. Returns the refreshed chart list."""
+    fn = (data.get("filename") or "").strip()
+    if not fn:
+        return JSONResponse({"error": "filename is required"}, 400)
+    members = {c["filename"] for c in appstate.meta_db.work_charts(work_key)["charts"]}
+    if fn not in members:
+        return JSONResponse({"error": "filename is not a chart of this work"}, 400)
+    appstate.meta_db.set_chart_preferred(work_key, fn)
+    return appstate.meta_db.work_charts(work_key)
+
+
+@router.delete("/api/work/{work_key:path}/preferred")
+def api_reset_work_preferred(work_key: str):
+    """Reset a work to auto-pick (drop the explicit preferred)."""
+    appstate.meta_db.clear_chart_preferred(work_key)
+    return appstate.meta_db.work_charts(work_key)
+
+
+@router.post("/api/favorites/toggle")
+def toggle_favorite(data: dict):
+    """Toggle a song's favorite status."""
+    filename = data.get("filename", "")
+    if not filename:
+        return {"error": "No filename"}
+    new_state = appstate.meta_db.toggle_favorite(filename)
+    return {"favorite": new_state}
+
+
+@router.get("/api/tags")
+def list_tags():
+    """All personal tags in use (over still-present songs), most-used first —
+    powers the tag filter UI."""
+    return {"tags": appstate.meta_db.all_tags()}
+
+
+@router.post("/api/saved/toggle")
+def api_toggle_saved(data: dict):
+    """Add/remove a song on the reserved Saved-for-Later playlist."""
+    filename = _clean_str(data.get("filename"))
+    if not filename:
+        return JSONResponse({"error": "filename required"}, status_code=400)
+    return {"saved": appstate.meta_db.toggle_saved(filename)}
+
+
+@router.get("/api/session/continue")
+def api_session_continue():
+    """The Continue-Playing card's song (most recent play) or null."""
+    return appstate.meta_db.continue_session()

lib/routers/loops.py

@@ -0,0 +1,60 @@
+"""Practice loops — saved A/B regions per song.
+
+Extracted verbatim from ``server.py`` (R3); only the decorator receiver
+(``@app`` -> ``@router``) and the singleton reads (``meta_db`` ->
+``appstate.meta_db``) changed. See ``appstate.py`` for why the reads stay
+module attributes.
+"""
+
+from fastapi import APIRouter
+
+import appstate
+
+router = APIRouter()
+
+
+@router.get("/api/loops")
+def list_loops(filename: str):
+    # Hold the DB lock for the read: the shared single connection
+    # (check_same_thread=False) is serialized through meta_db._lock by every
+    # writer, so an unlocked SELECT here can overlap a POST/DELETE commit.
+    db = appstate.meta_db
+    with db._lock:
+        rows = db.conn.execute(
+            "SELECT id, name, start_time, end_time FROM loops WHERE filename = ? ORDER BY start_time",
+            (filename,)
+        ).fetchall()
+    return [{"id": r[0], "name": r[1], "start": r[2], "end": r[3]} for r in rows]
+
+
+@router.post("/api/loops")
+def save_loop(data: dict):
+    filename = data.get("filename", "")
+    name = data.get("name", "").strip()
+    start = data.get("start")
+    end = data.get("end")
+    if not filename or start is None or end is None:
+        return {"error": "Missing fields"}
+    db = appstate.meta_db
+    with db._lock:
+        # COUNT + INSERT under one lock so two unnamed POSTs can't read the same
+        # count and both mint "Loop N" (the count is only used to name the row).
+        if not name:
+            count = db.conn.execute(
+                "SELECT COUNT(*) FROM loops WHERE filename = ?", (filename,)
+            ).fetchone()[0]
+            name = f"Loop {count + 1}"
+        db.conn.execute(
+            "INSERT INTO loops (filename, name, start_time, end_time) VALUES (?, ?, ?, ?)",
+            (filename, name, float(start), float(end))
+        )
+        db.conn.commit()
+    return {"ok": True, "name": name}
+
+
+@router.delete("/api/loops/{loop_id}")
+def delete_loop(loop_id: int):
+    with appstate.meta_db._lock:
+        appstate.meta_db.conn.execute("DELETE FROM loops WHERE id = ?", (loop_id,))
+        appstate.meta_db.conn.commit()
+    return {"ok": True}

lib/routers/playlists.py

@@ -0,0 +1,267 @@
+"""Playlists + custom playlist covers (fee[dB]ack v0.3.0).
+
+Extracted verbatim from ``server.py`` (R3). Edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``CONFIG_DIR`` -> ``appstate.config_dir``
+(both read at call time through the seam), and ``_clean_str`` now imports from
+``reqfields``. See ``appstate.py``.
+"""
+
+import logging
+import os
+import tempfile
+from pathlib import Path
+
+from fastapi import APIRouter
+from fastapi.responses import FileResponse, JSONResponse
+
+import appstate
+from reqfields import _clean_str
+
+log = logging.getLogger("feedBack.server")
+
+router = APIRouter()
+
+# Cache policy for the custom-cover file response: revalidate every time so a
+# replaced cover is never served stale (pairs with the mtime-ns URL token).
+_ART_CACHE_HEADERS = {"Cache-Control": "no-cache"}
+
+
+def _playlist_cover_path(pid) -> Path | None:
+    """Filesystem path of a playlist's optional custom cover image (PNG),
+    stored under CONFIG_DIR. Returns None for a non-integer id."""
+    try:
+        pid = int(pid)
+    except (TypeError, ValueError):
+        return None
+    return appstate.config_dir / "playlist_covers" / f"{pid}.png"
+
+
+def _playlist_cover_url(pid) -> str | None:
+    cover = _playlist_cover_path(pid)
+    if not cover or not cover.exists():
+        return None
+    try:
+        # Nanosecond mtime so a same-second replace/remove/re-upload still
+        # changes the cache-bust token (int seconds could collide → stale image).
+        mt = cover.stat().st_mtime_ns
+    except OSError:
+        mt = 0
+    return f"/api/playlists/{pid}/cover?v={mt}"
+
+
+@router.get("/api/playlists")
+def api_list_playlists():
+    lists = appstate.meta_db.list_playlists()
+    for pl in lists:
+        pl["cover_url"] = _playlist_cover_url(pl["id"])
+    return lists
+
+
+@router.post("/api/playlists")
+def api_create_playlist(data: dict):
+    name = _clean_str(data.get("name"))
+    if not (1 <= len(name) <= 100):
+        return JSONResponse({"error": "Playlist name must be 1–100 characters."}, status_code=400)
+    # kind='album' = a curated album (§7.2): hand-picked works, a chosen chart
+    # per slot, played front-to-back on the queue. Absent/None = a regular mix.
+    kind = _clean_str(data.get("kind")) or None
+    if kind not in (None, "album"):
+        return JSONResponse({"error": "kind must be 'album' or omitted"}, status_code=400)
+    return appstate.meta_db.create_playlist(name, kind=kind)
+
+
+@router.get("/api/playlists/{pid}")
+def api_get_playlist(pid: int):
+    pl = appstate.meta_db.get_playlist(pid)
+    if pl is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    pl["cover_url"] = _playlist_cover_url(pid)
+    return pl
+
+
+@router.patch("/api/playlists/{pid}")
+def api_rename_playlist(pid: int, data: dict):
+    pl = appstate.meta_db.get_playlist(pid)
+    if pl is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    if pl["system_key"]:
+        return JSONResponse({"error": "System playlists cannot be renamed."}, status_code=400)
+    name = _clean_str(data.get("name"))
+    if not (1 <= len(name) <= 100):
+        return JSONResponse({"error": "Playlist name must be 1–100 characters."}, status_code=400)
+    appstate.meta_db.rename_playlist(pid, name)
+    return appstate.meta_db.get_playlist(pid)
+
+
+@router.delete("/api/playlists/{pid}")
+def api_delete_playlist(pid: int):
+    pl = appstate.meta_db.get_playlist(pid)
+    if pl is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    if pl["system_key"]:
+        return JSONResponse({"error": "System playlists cannot be deleted."}, status_code=400)
+    if not appstate.meta_db.delete_playlist(pid):   # vanished under us (concurrent delete)
+        return JSONResponse({"error": "not found"}, status_code=404)
+    cover = _playlist_cover_path(pid)       # drop any custom cover with the playlist
+    if cover and cover.exists():
+        try:
+            cover.unlink()
+        except OSError:
+            pass
+    return {"ok": True}
+
+
+@router.post("/api/playlists/{pid}/songs")
+def api_add_playlist_song(pid: int, data: dict):
+    if appstate.meta_db.get_playlist(pid) is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    filename = _clean_str(data.get("filename"))
+    if not filename:
+        return JSONResponse({"error": "filename required"}, status_code=400)
+    if appstate.meta_db.add_playlist_song(pid, filename) is None:   # playlist vanished under us
+        return JSONResponse({"error": "not found"}, status_code=404)
+    pl = appstate.meta_db.get_playlist(pid)
+    return pl if pl is not None else JSONResponse({"error": "not found"}, status_code=404)
+
+
+@router.patch("/api/playlists/{pid}/songs/{filename:path}")
+def api_update_playlist_slot(pid: int, filename: str, data: dict):
+    """Edit one curated-album slot: {"arrangement": name|null} pins/clears the
+    slot's arrangement; {"chart_filename": fn} swaps the slot to another chart
+    of the same work (position + pin kept). Albums only — a mix has no slots."""
+    pl = appstate.meta_db.get_playlist(pid)
+    if pl is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    if pl.get("kind") != "album":
+        return JSONResponse({"error": "Slot editing is for albums."}, status_code=400)
+    kwargs = {}
+    if "chart_filename" in data:
+        new_fn = _clean_str(data.get("chart_filename"))
+        if not new_fn:
+            return JSONResponse({"error": "chart_filename must be a filename"}, status_code=400)
+        kwargs["new_filename"] = new_fn
+    if "arrangement" in data:
+        arr = data.get("arrangement")
+        if arr is not None and not (isinstance(arr, str) and 1 <= len(arr.strip()) <= 100):
+            return JSONResponse({"error": "arrangement must be a name or null"}, status_code=400)
+        kwargs["arrangement"] = arr.strip() if isinstance(arr, str) else None
+    if not kwargs:
+        return JSONResponse({"error": "nothing to update"}, status_code=400)
+    if appstate.meta_db.update_playlist_slot(pid, filename, **kwargs) is None:
+        return JSONResponse(
+            {"error": "no such slot, or the chart isn't a version of this song"},
+            status_code=400)
+    return appstate.meta_db.get_playlist(pid)
+
+
+@router.delete("/api/playlists/{pid}/songs/{filename:path}")
+def api_remove_playlist_song(pid: int, filename: str):
+    if appstate.meta_db.get_playlist(pid) is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    appstate.meta_db.remove_playlist_song(pid, filename)
+    pl = appstate.meta_db.get_playlist(pid)
+    return pl if pl is not None else JSONResponse({"error": "not found"}, status_code=404)
+
+
+@router.post("/api/playlists/{pid}/reorder")
+def api_reorder_playlist(pid: int, data: dict):
+    pl = appstate.meta_db.get_playlist(pid)
+    if pl is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    order = data.get("order")
+    if not isinstance(order, list) or not all(isinstance(f, str) for f in order):
+        return JSONResponse({"error": "order must be a list of filenames"}, status_code=400)
+    # Require an exact permutation of the playlist's current songs: a list with
+    # duplicates, omissions, or extras would otherwise produce duplicate
+    # positions / a partial reorder while still returning 200.
+    current = [s["filename"] for s in pl["songs"]]
+    if len(order) != len(current) or sorted(order) != sorted(current):
+        return JSONResponse(
+            {"error": "order must be a permutation of the playlist's current songs"},
+            status_code=400,
+        )
+    appstate.meta_db.reorder_playlist(pid, order)
+    return appstate.meta_db.get_playlist(pid)
+
+
+@router.post("/api/playlists/{pid}/cover")
+async def api_set_playlist_cover(pid: int, data: dict):
+    """Set a playlist's custom cover from a base64 / data-URL image (PNG/JPG).
+    Overrides the content-dependent (song-art) cover. Stored as a small PNG
+    thumbnail under CONFIG_DIR/playlist_covers/."""
+    if appstate.meta_db.get_playlist(pid) is None:
+        return JSONResponse({"error": "not found"}, status_code=404)
+    import base64
+    import io
+    b64 = data.get("image", "")
+    # Guard the type before the `","` membership test — a non-string image
+    # (e.g. {"image": 123} / null) would otherwise raise TypeError → 500.
+    # Mirrors the avatar/song-art upload guard.
+    if not isinstance(b64, str) or not b64:
+        return JSONResponse({"error": "No image data"}, status_code=400)
+    if "," in b64:
+        b64 = b64.split(",", 1)[1]
+    if not b64:
+        return JSONResponse({"error": "No image data"}, status_code=400)
+    try:
+        img_data = base64.b64decode(b64)
+    except Exception:
+        return JSONResponse({"error": "Invalid base64"}, status_code=400)
+    cover = _playlist_cover_path(pid)
+    cover.parent.mkdir(parents=True, exist_ok=True)
+    # Decode/validate the image — a bad payload is a CLIENT error (400), and the
+    # message stays generic so it can't echo internals.
+    try:
+        from PIL import Image
+        img = Image.open(io.BytesIO(img_data)).convert("RGB")
+        img.thumbnail((640, 640))                  # covers stay small
+    except Exception:
+        return JSONResponse({"error": "Invalid image"}, status_code=400)
+    # Persist. A save/replace failure is a SERVER error (500, logged, no
+    # filesystem detail leaked) — the pre-split handler mislabeled these as 400
+    # and echoed the exception. A unique temp name in the cover dir (not a shared
+    # `{pid}.png.tmp`) means two concurrent uploads can't clobber each other's
+    # temp file; the atomic replace publishes. Re-check the playlist still exists
+    # just before publishing so a delete that raced the decode above can't leave
+    # an orphan cover — cheap belt-and-braces; FeedBack is single-user
+    # (Principle I), so a full per-playlist lock would be for a race the
+    # deployment model precludes.
+    tmp = None
+    try:
+        # mkstemp is inside the try too: an unwritable dir / full disk raises
+        # here, and that's the same class of persistence failure as save/replace.
+        fd, tmp_name = tempfile.mkstemp(prefix=f".{pid}.", suffix=".png.tmp", dir=str(cover.parent))
+        tmp = Path(tmp_name)
+        with os.fdopen(fd, "wb") as f:
+            img.save(f, "PNG")
+        if appstate.meta_db.get_playlist(pid) is None:
+            tmp.unlink(missing_ok=True)
+            return JSONResponse({"error": "not found"}, status_code=404)
+        tmp.replace(cover)
+    except Exception:
+        if tmp is not None:
+            tmp.unlink(missing_ok=True)
+        log.exception("playlist cover save failed (pid=%s)", pid)
+        return JSONResponse({"error": "could not save cover"}, status_code=500)
+    return {"ok": True, "cover_url": _playlist_cover_url(pid)}
+
+
+@router.get("/api/playlists/{pid}/cover")
+def api_get_playlist_cover(pid: int):
+    cover = _playlist_cover_path(pid)
+    if not cover or not cover.exists():
+        return JSONResponse({"error": "not found"}, status_code=404)
+    # no-cache (revalidate) like song art, so a replaced cover is never served
+    # stale — pairs with the mtime-ns cache-bust token on the URL.
+    return FileResponse(str(cover), media_type="image/png", headers=_ART_CACHE_HEADERS)
+
+
+@router.delete("/api/playlists/{pid}/cover")
+def api_delete_playlist_cover(pid: int):
+    cover = _playlist_cover_path(pid)
+    if cover and cover.exists():
+        try:
+            cover.unlink()
+        except OSError:
+            pass
+    return {"ok": True}

lib/routers/profile.py

@@ -0,0 +1,138 @@
+"""Player profile — identity, avatars (bundled + custom uploads), and progress.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``CONFIG_DIR``/``STATIC_DIR`` ->
+``appstate.config_dir``/``appstate.static_dir`` (seam), ``_clean_str`` from
+``reqfields``, ``_get_progression_content()`` ->
+``appstate.get_progression_content()``. The bundled-avatar lister moves with it.
+"""
+
+import logging
+import secrets
+
+from fastapi import APIRouter
+from fastapi.responses import FileResponse, JSONResponse
+
+import appstate
+from reqfields import _clean_str
+
+log = logging.getLogger("feedBack.server")
+
+router = APIRouter()
+
+
+def _list_bundled_avatars() -> list[str]:
+    """Bundled default avatar filenames under static/v3/avatars/."""
+    d = appstate.static_dir / "v3" / "avatars"
+    if not d.is_dir():
+        return []
+    exts = {".svg", ".png", ".webp"}
+    return sorted(
+        p.name for p in d.iterdir()
+        if p.is_file() and p.suffix.lower() in exts and not p.name.startswith(".")
+    )
+
+
+@router.get("/api/profile")
+def api_get_profile():
+    profile = appstate.meta_db.get_profile()
+    # Equipped cosmetics ride along (resolved to their payloads) so the theme
+    # and avatar frame apply at boot without an extra request. Never let a
+    # cosmetics/content problem break the profile read.
+    cosmetics = {}
+    try:
+        shop = appstate.get_progression_content()["shop"]
+        for slot, item_id in appstate.meta_db.get_equipped().items():
+            item = shop.get(item_id)
+            if item:
+                cosmetics[slot] = {"item_id": item_id, "payload": item["payload"]}
+    except Exception:
+        log.warning("profile cosmetics enrich failed", exc_info=True)
+    profile["cosmetics"] = cosmetics
+    return profile
+
+
+
+@router.post("/api/profile")
+def api_set_profile(data: dict):
+    """Set/update the player profile. Body: {display_name, avatar:{type,value}}.
+    avatar.type is 'default' (value = bundled filename) or 'upload' (value =
+    the /api/profile/avatar/<name> URL returned by the upload endpoint); omit
+    avatar to keep the existing one (name-only edit)."""
+    name = _clean_str(data.get("display_name"))
+    if not (1 <= len(name) <= 32):
+        return JSONResponse({"error": "Display name must be 1–32 characters."}, status_code=400)
+    avatar = data.get("avatar")
+    if avatar is None:
+        avatar = {}            # omitted → keep the current avatar (name-only edit)
+    elif not isinstance(avatar, dict):
+        return JSONResponse({"error": "avatar must be an object."}, status_code=400)
+    atype = avatar.get("type")
+    aval = _clean_str(avatar.get("value"))
+    avatar_url = None
+    if atype == "default":
+        if aval not in _list_bundled_avatars():
+            return JSONResponse({"error": "Unknown default avatar."}, status_code=400)
+        avatar_url = f"/static/v3/avatars/{aval}"
+    elif atype == "upload":
+        from safepath import safe_join
+        fname = aval.rsplit("/", 1)[-1] if aval.startswith("/api/profile/avatar/") else ""
+        target = safe_join(appstate.config_dir / "avatars", fname) if fname else None
+        if target is None or not target.is_file():
+            return JSONResponse({"error": "Uploaded avatar not found."}, status_code=400)
+        avatar_url = f"/api/profile/avatar/{fname}"
+    elif atype:
+        return JSONResponse({"error": "Unknown avatar type."}, status_code=400)
+    # atype None/missing → keep the current avatar (name-only edit).
+    return appstate.meta_db.set_profile(name, avatar_url)
+
+
+@router.get("/api/profile/avatars")
+def api_list_avatars():
+    return [{"name": n, "url": f"/static/v3/avatars/{n}"} for n in _list_bundled_avatars()]
+
+
+@router.post("/api/profile/avatar")
+def api_upload_avatar(data: dict):
+    """Upload a custom avatar as base64 (mirrors the album-art upload pattern).
+    Re-encodes to a ≤512px PNG under appstate.config_dir/avatars/."""
+    import base64
+    import io
+    b64 = data.get("image", "")
+    if not isinstance(b64, str) or not b64:
+        return JSONResponse({"error": "No image data"}, status_code=400)
+    if "," in b64:
+        b64 = b64.split(",", 1)[1]
+    try:
+        raw = base64.b64decode(b64)
+    except Exception:
+        return JSONResponse({"error": "Invalid base64"}, status_code=400)
+    if len(raw) > 6 * 1024 * 1024:
+        return JSONResponse({"error": "Image too large (max 6 MB)."}, status_code=400)
+    avatars_dir = appstate.config_dir / "avatars"
+    avatars_dir.mkdir(parents=True, exist_ok=True)
+    try:
+        from PIL import Image
+        img = Image.open(io.BytesIO(raw)).convert("RGB")
+        img.thumbnail((512, 512))
+        fname = f"upload-{secrets.token_hex(4)}.png"  # token busts caches on change
+        img.save(str(avatars_dir / fname), "PNG")
+    except Exception as e:
+        return JSONResponse({"error": f"Invalid image: {e}"}, status_code=400)
+    return {"url": f"/api/profile/avatar/{fname}"}
+
+
+@router.get("/api/profile/avatar/{name}")
+def api_get_avatar(name: str):
+    from safepath import safe_join
+    target = safe_join(appstate.config_dir / "avatars", name)
+    if target is None or not target.is_file():
+        return JSONResponse({"error": "not found"}, status_code=404)
+    return FileResponse(str(target), media_type="image/png")
+
+
+@router.get("/api/profile/progress")
+def api_profile_progress():
+    """One call for the whole profile badge: {level, xp, xp_in_level,
+    xp_to_next, current_streak, best_streak, last_active_date}."""
+    return appstate.meta_db.get_progress()

lib/routers/progression.py

@@ -0,0 +1,230 @@
+"""Progression (spec 010) — mastery rank, challenges, quests, onboarding paths.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``_clean_str`` from ``reqfields``, and the
+two shared server accessors read through the seam:
+``_get_progression_content()`` -> ``appstate.get_progression_content()`` and
+``_builtin_diagnostic_filename()`` -> ``appstate.builtin_diagnostic_filename()``.
+The exclusive helpers (_goal_ui_progress, _progression_overview) + the
+_PROGRESSION_EVENT_TYPES whitelist move with it.
+"""
+
+import math
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+import appstate
+from reqfields import _clean_str
+
+router = APIRouter()
+
+
+def _goal_ui_progress(goal: dict, state: dict, streak: int, xp_total: int) -> tuple:
+    """(count, target) for a challenge/quest progress bar. Count goals show
+    n/target; threshold goals show how far the live stat is along the line."""
+    import progression as progression_mod
+    gtype = goal.get("type")
+    if gtype in progression_mod.COUNT_GOAL_TYPES:
+        target = int(goal.get("target") or 1)
+        count = target if state.get("completed") else min(int(state.get("count") or 0), target)
+        return count, target
+    if gtype == "streak_reached":
+        target = int(goal.get("days") or 1)
+        return (target if state.get("completed") else min(streak, target)), target
+    if gtype == "db_earned":
+        target = int(goal.get("amount") or 1)
+        return (target if state.get("completed") else min(xp_total, target)), target
+    return 0, 1
+
+
+def _progression_overview() -> dict:
+    """The full GET /api/progression payload (also the capability `inspect`
+    result): rank, onboarding, per-path challenge checklists, quests, wallet."""
+    import progression as progression_mod
+    from datetime import datetime as _dt
+    content = appstate.get_progression_content()
+    now = _dt.now()
+    appstate.meta_db.ensure_quest_period(content, now)
+
+    state = appstate.meta_db.get_progression_state()
+    player_paths = appstate.meta_db.get_player_paths()
+    challenge_state = appstate.meta_db.get_challenge_state()
+    wallet = appstate.meta_db.get_wallet()
+    streak_progress = appstate.meta_db.get_progress()
+    streak = int(streak_progress.get("current_streak") or 0)
+    xp_total = wallet["lifetime_db"]
+    keys = progression_mod.period_keys(now)
+
+    def _path_order(pid):
+        pdef = content["paths"].get(pid) or {}
+        return (pdef.get("order") or 0, pid)
+
+    paths_payload = []
+    for pid in sorted(player_paths, key=_path_order):
+        pdef = content["paths"].get(pid)
+        level = player_paths[pid]
+        if not pdef:
+            # Path selected under older content that no longer ships: keep its
+            # rank contribution visible rather than silently dropping it.
+            paths_payload.append({"id": pid, "name": pid, "icon": "", "level": level,
+                                  "max_level": level, "next": None})
+            continue
+        next_block = None
+        active = progression_mod.active_challenges(content, pid, level)
+        if active:
+            level_def = next(e for e in pdef["levels"] if e["level"] == level + 1)
+            challenges = []
+            completed_count = 0
+            for ch in active:
+                st = challenge_state.get(ch["id"]) or {}
+                count, target = _goal_ui_progress(ch["goal"], st, streak, xp_total)
+                if st.get("completed"):
+                    completed_count += 1
+                challenges.append({
+                    "id": ch["id"],
+                    "title": ch["title"],
+                    "description": ch["description"],
+                    "count": count,
+                    "target": target,
+                    "completed": bool(st.get("completed")),
+                    "completed_at": st.get("completed_at"),
+                })
+            next_block = {
+                "level": level + 1,
+                "required": level_def["required"],
+                "completed": completed_count,
+                "challenges": challenges,
+            }
+        paths_payload.append({
+            "id": pid,
+            "name": pdef["name"],
+            "icon": pdef["icon"],
+            "level": level,
+            "max_level": progression_mod.path_max_level(content, pid),
+            "next": next_block,
+        })
+
+    available = [
+        {"id": pid, "name": pdef["name"], "icon": pdef["icon"]}
+        for pid, pdef in sorted(content["paths"].items(), key=lambda kv: (kv[1].get("order") or 0, kv[0]))
+        if pid not in player_paths
+    ]
+
+    quest_rows = appstate.meta_db.get_quest_rows(keys)
+    quests_payload = {}
+    for period_type in ("daily", "weekly"):
+        pool = content["quests"][period_type]["pool"]
+        quests = []
+        for row in quest_rows:
+            if row["period_type"] != period_type:
+                continue
+            qdef = pool.get(row["quest_id"])
+            if not qdef:
+                continue  # removed from the pool mid-period: hide, keep the row
+            count, target = _goal_ui_progress(qdef["goal"], row, streak, xp_total)
+            quests.append({
+                "id": row["quest_id"],
+                "title": qdef["title"],
+                "description": qdef["description"],
+                "reward_db": row["reward_db"],
+                "count": count,
+                "target": target,
+                "completed": row["completed"],
+                "completed_at": row["completed_at"],
+            })
+        quests_payload[period_type] = {
+            "period_key": keys[period_type],
+            "resets_at": progression_mod.period_resets_at(period_type, now).isoformat(),
+            "quests": quests,
+        }
+
+    return {
+        "mastery_rank": progression_mod.mastery_rank(state["calibration_status"], player_paths),
+        "onboarding": {
+            "calibration_status": state["calibration_status"],
+            "calibration_completed_at": state["calibration_completed_at"],
+            "diagnostic_filename": appstate.builtin_diagnostic_filename(),
+        },
+        "paths": paths_payload,
+        "available_paths": available,
+        "quests": quests_payload,
+        "wallet": wallet,
+    }
+
+
+@router.get("/api/progression")
+def api_progression():
+    return _progression_overview()
+
+
+@router.post("/api/progression/paths")
+def api_progression_add_paths(data: dict):
+    """Select instrument paths. Body: {add: [path_id, ...]}. Idempotent;
+    removal is unsupported (Mastery Rank never decreases)."""
+    add = data.get("add")
+    if not isinstance(add, list) or not add:
+        return JSONResponse({"error": "add must be a non-empty list of path ids"}, status_code=400)
+    content = appstate.get_progression_content()
+    for pid in add:
+        if not isinstance(pid, str) or pid not in content["paths"]:
+            return JSONResponse({"error": f"unknown path: {pid!r}"}, status_code=400)
+    appstate.meta_db.add_player_paths(add)
+    return _progression_overview()
+
+
+@router.post("/api/progression/onboarding")
+def api_progression_onboarding(data: dict):
+    """Onboarding calibration choice. Body: {action: "skip"} — completing the
+    calibration needs no endpoint, it flows through the normal /api/stats path."""
+    if _clean_str(data.get("action")) != "skip":
+        return JSONResponse({"error": "action must be 'skip'"}, status_code=400)
+    # Spec invariant: onboarding requires picking at least one instrument path
+    # before finishing, so skipping straight to rank 1 with no paths would
+    # leave a rank that can never grow. Only enforced when the content bundle
+    # actually defines paths — broken/empty content must never brick onboarding.
+    if appstate.get_progression_content()["paths"] and not appstate.meta_db.get_player_paths():
+        return JSONResponse(
+            {"error": "select at least one instrument path before skipping calibration"},
+            status_code=400,
+        )
+    appstate.meta_db.skip_calibration()
+    return _progression_overview()
+
+
+# Externally postable progression events. song_completed is deliberately NOT
+# here: it is server-derived inside /api/stats so the scored-session authority
+# stays in one place.
+_PROGRESSION_EVENT_TYPES = {"minigame_run"}
+
+
+@router.post("/api/progression/events")
+def api_progression_events(data: dict):
+    """Generic progression-event intake for plugins (capability `record-event`).
+    Body: {type, payload}. Whitelisted types, scalar payload values only."""
+    etype = _clean_str(data.get("type"))
+    if etype not in _PROGRESSION_EVENT_TYPES:
+        return JSONResponse(
+            {"error": f"event type must be one of {sorted(_PROGRESSION_EVENT_TYPES)}"},
+            status_code=400,
+        )
+    payload = data.get("payload")
+    if payload is None:
+        payload = {}
+    if not isinstance(payload, dict) or len(payload) > 16:
+        return JSONResponse({"error": "payload must be a small object"}, status_code=400)
+    clean = {}
+    for key, value in payload.items():
+        if not isinstance(key, str) or len(key) > 64:
+            return JSONResponse({"error": "payload keys must be short strings"}, status_code=400)
+        if value is None:
+            continue
+        if isinstance(value, bool) or (
+            not isinstance(value, (int, float, str))
+        ) or (isinstance(value, float) and not math.isfinite(value)) or (
+            isinstance(value, str) and len(value) > 256
+        ):
+            return JSONResponse({"error": "payload values must be short strings or finite numbers"}, status_code=400)
+        clean[key] = value
+    summary = appstate.meta_db.record_progression_event(etype, clean, appstate.get_progression_content())
+    return {"ok": True, "progression": summary}

lib/routers/shop.py

@@ -0,0 +1,62 @@
+"""Cosmetics shop (spec 010) — buy/equip avatars & themes with earned currency.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``_get_progression_content()`` ->
+``appstate.get_progression_content()`` (the accessor is injected into the seam;
+its lazy content cache stays in server.py).
+"""
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+import appstate
+from reqfields import _clean_str
+
+router = APIRouter()
+
+
+@router.get("/api/shop")
+def api_shop():
+    content = appstate.get_progression_content()
+    owned = appstate.meta_db.get_owned_items()
+    equipped = appstate.meta_db.get_equipped()
+    items = [
+        {**item, "owned": iid in owned, "equipped": equipped.get(item["slot"]) == iid}
+        for iid, item in sorted(content["shop"].items())
+    ]
+    return {"items": items, "wallet": appstate.meta_db.get_wallet()}
+
+
+@router.post("/api/shop/buy")
+def api_shop_buy(data: dict):
+    """Spend Decibels on a cosmetic. Atomic: balance check + spend + ownership
+    in one transaction. Decibels are earned by playing only — never purchasable."""
+    item_id = _clean_str(data.get("item_id"))
+    item = appstate.get_progression_content()["shop"].get(item_id)
+    if not item:
+        return JSONResponse({"error": f"unknown item: {item_id!r}"}, status_code=400)
+    status, wallet = appstate.meta_db.buy_shop_item(item)
+    if status == "owned":
+        return JSONResponse({"error": "already owned", "wallet": wallet}, status_code=409)
+    if status == "insufficient":
+        return JSONResponse({"error": "insufficient balance", "wallet": wallet}, status_code=402)
+    return {"ok": True, "item_id": item_id, "wallet": wallet}
+
+
+@router.post("/api/shop/equip")
+def api_shop_equip(data: dict):
+    """Equip an owned cosmetic into its slot. Body: {slot, item_id|null}
+    (null unequips, restoring the default look)."""
+    import progression as progression_mod
+    slot = _clean_str(data.get("slot"))
+    if slot not in progression_mod.SHOP_SLOTS:
+        return JSONResponse({"error": f"slot must be one of {sorted(progression_mod.SHOP_SLOTS)}"}, status_code=400)
+    item_id = data.get("item_id")
+    if item_id is not None:
+        item_id = _clean_str(item_id)
+        item = appstate.get_progression_content()["shop"].get(item_id)
+        if not item or item["slot"] != slot:
+            return JSONResponse({"error": f"unknown item for slot {slot}: {item_id!r}"}, status_code=400)
+        if item_id not in appstate.meta_db.get_owned_items():
+            return JSONResponse({"error": "item not owned"}, status_code=403)
+    return {"ok": True, "equipped": appstate.meta_db.equip_item(slot, item_id)}

lib/routers/stats.py

@@ -0,0 +1,233 @@
+"""Gameplay scoring — XP award + per-song practice stats (record / recent / best /
+top / per-song). The `/api/stats/{filename:path}` route is registered LAST so its
+catch-all doesn't shadow the fixed /recent /best /top paths.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``_get_progression_content()`` /
+``_builtin_diagnostic_filename()`` read through the seam.
+"""
+
+import logging
+import math
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+import appstate
+from metadata_db import _as_int
+from reqfields import _clean_str
+
+log = logging.getLogger("feedBack.server")
+
+router = APIRouter()
+
+
+@router.post("/api/xp/award")
+def api_award_xp(data: dict):
+    """Award XP into the unified store. Body: {source, amount}. Returns the
+    new progress payload. The single XP authority — song-play, minigames, and
+    tutorials all feed this (no second curve)."""
+    try:
+        amount = _as_int(data.get("amount", 0))   # rejects bool / non-integral / inf
+    except (TypeError, ValueError, OverflowError):
+        return JSONResponse({"error": "amount must be an integer"}, status_code=400)
+    # Upper-bound it: an unbounded value overflows SQLite's 64-bit INTEGER on
+    # bind (→ 500) and no real run awards anywhere near this.
+    if not (0 <= amount <= 10_000_000):
+        return JSONResponse({"error": "amount must be between 0 and 10,000,000"}, status_code=400)
+    appstate.meta_db.award_xp(amount)
+    return appstate.meta_db.get_progress()
+
+
+@router.post("/api/stats")
+def api_record_stats(data: dict):
+    """Record a play. With `score`+`accuracy` → a scored session (plays += 1,
+    best_* = max, last_* = new) plus unified-XP + streak side-effects. With
+    only `lastPlayPosition`/`last_position` → a lightweight resume-position
+    touch (no plays change) so Continue-Playing works for non-scored plays."""
+    filename = _clean_str(data.get("filename"))
+    if not filename:
+        return JSONResponse({"error": "filename required"}, status_code=400)
+    # The recorder hands us URL-encoded filenames; canonicalize to the library
+    # key so stored rows line up with `songs` (and so the arrangement-count bound
+    # below resolves the real song). See MetadataDB._canonical_song_filename.
+    filename = appstate.meta_db._canonical_song_filename(filename)
+    arr_raw = data.get("arrangement", 0)
+    if arr_raw is None:
+        arrangement = 0
+    else:
+        try:
+            arrangement = _as_int(arr_raw)   # rejects bool / non-integral (1.9) / inf
+        except (TypeError, ValueError, OverflowError):
+            return JSONResponse({"error": "arrangement must be a non-negative integer"}, status_code=400)
+    # Reject (don't silently coerce to 0) so a malformed/out-of-range index
+    # can't corrupt arrangement 0's stats; also keeps it bindable to INTEGER.
+    if not (0 <= arrangement < 2**63):
+        return JSONResponse({"error": "arrangement must be a non-negative integer"}, status_code=400)
+    # Bound against the song's real arrangement count when it's a known library
+    # song, so a bad index can't create fake arrangement buckets that poison the
+    # per-song aggregate / Continue. Skipped when the song isn't in the library
+    # yet (count unknown — dead-song reads are filtered anyway).
+    _acount = appstate.meta_db.arrangement_count(filename)
+    if _acount and arrangement >= _acount:
+        return JSONResponse({"error": "arrangement out of range for this song"}, status_code=400)
+    score = data.get("score")
+    accuracy = data.get("accuracy")
+    last_pos = data.get("lastPlayPosition", data.get("last_position"))
+    if isinstance(last_pos, bool):   # float(False)=0.0 would otherwise store a bogus position
+        return JSONResponse({"error": "lastPlayPosition must be a finite number"}, status_code=400)
+
+    # A scored session needs BOTH score and accuracy. Exactly one provided is
+    # ambiguous — don't silently fall through to the position-only branch.
+    if (score is None) != (accuracy is None):
+        return JSONResponse({"error": "score and accuracy must be provided together"}, status_code=400)
+
+    if score is not None and accuracy is not None:
+        # Reject booleans explicitly — float(True) would otherwise record a play.
+        if isinstance(score, bool) or isinstance(accuracy, bool):
+            return JSONResponse({"error": "score/accuracy must be finite numbers"}, status_code=400)
+        # Reject NaN/Inf too: round(inf) raises OverflowError (→ 500), and a
+        # stored Inf/NaN later breaks JSON serialization of /api/stats reads.
+        try:
+            score = float(score)
+            accuracy = float(accuracy)
+            if not (math.isfinite(score) and math.isfinite(accuracy)):
+                raise ValueError("non-finite")
+            score = int(round(score))
+        except (TypeError, ValueError, OverflowError):
+            return JSONResponse({"error": "score/accuracy must be finite numbers"}, status_code=400)
+        # A huge-but-finite score passes isfinite() yet overflows SQLite's
+        # 64-bit INTEGER on bind (→ 500). Bound it to the int64 range.
+        if not (0 <= score < 2**63):
+            return JSONResponse({"error": "score out of range"}, status_code=400)
+        # accuracy is a 0..1 fraction (the recorder's contract); reject
+        # out-of-range values so they don't surface as >100% / negative in
+        # /api/stats/best and the badge UI.
+        if not (0 <= accuracy <= 1):
+            return JSONResponse({"error": "accuracy must be between 0 and 1"}, status_code=400)
+        # Validate the optional resume position in this branch too (the
+        # position-only branch below already rejects non-finite).
+        if last_pos is not None:
+            try:
+                last_pos = float(last_pos)
+                if not math.isfinite(last_pos):
+                    raise ValueError("non-finite")
+            except (TypeError, ValueError, OverflowError):
+                return JSONResponse({"error": "lastPlayPosition must be a finite number"}, status_code=400)
+        row = appstate.meta_db.record_session(filename, arrangement, score=score,
+                                     accuracy=accuracy, last_position=last_pos)
+        # Unified XP + streak side-effects — never let these drop the stat write.
+        progress = None
+        try:
+            from xp import xp_for_run
+            from datetime import date
+            appstate.meta_db.award_xp(xp_for_run(score))
+            appstate.meta_db.record_active_day(date.today().isoformat())
+            progress = appstate.meta_db.get_progress()
+        except Exception:
+            log.warning("stats side-effects (xp/streak) failed", exc_info=True)
+        # Progression engine (spec 010) — same never-drop-the-stat-write
+        # contract. Scored sessions are the server-derived `song_completed`
+        # authority (scored == note detection by construction); instrument is
+        # resolved from library arrangement metadata, after the XP award so
+        # db_earned goals see this run's Decibels.
+        progression_summary = None
+        try:
+            import progression as progression_mod
+            instrument = progression_mod.instrument_for_arrangement(
+                appstate.meta_db.arrangement_entry(filename, arrangement)
+            )
+            progression_summary = appstate.meta_db.record_progression_event(
+                "song_completed",
+                {
+                    "filename": filename,
+                    "instrument": instrument,
+                    "accuracy": accuracy,
+                    "score": score,
+                    "is_diagnostic": filename == appstate.builtin_diagnostic_filename(),
+                },
+                appstate.get_progression_content(),
+            )
+        except Exception:
+            log.warning("stats side-effects (progression) failed", exc_info=True)
+        return {"stats": row, "progress": progress, "progression": progression_summary}
+
+    # Position-only touch.
+    if last_pos is None:
+        return JSONResponse(
+            {"error": "provide score+accuracy (scored) or lastPlayPosition (resume)"},
+            status_code=400,
+        )
+    try:
+        pos = float(last_pos)
+        if not math.isfinite(pos):
+            raise ValueError("non-finite")
+        row = appstate.meta_db.touch_position(filename, arrangement, pos)
+    except (TypeError, ValueError, OverflowError):
+        return JSONResponse({"error": "lastPlayPosition must be a finite number"}, status_code=400)
+    # A resume session still counts as playing today: advance the streak (no XP —
+    # that's scoring-only) so a non-scored practice day keeps the streak alive,
+    # consistent with these sessions also surfacing in recent / continue.
+    progress = None
+    try:
+        from datetime import date
+        appstate.meta_db.record_active_day(date.today().isoformat())
+        progress = appstate.meta_db.get_progress()
+    except Exception:
+        log.warning("stats side-effects (streak) failed", exc_info=True)
+    return {"stats": row, "progress": progress}
+
+
+@router.get("/api/stats/recent")
+def api_recent_stats(limit: int = 12):
+    """Recently-played rows joined to song metadata for 'Jump back in'."""
+    from urllib.parse import quote
+    out = []
+    for r in appstate.meta_db.recent_stats(limit):
+        meta = appstate.meta_db.conn.execute(
+            "SELECT title, artist, tuning_name FROM songs WHERE filename = ?",
+            (r["filename"],),
+        ).fetchone()
+        title, artist, tuning_name = meta if meta else (None, None, None)
+        out.append({
+            **r,
+            "title": title or r["filename"],
+            "artist": artist or "",
+            "tuning_name": tuning_name or "",
+            "art_url": f"/api/song/{quote(r['filename'])}/art",
+        })
+    return out
+
+
+@router.get("/api/stats/best")
+def api_stats_best():
+    """{filename: best_accuracy} for all songs with a recorded best — one call
+    to badge the library grid (defined before the {filename} catch-all)."""
+    return appstate.meta_db.best_accuracy_map()
+
+
+@router.get("/api/stats/top")
+def api_top_stats(limit: int = 5):
+    """Top scored songs (best first), joined to song metadata, for the profile
+    'Your best scores' panel (defined before the {filename} catch-all)."""
+    from urllib.parse import quote
+    out = []
+    for r in appstate.meta_db.top_stats(limit):
+        meta = appstate.meta_db.conn.execute(
+            "SELECT title, artist, tuning_name FROM songs WHERE filename = ?",
+            (r["filename"],),
+        ).fetchone()
+        title, artist, tuning_name = meta if meta else (None, None, None)
+        out.append({
+            **r,
+            "title": title or r["filename"],
+            "artist": artist or "",
+            "tuning_name": tuning_name or "",
+            "art_url": f"/api/song/{quote(r['filename'])}/art",
+        })
+    return out
+
+
+@router.get("/api/stats/{filename:path}")
+def api_song_stats(filename: str):
+    return appstate.meta_db.get_song_stats(filename)

lib/routers/tunings.py

@@ -0,0 +1,46 @@
+"""The merged tuning catalog (/api/tunings).
+
+Extracted verbatim from server.py (R3) except @app->@router, CONFIG_DIR->
+appstate.config_dir, _load_config imported from lib/appconfig, and the tuning
+registry read through the appstate seam (appstate.tuning_providers — the same
+instance plugins register into via the plugin_context in server.py).
+"""
+
+from fastapi import APIRouter
+
+import appstate
+from appconfig import _load_config
+from tunings import DEFAULT_REFERENCE_PITCH, TUNING_PRESET_MIDIS, freqs_to_midis
+
+router = APIRouter()
+
+
+@router.get("/api/tunings")
+def get_tunings():
+    cfg = _load_config(appstate.config_dir / "config.json") or {}
+    ref = cfg.get("reference_pitch", DEFAULT_REFERENCE_PITCH)
+    try:
+        ref = float(ref)
+        if not (430.0 <= ref <= 450.0):
+            ref = DEFAULT_REFERENCE_PITCH
+    except (TypeError, ValueError):
+        ref = DEFAULT_REFERENCE_PITCH
+    merged = appstate.tuning_providers.get_merged(ref)
+    # tuningMidis: the same catalog as exact integer MIDI notes (low → high).
+    # Built-ins come straight from TUNING_PRESET_MIDIS (no float round-trip);
+    # provider-contributed entries are recovered from their frequencies at the
+    # served reference pitch. Every consumer today (the v3 badges, plugins)
+    # reconstructs midis client-side via log2 — a rounding footgun at non-440
+    # references — so serve the integers once, host-side. Additive: the
+    # existing referencePitch/tunings shape is unchanged.
+    tuning_midis: dict[str, dict[str, list[int]]] = {}
+    for key, names in merged.items():
+        builtin = TUNING_PRESET_MIDIS.get(key, {})
+        resolved: dict[str, list[int]] = {}
+        for name, freqs in names.items():
+            midis = builtin.get(name) or freqs_to_midis(freqs, ref)
+            if midis:
+                resolved[name] = list(midis)
+        if resolved:
+            tuning_midis[key] = resolved
+    return {"referencePitch": ref, "tunings": merged, "tuningMidis": tuning_midis}

lib/routers/version.py

@@ -0,0 +1,81 @@
+"""App version + source/license URLs (/api/version).
+
+Extracted verbatim from ``server.py`` (R3) except the decorator (``@app`` ->
+``@router``) and the VERSION-file lookup: ``Path(__file__).parent`` (app root
+when this lived at the top level) -> ``Path(__file__).resolve().parents[2]``
+(routers -> lib -> app root). VERSION ships at the app root in every packaging
+path (Dockerfile COPY, desktop bundle).
+"""
+
+import os
+from pathlib import Path
+
+from fastapi import APIRouter
+
+router = APIRouter()
+
+
+def _safe_http_url(raw):
+    """Return `raw` stripped + trailing-slash-stripped if it parses as an
+    http(s) URL with a non-empty host; else None.
+
+    Used to validate operator-supplied `APP_SOURCE_URL` / `APP_LICENSE_URL`
+    env vars before they reach `<a href>` in the UI. A bare prefix check
+    like `startswith(("http://","https://"))` accepts malformed inputs
+    such as `"https://"` (no host) or `"https:///foo"` (empty host) that
+    still produce broken hrefs — and, when used as a base for the default
+    `license_url`, garbage like `"https:///blob/main/LICENSE"`.
+    """
+    from urllib.parse import urlsplit
+    if not raw:
+        return None
+    s = raw.strip().rstrip("/")
+    if not s:
+        return None
+    try:
+        parsed = urlsplit(s)
+    except ValueError:
+        return None
+    if parsed.scheme.lower() not in ("http", "https"):
+        return None
+    # `netloc` includes any `user:pass@` and `:port` — strings like
+    # "http://:80/path" have non-empty netloc (":80") but no real
+    # hostname. Validate `hostname` so only URLs with an actual host
+    # are accepted.
+    if not parsed.hostname:
+        return None
+    return s
+
+
+@router.get("/api/version")
+def get_version():
+    env_version = os.environ.get("APP_VERSION", "").strip()
+    if env_version:
+        version = env_version
+    else:
+        version_file = Path(__file__).resolve().parents[2] / "VERSION"  # R3: app root from lib/routers/
+        version = "unknown"
+        if version_file.exists():
+            try:
+                version = version_file.read_text().strip()
+            except (OSError, UnicodeDecodeError):
+                pass
+    default_source_url = "https://github.com/got-feedback/feedBack"
+    # APP_SOURCE_URL / APP_LICENSE_URL flow straight into <a href> in the UI,
+    # so validate with urllib.parse rather than a bare prefix check — a prefix
+    # check accepts malformed values like "https://" (no host) which produce
+    # broken hrefs (and a constructed license_url like "https:///blob/main/LICENSE").
+    # _safe_http_url requires scheme in {http,https} AND a non-empty hostname
+    # (not just netloc — that would still accept port-only authorities like
+    # "http://:80/path"); fall back to the safe default otherwise.
+    source_url = _safe_http_url(os.environ.get("APP_SOURCE_URL")) or default_source_url
+    # APP_LICENSE_URL: explicit override for the LICENSE link. The default
+    # constructed value (source_url + "/blob/main/LICENSE") is GitHub-
+    # specific and assumes the repo's default branch is `main`; non-GitHub
+    # hosts (GitLab, Gitea, self-hosted) need an explicit value.
+    license_url = _safe_http_url(os.environ.get("APP_LICENSE_URL")) or (source_url + "/blob/main/LICENSE")
+    return {
+        "version": version,
+        "source_url": source_url,
+        "license_url": license_url,
+    }

lib/routers/wanted.py

@@ -0,0 +1,45 @@
+"""Wishlist / "wanted" API (feedBack#636) — songs the user wants but doesn't own.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``_clean_str`` from ``reqfields``.
+"""
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+import appstate
+from reqfields import _clean_str
+
+router = APIRouter()
+
+
+@router.get("/api/wanted")
+def api_list_wanted():
+    """The wishlist — songs the user wants but doesn't own yet (newest first)."""
+    return {"wanted": appstate.meta_db.list_wanted()}
+
+
+@router.post("/api/wanted")
+def api_add_wanted(data: dict):
+    """Add a not-owned song to the wishlist. `artist`/`title` are required (at
+    least one non-empty); `source`/`source_ref`/`note` are optional. Idempotent
+    on identity so producers (find_more ownership-diff, manual add) can re-post."""
+    if not isinstance(data, dict):
+        return JSONResponse({"error": "body must be an object"}, status_code=400)
+    artist = _clean_str(data.get("artist"))
+    title = _clean_str(data.get("title"))
+    if not artist and not title:
+        return JSONResponse({"error": "artist or title required"}, status_code=400)
+    row = appstate.meta_db.add_wanted(
+        artist=artist, title=title,
+        source=_clean_str(data.get("source")) or "manual",
+        source_ref=_clean_str(data.get("source_ref")),
+        note=_clean_str(data.get("note")),
+    )
+    return {"ok": True, "wanted": row}
+
+
+@router.delete("/api/wanted/{wanted_id}")
+def api_remove_wanted(wanted_id: int):
+    """Remove a wishlist entry by id."""
+    return {"ok": appstate.meta_db.remove_wanted(wanted_id)}

lib/safepath.py

@@ -26,6 +26,13 @@ def safe_join(root: Path, name: str) -> Path | None:
     """
     if not name:
         return None
+    # Reject embedded NULs explicitly. This used to ride on `.resolve()`
+    # raising ValueError, but on Python 3.13 (Windows) resolve() no longer
+    # raises for an embedded NUL, so the byte would otherwise leak through
+    # containment. An explicit guard is strictly-more-rejection (no effect on
+    # the zip-slip / traversal contract).
+    if "\x00" in name:
+        return None
     safe = name.replace("\\", "/")
     try:
         root_resolved = root.resolve()

lib/scan_worker.py

@@ -3,7 +3,7 @@
 This module is deliberately kept apart from ``server.py`` so that
 ``ProcessPoolExecutor`` workers can import and unpickle ``_scan_one``
 without dragging in ``server.py``'s import-time side effects
-(``configure_logging()``, ``meta_db = MetadataDB()`` opening/migrating
+(``configure_logging()``, ``meta_db = MetadataDB(CONFIG_DIR)`` opening/migrating
 SQLite, and ``register_plugin_api(app)`` registering routes).
 
 The background scan spawns its pool with the ``spawn`` start method (see
@@ -109,13 +109,14 @@ def _extract_meta_for_file(path: Path, dlc_root=None) -> dict:
     the root it already resolved; in-process callers can pass the resolver
     itself (e.g. `_get_dlc_dir`) to keep the lookup lazy.
 
-    FeedBack reads only its own `.sloppak` format and loose-folder XML
-    songs. Encrypted/proprietary archive formats are not supported and are
-    silently ignored (empty metadata) rather than decrypted.
+    FeedBack reads only its own song-package format (`.feedpak` / legacy
+    `.sloppak`) and loose-folder XML songs. Encrypted/proprietary archive
+    formats are not supported and are silently ignored (empty metadata)
+    rather than decrypted.
     """
-    # Sloppak is detected by `.sloppak` suffix only (cheap), so check it
-    # first — that way a user's loose folder named `foo.sloppak` still wins
-    # the sloppak branch instead of being misclassified.
+    # Packages are detected by suffix only (`.feedpak`/`.sloppak`, cheap), so
+    # check that first — that way a user's loose folder named `foo.feedpak`
+    # still wins the package branch instead of being misclassified.
     if sloppak_mod.is_sloppak(path):
         return _extract_meta_sloppak(path)
     if loosefolder_mod.is_loose_song(path):

lib/sloppak.py

@@ -13,7 +13,6 @@ See the format spec in the project's sloppak plan for the full layout.
 
 from __future__ import annotations
 
-import json
 import logging
 import math
 import shutil
@@ -37,6 +36,7 @@ SONG_EXTS = (FEEDPAK_EXT, SLOPPAK_EXT)  # accepted on read/discovery
 
 import yaml
 
+from jsonc import load_json
 from safepath import safe_join
 from song import (
     Song,
@@ -423,7 +423,7 @@ def load_song(
             if not arr_path.exists():
                 continue
             try:
-                data = json.loads(arr_path.read_text(encoding="utf-8"))
+                data = load_json(arr_path)
             except Exception as e:
                 log.debug("sloppak: failed to parse arrangement %r: %s", rel, e)
                 continue
@@ -489,7 +489,7 @@ def load_song(
         raw_nt = None
         if nt_path is not None and nt_path.exists():
             try:
-                raw_nt = json.loads(nt_path.read_text(encoding="utf-8"))
+                raw_nt = load_json(nt_path)
             except Exception as e:
                 log.warning("sloppak: failed to parse notation %r: %s", notation_rel, e)
         if raw_nt is not None:
@@ -528,7 +528,7 @@ def load_song(
             dt_path = None
         if dt_path is not None and dt_path.exists():
             try:
-                raw = json.loads(dt_path.read_text(encoding="utf-8"))
+                raw = load_json(dt_path)
             except Exception as e:
                 log.warning("sloppak: failed to parse drum_tab %r: %s", drum_tab_rel, e)
                 raw = None
@@ -588,7 +588,7 @@ def load_song(
             st_path = None
         if st_path is not None and st_path.exists():
             try:
-                raw = json.loads(st_path.read_text(encoding="utf-8"))
+                raw = load_json(st_path)
             except Exception as e:
                 log.warning("sloppak: failed to parse song_timeline %r: %s", song_timeline_rel, e)
                 raw = None
@@ -686,7 +686,7 @@ def load_song(
             lyr_path = None
         if lyr_path is not None and lyr_path.exists():
             try:
-                raw = json.loads(lyr_path.read_text(encoding="utf-8"))
+                raw = load_json(lyr_path)
             except Exception as e:
                 log.debug("sloppak: failed to parse lyrics %r: %s", lyrics_rel, e)
                 raw = None
@@ -703,20 +703,32 @@ def load_song(
                     and isinstance(e.get("d"), (int, float))
                 ]
                 if song.lyrics:
-                    # Provenance — populated by the converter (xml/notechart),
-                    # the WhisperX fallback (whisperx), or hand-edits
-                    # (user). Validate against the closed enum so a
-                    # hand-edited (or otherwise malformed) manifest can't
-                    # propagate a YAML dict / list / arbitrary string
-                    # into the highway WS `lyrics.source` field and out
-                    # to plugin badges. Anything outside the enum (or
-                    # the wrong type) falls back to "xml" — the spec's
-                    # back-compat default — instead of being stringified
-                    # and trusted.
-                    _ALLOWED_LYRICS_SOURCES = {"xml", "notechart", "whisperx", "user"}
-                    # Legacy alias: older manifests labelled note-chart-derived
-                    # lyrics with the source format's name; normalise it.
-                    _LYRICS_SOURCE_ALIASES = {"sng": "notechart"}
+                    # Provenance. The feedpak spec (§7.1) vocabulary is
+                    # {authored, transcribed, user}; older manifests + the
+                    # in-tree readers also use the source-format names
+                    # (xml/notechart) and the WhisperX engine name
+                    # (whisperx). Accept the union so both spec-compliant
+                    # writers (e.g. the stem_splitter plugin emitting
+                    # `transcribed`) and legacy packs validate. Validate
+                    # against the closed enum so a hand-edited (or otherwise
+                    # malformed) manifest can't propagate a YAML dict / list /
+                    # arbitrary string into the highway WS `lyrics.source`
+                    # field and out to plugin badges. Anything outside the
+                    # enum (or the wrong type) falls back to "xml" — the
+                    # back-compat default — instead of being stringified and
+                    # trusted.
+                    # Post-alias values only: `whisperx` is normalised to
+                    # `transcribed` before the membership check below, so (like
+                    # `sng`) it is intentionally absent from this set.
+                    _ALLOWED_LYRICS_SOURCES = {
+                        "xml", "notechart", "user",
+                        "authored", "transcribed",
+                    }
+                    # Legacy aliases: older manifests labelled note-chart-derived
+                    # lyrics with the source format's name, and the WhisperX
+                    # fallback with the engine name — normalise both to the
+                    # spec vocabulary the badges now expect.
+                    _LYRICS_SOURCE_ALIASES = {"sng": "notechart", "whisperx": "transcribed"}
                     raw_source = manifest.get("lyrics_source")
                     if isinstance(raw_source, str):
                         raw_source = _LYRICS_SOURCE_ALIASES.get(raw_source, raw_source)
@@ -773,7 +785,7 @@ def load_song(
             k_path = None
         if k_path is not None and k_path.exists():
             try:
-                raw = json.loads(k_path.read_text(encoding="utf-8"))
+                raw = load_json(k_path)
             except Exception as e:
                 log.warning("sloppak: failed to parse keys %r: %s", keys_rel, e)
                 raw = None
@@ -919,6 +931,12 @@ def extract_meta(path: Path) -> dict:
         "artist": str(manifest.get("artist", "")),
         "album": str(manifest.get("album", "")),
         "year": str(manifest.get("year", "") or ""),
+        # Primary genre from the feedpak `genres` list (spec 1.12.0); [0] = primary.
+        "genre": (lambda g: str(g[0]) if isinstance(g, list) and g else "")(manifest.get("genres")),
+        # Album track order from the feedpak `track`/`disc` fields (spec 1.12.0);
+        # None when unauthored (the album view then falls back to title order).
+        "track_number": (lambda v: int(v) if str(v if v is not None else "").strip().isdigit() else None)(manifest.get("track")),
+        "disc": (lambda v: int(v) if str(v if v is not None else "").strip().isdigit() else None)(manifest.get("disc")),
         "duration": float(manifest.get("duration", 0) or 0),
         "tuning_offsets": tuning_offsets,  # caller maps to a name via tunings.tuning_name
         "arrangements": arrangements,

lib/songmeta.py

@@ -10,9 +10,9 @@ source of truth, so the change survives both incremental and full rescans.
 only the keys present are overwritten, so an edit of just the title can't blank
 out the artist.
 
-Only feedBack's own ``.sloppak`` format (zip- or directory-form) is writable.
-Unknown / unsupported shapes return False and the caller keeps the DB-only
-update.
+Only feedBack's own song-package format (zip- or directory-form, ``.feedpak``
+or the legacy ``.sloppak`` suffix) is writable. Unknown / unsupported shapes
+return False and the caller keeps the DB-only update.
 """
 from __future__ import annotations
 
@@ -107,19 +107,75 @@ def write_sloppak_metadata(path: Path, fields: dict) -> bool:
     return _rewrite_zip_manifest(path, dumped)
 
 
+def gap_fill_sloppak(path: Path, additions: dict) -> bool:
+    """Append ABSENT top-level keys to a sloppak manifest (the gap-fill
+    contract: user-initiated, adds missing keys only, never replaces
+    anything the author set).
+
+    Unlike ``write_sloppak_metadata`` this does NOT re-serialize the
+    manifest — because every added key is absent by definition, the new
+    lines can simply be appended, so the author's existing bytes (key
+    order, comments, formatting) survive verbatim. Directory form gets a
+    one-time ``manifest.yaml.bak`` + temp + atomic replace; zip form goes
+    through the same backup/temp/replace rewriter the metadata editor
+    uses. Returns True if anything was written; raises ``ValueError`` if
+    a requested key already exists (callers are expected to have checked
+    — this is the last-line never-clobber guard)."""
+    import sloppak as sloppak_mod
+
+    path = Path(path)
+    if not additions:
+        return False
+    manifest = sloppak_mod.load_manifest(path) or {}
+    clash = sorted(k for k in additions if k in manifest)
+    if clash:
+        raise ValueError("gap-fill refused: key(s) already present: " + ", ".join(clash))
+
+    if path.is_dir():
+        mf = path / "manifest.yaml"
+        if not mf.exists() and (path / "manifest.yml").exists():
+            mf = path / "manifest.yml"
+        original = mf.read_text(encoding="utf-8")
+    else:
+        with zipfile.ZipFile(str(path), "r") as zin:
+            names = zin.namelist()
+            manifest_name = "manifest.yaml"
+            for cand in ("manifest.yaml", "manifest.yml"):
+                if cand in names:
+                    manifest_name = cand
+                    break
+            original = zin.read(manifest_name).decode("utf-8")
+
+    appended = original if original.endswith("\n") or not original else original + "\n"
+    appended += yaml.safe_dump(additions, sort_keys=False, allow_unicode=True)
+
+    if path.is_dir():
+        backup = mf.with_name(mf.name + ".bak")
+        if not backup.exists():
+            shutil.copy2(mf, backup)
+        tmp = mf.with_name(mf.name + ".tmp")
+        tmp.write_text(appended, encoding="utf-8")
+        tmp.replace(mf)
+        return True
+    return _rewrite_zip_manifest(path, appended)
+
+
 def write_song_metadata(path: Path, fields: dict) -> bool:
     """Persist edited title/artist/album/year into the song's file.
 
-    Dispatches by shape: ``.sloppak`` files and sloppak directories
+    Dispatches by shape: zip-form song packages (``.feedpak`` / legacy
+    ``.sloppak``, per ``sloppak.SONG_EXTS``) and package directories
     (manifest.yaml present). Loose-folder and unknown shapes return False
     (caller keeps the DB-only update). Returns True if the file was modified.
     """
+    from sloppak import SONG_EXTS
+
     path = Path(path)
     suffix = path.suffix.lower()
     if path.is_dir():
         if (path / "manifest.yaml").exists() or (path / "manifest.yml").exists():
             return write_sloppak_metadata(path, fields)
         return False
-    if suffix == ".sloppak":
+    if suffix in SONG_EXTS:
         return write_sloppak_metadata(path, fields)
     return False

lib/tunings.py

@@ -4,51 +4,148 @@ Kept separate from server.py so tests can import it without triggering
 FastAPI / SQLite module-level side effects.
 """
 
+from __future__ import annotations
+
+import math
+
 DEFAULT_REFERENCE_PITCH = 440.0
 
-# Canonical tuning frequencies at 440 Hz reference, keyed by instrument then
-# tuning name. This is the authoritative source; tuner/routes.py previously
-# held a copy — it was removed in favour of this one.
-DEFAULT_TUNINGS: dict[str, dict[str, list[float]]] = {
+# Canonical open strings, low to high, as MIDI notes. This is the host-level
+# source of truth for guitar/bass tuning profiles; UI surfaces derive names,
+# frequencies, and semitone offsets from these absolute pitches.
+STANDARD_OPEN_MIDIS: dict[str, list[int]] = {
+    "guitar-6": [40, 45, 50, 55, 59, 64],
+    "guitar-7": [35, 40, 45, 50, 55, 59, 64],
+    "guitar-8": [30, 35, 40, 45, 50, 55, 59, 64],
+    "bass-4": [28, 33, 38, 43],
+    "bass-5": [23, 28, 33, 38, 43],
+    "bass-6": [23, 28, 33, 38, 43, 48],
+}
+
+# Curated built-in profiles. This intentionally starts by absorbing the useful
+# Virtuoso guitar/bass coverage into host-owned data so the host selector,
+# tuner, practice tools, and plugins can converge on one profile model.
+TUNING_PRESET_MIDIS: dict[str, dict[str, list[int]]] = {
     "guitar-6": {
-        "Standard":    [82.41, 110.00, 146.83, 196.00, 246.94, 329.63],
-        "Eb Standard": [77.78, 103.83, 138.59, 185.00, 233.08, 311.13],
-        "Drop D":      [73.42, 110.00, 146.83, 196.00, 246.94, 329.63],
-        "D Standard":  [73.42,  98.00, 130.81, 174.61, 220.00, 293.66],
-        "Drop C":      [65.41,  98.00, 130.81, 174.61, 220.00, 293.66],
-        "Open G":      [73.42,  98.00, 146.83, 196.00, 246.94, 293.66],
-        "Open D":      [73.42, 110.00, 146.83, 185.00, 220.00, 293.66],
-        "DADGAD":      [73.42, 110.00, 146.83, 196.00, 220.00, 293.66],
-        "Open E":      [82.41, 123.47, 164.81, 207.65, 246.94, 329.63],
+        "Standard": [40, 45, 50, 55, 59, 64],
+        "Eb Standard": [39, 44, 49, 54, 58, 63],
+        "D Standard": [38, 43, 48, 53, 57, 62],
+        "C# Standard": [37, 42, 47, 52, 56, 61],
+        "C Standard": [36, 41, 46, 51, 55, 60],
+        "Drop D": [38, 45, 50, 55, 59, 64],
+        "Drop C": [36, 43, 48, 53, 57, 62],
+        "Drop B": [35, 42, 47, 52, 56, 61],
+        "Drop A": [33, 40, 45, 50, 54, 59],
+        "Drop Ab": [32, 39, 44, 49, 53, 58],
+        "Open G": [38, 43, 50, 55, 59, 62],
+        "Open D": [38, 45, 50, 54, 57, 62],
+        "DADGAD": [38, 45, 50, 55, 57, 62],
+        "Open E": [40, 47, 52, 56, 59, 64],
     },
     "guitar-7": {
-        "Standard":    [61.74, 82.41, 110.00, 146.83, 196.00, 246.94, 329.63],
-        "Drop A":      [55.00, 82.41, 110.00, 146.83, 196.00, 246.94, 329.63],
-        "A Standard":  [55.00, 73.42,  98.00, 130.81, 174.61, 220.00, 293.66],
-        "Drop G":      [49.00, 73.42, 110.00, 146.83, 196.00, 246.94, 329.63],
-        "Bb Standard": [58.27, 77.78, 103.83, 138.59, 185.00, 233.08, 311.13],
+        "Standard": [35, 40, 45, 50, 55, 59, 64],
+        "Bb Standard": [34, 39, 44, 49, 54, 58, 63],
+        "A Standard": [33, 38, 43, 48, 53, 57, 62],
+        "G Standard": [31, 36, 41, 46, 51, 55, 60],
+        "Drop A": [33, 40, 45, 50, 55, 59, 64],
+        "Drop G": [31, 38, 43, 48, 53, 57, 62],
+        "Drop F#": [30, 37, 42, 47, 52, 56, 61],
     },
     "guitar-8": {
-        "Standard":    [46.25, 61.74, 82.41, 110.00, 146.83, 196.00, 246.94, 329.63],
-        "Drop E":      [41.20, 61.74, 82.41, 110.00, 146.83, 196.00, 246.94, 329.63],
-        "E Standard":  [41.20, 55.00, 73.42,  98.00, 130.81, 174.61, 220.00, 293.66],
-        "Drop D":      [36.71, 55.00, 73.42,  98.00, 130.81, 174.61, 220.00, 293.66],
-        "Eb Standard": [38.89, 51.91, 69.30,  92.50, 123.47, 164.81, 207.65, 277.18],
+        "Standard": [30, 35, 40, 45, 50, 55, 59, 64],
+        "Drop E": [28, 35, 40, 45, 50, 55, 59, 64],
+        "Drop A + Drop E": [28, 33, 40, 45, 50, 55, 59, 64],
+        "E Standard": [28, 33, 38, 43, 48, 53, 57, 62],
+        "Eb Standard": [27, 32, 37, 42, 47, 52, 56, 61],
+        "Drop D": [26, 33, 38, 43, 48, 53, 57, 62],
     },
     "bass-4": {
-        "Standard":    [41.20, 55.00, 73.42,  98.00],
-        "Eb Standard": [38.89, 51.91, 69.30,  92.50],
-        "Drop D":      [36.71, 55.00, 73.42,  98.00],
-        "D Standard":  [36.71, 48.99, 65.41,  87.31],
-        "Drop C":      [32.70, 48.99, 65.41,  87.31],
+        "Standard": [28, 33, 38, 43],
+        "Eb Standard": [27, 32, 37, 42],
+        "D Standard": [26, 31, 36, 41],
+        "C# Standard": [25, 30, 35, 40],
+        "C Standard": [24, 29, 34, 39],
+        "Drop D": [26, 33, 38, 43],
+        "Drop C": [24, 31, 36, 41],
+        "BEAD": [23, 28, 33, 38],
     },
     "bass-5": {
-        "Standard":    [30.87, 41.20, 55.00, 73.42,  98.00],
-        "Eb Standard": [29.14, 38.89, 51.91, 69.30,  92.50],
-        "Drop D":      [30.87, 36.71, 55.00, 73.42,  98.00],
-        "D Standard":  [27.50, 36.71, 48.99, 65.41,  87.31],
-        "Drop C":      [27.50, 32.70, 48.99, 65.41,  87.31],
+        "Standard": [23, 28, 33, 38, 43],
+        "High C": [28, 33, 38, 43, 48],
+        "Eb Standard": [22, 27, 32, 37, 42],
+        "D Standard": [21, 26, 31, 36, 41],
+        "C# Standard": [20, 25, 30, 35, 40],
+        "C Standard": [19, 24, 29, 34, 39],
+        "Drop A": [21, 28, 33, 38, 43],
     },
+    "bass-6": {
+        "Standard": [23, 28, 33, 38, 43, 48],
+        "Eb Standard": [22, 27, 32, 37, 42, 47],
+        "D Standard": [21, 26, 31, 36, 41, 46],
+        "C# Standard": [20, 25, 30, 35, 40, 45],
+        "C Standard": [19, 24, 29, 34, 39, 44],
+    },
+}
+
+
+def midi_to_freq(midi: int, reference_pitch: float = DEFAULT_REFERENCE_PITCH) -> float:
+    """Return the frequency for a MIDI note at the supplied A4 reference."""
+    return reference_pitch * math.pow(2, (midi - 69) / 12)
+
+
+def open_midis_to_freqs(midis: list[int], reference_pitch: float = DEFAULT_REFERENCE_PITCH) -> list[float]:
+    """Return rounded frequencies for low-to-high MIDI open strings."""
+    return [round(midi_to_freq(m, reference_pitch), 2) for m in midis]
+
+
+def freqs_to_midis(freqs: list[float], reference_pitch: float = DEFAULT_REFERENCE_PITCH) -> list[int] | None:
+    """Return absolute open-string MIDI notes for frequencies at the supplied
+    A4 reference — the inverse of open_midis_to_freqs. None if any entry is
+    non-numeric or non-positive (a provider could hand us anything)."""
+    out: list[int] = []
+    for f in freqs:
+        try:
+            f = float(f)
+        except (TypeError, ValueError):
+            return None
+        if f <= 0:
+            return None
+        out.append(int(round(69 + 12 * math.log2(f / reference_pitch))))
+    return out
+
+
+def tuning_offsets_from_midis(instrument_key: str, midis: list[int]) -> list[int] | None:
+    """Return semitone offsets from the instrument's standard open strings."""
+    standard = STANDARD_OPEN_MIDIS.get(instrument_key)
+    if not standard or len(standard) != len(midis):
+        return None
+    return [int(m - s) for m, s in zip(midis, standard)]
+
+
+def tuning_midis_from_offsets(instrument_key: str, offsets: list[int]) -> list[int] | None:
+    """Return absolute open-string MIDI notes for host semitone offsets."""
+    standard = STANDARD_OPEN_MIDIS.get(instrument_key)
+    if not standard or len(standard) != len(offsets):
+        return None
+    return [int(s + o) for s, o in zip(standard, offsets)]
+
+
+def tuning_preset_offsets(instrument_key: str, name: str) -> list[int] | None:
+    """Return host semitone offsets for a named preset."""
+    midis = TUNING_PRESET_MIDIS.get(instrument_key, {}).get(name)
+    if not midis:
+        return None
+    return tuning_offsets_from_midis(instrument_key, midis)
+
+
+# Canonical tuning frequencies at 440 Hz reference, keyed by instrument then
+# tuning name. Kept for the existing /api/tunings contract.
+DEFAULT_TUNINGS: dict[str, dict[str, list[float]]] = {
+    instrument: {
+        name: open_midis_to_freqs(midis)
+        for name, midis in presets.items()
+    }
+    for instrument, presets in TUNING_PRESET_MIDIS.items()
 }
 
 
@@ -67,6 +164,256 @@ def apply_reference_pitch(
     }
 
 
+PROFILE_IDS = ("guitar-lead", "guitar-rhythm", "bass")
+PROFILE_PATHWAYS = ("songs", "practice", "learn", "studio")
+DEFAULT_ACTIVE_INSTRUMENT_PROFILE = "guitar-lead"
+PROFILE_DEFAULTS: dict[str, dict] = {
+    "guitar-lead": {
+        "id": "guitar-lead",
+        "label": "Lead Guitar",
+        "instrument": "guitar",
+        "role": "lead",
+        "string_count": 6,
+        "tuning": "Standard",
+        "reference_pitch": DEFAULT_REFERENCE_PITCH,
+        "pathway": "songs",
+    },
+    "guitar-rhythm": {
+        "id": "guitar-rhythm",
+        "label": "Rhythm Guitar",
+        "instrument": "guitar",
+        "role": "rhythm",
+        "string_count": 6,
+        "tuning": "Standard",
+        "reference_pitch": DEFAULT_REFERENCE_PITCH,
+        "pathway": "songs",
+    },
+    "bass": {
+        "id": "bass",
+        "label": "Bass",
+        "instrument": "bass",
+        "role": "bass",
+        "string_count": 4,
+        "tuning": "Standard",
+        "reference_pitch": DEFAULT_REFERENCE_PITCH,
+        "pathway": "songs",
+    },
+}
+
+
+def instrument_key(instrument: str, string_count: int) -> str:
+    return f"{instrument}-{string_count}"
+
+
+def default_instrument_profiles() -> dict[str, dict]:
+    return {profile_id: dict(profile) for profile_id, profile in PROFILE_DEFAULTS.items()}
+
+
+def _valid_reference_pitch(value) -> float | None:
+    if isinstance(value, bool):
+        return None
+    try:
+        ref = float(value)
+    except (TypeError, ValueError, OverflowError):
+        return None
+    if not math.isfinite(ref) or ref < 430.0 or ref > 450.0:
+        return None
+    return ref
+
+
+def _valid_tuning_for_key(key: str, tuning):
+    if isinstance(tuning, str):
+        if len(tuning) > 64:
+            return None
+        if tuning in TUNING_PRESET_MIDIS.get(key, {}):
+            return tuning
+        # A name that IS a built-in preset for a different key is a misapplied
+        # built-in (e.g. "Drop D" on a 5-string bass, whose low string is B) —
+        # reject it. A name unknown to every built-in table is a provider/custom
+        # tuning (the tuner plugin's, exposed via /api/tunings) that this pure
+        # layer can't resolve — accept it so settings round-trip; the provider
+        # owns its validity.
+        if any(tuning in names for names in TUNING_PRESET_MIDIS.values()):
+            return None
+        return tuning
+    if isinstance(tuning, list):
+        expected = len(STANDARD_OPEN_MIDIS.get(key, []))
+        if len(tuning) != expected:
+            return None
+        if any(isinstance(o, bool) or not isinstance(o, int) or o < -12 or o > 12 for o in tuning):
+            return None
+        return list(tuning)
+    return None
+
+
+def normalize_instrument_profile(profile_id: str, raw) -> tuple[dict | None, str | None]:
+    """Validate one persisted host instrument profile."""
+    base = dict(PROFILE_DEFAULTS.get(profile_id, {}))
+    if not base:
+        return None, f"unknown instrument profile: {profile_id}"
+    if raw is None:
+        return base, None
+    if not isinstance(raw, dict):
+        return None, f"instrument_profiles.{profile_id} must be an object"
+
+    instrument = raw.get("instrument", base["instrument"])
+    if instrument not in ("guitar", "bass"):
+        return None, f"instrument_profiles.{profile_id}.instrument must be 'guitar' or 'bass'"
+
+    try:
+        string_count = int(raw.get("string_count", base["string_count"]))
+    except (TypeError, ValueError, OverflowError):
+        return None, f"instrument_profiles.{profile_id}.string_count must be valid for the instrument"
+    key = instrument_key(instrument, string_count)
+    if key not in STANDARD_OPEN_MIDIS:
+        return None, f"instrument_profiles.{profile_id}.string_count must be valid for the instrument"
+
+    tuning = _valid_tuning_for_key(key, raw.get("tuning", base["tuning"]))
+    if tuning is None:
+        return None, f"instrument_profiles.{profile_id}.tuning must match {key}"
+
+    ref = _valid_reference_pitch(raw.get("reference_pitch", base["reference_pitch"]))
+    if ref is None:
+        return None, f"instrument_profiles.{profile_id}.reference_pitch must be a number between 430 and 450"
+
+    label = raw.get("label", base["label"])
+    if not isinstance(label, str) or len(label) > 64:
+        return None, f"instrument_profiles.{profile_id}.label must be a short string"
+    role = raw.get("role", base["role"])
+    if not isinstance(role, str) or len(role) > 32:
+        return None, f"instrument_profiles.{profile_id}.role must be a short string"
+    pathway = raw.get("pathway", base["pathway"])
+    if not isinstance(pathway, str) or pathway not in PROFILE_PATHWAYS:
+        return None, f"instrument_profiles.{profile_id}.pathway must be one of songs, practice, learn, studio"
+
+    out = dict(base)
+    out.update({
+        "id": profile_id,
+        "label": label,
+        "instrument": instrument,
+        "role": role,
+        "string_count": string_count,
+        "tuning": tuning,
+        "reference_pitch": ref,
+        "pathway": pathway,
+    })
+    return out, None
+
+
+def normalize_instrument_profiles(raw_profiles=None) -> tuple[dict[str, dict] | None, str | None]:
+    """Validate persisted host profiles, filling omitted built-ins with defaults."""
+    if raw_profiles is None:
+        return default_instrument_profiles(), None
+    if not isinstance(raw_profiles, dict):
+        return None, "instrument_profiles must be an object"
+    profiles = {}
+    for profile_id in PROFILE_IDS:
+        profile, error = normalize_instrument_profile(profile_id, raw_profiles.get(profile_id))
+        if error:
+            return None, error
+        profiles[profile_id] = profile
+    return profiles, None
+
+
+def active_profile_id(raw) -> str:
+    return raw if raw in PROFILE_DEFAULTS else DEFAULT_ACTIVE_INSTRUMENT_PROFILE
+
+
+def profile_from_legacy_settings(cfg: dict) -> dict:
+    """Build an active profile from the old flat settings keys."""
+    instrument = cfg.get("instrument") if cfg.get("instrument") in ("guitar", "bass") else "guitar"
+    fallback_sc = 4 if instrument == "bass" else 6
+    try:
+        sc = int(cfg.get("string_count", fallback_sc))
+    except (TypeError, ValueError, OverflowError):
+        sc = fallback_sc
+    key = instrument_key(instrument, sc)
+    if key not in STANDARD_OPEN_MIDIS:
+        sc = fallback_sc
+        key = instrument_key(instrument, sc)
+    tuning = _valid_tuning_for_key(key, cfg.get("tuning", "Standard")) or "Standard"
+    ref = _valid_reference_pitch(cfg.get("reference_pitch", DEFAULT_REFERENCE_PITCH)) or DEFAULT_REFERENCE_PITCH
+    pathway = cfg.get("pathway") if cfg.get("pathway") in PROFILE_PATHWAYS else "songs"
+    profile_id = "bass" if instrument == "bass" else DEFAULT_ACTIVE_INSTRUMENT_PROFILE
+    profile = dict(PROFILE_DEFAULTS[profile_id])
+    profile.update({
+        "instrument": instrument,
+        "string_count": sc,
+        "tuning": tuning,
+        "reference_pitch": ref,
+        "pathway": pathway,
+    })
+    return profile
+
+
+def settings_with_instrument_profiles(cfg: dict) -> dict:
+    """Return settings with canonical host profiles and mirrored flat keys."""
+    out = dict(cfg)
+    profiles, _error = normalize_instrument_profiles(out.get("instrument_profiles"))
+    if profiles is None:
+        profiles = default_instrument_profiles()
+    if "instrument_profiles" not in out:
+        legacy = profile_from_legacy_settings(out)
+        profiles[legacy["id"]] = legacy
+        # Default the active profile to the one migrated from the legacy flat
+        # fields, but DON'T clobber an explicit request — a fresh-config
+        # `POST {"active_instrument_profile": "bass"}` must switch, not be
+        # overwritten by the guitar-lead inferred from defaults. active_profile_id
+        # below normalizes an invalid value.
+        out.setdefault("active_instrument_profile", legacy["id"])
+    active = active_profile_id(out.get("active_instrument_profile"))
+    selected = profiles[active]
+    out["instrument_profiles"] = profiles
+    out["active_instrument_profile"] = active
+    out["instrument"] = selected["instrument"]
+    out["string_count"] = selected["string_count"]
+    out["tuning"] = selected["tuning"]
+    out["reference_pitch"] = selected["reference_pitch"]
+    out["pathway"] = selected["pathway"]
+    return out
+
+
+def apply_flat_instrument_patch_to_profiles(cfg: dict, updates: dict) -> dict:
+    """Mirror legacy flat instrument updates into the active host profile."""
+    out = settings_with_instrument_profiles(cfg)
+    if not any(k in updates for k in ("instrument", "string_count", "tuning", "reference_pitch", "pathway")):
+        return out
+    active = active_profile_id(out.get("active_instrument_profile"))
+    if "instrument" in updates:
+        active = "bass" if updates["instrument"] == "bass" else "guitar-lead"
+        out["active_instrument_profile"] = active
+    current = dict(out["instrument_profiles"][active])
+
+    if "instrument" in updates:
+        current["instrument"] = updates["instrument"]
+        if "string_count" not in updates:
+            current["string_count"] = 4 if updates["instrument"] == "bass" else 6
+    if "string_count" in updates:
+        current["string_count"] = updates["string_count"]
+    if "reference_pitch" in updates:
+        current["reference_pitch"] = updates["reference_pitch"]
+    if "pathway" in updates:
+        current["pathway"] = updates["pathway"]
+    if "tuning" in updates:
+        current["tuning"] = updates["tuning"]
+    else:
+        key = instrument_key(current["instrument"], current["string_count"])
+        if _valid_tuning_for_key(key, current.get("tuning")) is None:
+            current["tuning"] = "Standard"
+
+    profile, error = normalize_instrument_profile(active, current)
+    if error:
+        raise ValueError(error)
+    out["instrument_profiles"][active] = profile
+    out.update({
+        "instrument": profile["instrument"],
+        "string_count": profile["string_count"],
+        "tuning": profile["tuning"],
+        "reference_pitch": profile["reference_pitch"],
+        "pathway": profile["pathway"],
+    })
+    return out
+
 def tuning_name(offsets: list[int]) -> str:
     # All three pattern checks below are gated on `len(offsets) == 6`. The
     # naming conventions here are 6-string-specific — e.g. a 7-string all-zeros

package.json

@@ -8,9 +8,12 @@
     "test:headed": "playwright test --headed",
     "test:debug": "playwright test --debug",
     "test:js": "node --test tests/js/*.test.js 'tests/plugins/*/js/*.test.js'",
-    "install:playwright": "playwright install chromium"
+    "install:playwright": "playwright install chromium",
+    "lint": "eslint ."
   },
   "devDependencies": {
-    "@playwright/test": "^1.59.1"
+    "@playwright/test": "^1.59.1",
+    "eslint": "^9.39.4",
+    "eslint-plugin-import-x": "^4.17.1"
   }
 }

plugins/__init__.py

@@ -18,6 +18,54 @@ from safepath import safe_join
 log = logging.getLogger("feedBack.plugins")
 
 
+def _plugin_media_type(path: Path) -> str:
+    """Best-effort Content-Type for a served plugin file. `.js`/`.css` must come
+    back as JavaScript/CSS so `<script type=module>` / `addModule()` / a `<link>`
+    accept them; `mimetypes.guess_type` can miss these on a stripped platform
+    registry, so fall back explicitly (mirrors the assets/ route)."""
+    media_type = mimetypes.guess_type(path.name)[0]
+    if media_type is None and path.suffix == ".js":
+        return "application/javascript"
+    if media_type is None and path.suffix == ".css":
+        return "text/css"
+    return media_type or "application/octet-stream"
+
+
+def _plugin_file_etag(path: Path) -> str | None:
+    """Weak ETag from mtime+size — cheap, stable across reads, changes on edit.
+    This is what makes the live-edit loop work for module graphs: a conditional
+    GET revalidates and 304s unchanged files on refresh instead of re-downloading
+    the whole `src/` tree. Returns None if the file can't be stat'd."""
+    try:
+        st = path.stat()
+    except OSError:
+        return None
+    return f'W/"{st.st_mtime_ns:x}-{st.st_size:x}"'
+
+
+def _if_none_match(request: Request, etag: str) -> bool:
+    """True when the client's If-None-Match already holds `etag`."""
+    # ponytail: we serve one weak ETag; the browser echoes it back verbatim, so
+    # a direct compare is enough (comma-split tolerates a proxy concatenation).
+    return etag in [t.strip() for t in request.headers.get("if-none-match", "").split(",")]
+
+
+def _plugin_file_response(request: Request, path: Path, media_type: str) -> Response:
+    """Serve a plugin source/asset file with the live-edit cache contract:
+    `Cache-Control: no-cache` (browser may store but MUST revalidate) + a weak
+    ETag, and a bodyless 304 when the client's If-None-Match already matches.
+    Starlette's `FileResponse` emits an ETag but never evaluates If-None-Match
+    itself, so the conditional handling has to live here."""
+    headers = {"Cache-Control": "no-cache"}
+    etag = _plugin_file_etag(path)
+    if etag:
+        headers["ETag"] = etag
+        if _if_none_match(request, etag):
+            return Response(status_code=304, headers=headers)
+    # FileResponse sets etag/last-modified via setdefault, so the ETag above wins.
+    return FileResponse(path, media_type=media_type, headers=headers)
+
+
 PLUGINS_DIR = Path(__file__).parent
 # Holds only *ready* (loaded) plugins — those whose dependencies installed
 # and whose routes registered. A plugin GRADUATES from PENDING_PLUGINS into
@@ -1373,6 +1421,12 @@ def load_plugins(app: FastAPI, context: dict, progress_cb=None, route_setup_fn=N
             "version": manifest.get("version"),
             "has_screen": bool(manifest.get("screen")),
             "has_script": bool(manifest.get("script")),
+            # Module-migration (R0): `scriptType:"module"` tells the loader to
+            # inject screen.js as <script type="module">; `minHost` is the
+            # min core version a migrated plugin needs (passthrough only in R0 —
+            # enforcement is deferred to R4, master §4b). None when unset.
+            "script_type": manifest.get("scriptType"),
+            "min_host": manifest.get("minHost"),
             "has_settings": bool(manifest.get("settings")),
             "settings_category": _settings_category,
             # Drives the v3 shell's immersive (full-screen) mode for this
@@ -2089,6 +2143,11 @@ def register_plugin_api(app: FastAPI):
                 "fallback": p.get("fallback", False),
                 "has_screen": p["has_screen"],
                 "has_script": p["has_script"],
+                # Module-migration passthrough (R0). Re-read from the manifest
+                # like `version` above so stubbed test entries (built without
+                # _nav_entry) don't need the key.
+                "script_type": (p.get("_manifest") or {}).get("scriptType"),
+                "min_host": (p.get("_manifest") or {}).get("minHost"),
                 "has_settings": p["has_settings"],
                 # v3 immersive screen opt-in (full-screen plugin UI).
                 "fullscreen": p.get("fullscreen", False),
@@ -2142,6 +2201,9 @@ def register_plugin_api(app: FastAPI):
                 "fallback": False,
                 "has_screen": e.get("has_screen", False),
                 "has_script": e.get("has_script", False),
+                # Pending entries come from _nav_entry, so they carry these.
+                "script_type": e.get("script_type"),
+                "min_host": e.get("min_host"),
                 "has_settings": e.get("has_settings", False),
                 "settings_category": e.get("settings_category"),
                 "fullscreen": e.get("fullscreen", False),
@@ -2307,7 +2369,7 @@ def register_plugin_api(app: FastAPI):
         return HTMLResponse("", status_code=404)
 
     @app.get("/api/plugins/{plugin_id}/screen.js")
-    def plugin_screen_js(plugin_id: str):
+    def plugin_screen_js(request: Request, plugin_id: str):
         with PLUGINS_LOCK:
             snapshot = list(LOADED_PLUGINS)
         for p in snapshot:
@@ -2315,8 +2377,11 @@ def register_plugin_api(app: FastAPI):
                 if p.get("status", "ready") != "ready":
                     break
                 script_file = p["_dir"] / p["_manifest"].get("script", "screen.js")
-                if script_file.exists():
-                    return Response(script_file.read_text(encoding="utf-8"), media_type="application/javascript")
+                if script_file.is_file():
+                    # no-cache + ETag/304 so an edited screen.js reloads on
+                    # refresh while an unchanged one revalidates cheaply — the
+                    # same live-edit contract the src/ module graph relies on.
+                    return _plugin_file_response(request, script_file, "application/javascript")
         return Response("", status_code=404)
 
     @app.get("/api/plugins/{plugin_id}/settings.html")
@@ -2377,7 +2442,7 @@ def register_plugin_api(app: FastAPI):
         return Response("{}", status_code=404, media_type="application/json")
 
     @app.get("/api/plugins/{plugin_id}/assets/{asset_path:path}")
-    def plugin_asset(plugin_id: str, asset_path: str):
+    def plugin_asset(request: Request, plugin_id: str, asset_path: str):
         """Serve a static file a plugin bundles under its own ``assets/``
         directory (e.g. an AudioWorklet module, WASM, or image). Unlike the
         fixed screen.js/settings.html handlers above, this is a generic
@@ -2399,16 +2464,35 @@ def register_plugin_api(app: FastAPI):
                     log.warning("Plugin %r: asset path rejected: %r", plugin_id, asset_path)
                     break
                 if target.is_file():
-                    media_type = mimetypes.guess_type(target.name)[0]
-                    # .js must come back as JavaScript so addModule() / <script>
-                    # accept it; guess_type can miss this on some platforms.
-                    if media_type is None and target.suffix == ".js":
-                        media_type = "application/javascript"
-                    # .css must come back as text/css so a <link rel=stylesheet>
-                    # (the styles capability) is honoured; guess_type can miss it
-                    # on a stripped platform mimetypes registry, same as .js.
-                    elif media_type is None and target.suffix == ".css":
-                        media_type = "text/css"
-                    return FileResponse(target, media_type=media_type or "application/octet-stream")
+                    # no-cache + ETag/304 so a live-edited worklet/asset reloads
+                    # on refresh (bare FileResponse emits an ETag but never 304s).
+                    return _plugin_file_response(request, target, _plugin_media_type(target))
+                break
+        return Response("", status_code=404)
+
+    @app.get("/api/plugins/{plugin_id}/src/{src_path:path}")
+    def plugin_src(request: Request, plugin_id: str, src_path: str):
+        """Serve a file from a plugin's ES-module source tree under ``src/``.
+
+        This is the R0 host capability that lets a migrated plugin's
+        ``screen.js`` (a one-line ``import './src/main.js'``) load its whole
+        module graph. Containment mirrors the assets/ route exactly —
+        ``safe_join`` against ``<plugin>/src`` rejects ``..``, absolute paths,
+        and NUL bytes — and the live-edit cache contract (no-cache + ETag/304)
+        makes an edited module reload on refresh while unchanged ones 304.
+        Read-only; the src/ tree is source files, never executed server-side.
+        """
+        with PLUGINS_LOCK:
+            snapshot = list(LOADED_PLUGINS)
+        for p in snapshot:
+            if p["id"] == plugin_id:
+                if p.get("status", "ready") != "ready":
+                    break
+                target = safe_join(p["_dir"] / "src", src_path)
+                if target is None:
+                    log.warning("Plugin %r: src path rejected: %r", plugin_id, src_path)
+                    break
+                if target.is_file():
+                    return _plugin_file_response(request, target, _plugin_media_type(target))
                 break
         return Response("", status_code=404)

plugins/drum_highway_3d/.gitignore

@@ -0,0 +1,7 @@
+__pycache__/
+*.pyc
+.DS_Store
+Thumbs.db
+*.swp
+.vscode/
+.idea/

plugins/drum_highway_3d/LICENSE

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  Developers that use our General Public Licenses protect your rights
+with two steps: (1) assert copyright on the software, and (2) offer
+you this License which gives you legal permission to copy, distribute
+and/or modify the software.
+
+  A secondary benefit of defending all users' freedom is that
+improvements made in alternate versions of the program, if they
+receive widespread use, become available for other developers to
+incorporate.  Many developers of free software are heartened and
+encouraged by the resulting cooperation.  However, in the case of
+software used on network servers, this result may fail to come about.
+The GNU General Public License permits making a modified version and
+letting the public access it on a server without ever releasing its
+source code to the public.
+
+  The GNU Affero General Public License is designed specifically to
+ensure that, in such cases, the modified source code becomes available
+to the community.  It requires the operator of a network server to
+provide the source code of the modified version running there to the
+users of that server.  Therefore, public use of a modified version, on
+a publicly accessible server, gives the public access to the source
+code of the modified version.
+
+  An older license, called the Affero General Public License and
+published by Affero, was designed to accomplish similar goals.  This is
+a different license, not a version of the Affero GPL, but Affero has
+released a new version of the Affero GPL which permits relicensing under
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+
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plugins/drum_highway_3d/README.md

@@ -0,0 +1,100 @@
+# 3D Drum Highway — Mockup
+
+![3D Drum Highway mockup screenshot](screenshots/drum-highway-3d.png)
+
+An exploratory **pure-visual** sibling of `highway_3d`. Renders an 8-lane
+drum highway (7 lanes for hand pieces + a full-width kick bar) populated
+from a hardcoded demo pattern that loops indefinitely. Not yet wired to
+song data, hit detection, audio, or note_detect — this is here to play
+with the look-and-feel.
+
+To see it, load any song in the player, then pick **3D Drum Highway**
+from the viz picker. The mockup animates regardless of what song is
+playing.
+
+## Layout
+
+```
+ [HH]  [SNR]  [TM1]  [TM2]  [FT]  [CR]  [RD]    <- 7 lanes, left to right
+   |    |      |      |     |    |     |
+   v    v      v      v     v    v     v
+ -----  hit line  -----------------------------
+ ▓▓▓▓▓▓▓▓▓▓▓▓▓ KICK BAR ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓     <- full-width kick lane
+```
+
+- **Drums** (snare, toms, floor tom): flat disc geometry (`CylinderGeometry`),
+  palette-tinted, with subtle emissive pulse on approach. Snare gets a
+  thin white "wires" stripe.
+- **Cymbals** (hi-hat, crash, ride): faceted gem geometry (truncated
+  `CylinderGeometry`), metallic material, slightly translucent.
+- **Kick**: full-width amber bar across the base, brighter on approach.
+
+## Variants visible in the demo
+
+| Variant | How it reads |
+|---|---|
+| `accent` | Bigger note + white halo ring |
+| `ghost`  | Hollow ring (~65% size) instead of a solid disc |
+| `flam`   | Main note + a small grace disc offset slightly before |
+| `bell`   | Ride only — adds a bright dot in the center of the gem |
+
+The **Fill showcase** demo pattern fires every variant at least once in
+a few bars, plus a tom roll down the kit. Best read of what's possible.
+
+## Settings (Settings → Plugins → 3D Drum Highway)
+
+- **Palette** — shared 3 palettes with `highway_3d` (default / neon / pastel).
+- **Demo pattern** — rock backbeat / jazz swing / fill showcase.
+- **Camera angle** — 0 (down the lanes) to 1 (top-down). Default 0.35.
+
+All settings persist in `localStorage` under the `drum_h3d_*` prefix.
+
+## What this plugin is *not* doing yet
+
+(Historical note: this started as a pure-visual mockup; it now reads
+`bundle.drumTab` + `bundle.currentTime` and scores MIDI hits against the
+chart, so the old "no song-data wiring" caveats are gone.)
+
+- Sustain trails (drums don't sustain meaningfully)
+- Sticking labels, double kick, rolls — see the TODOs in `screen.js`
+  for the variant backlog
+
+## Ported helpers (keep in sync with highway_3d)
+
+Visual-parity code copied from `plugins/highway_3d/screen.js` — same
+function names, signatures, and constants on purpose, marked with
+`PORTED FROM highway_3d` comments at each site. If the guitar highway
+tunes one of these, mirror the change here (and in `keys_highway_3d`):
+
+- `_bloomEnsure()` / `_bloomDispose()` — EffectComposer + UnrealBloomPass
+  (0.65/0.5/0.82) on a multisampled HalfFloat target, ACES↔None tone-
+  mapping switch in `draw()`; addons dynamic-imported from
+  `/static/vendor/three/addons/` (no CDN fallback — direct render is the
+  graceful degrade)
+- `_sparkBurst()` / `_sparkUpdate()` — pooled additive Points hit sparks
+  (pool 160 here vs the guitar's 256)
+- `_makeGaussTex()` — soft-falloff DataTexture for the additive lane-flash
+  quads
+- `_timingHex()` — early/late/on-time feedback colors (green/cyan/amber)
+- `_ssActive()` — host splitscreen probe (minus the guitar's focus-API
+  checks, which it needs for input routing and we don't)
+- `BG_THEMES` / `_bgThemeColors()` — the scene theme table (same ids/values
+  as the guitar's, except `default` which is this plugin's original
+  palette); one pick drives both of the guitar's background/highway axes
+- `_applyCinematic()` — ambient/key rebalance (values tuned per plugin)
+- `BG_STYLES` (off/particles/lights/geometric) + `_bgGetAnalyser()` /
+  `_bgReadBands()` — background ambience + the stems-first audio-analyser
+  bridge (guitar's diagnostics plumbing dropped; butterchurn/image/video
+  out of scope)
+- `_drawScoreFx()` — the guitar's drawScoreFx overlay adapted to this
+  plugin's internal scoring (pops / tier rings / milestone bursts /
+  streak-break wash)
+
+## Why a separate plugin (vs. drum mode inside highway_3d)?
+
+Cleaner iteration. The drum highway is its own geometry, its own
+gameplay assumptions (lanes ≠ strings, no frets, no chord shapes,
+no sustains), and likely its own chart format. Forking the visuals
+in a sibling plugin lets the mockup move fast without risking
+regressions in the guitar viz that ships today. If the drum highway
+eventually matures, we can decide whether to merge or keep separate.

plugins/drum_highway_3d/assets/thumb.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="256" height="256" viewBox="0 0 256 256" role="img" aria-label="3D Drum Highway placeholder thumbnail">
+  <rect width="256" height="256" rx="36" fill="#0f172a"/>
+  <rect x="18" y="18" width="220" height="220" rx="28" fill="#1e293b" stroke="#334155" stroke-width="3"/>
+  <text x="128" y="150" font-family="Rubik, Arial, sans-serif" font-size="104" font-weight="800" fill="#38bdf8" text-anchor="middle">3D</text>
+</svg>

plugins/drum_highway_3d/plugin.json

@@ -0,0 +1,39 @@
+{
+  "id": "drum_highway_3d",
+  "name": "3D Drum Highway",
+  "version": "0.3.2",
+  "type": "visualization",
+  "bundled": true,
+  "script": "screen.js",
+  "settings": {
+    "html": "settings.html",
+    "category": "graphics"
+  },
+  "standards": [
+    "capability-pipelines.v1",
+    "plugin-runtime-idempotent.v1"
+  ],
+  "capabilities": {
+    "midi-input": {
+      "roles": [
+        "requester"
+      ],
+      "requests": [
+        "discover",
+        "list-sources",
+        "select-source",
+        "open-source",
+        "close-source"
+      ],
+      "mode": "active",
+      "compatibility": "degrade-noop",
+      "ownership": "requester-only",
+      "safety": "sensitive",
+      "description": "Reads the e-kit/MIDI-pad input through the core midi-input domain (Web-MIDI provider ships built-in with the domain). Absent domain \u2192 no MIDI devices, fail-soft.",
+      "version": 1
+    }
+  },
+  "category": "practice",
+  "description": "3D note highway for drum charts.",
+  "icon": "assets/thumb.svg"
+}

plugins/drum_highway_3d/settings.html

@@ -0,0 +1,615 @@
+<div role="group" aria-labelledby="drumh3d-heading">
+    <h3 id="drumh3d-heading" class="text-sm font-medium text-gray-400 mb-2">3D Drum Highway</h3>
+    <p class="text-xs text-gray-500 mb-3">
+        Pick a song with a drum tab (sloppak-spec §5.3), choose <em>3D
+        Drum Highway</em> from the viz picker. The plugin auto-attaches
+        to your MIDI controller and routes chart pieces through the kit
+        you configure below.
+    </p>
+
+    <!-- Palette -->
+    <div class="mt-3">
+        <label for="drumh3d-palette" class="text-xs font-medium text-gray-400 mb-1 block">Palette</label>
+        <select id="drumh3d-palette"
+            onchange="window.drumH3dSetPalette && window.drumH3dSetPalette(this.value); (window._drumH3dRenderPaletteSwatches || function(){})(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="default">Default (Classic)</option>
+            <option value="neon">Neon (saturated, electric)</option>
+            <option value="pastel">Pastel (soft, low contrast)</option>
+        </select>
+        <div class="mt-2 flex items-center gap-1" aria-hidden="true">
+            <span id="drumh3d-swatch-0" class="inline-block h-6 w-5 rounded border border-gray-700/60"></span>
+            <span id="drumh3d-swatch-1" class="inline-block h-6 w-5 rounded border border-gray-700/60"></span>
+            <span id="drumh3d-swatch-2" class="inline-block h-6 w-5 rounded border border-gray-700/60"></span>
+            <span id="drumh3d-swatch-3" class="inline-block h-6 w-5 rounded border border-gray-700/60"></span>
+            <span id="drumh3d-swatch-4" class="inline-block h-6 w-5 rounded border border-gray-700/60"></span>
+            <span id="drumh3d-swatch-5" class="inline-block h-6 w-5 rounded border border-gray-700/60"></span>
+            <span id="drumh3d-swatch-6" class="inline-block h-6 w-5 rounded border border-gray-700/60"></span>
+            <span id="drumh3d-swatch-7" class="inline-block h-6 w-5 rounded border border-gray-700/60"
+                  style="background:#ffa030"></span>
+        </div>
+    </div>
+
+    <!-- Camera angle -->
+    <div class="mt-4">
+        <label for="drumh3d-camera" class="text-xs font-medium text-gray-400 mb-1 block">
+            Camera angle <span id="drumh3d-camera-val" class="text-gray-500 font-mono">0.35</span>
+        </label>
+        <input type="range" id="drumh3d-camera"
+            min="0" max="1" step="0.05" value="0.35"
+            oninput="window.drumH3dSetCameraAngle && window.drumH3dSetCameraAngle(this.value); document.getElementById('drumh3d-camera-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">0 = down the lanes · 1 = top-down</p>
+    </div>
+
+    <!-- Graphics -->
+    <div class="mt-6 border-t border-gray-800 pt-4">
+        <h4 class="text-xs font-medium text-gray-300 mb-2">Graphics</h4>
+
+        <label for="drumh3d-fx-theme" class="text-xs font-medium text-gray-400 mb-1 block">Scene theme</label>
+        <select id="drumh3d-fx-theme"
+            onchange="window.drumH3dSetTheme && window.drumH3dSetTheme(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="default">Default (original)</option>
+            <option value="midnight">Midnight</option>
+            <option value="charcoal">Charcoal</option>
+            <option value="deeppurple">Deep Purple</option>
+            <option value="forest">Forest</option>
+            <option value="warmslate">Warm Slate</option>
+            <option value="deepfocus">Deep Focus</option>
+            <option value="deepsea">Deep Sea</option>
+            <option value="cathode">Cathode</option>
+            <option value="cathodegreen">Cathode Green</option>
+            <option value="hearth">Hearth</option>
+        </select>
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            Background, floor and lane colours — the same theme names as the
+            guitar highway, so your look carries across instruments. Piece
+            colours stay with the Palette above.
+        </p>
+
+        <label for="drumh3d-fx-cinematic" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer">
+            <input type="checkbox" id="drumh3d-fx-cinematic" checked
+                onchange="window.drumH3dSetFx && window.drumH3dSetFx('cinematic', this.checked)">
+            Cinematic lighting
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Dimmer ambience, stronger key light — more depth on the cymbals
+            and drumheads.
+        </p>
+
+        <label for="drumh3d-fx-glow" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Glow strength <span id="drumh3d-fx-glow-val" class="text-gray-500 font-mono">0.50</span>
+        </label>
+        <input type="range" id="drumh3d-fx-glow"
+            min="0" max="1" step="0.05" value="0.5"
+            oninput="window.drumH3dSetFx && window.drumH3dSetFx('glow', this.value); document.getElementById('drumh3d-fx-glow-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            How hard the notes and hit line self-illuminate (0.5 = stock).
+            Pairs with bloom.
+        </p>
+
+        <label for="drumh3d-fx-vibrancy" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Lane vibrancy <span id="drumh3d-fx-vibrancy-val" class="text-gray-500 font-mono">0.85</span>
+        </label>
+        <input type="range" id="drumh3d-fx-vibrancy"
+            min="0" max="1" step="0.05" value="0.85"
+            oninput="window.drumH3dSetFx && window.drumH3dSetFx('vibrancy', this.value); document.getElementById('drumh3d-fx-vibrancy-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            Lane stripe and accent-ring strength — lower for a calmer deck.
+        </p>
+
+        <label for="drumh3d-fx-bgstyle" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">Background ambience</label>
+        <select id="drumh3d-fx-bgstyle"
+            onchange="window.drumH3dSetBgStyle && window.drumH3dSetBgStyle(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="off">Off</option>
+            <option value="particles" selected>Particles</option>
+            <option value="lights">Stage lights</option>
+            <option value="geometric">Geometric</option>
+        </select>
+        <label for="drumh3d-fx-bgintensity" class="text-xs font-medium text-gray-400 mb-1 mt-2 block">
+            Ambience intensity <span id="drumh3d-fx-bgintensity-val" class="text-gray-500 font-mono">0.50</span>
+        </label>
+        <input type="range" id="drumh3d-fx-bgintensity"
+            min="0" max="1" step="0.05" value="0.5"
+            oninput="window.drumH3dSetFx && window.drumH3dSetFx('bgIntensity', this.value); document.getElementById('drumh3d-fx-bgintensity-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <label for="drumh3d-fx-bgreactive" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-2">
+            <input type="checkbox" id="drumh3d-fx-bgreactive" checked
+                onchange="window.drumH3dSetFx && window.drumH3dSetFx('bgReactive', this.checked)">
+            Audio-reactive ambience
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            The backdrop pulses with the mix (stems analyser when a sloppak
+            is loaded). Off = it animates on time only.
+        </p>
+
+        <label for="drumh3d-fx-scorefx" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="drumh3d-fx-scorefx" checked
+                onchange="window.drumH3dSetFx && window.drumH3dSetFx('scoreFx', this.checked)">
+            Score effects
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            +1 pops on hits, a ring pulse every 10-combo, milestone bursts at
+            25/50/100, and a brief red flicker when a streak breaks.
+        </p>
+
+        <label for="drumh3d-fx-bloom" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="drumh3d-fx-bloom" checked
+                onchange="window.drumH3dSetFx && window.drumH3dSetFx('bloom', this.checked)">
+            Glow (bloom)
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Soft light-bleed around the hit line and bright notes. Applies
+            live; turn off to reclaim GPU headroom on weak machines.
+        </p>
+
+        <label for="drumh3d-fx-sparks" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="drumh3d-fx-sparks" checked
+                onchange="window.drumH3dSetFx && window.drumH3dSetFx('sparks', this.checked)">
+            Hit sparks
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            A small particle burst on every scored pad hit.
+        </p>
+
+        <label for="drumh3d-fx-timing" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="drumh3d-fx-timing" checked
+                onchange="window.drumH3dSetFx && window.drumH3dSetFx('timingFx', this.checked)">
+            Timing colours
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Tint hit feedback by timing — on-time green, early cyan, late
+            amber. Off = always green.
+        </p>
+
+        <label for="drumh3d-fx-streak" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="drumh3d-fx-streak" checked
+                onchange="window.drumH3dSetFx && window.drumH3dSetFx('streakFx', this.checked)">
+            Streak feedback
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Spark bursts grow with your combo.
+        </p>
+
+        <label for="drumh3d-fx-hitfx" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Hit feedback intensity <span id="drumh3d-fx-hitfx-val" class="text-gray-500 font-mono">0.70</span>
+        </label>
+        <input type="range" id="drumh3d-fx-hitfx"
+            min="0" max="1" step="0.05" value="0.7"
+            oninput="window.drumH3dSetFx && window.drumH3dSetFx('hitFx', this.value); document.getElementById('drumh3d-fx-hitfx-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            Drives the lane flashes, approach glow and the kick camera pulse.
+            0 turns them off.
+        </p>
+    </div>
+
+    <!-- MIDI input -->
+    <div class="mt-6 border-t border-gray-800 pt-4">
+        <h4 class="text-xs font-medium text-gray-300 mb-2">MIDI input</h4>
+        <label for="drumh3d-midi-input" class="text-xs font-medium text-gray-400 mb-1 block">Device</label>
+        <select id="drumh3d-midi-input"
+            onchange="window.drumH3dSetMidiInput && window.drumH3dSetMidiInput(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-1.5 text-xs text-gray-300 outline-none">
+            <option value="">— none —</option>
+        </select>
+        <p class="text-xs text-gray-500 mt-1">
+            Auto-picks the first non-passthrough input on load. Pick "none" to pause hit and miss tracking.
+        </p>
+
+        <label for="drumh3d-synth-vol" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Kit volume <span id="drumh3d-synth-vol-val" class="text-gray-500 font-mono">0.70</span>
+        </label>
+        <input type="range" id="drumh3d-synth-vol"
+            min="0" max="1" step="0.01" value="0.7"
+            oninput="window.drumH3dSetSynthVolume && window.drumH3dSetSynthVolume(this.value); document.getElementById('drumh3d-synth-vol-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+    </div>
+
+    <!-- Kit configuration -->
+    <div class="mt-6 border-t border-gray-800 pt-4">
+        <h4 class="text-xs font-medium text-gray-300 mb-2">My kit</h4>
+        <p class="text-xs text-gray-500 mb-3">
+            Add the pieces you actually have, in the order you want them
+            on the highway (left → right). The default fallback routing
+            covers most common kit setups; use the fallbacks panel below
+            to reroute any chart piece to a different lane on your kit,
+            or set it to "—" to silently drop it.
+        </p>
+
+        <label class="text-xs font-medium text-gray-400 mb-1 block">Kit name</label>
+        <input type="text" id="drumh3d-kit-name" maxlength="80"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-1.5 text-xs text-gray-300 outline-none mb-3"
+            oninput="window._drumH3dKit && window._drumH3dKit.onNameInput(this.value)">
+
+        <label class="text-xs font-medium text-gray-400 mb-1 block">Lanes (left → right on the highway; kick is always a full-width bar)</label>
+        <div id="drumh3d-kit-lanes" class="space-y-1 mb-2"></div>
+
+        <div class="mt-2 mb-3">
+            <label class="text-xs font-medium text-gray-400 mb-1 block">Add a piece</label>
+            <select id="drumh3d-kit-add"
+                onchange="window._drumH3dKit && window._drumH3dKit.onAddPiece(this.value); this.value=''"
+                class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-1.5 text-xs text-gray-300 outline-none">
+                <option value="">— pick a piece to add —</option>
+            </select>
+        </div>
+
+        <details class="mt-2 mb-3">
+            <summary class="text-xs text-gray-400 cursor-pointer">Chart fallbacks for pieces I don't have</summary>
+            <p class="text-xs text-gray-500 mt-2 mb-2">
+                When a song uses a piece that isn't on your kit, route it
+                to one of your lanes. Set "—" to silently drop that piece.
+            </p>
+            <div id="drumh3d-kit-fallbacks" class="space-y-1"></div>
+        </details>
+
+        <div class="flex flex-wrap items-center gap-2 mt-3">
+            <button type="button"
+                onclick="window._drumH3dKit && window._drumH3dKit.copyToClipboard()"
+                class="px-3 py-1.5 bg-dark-600 hover:bg-dark-500 rounded-lg text-xs">📋 Copy kit</button>
+            <button type="button"
+                onclick="document.getElementById('drumh3d-kit-import-row').classList.toggle('hidden')"
+                class="px-3 py-1.5 bg-dark-600 hover:bg-dark-500 rounded-lg text-xs">📥 Import kit…</button>
+            <button type="button"
+                onclick="window._drumH3dKit && window._drumH3dKit.resetDefault()"
+                class="px-3 py-1.5 bg-dark-600 hover:bg-dark-500 rounded-lg text-xs">Reset</button>
+            <span id="drumh3d-kit-status" class="text-xs text-gray-500 ml-auto"></span>
+        </div>
+
+        <div id="drumh3d-kit-import-row" class="hidden mt-3">
+            <label class="text-xs font-medium text-gray-400 mb-1 block">Paste a shared kit</label>
+            <textarea id="drumh3d-kit-import-text" rows="3"
+                placeholder="Paste a base64 kit string here…"
+                class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-[10px] font-mono text-gray-300 outline-none"></textarea>
+            <button type="button"
+                onclick="window._drumH3dKit && window._drumH3dKit.importFromTextarea()"
+                class="mt-2 px-3 py-1.5 bg-emerald-700 hover:bg-emerald-600 rounded-lg text-xs">Apply imported kit</button>
+        </div>
+    </div>
+
+    <script>
+    (function () {
+        // Mirror of PALETTES in screen.js — kept in sync for swatch previews.
+        const PALETTES = {
+            default: [0xff2828, 0xffd400, 0x2080ff, 0xff8020, 0x30d040, 0xa040ff, 0xff6bd5, 0x6bffe6],
+            neon:    [0xff0030, 0xffe800, 0x0080ff, 0xff8030, 0x40ff50, 0xb050ff, 0xff40d0, 0x40ffd0],
+            pastel:  [0xe89aa0, 0xefdf90, 0x9adfee, 0xefb898, 0xa6e0a8, 0xc4a6e0, 0xe0a6c8, 0xa6e0d8],
+        };
+
+        function toHex(n) { return '#' + n.toString(16).padStart(6, '0'); }
+
+        // Palette swatch preview: read the FIRST 8 pieces of the active
+        // kit's lanes (or pad to 8) for colour reference.
+        window._drumH3dRenderPaletteSwatches = function (id) {
+            const pal = PALETTES[id] || PALETTES.default;
+            const kit = (window.drumH3dGetKit && window.drumH3dGetKit()) || null;
+            const lanes = (kit && kit.lanes) || [];
+            // The kick always shows amber — same as the renderer. Other
+            // lanes follow the piece's palette index from screen.js,
+            // retrieved via drumH3dGetPiecePaletteIdx() so settings.html
+            // stays in sync when pieces are added without any copy-paste.
+            const PALETTE_IDX = (window.drumH3dGetPiecePaletteIdx && window.drumH3dGetPiecePaletteIdx()) || {
+                kick: -1,  // sentinel — render amber
+                snare: 0, snare_xstick: 0,
+                hh_closed: 7, hh_open: 7, hh_pedal: 7,
+                tom_hi: 4, tom_mid: 2, tom_low: 5, tom_floor: 5,
+                crash_l: 1, crash_r: 1, splash: 1, china: 1,
+                ride: 3, ride_bell: 3,
+            };
+            for (let i = 0; i < 8; i++) {
+                const el = document.getElementById('drumh3d-swatch-' + i);
+                if (!el) continue;
+                const ln = lanes[i];
+                if (!ln) { el.style.background = '#000'; el.style.opacity = '0.3'; continue; }
+                el.style.opacity = '1';
+                const idx = PALETTE_IDX[ln.piece];
+                if (idx === -1) { el.style.background = '#ffa030'; continue; }
+                el.style.background = toHex(pal[idx ?? 0]);
+            }
+        };
+
+        // Read fresh inside renderKit() — they're set by screen.js's IIFE,
+        // which may not have finished evaluating when this inline script
+        // first runs if the user opens Settings before the player ever loaded.
+
+        // Friendly piece labels — self-contained so renderKit's callbacks
+        // (which run after our local PIECE_LABELS scope has cleared)
+        // still work.
+        const FRIENDLY = {
+            kick: 'Kick',
+            snare: 'Snare', snare_xstick: 'Snare (cross-stick)',
+            hh_closed: 'Hi-hat (closed)', hh_open: 'Hi-hat (open)', hh_pedal: 'Hi-hat (pedal)',
+            tom_hi: 'Tom — high', tom_mid: 'Tom — mid', tom_low: 'Tom — low', tom_floor: 'Floor tom',
+            crash_l: 'Crash (left)', crash_r: 'Crash (right)', splash: 'Splash', china: 'China',
+            ride: 'Ride', ride_bell: 'Ride bell',
+        };
+        function friendly(p) { return FRIENDLY[p] || p; }
+
+        // Render the current kit's lane list with reorder + remove buttons.
+        function renderKit() {
+            const kit = window.drumH3dGetKit ? window.drumH3dGetKit() : null;
+            if (!kit) {
+                // screen.js hasn't published its API yet — defer one tick.
+                // Happens when the settings panel opens before the player
+                // has loaded a song.
+                setTimeout(renderKit, 100);
+                return;
+            }
+            const PIECE_CATEGORY = window.drumH3dGetPieceCategory ? window.drumH3dGetPieceCategory() : {};
+            const ALL_PIECES = window.drumH3dGetAllPieces ? window.drumH3dGetAllPieces() : [];
+            document.getElementById('drumh3d-kit-name').value = kit.name || '';
+
+            // Lanes panel — order matters: up/down buttons reorder, x
+            // removes (also clears any fallback that pointed at the
+            // removed piece on the way out).
+            const lanesEl = document.getElementById('drumh3d-kit-lanes');
+            lanesEl.innerHTML = '';
+            const taken = new Set(kit.lanes.map(l => l.piece));
+            kit.lanes.forEach((ln, i) => {
+                const row = document.createElement('div');
+                row.className = 'flex items-center gap-2 px-2 py-1 bg-dark-700/60 rounded';
+                // Screen readers should hear the user-facing label
+                // ("Hi-hat (closed)") not the internal piece id ("hh_closed").
+                const pieceName = friendly(ln.piece);
+                row.innerHTML =
+                    `<span class="font-mono text-[10px] text-gray-500 w-6 text-center">${i}</span>` +
+                    `<span class="flex-1 text-xs text-gray-300">${pieceName}</span>` +
+                    `<button type="button" data-act="up"   data-i="${i}" class="px-1.5 py-0.5 text-xs text-gray-400 hover:text-white" ${i === 0 ? 'disabled' : ''} title="Move up" aria-label="Move ${pieceName} up">▲</button>` +
+                    `<button type="button" data-act="down" data-i="${i}" class="px-1.5 py-0.5 text-xs text-gray-400 hover:text-white" ${i === kit.lanes.length - 1 ? 'disabled' : ''} title="Move down" aria-label="Move ${pieceName} down">▼</button>` +
+                    `<button type="button" data-act="rm"   data-i="${i}" class="px-1.5 py-0.5 text-xs text-red-400 hover:text-red-300" title="Remove from kit" aria-label="Remove ${pieceName} from kit">✗</button>`;
+                lanesEl.appendChild(row);
+            });
+            lanesEl.querySelectorAll('button').forEach(btn => {
+                btn.onclick = () => {
+                    const i = parseInt(btn.dataset.i, 10);
+                    const act = btn.dataset.act;
+                    const next = JSON.parse(JSON.stringify(kit));
+                    if (act === 'up' && i > 0) {
+                        [next.lanes[i - 1], next.lanes[i]] = [next.lanes[i], next.lanes[i - 1]];
+                    } else if (act === 'down' && i < next.lanes.length - 1) {
+                        [next.lanes[i + 1], next.lanes[i]] = [next.lanes[i], next.lanes[i + 1]];
+                    } else if (act === 'rm') {
+                        const removed = next.lanes[i].piece;
+                        next.lanes.splice(i, 1);
+                        // Drop any fallback that targeted the removed piece
+                        // — it's no longer a valid target.
+                        for (const k of Object.keys(next.fallbacks || {})) {
+                            if (next.fallbacks[k] === removed) delete next.fallbacks[k];
+                        }
+                    } else { return; }
+                    // Guard: drumH3dSetKit returns false when validation
+                    // rejects the kit (e.g. empty lanes[] after last removal).
+                    if (!window.drumH3dSetKit(next)) {
+                        setStatus('Kit must have at least one lane', 'err');
+                    }
+                };
+            });
+
+            // Add-a-piece dropdown — pieces NOT already in lanes, grouped
+            // by category (kick / drums / cymbals).
+            const addSel = document.getElementById('drumh3d-kit-add');
+            addSel.innerHTML = '<option value="">— pick a piece to add —</option>';
+            const groups = { kick: [], drum: [], cymbal: [] };
+            for (const p of ALL_PIECES) {
+                if (taken.has(p)) continue;
+                const cat = PIECE_CATEGORY[p] || 'drum';
+                if (groups[cat]) groups[cat].push(p);
+            }
+            for (const [cat, label] of [['kick', 'Kick'], ['drum', 'Drums'], ['cymbal', 'Cymbals']]) {
+                if (!groups[cat].length) continue;
+                const og = document.createElement('optgroup');
+                og.label = label;
+                for (const p of groups[cat]) {
+                    const opt = document.createElement('option');
+                    opt.value = p;
+                    opt.textContent = friendly(p);
+                    og.appendChild(opt);
+                }
+                addSel.appendChild(og);
+            }
+
+            // Fallback list — every piece NOT in lanes gets a dropdown
+            // mapping it to one of the user's pieces (or "—" to drop).
+            const fbEl = document.getElementById('drumh3d-kit-fallbacks');
+            fbEl.innerHTML = '';
+            for (const p of ALL_PIECES) {
+                if (taken.has(p)) continue;
+                const row = document.createElement('div');
+                row.className = 'flex items-center gap-2 px-2 py-1';
+                const labelTxt = friendly(p);
+                const current = (kit.fallbacks && kit.fallbacks[p]) || '';
+                let optsHtml = '<option value="">— drop —</option>';
+                for (const ln of kit.lanes) {
+                    const sel = ln.piece === current ? ' selected' : '';
+                    optsHtml += `<option value="${ln.piece}"${sel}>${friendly(ln.piece)}</option>`;
+                }
+                row.innerHTML =
+                    `<span class="flex-1 text-xs text-gray-400">${labelTxt}</span>` +
+                    `<span class="text-xs text-gray-600">→</span>` +
+                    `<select data-from="${p}" class="bg-dark-700 border border-gray-800 rounded px-2 py-1 text-xs text-gray-300 outline-none">${optsHtml}</select>`;
+                fbEl.appendChild(row);
+            }
+            fbEl.querySelectorAll('select').forEach(s => {
+                s.onchange = () => {
+                    const next = JSON.parse(JSON.stringify(kit));
+                    next.fallbacks = next.fallbacks || {};
+                    if (s.value) next.fallbacks[s.dataset.from] = s.value;
+                    else delete next.fallbacks[s.dataset.from];
+                    window.drumH3dSetKit(next);  // event-driven renderKit() via drum_h3d:kit
+                };
+            });
+
+            // Refresh palette swatches so they reflect the new lane order.
+            if (window._drumH3dRenderPaletteSwatches) {
+                const pSel = document.getElementById('drumh3d-palette');
+                window._drumH3dRenderPaletteSwatches(pSel ? pSel.value : 'default');
+            }
+        }
+
+        function setStatus(msg, kind) {
+            const el = document.getElementById('drumh3d-kit-status');
+            if (!el) return;
+            el.textContent = msg;
+            el.className = 'text-xs ml-auto ' + (kind === 'err' ? 'text-red-400' : kind === 'ok' ? 'text-emerald-400' : 'text-gray-500');
+            setTimeout(() => { if (el.textContent === msg) el.textContent = ''; }, 3000);
+        }
+
+        // Expose the kit interaction surface to the inline onclick / onchange
+        // attributes used by the markup above.
+        window._drumH3dKit = {
+            onNameInput(name) {
+                // Use the name-only setter to avoid triggering 'drum_h3d:kit'
+                // on every keystroke — that event causes a full WebGL scene
+                // teardown/reinit which produces visible stutter while typing.
+                window.drumH3dSetKitName && window.drumH3dSetKitName(name);
+            },
+            onAddPiece(piece) {
+                if (!piece) return;
+                const kit = window.drumH3dGetKit();
+                kit.lanes.push({ piece });
+                window.drumH3dSetKit(kit);  // event-driven renderKit() via drum_h3d:kit
+            },
+            copyToClipboard() {
+                const b64 = window.drumH3dExportKit && window.drumH3dExportKit();
+                if (!b64) return setStatus('export failed', 'err');
+                const _showImportFallback = (str) => {
+                    // Clipboard unavailable — reveal the import row so the user can
+                    // copy the string from the textarea manually.
+                    document.getElementById('drumh3d-kit-import-row').classList.remove('hidden');
+                    const ta = document.getElementById('drumh3d-kit-import-text');
+                    ta.value = str;
+                    ta.focus();
+                    ta.select();
+                    setStatus('clipboard blocked — copy from the textarea below', 'err');
+                };
+                if (!navigator.clipboard) {
+                    _showImportFallback(b64);
+                    return;
+                }
+                navigator.clipboard.writeText(b64).then(
+                    () => setStatus('✓ kit copied', 'ok'),
+                    () => _showImportFallback(b64),
+                );
+            },
+            importFromTextarea() {
+                const txt = document.getElementById('drumh3d-kit-import-text').value;
+                if (!txt.trim()) return setStatus('paste a kit string first', 'err');
+                const ok = window.drumH3dImportKit && window.drumH3dImportKit(txt);
+                // drumH3dImportKit calls drumH3dSetKit which dispatches drum_h3d:kit;
+                // the event listener re-renders the panel, so no explicit renderKit().
+                if (ok) { setStatus('✓ kit imported', 'ok'); }
+                else setStatus('invalid kit string', 'err');
+            },
+            resetDefault() {
+                window.drumH3dResetKit && window.drumH3dResetKit();
+                // drumH3dResetKit calls drumH3dSetKit → dispatches drum_h3d:kit
+                // → event listener re-renders. No explicit renderKit() needed.
+                setStatus('✓ reset to default', 'ok');
+            },
+        };
+
+        // Re-render the kit list whenever the kit changes (covers external
+        // changes from setKit() / importKit() not initiated by this panel).
+        window.addEventListener('drum_h3d:kit', () => renderKit());
+
+        // ─── MIDI device picker ───────────────────────────────
+        function renderMidiPicker() {
+            const sel = document.getElementById('drumh3d-midi-input');
+            if (!sel) return;
+            const inputs = window.drumH3dListMidiInputs ? window.drumH3dListMidiInputs() : [];
+            const current = window.drumH3dGetMidiInputId ? window.drumH3dGetMidiInputId() : '';
+            sel.innerHTML = '<option value="">— none —</option>';
+            for (const inp of inputs) {
+                const opt = document.createElement('option');
+                opt.value = inp.id;
+                opt.textContent = inp.name;
+                if (inp.id === current) opt.selected = true;
+                sel.appendChild(opt);
+            }
+            // Sync volume slider with the actual persisted value (default
+            // 0.7 if storage was empty or never written).
+            const vol = window.drumH3dGetSynthVolume ? window.drumH3dGetSynthVolume() : 0.7;
+            const volSlider = document.getElementById('drumh3d-synth-vol');
+            const volLabel = document.getElementById('drumh3d-synth-vol-val');
+            if (volSlider) volSlider.value = String(vol);
+            if (volLabel) volLabel.textContent = parseFloat(vol).toFixed(2);
+        }
+        window.addEventListener('drum_h3d:midi_devices', renderMidiPicker);
+        // Kick off MIDI initialisation if the player viz never ran (user
+        // opened Settings → 3D Drum Highway directly). _midiInit is
+        // idempotent so this is safe even when the viz is also active.
+        // Re-render the picker when the access promise settles.
+        (function pollMidi() {
+            if (window.drumH3dEnsureMidiInit) {
+                Promise.resolve(window.drumH3dEnsureMidiInit()).then(renderMidiPicker);
+                renderMidiPicker();  // first paint with whatever's cached
+            } else {
+                setTimeout(pollMidi, 100);
+            }
+        })();
+
+        // Hydrate controls from stored config on first paint.
+        // Narrow the try/catch to just localStorage reads — renderKit() and
+        // swatches must always run even when storage is blocked/disabled.
+        const pSel = document.getElementById('drumh3d-palette');
+        const cam = document.getElementById('drumh3d-camera');
+        const camVal = document.getElementById('drumh3d-camera-val');
+        try {
+            const storedPal = localStorage.getItem('drum_h3d_palette');
+            if (storedPal && PALETTES[storedPal]) pSel.value = storedPal;
+
+            const storedCam = parseFloat(localStorage.getItem('drum_h3d_camera_angle'));
+            if (Number.isFinite(storedCam)) {
+                const c = Math.min(1, Math.max(0, storedCam));
+                cam.value = String(c);
+                camVal.textContent = c.toFixed(2);
+            }
+
+            // FX toggles (drum_h3d_bg_* — guitar-parity graphics controls).
+            // Only explicit values override; absent/corrupt keys keep the
+            // default (ON), matching screen.js readFxSettings.
+            const hydrateFxBool = (key, elId) => {
+                const raw = localStorage.getItem('drum_h3d_bg_' + key);
+                if (raw === '1' || raw === 'true') document.getElementById(elId).checked = true;
+                else if (raw === '0' || raw === 'false') document.getElementById(elId).checked = false;
+            };
+            hydrateFxBool('bloom', 'drumh3d-fx-bloom');
+            hydrateFxBool('sparks', 'drumh3d-fx-sparks');
+            hydrateFxBool('timingFx', 'drumh3d-fx-timing');
+            hydrateFxBool('streakFx', 'drumh3d-fx-streak');
+            hydrateFxBool('cinematic', 'drumh3d-fx-cinematic');
+            hydrateFxBool('bgReactive', 'drumh3d-fx-bgreactive');
+            hydrateFxBool('scoreFx', 'drumh3d-fx-scorefx');
+            const hydrateFxRange = (key, elId, valId) => {
+                const n = parseFloat(localStorage.getItem('drum_h3d_bg_' + key));
+                if (!Number.isFinite(n)) return;
+                const v = Math.min(1, Math.max(0, n));
+                document.getElementById(elId).value = String(v);
+                document.getElementById(valId).textContent = v.toFixed(2);
+            };
+            hydrateFxRange('hitFx', 'drumh3d-fx-hitfx', 'drumh3d-fx-hitfx-val');
+            hydrateFxRange('glow', 'drumh3d-fx-glow', 'drumh3d-fx-glow-val');
+            hydrateFxRange('vibrancy', 'drumh3d-fx-vibrancy', 'drumh3d-fx-vibrancy-val');
+            hydrateFxRange('bgIntensity', 'drumh3d-fx-bgintensity', 'drumh3d-fx-bgintensity-val');
+            const storedStyle = localStorage.getItem('drum_h3d_bg_style');
+            const styleSel = document.getElementById('drumh3d-fx-bgstyle');
+            if (storedStyle && Array.from(styleSel.options).some(o => o.value === storedStyle)) {
+                styleSel.value = storedStyle;
+            }
+            const storedTheme = localStorage.getItem('drum_h3d_bg_theme');
+            const themeSel = document.getElementById('drumh3d-fx-theme');
+            if (storedTheme && Array.from(themeSel.options).some(o => o.value === storedTheme)) {
+                themeSel.value = storedTheme;
+            }
+        } catch (e) {
+            console.warn('[Drum-Hwy3D settings] hydration failed:', e);
+        }
+        renderKit();
+        window._drumH3dRenderPaletteSwatches(pSel.value);
+    })();
+    </script>
+</div>

plugins/drum_highway_3d/tests/camera_bridge.test.js

@@ -0,0 +1,78 @@
+// Camera Director bridge resolver tests: per-panel select, global fallback,
+// null-when-absent, throw-safety, and the splitscreen global-name alias. Loads
+// screen.js in a bare vm window and exercises the __test exports (no DOM/WebGL).
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+function load() {
+    const window = {
+        console,
+        location: { protocol: 'http:', host: 'localhost' },
+        slopsmith: {},
+    };
+    window.window = window;
+    window.globalThis = window;
+    const context = vm.createContext(window);
+    const src = fs.readFileSync(path.join(__dirname, '..', 'screen.js'), 'utf8');
+    vm.runInContext(src, context, { filename: 'screen.js' });
+    return { window, __test: window.slopsmithViz_drum_highway_3d.__test };
+}
+
+test('_resolveFreeCam: per-panel camera under splitscreen', () => {
+    const { __test } = load();
+    const c0 = {}, c1 = {};
+    const ss = { panelIndexFor: (c) => (c === c0 ? 0 : 1) };
+    const map = { 0: { id: 'p0' }, 1: { id: 'p1' } };
+    assert.equal(__test._resolveFreeCam(c0, ss, map, { id: 'g' }).id, 'p0');
+    assert.equal(__test._resolveFreeCam(c1, ss, map, { id: 'g' }).id, 'p1');
+});
+
+test('_resolveFreeCam: falls back to global when there is no panel map', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 0 }, null, g), g);
+});
+
+test('_resolveFreeCam: falls back to global when the panel has no map entry', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    const ss = { panelIndexFor: () => 3 };            // index 3 absent from map
+    assert.equal(__test._resolveFreeCam({}, ss, { 0: {} }, g), g);
+});
+
+test('_resolveFreeCam: null when Camera Director is absent (no global)', () => {
+    const { __test } = load();
+    assert.equal(__test._resolveFreeCam({}, null, null, null), null);
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 0 }, {}, undefined), null);
+});
+
+test('_resolveFreeCam: throw-safe on panelIndexFor → falls back to global', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    const ss = { panelIndexFor: () => { throw new Error('boom'); } };
+    assert.equal(__test._resolveFreeCam({}, ss, { 0: {} }, g), g);
+});
+
+test('_resolveFreeCam: NaN/negative/float/string index → falls back to global', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => NaN }, { 0: {} }, g), g);
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => -1 }, { 0: {} }, g), g);
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 0.5 }, { 0: {} }, g), g);
+    // A string/prototype key must not resolve an inherited property (e.g. toString).
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 'toString' }, {}, g), g);
+});
+
+test('_ssApi: null when neither global set; slopsmith alias; feedBack canonical wins', () => {
+    const { window, __test } = load();
+    assert.equal(__test._ssApi(), null);
+    const legacy = { panelIndexFor: () => 0 };
+    window.slopsmithSplitscreen = legacy;
+    assert.equal(__test._ssApi(), legacy);            // legacy alias picked up
+    const current = { panelIndexFor: () => 1 };
+    window.feedBackSplitscreen = current;
+    assert.equal(__test._ssApi(), current);           // canonical name takes precedence
+});

plugins/drum_highway_3d/tests/data_layer.test.js

@@ -0,0 +1,164 @@
+// Pure data-layer tests: load screen.js in a bare vm window and exercise the
+// __test exports (no DOM, no WebGL, no network). Doubles as a lint that no
+// module-scope code touches document/localStorage outside a try/catch —
+// the vm window deliberately provides neither.
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+function load() {
+    const window = {
+        console,
+        location: { protocol: 'http:', host: 'localhost' },
+        slopsmith: {},
+    };
+    window.window = window;
+    window.globalThis = window;
+    const context = vm.createContext(window);
+    const src = fs.readFileSync(path.join(__dirname, '..', 'screen.js'), 'utf8');
+    vm.runInContext(src, context, { filename: 'screen.js' });
+    return window.slopsmithViz_drum_highway_3d;
+}
+
+test('module loads in a bare vm (no DOM / localStorage at module scope)', () => {
+    const factory = load();
+    assert.equal(typeof factory, 'function');
+    assert.equal(factory.contextType, 'webgl2');
+});
+
+test('_variantForHit: ghost > flam > bell > accent > normal precedence', () => {
+    const { _variantForHit } = load().__test;
+    assert.equal(_variantForHit({ g: true, f: true, v: 120 }), 'ghost');
+    assert.equal(_variantForHit({ f: true, v: 120 }), 'flam');
+    assert.equal(_variantForHit({ p: 'ride_bell' }), 'bell');
+    assert.equal(_variantForHit({ v: 100 }), 'accent');
+    assert.equal(_variantForHit({ v: 127 }), 'accent');
+    assert.equal(_variantForHit({ v: 99 }), 'normal');
+    // Missing velocity defaults to 100 → accent.
+    assert.equal(_variantForHit({}), 'accent');
+});
+
+test('matchesArrangement: claims drum arrangements', () => {
+    const matches = load().matchesArrangement;
+    assert.equal(matches({ has_drum_tab: true, arrangement: 'Drums' }), true);
+    assert.equal(matches({ has_drum_tab: true, arrangement: 'Drum Kit' }), true);
+    assert.equal(matches({ has_drum_tab: true, arrangement: 'Percussion' }), true);
+});
+
+test('matchesArrangement: never claims without a drum tab', () => {
+    const matches = load().matchesArrangement;
+    assert.equal(matches(null), false);
+    assert.equal(matches({}), false);
+    assert.equal(matches({ arrangement: 'Drums' }), false);
+});
+
+test('matchesArrangement: steal-guard — guitar arrangements stay with highway_3d', () => {
+    const matches = load().matchesArrangement;
+    // Full-band pack (drum_tab present) playing a guitar-family part:
+    // first-match-wins Auto order must not hand these to the drum highway.
+    for (const arr of ['Lead', 'Rhythm', 'Bass', 'Combo', 'Guitar 22', 'Alt. Lead']) {
+        assert.equal(matches({ has_drum_tab: true, arrangement: arr }), false, arr);
+    }
+    // Keys notation present → the keys/staff viz take it.
+    assert.equal(matches({ has_drum_tab: true, has_notation: true, arrangement: 'Piano' }), false);
+});
+
+test('matchesArrangement: claims packs nothing more specific can render', () => {
+    const matches = load().matchesArrangement;
+    // Drum tab + nondescript arrangement, no notation → drummable, claim it.
+    assert.equal(matches({ has_drum_tab: true, arrangement: '' }), true);
+    assert.equal(matches({ has_drum_tab: true }), true);
+    // Word-boundary check: "BasslineKeys"-style names don't contain a
+    // guitar-family word as a whole word.
+    assert.equal(matches({ has_drum_tab: true, arrangement: 'Bassline' }), true);
+});
+
+test('readFxSettings: defaults survive a localStorage-less environment', () => {
+    const { readFxSettings, FX_DEFAULTS } = load().__test;
+    // The vm window has no localStorage — the try/catch must eat the
+    // ReferenceError and hand back pure defaults (everything ON).
+    assert.deepEqual(readFxSettings(), FX_DEFAULTS);
+    assert.equal(FX_DEFAULTS.bloom, true);
+});
+
+test('MIDI map: open hi-hat is a first-class piece (46 → hh_open)', () => {
+    const { MIDI_TO_PIECE, HIT_TOLERANCE_S } = load().__test;
+    assert.equal(MIDI_TO_PIECE[46], 'hh_open');
+    assert.equal(MIDI_TO_PIECE[42], 'hh_closed');
+    assert.equal(MIDI_TO_PIECE[35], 'kick');
+    assert.equal(MIDI_TO_PIECE[36], 'kick');
+    // ±50 ms window matches the 2D drums plugin.
+    assert.equal(HIT_TOLERANCE_S, 0.05);
+});
+
+test('_classifyTiming: OK band is 40% of the window, sign maps early/late', () => {
+    const { _classifyTiming, HIT_TOLERANCE_S } = load().__test;
+    const tol = HIT_TOLERANCE_S;         // 0.05
+    assert.equal(_classifyTiming(0, tol), 'OK');
+    assert.equal(_classifyTiming(tol * 0.4, tol), 'OK');    // boundary inclusive
+    assert.equal(_classifyTiming(-tol * 0.4, tol), 'OK');
+    // delta = note.t - now: positive → struck before the note → EARLY.
+    assert.equal(_classifyTiming(tol * 0.41, tol), 'EARLY');
+    assert.equal(_classifyTiming(-tol * 0.41, tol), 'LATE');
+    assert.equal(_classifyTiming(tol, tol), 'EARLY');
+    assert.equal(_classifyTiming(-tol, tol), 'LATE');
+    // Degenerate inputs read as on-time rather than throwing.
+    assert.equal(_classifyTiming(NaN, tol), 'OK');
+});
+
+test('FX defaults: hit-FX controls ship enabled', () => {
+    const { FX_DEFAULTS } = load().__test;
+    assert.equal(FX_DEFAULTS.sparks, true);
+    assert.equal(FX_DEFAULTS.timingFx, true);
+    assert.equal(FX_DEFAULTS.streakFx, true);
+    assert.equal(FX_DEFAULTS.hitFx, 0.7);
+});
+
+test('themes: table ids match the guitar highway, default is the stock palette', () => {
+    const { BG_THEMES, _bgThemeColors } = load().__test;
+    // Same id set as highway_3d's BG_THEMES (cross-instrument consistency).
+    assert.deepEqual(Object.keys(BG_THEMES), [
+        'default', 'midnight', 'charcoal', 'deeppurple', 'forest', 'warmslate',
+        'deepfocus', 'deepsea', 'cathode', 'cathodegreen', 'hearth',
+    ]);
+    // 'default' preserves THIS plugin's original look byte-for-byte.
+    assert.equal(BG_THEMES.default.clear, 0x1a1a2e);
+    assert.equal(BG_THEMES.default.board, 0x0a0e1a);
+    assert.equal(BG_THEMES.default.lane, undefined); // stock stripes fallback
+    // Unknown ids fall back to default.
+    assert.equal(_bgThemeColors('nonsense'), BG_THEMES.default);
+    // Every non-default theme carries a lane pair (the axis differentiator).
+    for (const [id, t] of Object.entries(BG_THEMES)) {
+        if (id === 'default') continue;
+        assert.ok(t.lane != null && t.laneDim != null, id + ' lane pair');
+        assert.equal(t.clear, t.fog, id + ' clear==fog (horizon dissolve)');
+    }
+});
+
+test('readThemeSetting: defaults without localStorage; validates ids', () => {
+    const { readThemeSetting } = load().__test;
+    assert.equal(readThemeSetting(), 'default');
+});
+
+test('FX defaults: theme-PR controls ship enabled at stock-neutral values', () => {
+    const { FX_DEFAULTS } = load().__test;
+    assert.equal(FX_DEFAULTS.cinematic, true);
+    assert.equal(FX_DEFAULTS.glow, 0.5);      // 0.5 = 1.0x multiplier (stock)
+    assert.equal(FX_DEFAULTS.vibrancy, 0.85); // ≈ the stock 0.32 stripe base
+});
+
+test('bg styles: validated id set, particles default, no out-of-scope styles', () => {
+    const { BG_STYLE_IDS, readBgStyleSetting } = load().__test;
+    // Host-realm copy — the vm array's foreign prototype trips deepEqual.
+    assert.deepEqual([...BG_STYLE_IDS], ['off', 'particles', 'lights', 'geometric']);
+    assert.equal(readBgStyleSetting(), 'particles'); // no localStorage in the vm
+});
+
+test('FX defaults: ambience + score FX ship enabled', () => {
+    const { FX_DEFAULTS } = load().__test;
+    assert.equal(FX_DEFAULTS.scoreFx, true);
+    assert.equal(FX_DEFAULTS.bgIntensity, 0.5);
+    assert.equal(FX_DEFAULTS.bgReactive, true);
+});

plugins/highway_3d/CLAUDE.md

@@ -157,6 +157,8 @@ Every per-frame renderer call receives a `bundle` from feedBack core. Fields use
 
 `tuning` and `capo` aren't consumed by this plugin.
 
+Core reuses the bundle OBJECT across frames (mutated in place); never cache it or compare its identity between frames — field values are only valid for the current draw call. Field-identity caches on ARRAY fields (this plugin's `_mergeCacheChordsRef === bundle.chords` etc.) remain valid: arrays still swap reference when chart data changes. Core also exposes `bundle.lowerBoundT(arr, time)` (lower-bound on `.t`, notes/chords) and `bundle.lowerBoundTime(arr, time)` (on `.time`, beats/anchors/sections) — prefer these over the local `lowerBoundT` helper when a downlevel-host fallback isn't needed.
+
 ### Score FX (notedetect game-scoring layer)
 
 - **"+N" score pops** → `_fxSpawnPop()` from `drawNote()` (just after the provider verdict-override block), drawn by `drawScoreFx()` (called from the `lyricsCtx` block in `draw()`, right after `drawNotedetectLabels()`). Fixed 24-slot pool (`_fxPops`), deduped per `popKey` via the TTL'd `_fxSeen` map (pruned in `drawScoreFx`). Pops rise/fade over 700 ms; font size scales with the multiplier tier.

plugins/highway_3d/plugin.json

@@ -1,7 +1,7 @@
 {
     "id": "highway_3d",
     "name": "3D Highway",
-    "version": "3.30.0",
+    "version": "3.31.5",
     "type": "visualization",
     "bundled": true,
     "script": "screen.js",

plugins/input_setup/screen.js

@@ -51,15 +51,16 @@
             sources = sources.filter((s) => s
                 && !/midi/i.test(String(s.providerId || ''))
                 && !/^midi-input/i.test(String(s.label || '')));
-            // De-dupe by display label — the desktop engine enumerates the same
-            // device under several driver types, so the same name can repeat.
-            const seen = new Set();
-            sources = sources.filter((s) => {
-                const key = String(s.label || '').toLowerCase();
-                if (seen.has(key)) return false;
-                seen.add(key);
-                return true;
-            });
+            // No label de-dupe here. The audio-input capability already
+            // collapses exact duplicates by logicalSourceKey
+            // (_visibleInputSources), so nothing it returns shares a key. A
+            // device that enumerates under several driver types (ASIO / Windows
+            // Audio / DirectSound) has a DISTINCT key per type and is now
+            // labelled with its driver type (e.g. "Focusrite (ASIO)") — each is
+            // a real, separately-selectable input the user must be able to see.
+            // The old bare-label collapse also kept whichever variant sorted
+            // first, which could silently drop the one that was actually
+            // `selected` below.
             const selected = sources.find((s) => s && s.selected) || null;
             return { sources, selected };
         } catch (_) { return { sources: [], selected: null }; }

plugins/keys_highway_3d/LICENSE

@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU Affero General Public License is a free, copyleft license for
+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+our General Public Licenses are intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  Developers that use our General Public Licenses protect your rights
+with two steps: (1) assert copyright on the software, and (2) offer
+you this License which gives you legal permission to copy, distribute
+and/or modify the software.
+
+  A secondary benefit of defending all users' freedom is that
+improvements made in alternate versions of the program, if they
+receive widespread use, become available for other developers to
+incorporate.  Many developers of free software are heartened and
+encouraged by the resulting cooperation.  However, in the case of
+software used on network servers, this result may fail to come about.
+The GNU General Public License permits making a modified version and
+letting the public access it on a server without ever releasing its
+source code to the public.
+
+  The GNU Affero General Public License is designed specifically to
+ensure that, in such cases, the modified source code becomes available
+to the community.  It requires the operator of a network server to
+provide the source code of the modified version running there to the
+users of that server.  Therefore, public use of a modified version, on
+a publicly accessible server, gives the public access to the source
+code of the modified version.
+
+  An older license, called the Affero General Public License and
+published by Affero, was designed to accomplish similar goals.  This is
+a different license, not a version of the Affero GPL, but Affero has
+released a new version of the Affero GPL which permits relicensing under
+this license.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                       TERMS AND CONDITIONS
+
+  0. Definitions.
+
+  "This License" refers to version 3 of the GNU Affero General Public License.
+
+  "Copyright" also means copyright-like laws that apply to other kinds of
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+
+  "The Program" refers to any copyrightable work licensed under this
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+"recipients" may be individuals or organizations.
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+  To "modify" a work means to copy from or adapt all or part of the work
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plugins/keys_highway_3d/README.md

@@ -0,0 +1,76 @@
+# Keys Highway 3D
+
+RS+-style falling-note 3D piano highway for [Slopsmith](https://github.com/got-feedback/feedback), fed by the **Sloppak Notation Format** (sloppak-spec §5.3) — part of the piano/keys first-class epic (slopsmith#828, plugin workstream slopsmith#824).
+
+- Consumes the `notation_info` / `notation_measures` highway-WS stream over a private per-instance socket and flattens measure → staff → voice → beat → note into `{midi, t, durSec, hand}` (durations derived from written `dur`/`dot`/`tu` at the running tempo; ties extend; overlap-clamped).
+- 3D perspective highway to a vanishing point with a real white/black-key keyboard; per-key **pitch-class colors** (Synthesia convention — C red, D yellow, E blue, …) with hand (rh/lh) as a secondary brightness cue. Selectable **note-color palettes** (settings → Note colors, `keys3d_bg_palette`, default the per-octave scheme): a per-octave rainbow (each octave its own hue, darker sharps), the original per-pitch "Rainbow" table, vivid/pastel per-pitch variants, and single-hue two-tone palettes (uniform naturals, darker sharps) for players who want "black key coming" to read at a glance; notes, key glow, lane guides and hit flames all follow the pick live.
+- Full RS+ visual treatment: key **letter glyphs** printed on the active-range key tops (cached CanvasTextures), **bevelled gem-style note blocks** (ExtrudeGeometry, geometry/material caches keyed by size and pitch-class×hand), **floating bar numbers** scrolling with the notes, **active-range lane dimming** so the playable span pops, and a **glowing pulsing hit-line** (layered additive gradient planes — no postprocessing).
+- Performance discipline: no per-frame allocations or DOM queries in `draw()`. Chart-scoped resources — note geometries/materials, bar-number and glow textures — are cached and disposed on chart teardown; the key-letter glyph `CanvasTexture`s live in a shared module-level cache that survives teardown and is reused across instances.
+- Auto-selected for arrangements with notation via `matchesArrangement(songInfo.has_notation)`; capability-native `visualization` provider declaration.
+- **Camera settings**: camera-rig presets (`keys3d_bg_camera` — classic low rig / elevated / overhead; default overhead, applied live, adaptive pan-zoom preserved) with base-rig fine-tune sliders for height, distance and tilt (`keys3d_bg_camHeight` / `camDist` / `camTilt`) that nudge the vantage point the follow-motion orbits. Numeric FX keys clamp to per-key declared ranges (`FX_RANGES`, default 0–1).
+- **Highway-layout options** (settings → Highway layout). **Sharps & flats**
+  (`keys3d_bg_sharpMode`, string; default `realistic`) picks the sharp layout:
+  `floating` (original raised-plane sharps, white-only lanes); `flat` (one plane,
+  zero-overlap piano-shaped tiled lanes — white lanes trimmed where a sharp adjoins
+  them, and each sharp leaned toward the edge natural beside it so the naturals come
+  out close to even: C/D/E/F/B equal, G/A a hair smaller since G# can't lean; pure
+  `laneSpanFlat()`); `realistic` (one plane, bars sized like the physical keys — full
+  naturals always rendered full, full black keys drawn on top and only occluding a
+  natural where a sharp note actually coincides in time; pure `laneSpanReal()`).
+  **Lane color opacity** (`keys3d_bg_laneOpacity`, 0–1, default 0) fades the
+  pitch-class lane tint; at 0 (default) the strips are a dark floor with guide lines
+  only at the key-block boundaries (E→F and each octave B→C), so each block is bounded
+  rather than every lane — the notes keep their colors; toward 1 it fills in full,
+  vivid colored lanes. The strips, per-lane separators and block lines crossfade with
+  this value. **Octave separators** (`keys3d_bg_octaveGaps`, default on) widens the
+  gap a touch at each B→C octave boundary. **Octave line contrast**
+  (`keys3d_bg_octaveContrast`, 0–1, default 0.5) scales how hard the B→C octave line
+  reads; it is drawn as a dark layer (scaled by lane opacity) plus a bright layer
+  (scaled by its inverse), so it auto-shifts dark→bright as the lanes fade — no mode
+  switch needed. All are geometry-time — applied on the next chart build via
+  `init()`'s re-read.
+- **Web MIDI input scoring**: module-level MIDI singleton (one access per tab, focused-instance routing) with device auto-connect by saved id+name, loopback blocklist, channel filter, transpose and CC64 sustain (`keys3d_` localStorage prefix; `window.keysH3d*` settings API). Hit detection matches played MIDI against the flattened chart notes within ±0.10 s with per-note dedupe and a missed-note sweep (only while a device is connected — never retroactive across a mid-song connect).
+- **Live hit feedback on the MIDI path** (not the chart): key depress (~4° back-edge pivot, ~120 ms spring; the key letter rides along), wrong-note red key flash, and a vertical flame flare on hits (pooled additive sprites, white-hot base fading into the pitch-class color, ~400 ms).
+- **End-of-run stats**: POSTs `/api/stats` `{filename, arrangement, score, accuracy}` exactly once per run with the same formula as the guitar notedetect path (`accuracy = hits / max(1, hits+misses)`, `score = round(hits·100·accuracy)`), then notifies the progression core when present.
+- **Capability wiring** (all guarded for servers without the hosts): registers as a note-detection `midi` provider (`keys-midi`, `verify.target`), opens a per-song binding scoped to the chart's keys range, reports hit/miss observability events, and exposes Web MIDI inputs to the audio-input domain with pseudonymized labels (`midi-input-1`, …) via `source.enumerate/describe/open/close`.
+- Headless test hook: `window.__keysHwTest = { injectNoteOn(midi, when), getScore() }`.
+
+## Tests
+
+```
+node --test tests/*.test.js
+```
+
+## Ported helpers (keep in sync with highway_3d)
+
+Visual-parity code copied from `plugins/highway_3d/screen.js` — same
+function names, signatures, and constants on purpose, marked with
+`PORTED FROM highway_3d` comments at each site. If the guitar highway
+tunes one of these, mirror the change here (and in `drum_highway_3d`):
+
+- `_bloomEnsure()` / `_bloomDispose()` — EffectComposer + UnrealBloomPass
+  (0.65/0.5/0.82) on a multisampled HalfFloat target, ACES↔None tone-
+  mapping switch in `draw()`; addons dynamic-imported from
+  `/static/vendor/three/addons/` (no CDN fallback — direct render is the
+  graceful degrade)
+- `_sparkBurst()` / `_sparkUpdate()` — pooled additive Points hit sparks
+  (pool 96 here — the flame sprites carry most of the hit feedback)
+- `_timingHex()` / `_classifyTiming()` — early/late/on-time feedback
+  colors (green/cyan/amber) + the 40%-window classifier
+- `_ssActive()` — host splitscreen probe (minus the guitar's focus-API
+  checks, which it needs for input routing and we don't)
+- `BG_THEMES` / `_bgThemeColors()` — the scene theme table (same ids/values
+  as the guitar's, except `default` which is this plugin's original
+  palette); one pick drives background gradient + floor + lane rails
+- `_makeStudioEnv()` — procedural PMREM studio environment (shared with
+  drum_highway_3d; RoomEnvironment isn't vendored)
+- `_applyCinematic()` — ambient/key rebalance (values tuned per plugin)
+- `BG_STYLES` (off/particles/lights/geometric) + `_bgGetAnalyser()` /
+  `_bgReadBands()` — background ambience + the stems-first audio-analyser
+  bridge (shared with drum_highway_3d)
+- `_drawScoreFx()` — score overlay (pops / tier rings / milestone bursts /
+  streak-break wash), drum_highway_3d pattern
+
+## License
+
+AGPL-3.0.

plugins/keys_highway_3d/assets/thumb.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="256" height="256" viewBox="0 0 256 256" role="img" aria-label="Keys Highway 3D placeholder thumbnail">
+  <rect width="256" height="256" rx="36" fill="#0f172a"/>
+  <rect x="18" y="18" width="220" height="220" rx="28" fill="#1e293b" stroke="#334155" stroke-width="3"/>
+  <text x="128" y="150" font-family="Rubik, Arial, sans-serif" font-size="104" font-weight="800" fill="#38bdf8" text-anchor="middle">KH</text>
+</svg>

plugins/keys_highway_3d/plugin.json

@@ -0,0 +1,68 @@
+{
+  "id": "keys_highway_3d",
+  "name": "Keys Highway 3D",
+  "version": "0.2.1",
+  "description": "RS+-style 3D falling-note piano highway fed by the Sloppak Notation Format, with Web MIDI input scoring.",
+  "type": "visualization",
+  "bundled": true,
+  "script": "screen.js",
+  "settings": {
+    "html": "settings.html",
+    "category": "graphics"
+  },
+  "standards": [
+    "capability-pipelines.v1",
+    "plugin-runtime-idempotent.v1"
+  ],
+  "capabilities": {
+    "visualization": {
+      "roles": [
+        "provider"
+      ],
+      "operations": [
+        "renderer.create",
+        "renderer.destroy"
+      ],
+      "emits": [
+        "renderer-ready",
+        "renderer-failed"
+      ],
+      "mode": "active",
+      "safety": "safe"
+    },
+    "note-detection": {
+      "roles": [
+        "provider"
+      ],
+      "operations": [
+        "verify.target"
+      ],
+      "emits": [
+        "hit",
+        "miss"
+      ],
+      "mode": "active",
+      "safety": "sensitive"
+    },
+    "midi-input": {
+      "roles": [
+        "requester"
+      ],
+      "requests": [
+        "discover",
+        "list-sources",
+        "select-source",
+        "open-source",
+        "close-source"
+      ],
+      "mode": "active",
+      "compatibility": "degrade-noop",
+      "ownership": "requester-only",
+      "safety": "sensitive",
+      "description": "Reads the MIDI keyboard input through the core midi-input domain (Web-MIDI provider ships built-in with the domain). Absent domain \u2192 no MIDI devices, fail-soft.",
+      "version": 1
+    }
+  },
+  "category": "practice",
+  "icon": "assets/thumb.svg"
+}

plugins/keys_highway_3d/settings.html

@@ -0,0 +1,367 @@
+<div role="group" aria-labelledby="keysh3d-heading">
+    <h3 id="keysh3d-heading" class="text-sm font-medium text-gray-400 mb-2">3D Keys Highway</h3>
+    <p class="text-xs text-gray-500 mb-3">
+        Pick a song with keys notation (sloppak-spec §5.3) and choose
+        <em>Keys Highway 3D</em> from the viz picker (Auto selects it for
+        notation charts). The plugin auto-attaches to your MIDI keyboard;
+        device, channel and transpose are configured from the player for
+        now — this panel holds the graphics controls.
+    </p>
+
+    <!-- Graphics -->
+    <div class="mt-3">
+        <h4 class="text-xs font-medium text-gray-300 mb-2">Graphics</h4>
+
+        <label for="keysh3d-fx-palette" class="text-xs font-medium text-gray-400 mb-1 block">Note colors</label>
+        <select id="keysh3d-fx-palette"
+            onchange="window.keys3dSetPalette && window.keys3dSetPalette(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="octaves" selected>Octaves (color per octave, darker sharps)</option>
+            <option value="emerald">Emerald (green, darker sharps)</option>
+            <option value="ice">Ice (blue, darker sharps)</option>
+            <option value="classic">Rainbow (per-pitch)</option>
+            <option value="vivid">Vivid (per-pitch, punchier)</option>
+            <option value="pastel">Pastel (per-pitch, soft)</option>
+        </select>
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            Choose the color scheme for the falling notes, key glow, lane
+            guides and hit flames. Each option is described in its own label.
+        </p>
+
+        <label for="keysh3d-fx-theme" class="text-xs font-medium text-gray-400 mb-1 block">Scene theme</label>
+        <select id="keysh3d-fx-theme"
+            onchange="window.keys3dSetTheme && window.keys3dSetTheme(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="default">Default (original)</option>
+            <option value="midnight">Midnight</option>
+            <option value="charcoal">Charcoal</option>
+            <option value="deeppurple">Deep Purple</option>
+            <option value="forest">Forest</option>
+            <option value="warmslate">Warm Slate</option>
+            <option value="deepfocus">Deep Focus</option>
+            <option value="deepsea">Deep Sea</option>
+            <option value="cathode">Cathode</option>
+            <option value="cathodegreen">Cathode Green</option>
+            <option value="hearth">Hearth</option>
+        </select>
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            Background gradient, floor and lane rails — the same theme names
+            as the guitar highway. Note colors come from the
+            "Note colors" palette above.
+        </p>
+
+        <label for="keysh3d-fx-camera" class="text-xs font-medium text-gray-400 mb-1 block">Camera angle</label>
+        <select id="keysh3d-fx-camera"
+            onchange="window.keys3dSetCamera && window.keys3dSetCamera(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="classic">Classic (low, deep runway)</option>
+            <option value="elevated">Elevated (higher, more board)</option>
+            <option value="overhead" selected>Overhead (top-down reading view)</option>
+        </select>
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            Where the camera sits. Classic is the original low rig; Elevated
+            lifts it for a fuller view of the keybed; Overhead looks down the
+            lanes for a sheet-reading feel. Applies live, keeps the
+            auto-pan/zoom that follows your hands.
+        </p>
+
+        <label for="keysh3d-fx-camheight" class="text-xs font-medium text-gray-400 mb-1 block">
+            Camera height <span id="keysh3d-fx-camheight-val" class="text-gray-500 font-mono">1.00</span>
+        </label>
+        <input type="range" id="keysh3d-fx-camheight"
+            min="0.4" max="2.2" step="0.02" value="1"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('camHeight', this.value); document.getElementById('keysh3d-fx-camheight-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            Raise or lower the camera around the angle above (higher = more
+            top-down). Fine-tunes the base view; the follow-motion stays.
+        </p>
+
+        <label for="keysh3d-fx-camdist" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Camera distance <span id="keysh3d-fx-camdist-val" class="text-gray-500 font-mono">1.00</span>
+        </label>
+        <input type="range" id="keysh3d-fx-camdist"
+            min="0.4" max="2.2" step="0.02" value="1"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('camDist', this.value); document.getElementById('keysh3d-fx-camdist-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            Pull the camera back or push it in (larger = further away, smaller
+            = closer).
+        </p>
+
+        <label for="keysh3d-fx-camtilt" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Camera tilt <span id="keysh3d-fx-camtilt-val" class="text-gray-500 font-mono">0.00</span>
+        </label>
+        <input type="range" id="keysh3d-fx-camtilt"
+            min="-1" max="1" step="0.02" value="0"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('camTilt', this.value); document.getElementById('keysh3d-fx-camtilt-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            Tilt the view up (+) or down (−) without moving the camera —
+            aims higher up the runway or down toward the keys. 0 = neutral.
+        </p>
+
+        <h4 class="text-xs font-medium text-gray-300 mb-2 mt-4">Highway layout</h4>
+
+        <label for="keysh3d-fx-sharpmode" class="text-xs font-medium text-gray-400 mb-1 block">Sharps &amp; flats</label>
+        <select id="keysh3d-fx-sharpmode"
+            onchange="window.keys3dSetSharpMode && window.keys3dSetSharpMode(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="floating">Floating</option>
+            <option value="flat">Non-floating</option>
+            <option value="realistic" selected>Realistic key sizes (default — best with no colored lanes)</option>
+        </select>
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            How sharps and flats are drawn. <em>Floating</em>: they ride a raised
+            plane above the naturals. <em>Non-floating</em>: everything on one
+            plane, each key its own even piano-shaped lane. <em>Realistic key
+            sizes</em>: one plane, bars sized like the real keys (full naturals,
+            full black keys on top). Applies next time you open a song.
+        </p>
+
+        <label for="keysh3d-fx-laneopacity" class="text-xs font-medium text-gray-400 mb-1 block">
+            Lane color opacity <span id="keysh3d-fx-laneopacity-val" class="text-gray-500 font-mono">0.00</span>
+        </label>
+        <input type="range" id="keysh3d-fx-laneopacity"
+            min="0" max="1" step="0.05" value="0"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('laneOpacity', this.value); document.getElementById('keysh3d-fx-laneopacity-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            How strongly each lane is tinted its note color. 0.00 (default) is a
+            dark floor with plain guide lines only between the key blocks (at E–F
+            and each octave); the notes keep their colors and pop off the floor.
+            Raise toward 1.00 for full, vivid colored lanes. Applies next time you
+            open a song.
+        </p>
+
+        <label for="keysh3d-fx-octavegaps" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="keysh3d-fx-octavegaps" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('octaveGaps', this.checked)">
+            Octave separators
+        </label>
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            Widen the gap a little at each octave boundary (every B to the C
+            above it) so octaves are easier to read. Applies next time you open
+            a song.
+        </p>
+
+        <label for="keysh3d-fx-octavecontrast" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Octave line contrast <span id="keysh3d-fx-octavecontrast-val" class="text-gray-500 font-mono">0.50</span>
+        </label>
+        <input type="range" id="keysh3d-fx-octavecontrast"
+            min="0" max="1" step="0.05" value="0.5"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('octaveContrast', this.value); document.getElementById('keysh3d-fx-octavecontrast-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1 mb-3">
+            How strongly the octave line (every B to C) stands out. It adapts to
+            the lane color opacity automatically — darkening the line against
+            bright lanes and brightening it as you fade them toward the dark
+            floor. Applies next time you open a song.
+        </p>
+
+        <label for="keysh3d-fx-cinematic" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer">
+            <input type="checkbox" id="keysh3d-fx-cinematic" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('cinematic', this.checked)">
+            Cinematic lighting
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Dimmer ambience, stronger key light — deeper shading on the keys
+            and gems.
+        </p>
+
+        <label for="keysh3d-fx-glow" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Glow strength <span id="keysh3d-fx-glow-val" class="text-gray-500 font-mono">0.50</span>
+        </label>
+        <input type="range" id="keysh3d-fx-glow"
+            min="0" max="1" step="0.05" value="0.5"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('glow', this.value); document.getElementById('keysh3d-fx-glow-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            How hard the notes, key glow and sustain consume-flash
+            self-illuminate (0.5 = stock). Pairs with bloom.
+        </p>
+
+        <label for="keysh3d-fx-bgstyle" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">Background ambience</label>
+        <select id="keysh3d-fx-bgstyle"
+            onchange="window.keys3dSetBgStyle && window.keys3dSetBgStyle(this.value)"
+            class="w-full bg-dark-700 border border-gray-800 rounded-lg px-3 py-2 text-xs text-gray-300 outline-none">
+            <option value="off">Off</option>
+            <option value="particles" selected>Particles</option>
+            <option value="lights">Stage lights</option>
+            <option value="geometric">Geometric</option>
+        </select>
+        <label for="keysh3d-fx-bgintensity" class="text-xs font-medium text-gray-400 mb-1 mt-2 block">
+            Ambience intensity <span id="keysh3d-fx-bgintensity-val" class="text-gray-500 font-mono">0.50</span>
+        </label>
+        <input type="range" id="keysh3d-fx-bgintensity"
+            min="0" max="1" step="0.05" value="0.5"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('bgIntensity', this.value); document.getElementById('keysh3d-fx-bgintensity-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <label for="keysh3d-fx-bgreactive" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-2">
+            <input type="checkbox" id="keysh3d-fx-bgreactive" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('bgReactive', this.checked)">
+            Audio-reactive ambience
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            The backdrop pulses with the mix (stems analyser when a sloppak
+            is loaded). Off = it animates on time only.
+        </p>
+
+        <label for="keysh3d-fx-scorefx" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="keysh3d-fx-scorefx" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('scoreFx', this.checked)">
+            Score effects
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            +1 pops on scored presses, a ring pulse every 10-combo,
+            milestone bursts at 25/50/100, and a brief red flicker when a
+            streak breaks.
+        </p>
+
+        <label for="keysh3d-fx-bloom" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="keysh3d-fx-bloom" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('bloom', this.checked)">
+            Glow (bloom)
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Soft light-bleed around the hit line, hit flames and consumed
+            sustains. Applies live; turn off to reclaim GPU headroom on
+            weak machines.
+        </p>
+
+        <label for="keysh3d-fx-sparks" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="keysh3d-fx-sparks" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('sparks', this.checked)">
+            Hit sparks
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            A small particle burst on every scored key press, beside the
+            pitch-colored flame.
+        </p>
+
+        <label for="keysh3d-fx-timing" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="keysh3d-fx-timing" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('timingFx', this.checked)">
+            Timing colors
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Tint the sparks by timing — on-time green, early cyan, late
+            amber. Off = always green.
+        </p>
+
+        <label for="keysh3d-fx-streak" class="flex items-center gap-2 text-xs text-gray-300 cursor-pointer mt-3">
+            <input type="checkbox" id="keysh3d-fx-streak" checked
+                onchange="window.keys3dSetFx && window.keys3dSetFx('streakFx', this.checked)">
+            Streak feedback
+        </label>
+        <p class="text-xs text-gray-500 mt-1">
+            Spark bursts grow with your combo.
+        </p>
+
+        <label for="keysh3d-fx-hitfx" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Hit feedback intensity <span id="keysh3d-fx-hitfx-val" class="text-gray-500 font-mono">0.70</span>
+        </label>
+        <input type="range" id="keysh3d-fx-hitfx"
+            min="0" max="1" step="0.05" value="0.7"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('hitFx', this.value); document.getElementById('keysh3d-fx-hitfx-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            Drives the hit-line brightness kick on scored presses. 0 turns
+            it off.
+        </p>
+
+        <label for="keysh3d-fx-vibrancy" class="text-xs font-medium text-gray-400 mb-1 mt-3 block">
+            Note vibrancy <span id="keysh3d-fx-vibrancy-val" class="text-gray-500 font-mono">0.85</span>
+        </label>
+        <input type="range" id="keysh3d-fx-vibrancy"
+            min="0" max="1" step="0.05" value="0.85"
+            oninput="window.keys3dSetFx && window.keys3dSetFx('vibrancy', this.value); document.getElementById('keysh3d-fx-vibrancy-val').textContent = parseFloat(this.value).toFixed(2)"
+            class="w-full">
+        <p class="text-xs text-gray-500 mt-1">
+            Note-gem solidity and lane-guide strength — lower to see more of
+            the keyboard through the notes.
+        </p>
+    </div>
+
+    <script>
+    (function () {
+        'use strict';
+        // Hydrate controls from stored config on first paint. Narrow the
+        // try/catch to just the localStorage reads (drum_highway_3d
+        // settings-hydration convention).
+        try {
+            // FX toggles (keys3d_bg_* — guitar-parity graphics controls).
+            // Only explicit values override; absent/corrupt keys keep the
+            // default (ON), matching screen.js readFxSettings.
+            const hydrateFxBool = (key, elId) => {
+                const raw = localStorage.getItem('keys3d_bg_' + key);
+                if (raw === '1' || raw === 'true') document.getElementById(elId).checked = true;
+                else if (raw === '0' || raw === 'false') document.getElementById(elId).checked = false;
+            };
+            hydrateFxBool('bloom', 'keysh3d-fx-bloom');
+            hydrateFxBool('sparks', 'keysh3d-fx-sparks');
+            hydrateFxBool('timingFx', 'keysh3d-fx-timing');
+            hydrateFxBool('streakFx', 'keysh3d-fx-streak');
+            hydrateFxBool('cinematic', 'keysh3d-fx-cinematic');
+            hydrateFxBool('bgReactive', 'keysh3d-fx-bgreactive');
+            hydrateFxBool('scoreFx', 'keysh3d-fx-scorefx');
+            // Highway-layout: octaveGaps defaults ON (bool); laneOpacity /
+            // octaveContrast are 0-1 sliders hydrated with hydrateFxRange below.
+            hydrateFxBool('octaveGaps', 'keysh3d-fx-octavegaps');
+            const hydrateFxRange = (key, elId, valId) => {
+                const n = parseFloat(localStorage.getItem('keys3d_bg_' + key));
+                if (!Number.isFinite(n)) return;
+                const v = Math.min(1, Math.max(0, n));
+                document.getElementById(elId).value = String(v);
+                document.getElementById(valId).textContent = v.toFixed(2);
+            };
+            hydrateFxRange('hitFx', 'keysh3d-fx-hitfx', 'keysh3d-fx-hitfx-val');
+            hydrateFxRange('vibrancy', 'keysh3d-fx-vibrancy', 'keysh3d-fx-vibrancy-val');
+            hydrateFxRange('glow', 'keysh3d-fx-glow', 'keysh3d-fx-glow-val');
+            hydrateFxRange('bgIntensity', 'keysh3d-fx-bgintensity', 'keysh3d-fx-bgintensity-val');
+            hydrateFxRange('laneOpacity', 'keysh3d-fx-laneopacity', 'keysh3d-fx-laneopacity-val');
+            hydrateFxRange('octaveContrast', 'keysh3d-fx-octavecontrast', 'keysh3d-fx-octavecontrast-val');
+            // Camera fine-tune sliders live outside 0-1 — clamp to the
+            // control's own min/max (mirrors screen.js FX_RANGES).
+            const hydrateFxRangeIn = (key, elId, valId) => {
+                const n = parseFloat(localStorage.getItem('keys3d_bg_' + key));
+                if (!Number.isFinite(n)) return;
+                const el = document.getElementById(elId);
+                const v = Math.min(parseFloat(el.max), Math.max(parseFloat(el.min), n));
+                el.value = String(v);
+                document.getElementById(valId).textContent = v.toFixed(2);
+            };
+            hydrateFxRangeIn('camHeight', 'keysh3d-fx-camheight', 'keysh3d-fx-camheight-val');
+            hydrateFxRangeIn('camDist', 'keysh3d-fx-camdist', 'keysh3d-fx-camdist-val');
+            hydrateFxRangeIn('camTilt', 'keysh3d-fx-camtilt', 'keysh3d-fx-camtilt-val');
+            const storedCamera = localStorage.getItem('keys3d_bg_camera');
+            const cameraSel = document.getElementById('keysh3d-fx-camera');
+            if (storedCamera && Array.from(cameraSel.options).some(o => o.value === storedCamera)) {
+                cameraSel.value = storedCamera;
+            }
+            const storedStyle = localStorage.getItem('keys3d_bg_style');
+            const styleSel = document.getElementById('keysh3d-fx-bgstyle');
+            if (storedStyle && Array.from(styleSel.options).some(o => o.value === storedStyle)) {
+                styleSel.value = storedStyle;
+            }
+            const storedTheme = localStorage.getItem('keys3d_bg_theme');
+            const themeSel = document.getElementById('keysh3d-fx-theme');
+            if (storedTheme && Array.from(themeSel.options).some(o => o.value === storedTheme)) {
+                themeSel.value = storedTheme;
+            }
+            const storedPalette = localStorage.getItem('keys3d_bg_palette');
+            const paletteSel = document.getElementById('keysh3d-fx-palette');
+            if (storedPalette && Array.from(paletteSel.options).some(o => o.value === storedPalette)) {
+                paletteSel.value = storedPalette;
+            }
+            const storedSharp = localStorage.getItem('keys3d_bg_sharpMode');
+            const sharpSel = document.getElementById('keysh3d-fx-sharpmode');
+            if (storedSharp && Array.from(sharpSel.options).some(o => o.value === storedSharp)) {
+                sharpSel.value = storedSharp;
+            }
+        } catch (e) {
+            console.warn('[Keys-Hwy3D settings] hydration failed:', e);
+        }
+    })();
+    </script>
+</div>

plugins/keys_highway_3d/tests/camera_bridge.test.js

@@ -0,0 +1,78 @@
+// Camera Director bridge resolver tests: per-panel select, global fallback,
+// null-when-absent, throw-safety, and the splitscreen global-name alias. Loads
+// screen.js in a bare vm window and exercises the __test exports (no DOM/WebGL).
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+function load() {
+    const window = {
+        console,
+        location: { protocol: 'http:', host: 'localhost' },
+        slopsmith: {},
+    };
+    window.window = window;
+    window.globalThis = window;
+    const context = vm.createContext(window);
+    const src = fs.readFileSync(path.join(__dirname, '..', 'screen.js'), 'utf8');
+    vm.runInContext(src, context, { filename: 'screen.js' });
+    return { window, __test: window.slopsmithViz_keys_highway_3d.__test };
+}
+
+test('_resolveFreeCam: per-panel camera under splitscreen', () => {
+    const { __test } = load();
+    const c0 = {}, c1 = {};
+    const ss = { panelIndexFor: (c) => (c === c0 ? 0 : 1) };
+    const map = { 0: { id: 'p0' }, 1: { id: 'p1' } };
+    assert.equal(__test._resolveFreeCam(c0, ss, map, { id: 'g' }).id, 'p0');
+    assert.equal(__test._resolveFreeCam(c1, ss, map, { id: 'g' }).id, 'p1');
+});
+
+test('_resolveFreeCam: falls back to global when there is no panel map', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 0 }, null, g), g);
+});
+
+test('_resolveFreeCam: falls back to global when the panel has no map entry', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    const ss = { panelIndexFor: () => 3 };            // index 3 absent from map
+    assert.equal(__test._resolveFreeCam({}, ss, { 0: {} }, g), g);
+});
+
+test('_resolveFreeCam: null when Camera Director is absent (no global)', () => {
+    const { __test } = load();
+    assert.equal(__test._resolveFreeCam({}, null, null, null), null);
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 0 }, {}, undefined), null);
+});
+
+test('_resolveFreeCam: throw-safe on panelIndexFor → falls back to global', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    const ss = { panelIndexFor: () => { throw new Error('boom'); } };
+    assert.equal(__test._resolveFreeCam({}, ss, { 0: {} }, g), g);
+});
+
+test('_resolveFreeCam: NaN/negative/float/string index → falls back to global', () => {
+    const { __test } = load();
+    const g = { id: 'global' };
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => NaN }, { 0: {} }, g), g);
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => -1 }, { 0: {} }, g), g);
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 0.5 }, { 0: {} }, g), g);
+    // A string/prototype key must not resolve an inherited property (e.g. toString).
+    assert.equal(__test._resolveFreeCam({}, { panelIndexFor: () => 'toString' }, {}, g), g);
+});
+
+test('_ssApi: null when neither global set; slopsmith alias; feedBack canonical wins', () => {
+    const { window, __test } = load();
+    assert.equal(__test._ssApi(), null);
+    const legacy = { panelIndexFor: () => 0 };
+    window.slopsmithSplitscreen = legacy;
+    assert.equal(__test._ssApi(), legacy);            // legacy alias picked up
+    const current = { panelIndexFor: () => 1 };
+    window.feedBackSplitscreen = current;
+    assert.equal(__test._ssApi(), current);           // canonical name takes precedence
+});

plugins/keys_highway_3d/tests/data_layer.test.js

@@ -0,0 +1,286 @@
+// Pure data-layer tests: load screen.js in a bare vm window and exercise the
+// __test exports (no DOM, no WebGL, no network).
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+function load() {
+    const window = {
+        console,
+        location: { protocol: 'http:', host: 'localhost' },
+        slopsmith: {},
+    };
+    window.window = window;
+    window.globalThis = window;
+    const context = vm.createContext(window);
+    const src = fs.readFileSync(path.join(__dirname, '..', 'screen.js'), 'utf8');
+    vm.runInContext(src, context, { filename: 'screen.js' });
+    return window.slopsmithViz_keys_highway_3d.__test;
+}
+
+test('beatDurSec: base, dotted, double-dotted, tuplet', () => {
+    const { beatDurSec } = load();
+    // 120 BPM → quarter = 0.5s
+    assert.equal(beatDurSec({ dur: 4 }, 120), 0.5);
+    assert.equal(beatDurSec({ dur: 2 }, 120), 1.0);
+    assert.equal(beatDurSec({ dur: 8 }, 120), 0.25);
+    // dotted quarter = 0.75s; double-dotted = 0.875s
+    assert.equal(beatDurSec({ dur: 4, dot: 1 }, 120), 0.75);
+    assert.equal(beatDurSec({ dur: 4, dot: 2 }, 120), 0.875);
+    // triplet eighth: 0.25 * 2/3
+    assert.ok(Math.abs(beatDurSec({ dur: 8, tu: [3, 2] }, 120) - 0.25 * 2 / 3) < 1e-9);
+    // invalid → null
+    assert.equal(beatDurSec({ dur: 0 }, 120), null);
+    assert.equal(beatDurSec({ dur: 4 }, null), null);
+});
+
+function measure(idx, t, opts = {}) {
+    return { idx, t, ...opts };
+}
+
+test('flattenNotation: basic two-hand flatten, sorted, durSec from tempo', () => {
+    const { flattenNotation } = load();
+    const notes = flattenNotation([
+        {
+            idx: 1, t: 0, tempo: 120,
+            staves: {
+                rh: { voices: [{ v: 1, beats: [
+                    { t: 0.5, dur: 4, notes: [{ midi: 64 }] },
+                    { t: 1.0, dur: 8, notes: [{ midi: 67 }] },
+                ] }] },
+                lh: { voices: [{ v: 1, beats: [
+                    { t: 0.0, dur: 2, notes: [{ midi: 48 }] },
+                ] }] },
+            },
+        },
+    ]);
+    assert.equal(notes.length, 3);
+    assert.deepEqual(JSON.parse(JSON.stringify(notes.map(n => n.midi))), [48, 64, 67]); // time-sorted
+    assert.equal(notes[0].hand, 'lh');
+    assert.equal(notes[0].durSec, 1.0);   // half at 120
+    assert.equal(notes[1].durSec, 0.5);   // quarter
+    assert.equal(notes[2].durSec, 0.25);  // eighth
+    assert.equal(notes[1].measureIdx, 1);
+});
+
+test('flattenNotation: tempo state carries across measures and changes apply', () => {
+    const { flattenNotation } = load();
+    const notes = flattenNotation([
+        measure(1, 0, { tempo: 120, staves: { rh: { voices: [{ v: 1, beats: [{ t: 0, dur: 4, notes: [{ midi: 60 }] }] }] } } }),
+        measure(2, 2, { staves: { rh: { voices: [{ v: 1, beats: [{ t: 2, dur: 4, notes: [{ midi: 62 }] }] }] } } }),
+        measure(3, 4, { tempo: 60, staves: { rh: { voices: [{ v: 1, beats: [{ t: 4, dur: 4, notes: [{ midi: 64 }] }] }] } } }),
+    ]);
+    assert.equal(notes[0].durSec, 0.5); // 120 BPM
+    assert.equal(notes[1].durSec, 0.5); // tempo carried
+    assert.equal(notes[2].durSec, 1.0); // 60 BPM
+});
+
+test('flattenNotation: tied notes extend instead of emitting a new block', () => {
+    const { flattenNotation } = load();
+    const notes = flattenNotation([
+        {
+            idx: 1, t: 0, tempo: 120,
+            staves: { rh: { voices: [{ v: 1, beats: [
+                { t: 0.0, dur: 2, notes: [{ midi: 60 }] },
+                { t: 1.0, dur: 2, notes: [{ midi: 60, tied: true }] },
+            ] }] } },
+        },
+    ]);
+    assert.equal(notes.length, 1);
+    assert.equal(notes[0].durSec, 2.0); // half + tied half
+});
+
+test('flattenNotation: no tempo anywhere falls back to next-onset gap', () => {
+    const { flattenNotation } = load();
+    const notes = flattenNotation([
+        {
+            idx: 1, t: 0,
+            staves: { rh: { voices: [{ v: 1, beats: [
+                { t: 0.0, dur: 4, notes: [{ midi: 60 }] },
+                { t: 0.8, dur: 4, notes: [{ midi: 62 }] },
+            ] }] } },
+        },
+    ]);
+    assert.ok(Math.abs(notes[0].durSec - 0.8) < 1e-9);
+    assert.equal(notes[1].durSec, 2.0); // final-beat fallback
+});
+
+test('flattenNotation: overlap clamp against next same-hand same-midi onset', () => {
+    const { flattenNotation } = load();
+    const notes = flattenNotation([
+        {
+            idx: 1, t: 0, tempo: 30, // whole note = 8s — way past the next onset
+            staves: { rh: { voices: [{ v: 1, beats: [
+                { t: 0.0, dur: 1, notes: [{ midi: 60 }] },
+                { t: 1.0, dur: 1, notes: [{ midi: 60 }] },
+            ] }] } },
+        },
+    ]);
+    assert.equal(notes[0].durSec, 1.0); // clamped to next onset
+});
+
+test('flattenNotation: rests, malformed beats, and out-of-range midi are skipped', () => {
+    const { flattenNotation } = load();
+    const notes = flattenNotation([
+        {
+            idx: 1, t: 0, tempo: 120,
+            staves: { rh: { voices: [{ v: 1, beats: [
+                { t: 0.0, dur: 4, rest: true },
+                { t: 0.5, dur: 4, notes: [{ midi: 200 }] },
+                null,
+                { t: 1.0, dur: 4, notes: [{ midi: 64 }] },
+            ] }] } },
+        },
+    ]);
+    assert.equal(notes.length, 1);
+    assert.equal(notes[0].midi, 64);
+});
+
+test('keyRange pads and clamps to the 88-key piano, keeps active span explicit', () => {
+    const { keyRange } = load();
+    assert.deepEqual(
+        JSON.parse(JSON.stringify(keyRange([{ midi: 60 }, { midi: 72 }]))),
+        { low: 58, high: 74, activeLow: 60, activeHigh: 72 },
+    );
+    // At the clamp edges the active span still reflects the chart extremes
+    // (not low+pad — that would mark A0/C8 inactive when actually played).
+    assert.deepEqual(
+        JSON.parse(JSON.stringify(keyRange([{ midi: 21 }, { midi: 108 }]))),
+        { low: 21, high: 108, activeLow: 21, activeHigh: 108 },
+    );
+    const empty = keyRange([]);
+    assert.ok(empty.low < 60 && empty.high > 60);
+    assert.ok(empty.activeLow > empty.activeHigh, 'empty chart has an empty active span');
+});
+
+test('noteLetter maps midi to pitch-class letters', () => {
+    const { noteLetter } = load();
+    assert.equal(noteLetter(60), 'C');
+    assert.equal(noteLetter(61), 'C#');
+    assert.equal(noteLetter(69), 'A');
+    assert.equal(noteLetter(71), 'B');
+    assert.equal(noteLetter(72), 'C');  // octave wraps
+    assert.equal(noteLetter(21), 'A');  // A0
+});
+
+test('scrollZ: events sit at hitZ exactly at their time and approach from -Z', () => {
+    const { scrollZ } = load();
+    const hitZ = -0.5, speed = 2.0;
+    // At now === eventT the event is exactly on the hit-line.
+    assert.equal(scrollZ(10, 10, hitZ, speed), hitZ);
+    // 1s before its time it is `speed` units further away (towards -Z).
+    assert.equal(scrollZ(10, 9, hitZ, speed), hitZ - speed);
+    // After its time it has moved past the hit-line (towards +Z).
+    assert.equal(scrollZ(10, 11, hitZ, speed), hitZ + speed);
+    // Marker and note-front-edge maths agree by construction: a note of
+    // length L positioned at scrollZ(t) - L/2 has its front edge at
+    // scrollZ(t).
+    const len = 0.8;
+    assert.equal(scrollZ(10, 10, hitZ, speed) - len / 2 + len / 2, hitZ);
+});
+
+test('measureMarkers extracts idx/t pairs', () => {
+    const { measureMarkers } = load();
+    assert.deepEqual(
+        JSON.parse(JSON.stringify(measureMarkers([{ idx: 1, t: 0 }, { idx: 2, t: 2.5 }, { bogus: true }]))),
+        [{ idx: 1, t: 0 }, { idx: 2, t: 2.5 }],
+    );
+});
+
+test('_pickMidiTarget: no plugin-local pick defers to the domain-wide selection, not "first device"', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [
+        { id: 'a', name: 'Device A', key: 'web-midi::a' },
+        { id: 'b', name: 'Device B', key: 'web-midi::b' },
+    ];
+    // Fresh install / never picked here — must use the Input Setup global,
+    // NOT fall through to inputs[0].
+    const target = _pickMidiTarget(inputs, null, 'web-midi::b', true);
+    assert.equal(target.id, 'b');
+});
+
+test('_pickMidiTarget: the domain-wide selection is the source of truth — it wins over a stale plugin-local pick', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [
+        { id: 'a', name: 'Device A', key: 'web-midi::a' },
+        { id: 'b', name: 'Device B', key: 'web-midi::b' },
+    ];
+    // A stale local pick (e.g. left by a pre-fix build's auto-connect) must
+    // NOT override the device the user configured in Settings → Input Setup.
+    const target = _pickMidiTarget(inputs, { id: 'a', name: 'Device A', key: 'web-midi::a' }, 'web-midi::b', true);
+    assert.equal(target.id, 'b');
+});
+
+test('_pickMidiTarget: local pick is used as a fallback when no global is configured', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [
+        { id: 'a', name: 'Device A', key: 'web-midi::a' },
+        { id: 'b', name: 'Device B', key: 'web-midi::b' },
+    ];
+    const target = _pickMidiTarget(inputs, { id: 'a', name: 'Device A', key: 'web-midi::a' }, null, true);
+    assert.equal(target.id, 'a');
+});
+
+test('_pickMidiTarget: local pick name-recovers when its logicalSourceKey went stale (id regeneration)', () => {
+    const { _pickMidiTarget } = load();
+    // Same physical device, new id/key across a reload; the saved key/id miss
+    // but the name still matches.
+    const inputs = [{ id: 'a2', name: 'Device A', key: 'web-midi::a2' }];
+    const target = _pickMidiTarget(inputs, { id: 'a1', name: 'Device A', key: 'web-midi::a1' }, null, true);
+    assert.equal(target.id, 'a2');
+});
+
+test('_pickMidiTarget: domain-wide selection is ignored if it names a blocklisted loopback port', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [
+        { id: 'thru', name: 'IAC Driver Bus 1', key: 'web-midi::thru' },
+        { id: 'b', name: 'Device B', key: 'web-midi::b' },
+    ];
+    const target = _pickMidiTarget(inputs, null, 'web-midi::thru', true);
+    assert.equal(target.id, 'b'); // falls through to the first non-loopback device
+});
+
+test('_pickMidiTarget: when every present device is a loopback, connect to nothing (never a dead port)', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [
+        { id: 'thru', name: 'MIDI Through Port-0', key: 'web-midi::thru' },
+        { id: 'iac', name: 'IAC Driver Bus 1', key: 'web-midi::iac' },
+    ];
+    // No non-loopback device exists — must NOT fall back to inputs[0] (a port
+    // that carries no input and would silently eat every note).
+    const target = _pickMidiTarget(inputs, null, null, true);
+    assert.equal(target, null);
+});
+
+test('_pickMidiTarget: explicit "None" opt-out still wins over any global default', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [{ id: 'a', name: 'Device A', key: 'web-midi::a' }];
+    const target = _pickMidiTarget(inputs, { id: '', name: '' }, 'web-midi::a', true);
+    assert.equal(target, null);
+});
+
+test('_pickMidiTarget: a present global wins even during hotplug recovery', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [{ id: 'b', name: 'Device B', key: 'web-midi::b' }];
+    // The configured global device is present — reconnect to it, don't bail.
+    const target = _pickMidiTarget(inputs, null, 'web-midi::b', false);
+    assert.equal(target.id, 'b');
+});
+
+test('_pickMidiTarget: recovery (allowFallback=false) preserves an absent configured device instead of grabbing a random one', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [{ id: 'b', name: 'Device B', key: 'web-midi::b' }];
+    // The configured device ('x', global) is currently unplugged; a transient
+    // recovery must NOT switch to the unrelated device that is present.
+    const target = _pickMidiTarget(inputs, null, 'web-midi::x', false);
+    assert.equal(target, null);
+});
+
+test('_pickMidiTarget: recovery with no preference at all still allows a first-hotplug grab', () => {
+    const { _pickMidiTarget } = load();
+    const inputs = [{ id: 'b', name: 'Device B', key: 'web-midi::b' }];
+    const target = _pickMidiTarget(inputs, null, null, false);
+    assert.equal(target.id, 'b');
+});

plugins/keys_highway_3d/tests/fx_settings.test.js

@@ -0,0 +1,552 @@
+// FX-settings scaffold tests (guitar-highway parity controls). Same bare-vm
+// harness as data_layer.test.js — no DOM, no localStorage — which doubles as
+// a lint that the new module-scope FX code stays side-effect safe.
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+function load(extraWindow) {
+    const window = {
+        console,
+        location: { protocol: 'http:', host: 'localhost' },
+        slopsmith: {},
+        ...extraWindow,
+    };
+    window.window = window;
+    window.globalThis = window;
+    const context = vm.createContext(window);
+    const src = fs.readFileSync(path.join(__dirname, '..', 'screen.js'), 'utf8');
+    vm.runInContext(src, context, { filename: 'screen.js' });
+    return window;
+}
+
+test('readFxSettings: defaults survive a localStorage-less environment', () => {
+    const { readFxSettings, FX_DEFAULTS } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.deepEqual(readFxSettings(), FX_DEFAULTS);
+    assert.equal(FX_DEFAULTS.bloom, true); // effects on by default
+});
+
+test('readFxSettings: reads keys3d_bg_* overrides and coerces types', () => {
+    const store = { keys3d_bg_bloom: '0' };
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+    });
+    const { readFxSettings } = win.slopsmithViz_keys_highway_3d.__test;
+    assert.equal(readFxSettings().bloom, false);
+    store.keys3d_bg_bloom = 'true';
+    assert.equal(readFxSettings().bloom, true);
+    store.keys3d_bg_bloom = 'false';
+    assert.equal(readFxSettings().bloom, false);
+    // Corrupt/foreign value → keep the default rather than silently
+    // disabling the effect.
+    store.keys3d_bg_bloom = 'banana';
+    assert.equal(readFxSettings().bloom, true);
+});
+
+test('keys3dSetFx: persists, coerces, and ignores unknown keys', () => {
+    const store = {};
+    const events = [];
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+        dispatchEvent: (ev) => { events.push(ev); return true; },
+        CustomEvent: class CustomEvent {
+            constructor(type, opts) { this.type = type; this.detail = opts && opts.detail; }
+        },
+    });
+    win.keys3dSetFx('bloom', false);
+    assert.equal(store.keys3d_bg_bloom, '0');
+    // String forms round-trip like the reader's accepted representations.
+    win.keys3dSetFx('bloom', 'false');
+    assert.equal(store.keys3d_bg_bloom, '0');
+    win.keys3dSetFx('bloom', 'true');
+    assert.equal(store.keys3d_bg_bloom, '1');
+    win.keys3dSetFx('bloom', false);
+    assert.equal(events.length, 4);
+    assert.equal(events[0].type, 'keys3d:settings');
+    // Field-wise (the detail object was built inside the vm realm, so a
+    // deep-strict compare would trip on its foreign Object.prototype).
+    assert.equal(events[0].detail.fx.bloom, false);
+    assert.deepEqual(Object.keys(events[0].detail.fx), ['bloom']);
+    // Unknown key: no write, no event.
+    win.keys3dSetFx('nonsense', 1);
+    assert.equal(events.length, 4);
+    assert.ok(!('keys3d_bg_nonsense' in store));
+});
+
+test('_classifyTiming: OK band is 40% of the window, sign maps early/late', () => {
+    const { _classifyTiming } = load().slopsmithViz_keys_highway_3d.__test;
+    const tol = 0.10;                    // keys HIT_TOLERANCE_S
+    assert.equal(_classifyTiming(0, tol), 'OK');
+    assert.equal(_classifyTiming(tol * 0.4, tol), 'OK');
+    assert.equal(_classifyTiming(-tol * 0.4, tol), 'OK');
+    // delta = note.t - now: positive → struck before the note → EARLY.
+    assert.equal(_classifyTiming(tol * 0.41, tol), 'EARLY');
+    assert.equal(_classifyTiming(-tol * 0.41, tol), 'LATE');
+    assert.equal(_classifyTiming(NaN, tol), 'OK');
+});
+
+test('noteKey prefix round-trips the matched note time (timing-delta source)', () => {
+    const { noteKey } = load().slopsmithViz_keys_highway_3d.__test;
+    // _checkHit derives the timing delta as parseFloat(judgeHit's key) - t;
+    // this pins the serialization that makes that recovery valid.
+    assert.equal(parseFloat(noteKey(12.3456, 60)), 12.346);
+    assert.equal(parseFloat(noteKey(0, 21)), 0);
+});
+
+test('FX defaults: hit-FX + vibrancy controls ship enabled', () => {
+    const { FX_DEFAULTS } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.equal(FX_DEFAULTS.sparks, true);
+    assert.equal(FX_DEFAULTS.timingFx, true);
+    assert.equal(FX_DEFAULTS.streakFx, true);
+    assert.equal(FX_DEFAULTS.hitFx, 0.7);
+    assert.equal(FX_DEFAULTS.vibrancy, 0.85);
+});
+
+test('themes: table ids match the guitar highway, default is the stock palette', () => {
+    const { BG_THEMES, _bgThemeColors, readThemeSetting } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.deepEqual(Object.keys(BG_THEMES), [
+        'default', 'midnight', 'charcoal', 'deeppurple', 'forest', 'warmslate',
+        'deepfocus', 'deepsea', 'cathode', 'cathodegreen', 'hearth',
+    ]);
+    // 'default' preserves THIS plugin's original look.
+    assert.equal(BG_THEMES.default.clear, 0x1a1a2e);
+    assert.equal(BG_THEMES.default.board, 0x141422);
+    assert.equal(BG_THEMES.default.laneDim, 0x2a2a3e);
+    assert.equal(_bgThemeColors('nonsense'), BG_THEMES.default);
+    assert.equal(readThemeSetting(), 'default'); // no localStorage in the vm
+    for (const [id, t] of Object.entries(BG_THEMES)) {
+        assert.equal(t.clear, t.fog, id + ' clear==fog (horizon dissolve)');
+        assert.ok(t.laneDim != null, id + ' rail color');
+    }
+});
+
+test('FX defaults: theme-PR controls ship enabled at stock-neutral values', () => {
+    const { FX_DEFAULTS } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.equal(FX_DEFAULTS.cinematic, true);
+    assert.equal(FX_DEFAULTS.glow, 0.5);   // 0.5 = 1.0x multiplier (stock)
+});
+
+
+test('bg styles: validated id set, particles default', () => {
+    const { BG_STYLE_IDS, readBgStyleSetting } = load().slopsmithViz_keys_highway_3d.__test;
+    // Host-realm copy — the vm array's foreign prototype trips deepEqual.
+    assert.deepEqual([...BG_STYLE_IDS], ['off', 'particles', 'lights', 'geometric']);
+    assert.equal(readBgStyleSetting(), 'particles');
+});
+
+test('FX defaults: ambience + score FX ship enabled', () => {
+    const { FX_DEFAULTS } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.equal(FX_DEFAULTS.scoreFx, true);
+    assert.equal(FX_DEFAULTS.bgIntensity, 0.5);
+    assert.equal(FX_DEFAULTS.bgReactive, true);
+});
+
+/* ── Note-colour palettes (feat/keys3d-note-palettes) ────────────────── */
+
+test('note palettes: 12 entries each, classic IS the stock table', () => {
+    const { NOTE_PALETTES, PITCH_CLASS_COLORS } =
+        load().slopsmithViz_keys_highway_3d.__test;
+    assert.deepEqual(Object.keys(NOTE_PALETTES),
+        ['classic', 'emerald', 'vivid', 'pastel', 'ice']);
+    for (const [id, colors] of Object.entries(NOTE_PALETTES)) {
+        assert.equal(colors.length, 12, id + ' has one colour per pitch class');
+        for (const c of colors) {
+            assert.ok(Number.isInteger(c) && c >= 0 && c <= 0xffffff,
+                id + ' colours are 24-bit ints');
+        }
+    }
+    // 'classic' preserves the shipped look byte-identically — it is the
+    // same array, not a copy that could drift.
+    assert.equal(NOTE_PALETTES.classic, PITCH_CLASS_COLORS);
+    assert.equal(PITCH_CLASS_COLORS[0], 0xff3030); // C stays red in classic
+});
+
+test('note palettes: two-tone tables use darker sharps than naturals', () => {
+    const { NOTE_PALETTES } = load().slopsmithViz_keys_highway_3d.__test;
+    const luma = (c) =>
+        0.2126 * ((c >> 16) & 0xff) + 0.7152 * ((c >> 8) & 0xff) + 0.0722 * (c & 0xff);
+    for (const id of ['emerald', 'ice']) {
+        const p = NOTE_PALETTES[id];
+        for (const sharp of [1, 3, 6, 8, 10]) {
+            assert.ok(luma(p[sharp]) < luma(p[0]),
+                id + ' sharp pc ' + sharp + ' darker than naturals');
+        }
+    }
+});
+
+test('readPaletteSetting: octaves default, validated overrides only', () => {
+    // No localStorage in the vm → the plug-and-play default.
+    const bare = load().slopsmithViz_keys_highway_3d.__test;
+    assert.equal(bare.readPaletteSetting(), 'octaves');
+    // An explicit non-default value (classic) overrides.
+    const store = { keys3d_bg_palette: 'classic' };
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+    });
+    const { readPaletteSetting } = win.slopsmithViz_keys_highway_3d.__test;
+    assert.equal(readPaletteSetting(), 'classic');
+    // Corrupt/foreign value → the default rather than an undefined scheme.
+    store.keys3d_bg_palette = 'banana';
+    assert.equal(readPaletteSetting(), 'octaves');
+});
+
+test('keys3dSetPalette: persists + dispatches valid ids, ignores unknown', () => {
+    const store = {};
+    const events = [];
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+        dispatchEvent: (ev) => { events.push(ev); return true; },
+        CustomEvent: class CustomEvent {
+            constructor(type, opts) { this.type = type; this.detail = opts && opts.detail; }
+        },
+    });
+    win.keys3dSetPalette('emerald');
+    assert.equal(store.keys3d_bg_palette, 'emerald');
+    assert.equal(events.length, 1);
+    assert.equal(events[0].type, 'keys3d:settings');
+    assert.equal(events[0].detail.palette, 'emerald');
+    // Unknown id: no write, no event.
+    win.keys3dSetPalette('banana');
+    assert.equal(store.keys3d_bg_palette, 'emerald');
+    assert.equal(events.length, 1);
+    // 'octaves' (procedural, not a 12-array) is a valid selectable id.
+    win.keys3dSetPalette('octaves');
+    assert.equal(store.keys3d_bg_palette, 'octaves');
+    assert.equal(events.length, 2);
+});
+
+test('PALETTE_IDS: the array palettes plus the procedural octaves scheme', () => {
+    const { PALETTE_IDS, NOTE_PALETTES } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.deepEqual([...PALETTE_IDS],
+        [...Object.keys(NOTE_PALETTES), 'octaves']);
+    assert.ok(PALETTE_IDS.indexOf('octaves') !== -1);
+    assert.ok(!('octaves' in NOTE_PALETTES)); // it is NOT a 12-entry table
+});
+
+test('octaveNoteColor: hue steps per octave, loops, sharps darker, sub-C1 distinct', () => {
+    const { octaveNoteColor, OCTAVE_HUES } = load().slopsmithViz_keys_highway_3d.__test;
+    const luma = (c) =>
+        0.2126 * ((c >> 16) & 0xff) + 0.7152 * ((c >> 8) & 0xff) + 0.0722 * (c & 0xff);
+    // C1 (midi 24) = first hue; C2 (36) = second; C8 (108) = 8th (index 7).
+    assert.equal(octaveNoteColor(24), OCTAVE_HUES[0]);   // C1 red
+    assert.equal(octaveNoteColor(35), OCTAVE_HUES[0]);   // B1 still octave 1
+    assert.equal(octaveNoteColor(36), OCTAVE_HUES[1]);   // C2 orange
+    assert.equal(octaveNoteColor(60), OCTAVE_HUES[3]);   // C4 (middle C)
+    assert.equal(octaveNoteColor(108), OCTAVE_HUES[7]);  // C8 last hue
+    // Naturals across one octave (C1..B1 whites) all share the octave hue.
+    for (const nat of [24, 26, 28, 29, 31, 33, 35]) {
+        assert.equal(octaveNoteColor(nat), OCTAVE_HUES[0], 'natural ' + nat);
+    }
+    // Sharps in an octave are a DARKER shade of that same hue.
+    for (const sharp of [25, 27, 30, 32, 34]) { // C#1..A#1
+        assert.ok(luma(octaveNoteColor(sharp)) < luma(OCTAVE_HUES[0]),
+            'sharp ' + sharp + ' darker than the octave natural');
+    }
+    // The three keys below C1 (A0/A#0/B0) share a distinct sub-C1 colour,
+    // different from the red octave-1 start.
+    assert.equal(octaveNoteColor(21), octaveNoteColor(23)); // A0 == B0 hue
+    assert.notEqual(octaveNoteColor(21), OCTAVE_HUES[0]);
+    // Loop: an octave past the table wraps (safety for out-of-88 midi).
+    assert.equal(octaveNoteColor(24 + 12 * OCTAVE_HUES.length), OCTAVE_HUES[0]);
+});
+
+/* ── Camera presets + fine-tune (feat/keys3d-camera) ─────────────────── */
+
+test('FX defaults: camera height/distance/tilt all neutral (preset carries the tuned aim)', () => {
+    const { FX_DEFAULTS, FX_RANGES } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.equal(FX_DEFAULTS.camHeight, 1.0);
+    assert.equal(FX_DEFAULTS.camDist, 1.0);
+    // Tilt ships NEUTRAL (0): the tuned plug-and-play aim now lives in
+    // CAM_PRESETS.overhead.lookY, so the fine-tune only nudges from a preset
+    // and 'classic' + this default reproduces the exact historical rig.
+    assert.equal(FX_DEFAULTS.camTilt, 0.0);
+    assert.ok(FX_DEFAULTS.camTilt >= FX_RANGES.camTilt[0] && FX_DEFAULTS.camTilt <= FX_RANGES.camTilt[1]);
+    // Height/distance bracket 1 (can go lower AND higher); tilt spans 0.
+    assert.ok(FX_RANGES.camHeight[0] < 1 && 1 < FX_RANGES.camHeight[1]);
+    assert.ok(FX_RANGES.camDist[0] < 1 && 1 < FX_RANGES.camDist[1]);
+    assert.ok(FX_RANGES.camTilt[0] < 0 && 0 < FX_RANGES.camTilt[1]);
+});
+
+test('camTilt: negative values survive the clamp (down-tilt must be reachable)', () => {
+    const store = {};
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+        dispatchEvent: () => true,
+        CustomEvent: class { constructor(t, o) { this.type = t; this.detail = o && o.detail; } },
+    });
+    const { FX_RANGES } = win.slopsmithViz_keys_highway_3d.__test;
+    win.keys3dSetFx('camTilt', -0.5);
+    assert.equal(store.keys3d_bg_camTilt, '-0.5');   // NOT crushed to 0 by a 0-1 clamp
+    win.keys3dSetFx('camTilt', -99);
+    assert.equal(parseFloat(store.keys3d_bg_camTilt), FX_RANGES.camTilt[0]);
+});
+
+test('FX ranges: reader + setter clamp to the declared range, not 0-1', () => {
+    const store = { keys3d_bg_camHeight: '5', keys3d_bg_camDist: '0.01' };
+    const events = [];
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+        dispatchEvent: (ev) => { events.push(ev); return true; },
+        CustomEvent: class CustomEvent {
+            constructor(type, opts) { this.type = type; this.detail = opts && opts.detail; }
+        },
+    });
+    const { readFxSettings, FX_RANGES } = win.slopsmithViz_keys_highway_3d.__test;
+    // Reader: corrupt/out-of-range writes clamp to the declared bounds.
+    assert.equal(readFxSettings().camHeight, FX_RANGES.camHeight[1]);
+    assert.equal(readFxSettings().camDist, FX_RANGES.camDist[0]);
+    // Setter: same clamp on the way in; a value above 1 must survive
+    // (the historical 0-1 clamp would have crushed 1.3 to 1).
+    win.keys3dSetFx('camHeight', 1.3);
+    assert.equal(store.keys3d_bg_camHeight, '1.3');
+    win.keys3dSetFx('camDist', 99);
+    assert.equal(parseFloat(store.keys3d_bg_camDist), FX_RANGES.camDist[1]);
+    // Un-ranged keys keep the historical 0-1 clamp.
+    win.keys3dSetFx('vibrancy', 2);
+    assert.equal(store.keys3d_bg_vibrancy, '1');
+});
+
+test('scrollZ: distance-to-hitline scales linearly with the speed argument', () => {
+    const { scrollZ } = load().slopsmithViz_keys_highway_3d.__test;
+    const hitZ = 0;
+    const d1 = scrollZ(2, 0, hitZ, 130) - hitZ;   // 2s ahead at stock speed
+    const d2 = scrollZ(2, 0, hitZ, 260) - hitZ;   // same note at 2x speed
+    assert.equal(d2, d1 * 2);
+    // At the hit moment the note is at the hit-line regardless of speed.
+    assert.equal(scrollZ(5, 5, hitZ, 130), hitZ);
+    assert.equal(scrollZ(5, 5, hitZ, 260), hitZ);
+});
+
+test('camera presets: classic preserves the stock rig, overhead is the default', () => {
+    const { CAM_PRESETS, readCameraSetting } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.deepEqual(Object.keys(CAM_PRESETS), ['classic', 'elevated', 'overhead']);
+    // 'classic' preserves the historical constants (pre-K units) even though
+    // it is no longer the default — anyone who picks it gets the old rig back
+    // EXACTLY, because camTilt now defaults to 0 (neutral): effective aim =
+    // classic.lookY + 0*CAM_TILT_UNITS = 8, the historical LOOK_Y.
+    assert.deepEqual({ ...CAM_PRESETS.classic },
+        { fov: 40, y: 46, z: 112, lookY: 8, lookZ: -165 });
+    for (const [id, p] of Object.entries(CAM_PRESETS)) {
+        for (const f of ['fov', 'y', 'z', 'lookY', 'lookZ']) {
+            assert.ok(Number.isFinite(p[f]), id + '.' + f + ' is a number');
+        }
+        assert.ok(p.y > 0 && p.z > 0, id + ' sits above and behind the keys');
+    }
+    assert.equal(readCameraSetting(), 'overhead'); // no localStorage in the vm → tuned default
+});
+
+test('camera default look is unchanged: overhead bakes the old tuned tilt, camTilt is neutral', () => {
+    const { CAM_PRESETS, FX_DEFAULTS } = load().slopsmithViz_keys_highway_3d.__test;
+    const CAM_TILT_UNITS = 55; // full-swing of the camTilt offset at ±1 (screen.js)
+    // The shipped default look = overhead preset + the default camTilt. Before,
+    // that was lookY 0 + (−0.6 × 55) = −33; the tuned aim now lives in the
+    // preset (lookY −33) with a neutral camTilt (0), so the effective aim — and
+    // thus the out-of-the-box framing — is byte-identical.
+    const effOverhead = CAM_PRESETS.overhead.lookY + FX_DEFAULTS.camTilt * CAM_TILT_UNITS;
+    assert.equal(effOverhead, -33);
+    // 'classic' + the neutral default reproduces the historical LOOK_Y (8) —
+    // the "pick Classic for the original look" promise, now actually true.
+    const effClassic = CAM_PRESETS.classic.lookY + FX_DEFAULTS.camTilt * CAM_TILT_UNITS;
+    assert.equal(effClassic, 8);
+});
+
+test('keys3dSetCamera: persists + dispatches valid ids, ignores unknown', () => {
+    const store = {};
+    const events = [];
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+        dispatchEvent: (ev) => { events.push(ev); return true; },
+        CustomEvent: class CustomEvent {
+            constructor(type, opts) { this.type = type; this.detail = opts && opts.detail; }
+        },
+    });
+    win.keys3dSetCamera('overhead');
+    assert.equal(store.keys3d_bg_camera, 'overhead');
+    assert.equal(events.length, 1);
+    assert.equal(events[0].type, 'keys3d:settings');
+    assert.equal(events[0].detail.camera, 'overhead');
+    win.keys3dSetCamera('helicopter');
+    assert.equal(store.keys3d_bg_camera, 'overhead');
+    assert.equal(events.length, 1);
+    const { readCameraSetting } = win.slopsmithViz_keys_highway_3d.__test;
+    assert.equal(readCameraSetting(), 'overhead');
+    store.keys3d_bg_camera = 'garbage';
+    assert.equal(readCameraSetting(), 'overhead');
+});
+
+/* ── Flat-sharps / piano-shaped lanes (feat/keys3d-flat-lanes) ───────── */
+
+test('FX defaults: octave separators on, lanes off (minimal default look)', () => {
+    const { FX_DEFAULTS } = load().slopsmithViz_keys_highway_3d.__test;
+    assert.equal(FX_DEFAULTS.octaveGaps, true);   // octave separators ship on
+    assert.equal(FX_DEFAULTS.laneOpacity, 0.0);   // dark floor + guide lines by default
+    assert.equal(FX_DEFAULTS.octaveContrast, 0.5);
+    // Sharp LAYOUT is a string setting, not an FX bool.
+    assert.equal('flatSharps' in FX_DEFAULTS, false);
+    assert.equal('laneColors' in FX_DEFAULTS, false); // superseded by laneOpacity
+});
+
+test('keys3dSetFx: highway-layout controls persist (bool + sliders)', () => {
+    const store = {};
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+        dispatchEvent: () => true,
+        CustomEvent: class { constructor(t, o) { this.type = t; this.detail = o && o.detail; } },
+    });
+    win.keys3dSetFx('octaveGaps', true);
+    assert.equal(store.keys3d_bg_octaveGaps, '1');
+    // laneOpacity / octaveContrast are 0-1 numbers, persisted verbatim + clamped.
+    win.keys3dSetFx('laneOpacity', 0.35);
+    assert.equal(store.keys3d_bg_laneOpacity, '0.35');
+    win.keys3dSetFx('laneOpacity', 5); // clamps to the 0-1 range
+    assert.equal(store.keys3d_bg_laneOpacity, '1');
+    win.keys3dSetFx('octaveContrast', 0.8);
+    assert.equal(store.keys3d_bg_octaveContrast, '0.8');
+});
+
+test('sharpMode: realistic default, validated ids, persists + dispatches', () => {
+    const bare = load().slopsmithViz_keys_highway_3d.__test;
+    assert.deepEqual([...bare.SHARP_MODES], ['floating', 'flat', 'realistic']);
+    assert.equal(bare.readSharpModeSetting(), 'realistic'); // no localStorage → default
+    const store = {};
+    const events = [];
+    const win = load({
+        localStorage: {
+            getItem: (k) => (k in store ? store[k] : null),
+            setItem: (k, v) => { store[k] = v; },
+        },
+        dispatchEvent: (ev) => { events.push(ev); return true; },
+        CustomEvent: class { constructor(t, o) { this.type = t; this.detail = o && o.detail; } },
+    });
+    win.keys3dSetSharpMode('flat'); // a non-default id, to exercise persistence
+    assert.equal(store.keys3d_bg_sharpMode, 'flat');
+    assert.equal(events[0].detail.sharpMode, 'flat');
+    assert.equal(win.slopsmithViz_keys_highway_3d.__test.readSharpModeSetting(), 'flat');
+    // Unknown id ignored (no write, no event).
+    win.keys3dSetSharpMode('bogus');
+    assert.equal(store.keys3d_bg_sharpMode, 'flat');
+    assert.equal(events.length, 1);
+});
+
+test('laneSpanFlat (V5): lanes tile with zero overlap and even the naturals', () => {
+    const { laneSpanFlat, _isBlackPc } = load().slopsmithViz_keys_highway_3d.__test;
+    const sh = 2.2, shift = 2.2 / 3;
+    const dims = { whiteW: 12, sharpHalf: sh, shift, octGap: 0.9 }; // mirrors shipped LANE_DIMS_FLAT
+    // cx for one octave: whites on integer slots, blacks on half-slots — the
+    // same slot geometry keyLayout/keyX produce (cx = slot * whiteW=12).
+    const CX = {
+        60: 0, 61: 6, 62: 12, 63: 18, 64: 24, 65: 36, 66: 42,
+        67: 48, 68: 54, 69: 60, 70: 66, 71: 72, 72: 84,
+    };
+    const midis = [60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72];
+    const spans = midis.map((m) => laneSpanFlat(m, _isBlackPc(m), CX[m], dims, false));
+    const wOf = (s) => s.right - s.left;
+    const w = (m) => wOf(spans[midis.indexOf(m)]);
+    // Zero-overlap tiling: every lane abuts the previous one (no gap, no overlap).
+    for (let i = 1; i < spans.length; i++) {
+        assert.ok(Math.abs(spans[i].left - spans[i - 1].right) < 1e-9, 'lane ' + midis[i] + ' abuts');
+    }
+    // Sharps are all the same width.
+    for (const m of [61, 63, 66, 68, 70]) {
+        assert.ok(Math.abs(w(m) - 2 * sh) < 1e-9, 'sharp ' + m + ' width');
+    }
+    // The lean evens the naturals: C, D, E, F, B all come out equal.
+    for (const m of [62, 64, 65, 71]) {
+        assert.ok(Math.abs(w(m) - w(60)) < 1e-9, 'natural ' + m + ' == C (evened)');
+    }
+    // G and A are the only slightly-smaller naturals (G# can't lean) — still
+    // clearly wider than a sharp, and MUCH closer to the rest than plain V2
+    // (which would leave D at 12−2·sh, far below C's 12−sh).
+    assert.ok(Math.abs(w(67) - w(69)) < 1e-9, 'G == A');
+    assert.ok(w(67) < w(60) && w(67) > 2 * sh, 'G/A a touch smaller, still wider than a sharp');
+    assert.ok(w(60) - w(67) < sh, 'natural spread is under one sharp-width');
+});
+
+test('laneSpanReal (V4): naturals uniform, sharps full-width and overlapping', () => {
+    const { laneSpanReal } = load().slopsmithViz_keys_highway_3d.__test;
+    const dims = { natHalf: 5.64, sharpHalf: 3.2, octGap: 0.9 }; // mirrors LANE_DIMS_REAL
+    const wOf = (s) => s.right - s.left;
+    // Every natural is the same full width, whatever its neighbours.
+    for (const [midi, slot] of [[60, 0], [62, 1], [64, 2], [67, 4], [71, 6]]) {
+        assert.ok(Math.abs(wOf(laneSpanReal(midi, false, slot * 12, dims, false)) - 2 * 5.64) < 1e-9,
+            'natural ' + midi + ' uniform');
+    }
+    // Sharps are the full (wider) black-key width and overlap their naturals.
+    const C = laneSpanReal(60, false, 0, dims, false);
+    const Cs = laneSpanReal(61, true, 6, dims, false);
+    assert.ok(Math.abs(wOf(Cs) - 2 * 3.2) < 1e-9, 'sharp full width');
+    assert.ok(Cs.left < C.right, 'sharp overlaps (tucks over) the natural');
+});
+
+test('laneSpanFlat (V5): octaveGaps widens B→C by octGap, sharps unaffected', () => {
+    const { laneSpanFlat } = load().slopsmithViz_keys_highway_3d.__test;
+    const dims = { whiteW: 12, sharpHalf: 2.2, shift: 2.2 / 3, octGap: 0.9 };
+    const gapOff = laneSpanFlat(72, false, 84, dims, false).left - laneSpanFlat(71, false, 72, dims, false).right;
+    const gapOn = laneSpanFlat(72, false, 84, dims, true).left - laneSpanFlat(71, false, 72, dims, true).right;
+    assert.ok(Math.abs((gapOn - gapOff) - dims.octGap) < 1e-9, 'B→C divider grows by octGap');
+    // Sharps are unaffected by the octave-gap option.
+    const s = laneSpanFlat(61, true, 6, dims, true);
+    assert.ok(Math.abs((s.right - s.left) - 2 * dims.sharpHalf) < 1e-9, 'sharp width unchanged by gaps');
+});
+
+test('laneSpanFlat (V5): active-range boundary key is NOT trimmed by an out-of-range neighbor sharp', () => {
+    const { laneSpanFlat } = load().slopsmithViz_keys_highway_3d.__test;
+    const dims = { whiteW: 12, sharpHalf: 2.2, shift: 2.2 / 3, octGap: 0.9 }; // mirrors LANE_DIMS_FLAT
+    // F (midi 65, cx 36): its upper neighbor F# (66) is a sharp. When F sits
+    // at range.activeHigh and F# is excluded from the active range, F# never
+    // gets a lane drawn (see the activeLow/activeHigh skip around the
+    // lane-strip loop) — trimming F's right edge for it would leave a dark,
+    // unfilled sliver. The edge should stay full instead.
+    const highBoundary = { activeLow: 60, activeHigh: 65 };
+    const fAtBoundary = laneSpanFlat(65, false, 36, dims, false, highBoundary);
+    assert.ok(Math.abs(fAtBoundary.right - (36 + dims.whiteW / 2)) < 1e-9,
+        'F right edge stays full when F# is out of the active range');
+    // Same key, but now F# IS in the active range: normal zero-overlap
+    // tiling applies — the trim matches the ungated (no-range) call exactly,
+    // so in-range geometry is unaffected by this fix.
+    const highIncluded = { activeLow: 60, activeHigh: 66 };
+    const fWithSharpInRange = laneSpanFlat(65, false, 36, dims, false, highIncluded);
+    const fUngated = laneSpanFlat(65, false, 36, dims, false);
+    assert.ok(Math.abs(fWithSharpInRange.right - fUngated.right) < 1e-9,
+        'F trims normally once F# is back in range');
+    assert.ok(fWithSharpInRange.right < fAtBoundary.right, 'in-range trim is narrower than the boundary full edge');
+
+    // Symmetric case on the low edge: D (midi 62, cx 12), lower neighbor C#
+    // (61) excluded when D sits at range.activeLow.
+    const lowBoundary = { activeLow: 62, activeHigh: 72 };
+    const dAtBoundary = laneSpanFlat(62, false, 12, dims, false, lowBoundary);
+    assert.ok(Math.abs(dAtBoundary.left - (12 - dims.whiteW / 2)) < 1e-9,
+        'D left edge stays full when C# is out of the active range');
+    const lowIncluded = { activeLow: 61, activeHigh: 72 };
+    const dWithSharpInRange = laneSpanFlat(62, false, 12, dims, false, lowIncluded);
+    const dUngated = laneSpanFlat(62, false, 12, dims, false);
+    assert.ok(Math.abs(dWithSharpInRange.left - dUngated.left) < 1e-9,
+        'D trims normally once C# is back in range');
+});
+

plugins/keys_highway_3d/tests/scoring.test.js

@@ -0,0 +1,154 @@
+// Pure MIDI-scoring tests: load screen.js in a bare vm window and exercise
+// the __test exports (no DOM, no WebGL, no MIDI device, no network).
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+function load() {
+    const window = {
+        console,
+        location: { protocol: 'http:', host: 'localhost' },
+        slopsmith: {},
+    };
+    window.window = window;
+    window.globalThis = window;
+    const context = vm.createContext(window);
+    const src = fs.readFileSync(path.join(__dirname, '..', 'screen.js'), 'utf8');
+    vm.runInContext(src, context, { filename: 'screen.js' });
+    return window.slopsmithViz_keys_highway_3d.__test;
+}
+
+const TOL = 0.10;
+
+test('accuracyOf/scoreOf mirror the notedetect stats formula', () => {
+    const { accuracyOf, scoreOf } = load();
+    // accuracy = hits / max(1, hits + misses)
+    assert.equal(accuracyOf(0, 0), 0);
+    assert.equal(accuracyOf(10, 0), 1);
+    assert.equal(accuracyOf(3, 1), 0.75);
+    // score = round(hits * 100 * accuracy)
+    assert.equal(scoreOf(0, 0), 0);
+    assert.equal(scoreOf(10, 0), 1000);
+    assert.equal(scoreOf(3, 1), Math.round(3 * 100 * 0.75));
+    // Monotonic in accuracy at fixed hits.
+    assert.ok(scoreOf(5, 0) > scoreOf(5, 5));
+});
+
+test('judgeHit: exact note inside ±0.10 s window hits; outside misses', () => {
+    const { judgeHit } = load();
+    const notes = [
+        { midi: 60, t: 1.0 },
+        { midi: 64, t: 1.0 },
+        { midi: 62, t: 2.0 },
+    ];
+    const hitKeys = new Set();
+    // On time.
+    assert.equal(judgeHit(notes, 60, 1.0, hitKeys, TOL), '1.000|60');
+    // Near the edge of the window (the exact ±0.10 boundary is float-
+    // representation dependent, same as the piano plugin).
+    assert.equal(judgeHit(notes, 62, 2.099, hitKeys, TOL), '2.000|62');
+    assert.equal(judgeHit(notes, 64, 0.901, hitKeys, TOL), '1.000|64');
+    // Just outside the window.
+    assert.equal(judgeHit(notes, 60, 1.11, hitKeys, TOL), null);
+    // Wrong note — nothing at that midi anywhere near.
+    assert.equal(judgeHit(notes, 65, 1.0, hitKeys, TOL), null);
+});
+
+test('judgeHit: dedupes by t|midi — a chart note can only be hit once', () => {
+    const { judgeHit } = load();
+    const notes = [{ midi: 60, t: 1.0 }, { midi: 60, t: 1.15 }];
+    const hitKeys = new Set();
+    const first = judgeHit(notes, 60, 1.02, hitKeys, TOL);
+    assert.equal(first, '1.000|60');
+    hitKeys.add(first);
+    // Second strike near the same time falls through to the NEXT un-hit
+    // chart note at the same midi (double-stop repeats).
+    const second = judgeHit(notes, 60, 1.06, hitKeys, TOL);
+    assert.equal(second, '1.150|60');
+    hitKeys.add(second);
+    // Third strike: both consumed → wrong note.
+    assert.equal(judgeHit(notes, 60, 1.1, hitKeys, TOL), null);
+});
+
+test('judgeHit: empty/absent chart never judges', () => {
+    const { judgeHit } = load();
+    assert.equal(judgeHit([], 60, 1.0, new Set(), TOL), null);
+    assert.equal(judgeHit(null, 60, 1.0, new Set(), TOL), null);
+});
+
+test('sweepMissed: marks elapsed unhit notes once, respects hit + floor', () => {
+    const { sweepMissed, noteKey } = load();
+    const notes = [
+        { midi: 60, t: 1.0 },
+        { midi: 62, t: 1.5 },
+        { midi: 64, t: 5.0 },
+    ];
+    const hitKeys = new Set([noteKey(1.0, 60)]); // 60@1.0 was hit
+    const missedKeys = new Set();
+    const missed = [];
+    // At t=2.0 the windows for 1.0 and 1.5 have elapsed; 5.0 is pending.
+    const n1 = sweepMissed(notes, 2.0, hitKeys, missedKeys, TOL, null, n => missed.push(n.midi));
+    assert.equal(n1, 1);
+    assert.deepEqual(missed, [62]);
+    assert.ok(missedKeys.has(noteKey(1.5, 62)));
+    // Sweeping again counts nothing new (idempotent per note).
+    assert.equal(sweepMissed(notes, 2.1, hitKeys, missedKeys, TOL, null), 0);
+    // Floor: a device connected at t=6 must not retro-miss the 5.0 note.
+    const hk2 = new Set(), mk2 = new Set();
+    assert.equal(sweepMissed(notes, 6.0, hk2, mk2, TOL, 6.0), 0);
+});
+
+test('sweepMissed: a note exactly at the connect floor is not retro-missed', () => {
+    // Off-by-one guard: floor is the connect instant; a note whose onset
+    // equals it (device connected exactly as the onset passed) must be
+    // excluded, not swept. Floor comparison is `<=`, not `<`.
+    const { sweepMissed } = load();
+    const notes = [{ midi: 60, t: 5.0 }, { midi: 62, t: 6.0 }];
+    const missedKeys = new Set();
+    const missed = [];
+    const n = sweepMissed(notes, 7.0, new Set(), missedKeys, TOL, 5.0,
+        m => missed.push(m.midi));
+    assert.equal(n, 1);
+    assert.deepEqual(missed, [62]);
+});
+
+test('sweepMissed: a long frame stall cannot let elapsed notes slip past', () => {
+    const { sweepMissed } = load();
+    const notes = [{ midi: 60, t: 1.0 }, { midi: 62, t: 3.0 }];
+    const missedKeys = new Set();
+    // The previous sweep ran at t≈0; the next runs 10 s later (backgrounded
+    // tab / render hitch). Both elapsed notes must still be counted.
+    assert.equal(sweepMissed(notes, 10.0, new Set(), missedKeys, TOL, null), 2);
+});
+
+test('sweepMissed: cursor advances monotonically and never recounts', () => {
+    const { sweepMissed } = load();
+    const notes = [
+        { midi: 60, t: 1.0 },
+        { midi: 62, t: 2.0 },
+        { midi: 64, t: 9.0 },
+    ];
+    const hitKeys = new Set(), missedKeys = new Set();
+    const cursor = { idx: 0 };
+    assert.equal(sweepMissed(notes, 1.5, hitKeys, missedKeys, TOL, null, null, cursor), 1);
+    assert.equal(cursor.idx, 1);
+    // Stall to t=8: the 2.0 note is counted exactly once from the cursor.
+    assert.equal(sweepMissed(notes, 8.0, hitKeys, missedKeys, TOL, null, null, cursor), 1);
+    assert.equal(cursor.idx, 2);
+    // Seek BACKWARDS: the cursor does not rewind, nothing is recounted.
+    assert.equal(sweepMissed(notes, 1.5, hitKeys, missedKeys, TOL, null, null, cursor), 0);
+    // The cursor still advances past pre-floor notes without counting them.
+    const c2 = { idx: 0 };
+    const mk2 = new Set();
+    assert.equal(sweepMissed(notes, 8.0, new Set(), mk2, TOL, 5.0, null, c2), 0);
+    assert.equal(c2.idx, 2);
+});
+
+test('noteKey quantises time to ms so float drift cannot double-count', () => {
+    const { noteKey } = load();
+    assert.equal(noteKey(1.0004, 60), noteKey(1.0001, 60));
+    assert.notEqual(noteKey(1.002, 60), noteKey(1.0001, 60));
+    assert.notEqual(noteKey(1.0, 60), noteKey(1.0, 61));
+});

plugins/tuner/plugin.json

@@ -1,7 +1,7 @@
 {
   "id": "tuner",
   "name": "Guitar/Bass Tuner",
-  "version": "1.3.1",
+  "version": "1.3.4",
   "bundled": true,
   "private": false,
   "script": "screen.js",

plugins/tuner/routes.py

@@ -33,10 +33,9 @@ def setup(app: FastAPI, context: dict):
             "lastInstrument": DEFAULT_INSTRUMENT,
             "freeTune": False,
             "customTunings": {},
-            "disabledTunings": [],
-            "showFloatingButton": True,
             "visualizationMode": "default",
             "audioInputMode": "auto",
+            "autoOpenOnTuningChange": False,
         }
         if not config_file.exists():
             return defaults
@@ -50,16 +49,17 @@ def setup(app: FastAPI, context: dict):
             res["lastInstrument"] = str(data.get("lastInstrument", DEFAULT_INSTRUMENT))
             res["freeTune"] = bool(data.get("freeTune", False))
             res["customTunings"] = data.get("customTunings", {})
-            res["disabledTunings"] = data.get("disabledTunings", [])
-            res["showFloatingButton"] = bool(data.get("showFloatingButton", True))
             res["visualizationMode"] = str(data.get("visualizationMode", "default"))
             raw_mode = str(data.get("audioInputMode", "auto"))
             res["audioInputMode"] = raw_mode if raw_mode in ("auto", "browser") else "auto"
+            # Fail closed: only a real JSON boolean enables the opt-in. A hand-edited /
+            # migrated / bad-client value (e.g. the string "false" or "0") must NOT be
+            # coerced to True by bool().
+            _auto_open = data.get("autoOpenOnTuningChange", False)
+            res["autoOpenOnTuningChange"] = _auto_open if isinstance(_auto_open, bool) else False
 
             if not isinstance(res["customTunings"], dict):
                 res["customTunings"] = {}
-            if not isinstance(res["disabledTunings"], list):
-                res["disabledTunings"] = []
 
             # Migrate custom tunings from old flat-list format
             res["customTunings"] = {
@@ -67,12 +67,6 @@ def setup(app: FastAPI, context: dict):
                 for name, val in res["customTunings"].items()
             }
 
-            # Strip legacy disabledTunings entries that lack compound "instrument:name" format
-            res["disabledTunings"] = [
-                e for e in res["disabledTunings"]
-                if isinstance(e, str) and ":" in e
-            ]
-
             return res
         except Exception:
             return defaults
@@ -80,8 +74,10 @@ def setup(app: FastAPI, context: dict):
     def _write(data: dict) -> None:
         config_dir.mkdir(parents=True, exist_ok=True)
         current = _read()
-        # Strip keys that belong to core, not to this plugin's config.
-        for key in ("defaultTunings", "referencePitch"):
+        # Strip keys that belong to core, not to this plugin's config, plus
+        # retired keys (disabledTunings/showFloatingButton — their settings UI
+        # was removed) so a stale client can't re-persist them.
+        for key in ("defaultTunings", "referencePitch", "disabledTunings", "showFloatingButton"):
             data = {k: v for k, v in data.items() if k != key}
         current.update(data)
         config_file.write_text(json.dumps(current, indent=2), encoding="utf-8")

plugins/tuner/screen.js

@@ -13,8 +13,17 @@
     let _lastAutoOpenSessionKey = null;
     let _autoOpenDismissedSessionKey = null;
     let _autoOpenGeneration = 0;
+    // Bumped on every enable()/disable() so an in-flight open (which awaits audio start
+    // with the panel already visible) can detect it was dismissed mid-open and NOT flip
+    // _state.enabled on afterwards — avoiding a zombie enabled-but-hidden tuner.
+    let _openGen = 0;
     let _onAutoOpenSongLoading = null;
     let _onAutoOpenSongReady = null;
+    // Autoplay gate (E2): when the feature is on, hold playback on song:loading and
+    // release it once we know we won't open (covered / unchanged) or the tuner is
+    // dismissed — so playback waits behind a genuinely-needed retune.
+    let _autoplayRelease = null;
+    let _gateClaimed = false;
 
     // ── Shared mutable state (read/written by screen.js; UI reads via closure) ──
     const _state = {
@@ -33,7 +42,6 @@
         _allTunings: {},
         referencePitch: 440,
         visualizationMode: 'default',
-        showFloatingButton: true,
         currentSongOffsets: null,
         currentSongIsBass: false,
         currentSongStringCount: 0,
@@ -83,10 +91,6 @@
     }
 
     // ── Tuning helpers ────────────────────────────────────────────────
-    function _isTuningEnabled(instrument, name) {
-        return !((_state._serverConfig ? _state._serverConfig.disabledTunings : null) || []).includes(instrument + ':' + name);
-    }
-
     function _instrumentForTuning(name) {
         for (var key in _state._allTunings) {
             if (_state._allTunings[key] && _state._allTunings[key][name]) return key;
@@ -95,11 +99,7 @@
     }
 
     function _buildTuningsForInstrument(instrument) {
-        const all = _state._allTunings[instrument] || {};
-        const disabled = (_state._serverConfig ? _state._serverConfig.disabledTunings : null) || [];
-        return Object.fromEntries(
-            Object.entries(all).filter(([name]) => !disabled.includes(instrument + ':' + name))
-        );
+        return { ...(_state._allTunings[instrument] || {}) };
     }
 
     function _tuningIdentityKey(songInfo) {
@@ -133,15 +133,259 @@
         return filename + '::' + arr;
     }
 
+    // ── §4 instrument-coverage ────────────────────────────────────────────────
+    // FeedBack is tune-to-song: the highway draws tab in the SONG's tuning, so the
+    // player tunes their instrument to match. We therefore only auto-open when the
+    // player's CURRENT physical tuning doesn't already cover the song — i.e. the
+    // song's open-string tuning isn't an exact contiguous run inside the player's
+    // strings, OR the global reference differs. So an 8-string F# player isn't
+    // nagged for a 6-/7-string standard song (its top strings already match), but a
+    // Drop-A song whose dropped open string the player lacks still prompts.
+    function _openMidisFromFreqs(freqs) {
+        const u = window._tunerUtils;
+        if (!u || !Array.isArray(freqs)) return null;
+        return freqs.map((f) => Math.round(u.freqToMidi(f)));
+    }
+
+    // The song's open-string MIDI (at A440; centOffset handled separately as a
+    // global). Mirrors _tuningIdentityKey's isBass / string-count derivation.
+    function _songOpenMidis(songInfo) {
+        const u = window._tunerUtils;
+        if (!u || !songInfo || !Array.isArray(songInfo.tuning) || !songInfo.tuning.length) return null;
+        const ctx = (typeof window.feedBack?.songTuningContext === 'function')
+            ? window.feedBack.songTuningContext(songInfo)
+            : { stringCount: songInfo.stringCount, arrangement: songInfo.arrangement, arrangement_smart_name: songInfo.arrangement_smart_name };
+        const isBass = (typeof window.feedBack?.isBassArrangement === 'function')
+            ? window.feedBack.isBassArrangement(ctx)
+            : (songInfo.arrangement || '').toLowerCase().includes('bass');
+        const sc = (typeof window.feedBack?.effectiveStringCount === 'function')
+            ? window.feedBack.effectiveStringCount(songInfo.tuning, ctx)
+            : (songInfo.stringCount || songInfo.tuning.length);
+        if (!sc || sc <= 0) return null;
+        const offsets = songInfo.tuning.slice(0, sc);
+        if (!offsets.length) return null;
+        return _openMidisFromFreqs(u.offsetsToFreqs(offsets, isBass));
+    }
+
+    // The player's CURRENT physical tuning. Prefer the host-owned live working
+    // tuning (window.feedBack.workingTuning) — what the instrument is *actually* in
+    // right now, which advances as the player retunes — so coverage prompts fire in
+    // BOTH directions (E→C# and back), not only away from a fixed profile. Feature-
+    // detected: on a host without the working-tuning capability, or before it's been
+    // set, we fall back to the static /api/settings instrument tuning (today's
+    // behavior). Returns { midis, refCents } or null.
+    // The SELECTED physical instrument's working-tuning slot identity, from /api/settings.
+    // The read (_playerTuning) and the write (_publishWorkingTuning) MUST agree on this
+    // key — the working tuning is a property of the player's selected instrument, not of
+    // any one song — or a published tuning lands in a slot coverage never reads back.
+    // Returns { isBass, sc, key }.
+    function _selectedInstrument(s) {
+        const isBass = !!(s && s.instrument === 'bass');
+        const sc = (s && Number(s.string_count)) || (isBass ? 4 : 6);
+        return { isBass, sc, key: (isBass ? 'bass' : 'guitar') + '-' + sc };
+    }
+
+    // Memoize the player's tuning: it depends only on /api/settings + the working
+    // tuning, which change on instrument:changed / working-tuning-changed (NOT per song).
+    // Without this, a consumer that evaluates coverage for many items at once — the
+    // library's per-song tuning-match chips — would fire one /api/settings fetch PER item
+    // per paint. Cache the promise so they all share one read; invalidate on the events
+    // that change the answer, AND expire after a short TTL so a settings write that
+    // doesn't emit an event (e.g. the input-setup flow) still heals within seconds.
+    let _playerTuningPromise = null;
+    let _playerTuningAt = 0;
+    const _PLAYER_TUNING_TTL_MS = 3000;
+    function _playerTuning() {
+        const now = (typeof Date !== 'undefined' && Date.now) ? Date.now() : 0;
+        if (!_playerTuningPromise || (now - _playerTuningAt) > _PLAYER_TUNING_TTL_MS) {
+            _playerTuningAt = now;
+            const p = _computePlayerTuning();
+            _playerTuningPromise = p;
+            // Never pin a transient failure: if the read yields null (or rejects), drop
+            // the cache so the next call retries. A real result stays until invalidation/TTL.
+            p.then((r) => { if (r == null && _playerTuningPromise === p) _playerTuningPromise = null; },
+                () => { if (_playerTuningPromise === p) _playerTuningPromise = null; });
+        }
+        return _playerTuningPromise;
+    }
+    function _invalidatePlayerTuning() { _playerTuningPromise = null; }
+
+    async function _computePlayerTuning() {
+        const u = window._tunerUtils;
+        if (!u) return null;
+        // Instrument IDENTITY (which instrument is selected) + the static fallback
+        // tuning, from /api/settings.
+        let s = null;
+        try { s = await fetch('/api/settings').then((r) => (r && r.ok ? r.json() : null)); }
+        catch (_) { s = null; }
+        const { isBass, sc, key } = _selectedInstrument(s);
+        // Cache the resolved selection so the (synchronous) publish-on-clear writes to
+        // the EXACT slot this read path uses — no second /api/settings fetch that could
+        // race an instrument switch. Only cache when settings were actually read: on a
+        // fetch failure we keep the last confident selection (or none → publish skips)
+        // rather than recording a bogus default-instrument slot to publish into later.
+        // Coverage runs before any auto-open, so this is set by the time a clear can publish.
+        if (s) {
+            _state._playerSelected = { isBass, sc, key, refPitch: Number(s.reference_pitch) || 440 };
+        }
+        // The LIVE per-instrument working tuning (advances as the player retunes) —
+        // this is what makes coverage prompt in BOTH directions, not only away from a
+        // fixed profile. Feature-detected; falls back to the static settings tuning
+        // when unset / no host capability.
+        const wt = (window.feedBack && window.feedBack.workingTuning
+            && typeof window.feedBack.workingTuning.get === 'function')
+            ? window.feedBack.workingTuning.get(key) : null;
+        const wtHasOffsets = !!(wt && Array.isArray(wt.offsets) && wt.offsets.length);
+        let freqs = null;
+        if (wtHasOffsets) {
+            freqs = u.offsetsToFreqs(wt.offsets.slice(0, sc), isBass);
+        } else if (s && Array.isArray(s.tuning)) {
+            freqs = u.offsetsToFreqs(s.tuning.slice(0, sc), isBass);
+        } else if (s && typeof s.tuning === 'string') {
+            const named = _state._allTunings && _state._allTunings[key];
+            if (named && Array.isArray(named[s.tuning])) freqs = named[s.tuning];
+        }
+        if (!freqs) {
+            // No confident instrument identity — settings absent, OR present but carrying
+            // no instrument/string_count/tuning (a fresh profile: /api/settings omits them)
+            // — and no live working tuning. We can't tell the player's tuning, so fail
+            // toward prompting (null → not-covered) rather than silently assuming standard
+            // and suppressing a genuinely-needed prompt.
+            const hasIdentity = !!(s && (s.instrument || s.string_count || s.tuning));
+            if (!hasIdentity && !wtHasOffsets) return null;
+            freqs = u.offsetsToFreqs(new Array(sc).fill(0), isBass);   // standard fallback
+        }
+        const midis = _openMidisFromFreqs(freqs);
+        if (!midis) return null;
+        const refPitch = (wt && Number(wt.referencePitch)) || (s && Number(s.reference_pitch)) || 440;
+        return { midis, refCents: 1200 * Math.log2(refPitch / 440) };
+    }
+
+    // PR: host workingTuning — when the player clears an AUTO-OPENED tuner we assume
+    // they tuned their (selected) instrument to the song, so publish the song's tuning
+    // as the live working tuning for that instrument ('assumed' — PR 4's explicit
+    // "I tuned / Skip" will replace this heuristic). After the instrument->chart routing
+    // PR the loaded arrangement matches the selected instrument, so the song's tuning IS
+    // the player's instrument's new tuning.
+    //
+    // We write to the SELECTED instrument's slot (the exact key _playerTuning reads),
+    // NOT a song-derived one, so the publish can't be stranded in a slot coverage never
+    // looks at. If the cleared song is a chart for the OTHER instrument (a manual switch
+    // to e.g. the bass part while guitar is selected), we skip — that isn't evidence the
+    // selected instrument was retuned, and writing it would pollute the wrong slot.
+    //
+    // Synchronous, off the selection _playerTuning last resolved (`_state._playerSelected`)
+    // — an auto-open always runs a coverage check first, so it's populated by the time a
+    // clear can publish. Reusing it (rather than re-fetching /api/settings here) keeps the
+    // write key identical to the read key and avoids racing an instrument switch.
+    function _publishWorkingTuning(songInfo) {
+        const wt = window.feedBack && window.feedBack.workingTuning;
+        if (!wt || typeof wt.set !== 'function') return;
+        if (!songInfo || !Array.isArray(songInfo.tuning) || !songInfo.tuning.length) return;
+        const sel = _state._playerSelected;
+        if (!sel || !sel.key || !(sel.sc > 0)) return;   // coverage hasn't resolved the instrument yet
+        const ctx = (typeof window.feedBack?.songTuningContext === 'function')
+            ? window.feedBack.songTuningContext(songInfo)
+            : { stringCount: songInfo.stringCount, arrangement: songInfo.arrangement, arrangement_smart_name: songInfo.arrangement_smart_name };
+        const songIsBass = (typeof window.feedBack?.isBassArrangement === 'function')
+            ? window.feedBack.isBassArrangement(ctx)
+            : (songInfo.arrangement || '').toLowerCase().includes('bass');
+        if (songIsBass !== sel.isBass) return;   // cross-instrument chart — don't pollute the selected slot
+        wt.set({
+            offsets: songInfo.tuning.slice(0, sel.sc),
+            stringCount: sel.sc,
+            instrument: sel.isBass ? 'bass' : 'guitar',
+            referencePitch: sel.refPitch,
+            source: 'tuner',
+        }, { instrument: sel.key, provenance: 'assumed' });
+    }
+
+    // The retune the player would need to match this song, as a structured report:
+    //   { covered, retune: [{ from, to }], reference, cantCover }
+    // — covered: the physical tuning already matches (the song's open strings are an
+    //   exact contiguous run inside the player's strings) → no retune;
+    // — retune: the per-string note changes (e.g. { from:'B', to:'A' }) of the best
+    //   contiguous alignment — what the badge cue names;
+    // — reference: a whole-instrument A4/centOffset mismatch (A440 vs A432, octave);
+    // — cantCover: the song needs more strings than the instrument has.
+    // Conservative: any missing data → { covered:false } so a needed prompt/cue is
+    // never silently dropped on a fetch hiccup.
+    async function _computeCoverageReport(songInfo) {
+        const u = window._tunerUtils;
+        const none = { covered: false, retune: [], reference: false, cantCover: false };
+        if (!u) return none;
+        const song = _songOpenMidis(songInfo);
+        if (!song || !song.length) return none;
+        const player = await _playerTuning();
+        if (!player || !player.midis.length) return none;
+        const reference = Math.abs((Number(songInfo?.centOffset) || 0) - player.refCents) > 25;
+        if (player.midis.length < song.length) return { covered: false, retune: [], reference, cantCover: true };
+        // Best contiguous alignment = the run with the fewest per-string mismatches
+        // (extended-range adds strings at the ends — match by pitch, not index).
+        let best = null;
+        for (let start = 0; start + song.length <= player.midis.length; start++) {
+            const diffs = [];
+            for (let i = 0; i < song.length; i++) {
+                const pm = player.midis[start + i];
+                if (pm !== song[i]) diffs.push({ from: u.midiToNote(pm, false), to: u.midiToNote(song[i], false) });
+            }
+            if (!best || diffs.length < best.length) best = diffs;
+            if (!diffs.length) break;
+        }
+        const covered = !reference && best.length === 0;
+        return { covered, retune: covered ? [] : best, reference, cantCover: false };
+    }
+
+    // Dedup the coverage computation (which fetches /api/settings): the auto-open gate
+    // AND the badge cue both call this on the same song:ready. Cache the in-flight/last
+    // result per song so they share ONE fetch. Invalidated when anything that changes the
+    // answer happens — a new song (song:loading), an instrument switch (instrument:changed),
+    // or a retune (working-tuning-changed) — so the cache can never go stale within a song.
+    let _coverageCache = null;   // { key, promise }
+    function _coverageReport(songInfo) {
+        const key = _autoOpenSessionKey(songInfo) + '|'
+            + (songInfo && Array.isArray(songInfo.tuning) ? songInfo.tuning.join(',') : '')
+            + '|' + (songInfo && songInfo.centOffset != null ? songInfo.centOffset : '');   // coverage uses centOffset
+        if (_coverageCache && _coverageCache.key === key) return _coverageCache.promise;
+        const promise = _computeCoverageReport(songInfo);
+        _coverageCache = { key, promise };
+        return promise;
+    }
+    function _invalidateCoverageCache() { _coverageCache = null; }
+
+    // Boolean form used to gate the auto-open prompt.
+    async function _coveredByPlayerInstrument(songInfo) {
+        return (await _coverageReport(songInfo)).covered;
+    }
+
+    function _releaseGate() {
+        if (_autoplayRelease) { try { _autoplayRelease(); } catch (_) { /* */ } _autoplayRelease = null; }
+    }
+
     function _onAutoOpenSongLoadingHandler() {
         _autoOpenGeneration++;
         _autoOpenDismissedSessionKey = null;
         _lastAutoOpenSessionKey = null;
+        _invalidateCoverageCache();
+        // Claim the autoplay gate NOW (synchronously, before song:ready) when the
+        // feature is on, so playback can wait behind a needed retune. Released on
+        // song:ready if we don't open, or when the tuner is dismissed.
+        _releaseGate();
+        _gateClaimed = false;
+        _autoplayRelease = (_state._serverConfig && _state._serverConfig.autoOpenOnTuningChange
+            && window.feedBack && typeof window.feedBack.holdAutoplay === 'function')
+            ? window.feedBack.holdAutoplay() : null;
     }
 
     async function _maybeAutoOpenOnTuningChange() {
         if (!document.getElementById('player')?.classList.contains('active')) return;
 
+        // Opt-in (default off): only auto-open when the user enabled it in the
+        // tuner settings. Ensure config is loaded so the first song:ready after
+        // boot still reads the real flag; fail closed if it can't load.
+        if (!_state._serverConfig) { try { await loadConfig(); } catch (_) { /* */ } }
+        if (!_state._serverConfig || !_state._serverConfig.autoOpenOnTuningChange) return;
+
         const songInfo = window.highway?.getSongInfo?.() || window.feedBack?.currentSong;
         if (!songInfo) return;
 
@@ -165,10 +409,21 @@
         if (_lastAutoOpenSessionKey === sessionKey) return;
         if (!window.tuner || typeof window.tuner.enable !== 'function') return;
 
+        // §4: skip the prompt when the player's physical instrument already covers
+        // this song's tuning (e.g. an 8-string F# playing a 6-/7-string standard
+        // song). Async (fetches /api/settings) — re-check the generation after.
+        const covered = await _coveredByPlayerInstrument(songInfo);
+        if (myGen !== _autoOpenGeneration) return;
+        if (covered) return;
+
         _lastAutoOpenSessionKey = sessionKey;
         try {
-            await window.tuner.enable();
+            await window.tuner.enable({ auto: true });
             if (myGen !== _autoOpenGeneration) return;
+            _gateClaimed = true;   // tuner is open → keep the autoplay gate until it's dismissed
+            // The hold is now intentional and user-dismissable — cancel the fail-open
+            // backstop so it can't start playback while the player is still tuning.
+            if (_autoplayRelease && typeof _autoplayRelease.settle === 'function') _autoplayRelease.settle();
         } catch (e) {
             console.warn('Tuner: auto-open failed:', e && e.message ? e.message : e);
             if (_lastAutoOpenSessionKey === sessionKey) _lastAutoOpenSessionKey = null;
@@ -183,9 +438,26 @@
     function _installAutoOpenListeners() {
         if (_onAutoOpenSongLoading || !window.feedBack?.on) return;
         _onAutoOpenSongLoading = _onAutoOpenSongLoadingHandler;
-        _onAutoOpenSongReady = () => { _maybeAutoOpenOnTuningChange(); };
+        _onAutoOpenSongReady = async () => {
+            const myGen = _autoOpenGeneration;
+            await _maybeAutoOpenOnTuningChange();
+            // A newer song:loading may have superseded us while awaiting — it owns the
+            // gate/_gateClaimed now, so don't release its hold based on our stale view.
+            if (myGen !== _autoOpenGeneration) return;
+            if (!_gateClaimed) _releaseGate();   // not gating this song → let it play
+        };
         window.feedBack.on('song:loading', _onAutoOpenSongLoading);
         window.feedBack.on('song:ready', _onAutoOpenSongReady);
+        // The badge (static/v3/badges.js) emits this on the feedBack bus when the player
+        // switches instrument. Drop the cached selection so a publish-on-clear can't write
+        // to the previously-selected instrument's slot; the next coverage read re-resolves
+        // it. Until then _publishWorkingTuning skips (safe — no mis-slotted write).
+        window.feedBack.on('instrument:changed', () => {
+            _state._playerSelected = null; _invalidatePlayerTuning(); _invalidateCoverageCache();
+        });
+        // A retune (working tuning published on a tuner clear) changes coverage for the
+        // current song — drop the cached player tuning + report so a re-evaluation recomputes.
+        window.feedBack.on('working-tuning-changed', () => { _invalidatePlayerTuning(); _invalidateCoverageCache(); });
     }
 
     // ── Player sync helpers ───────────────────────────────────────────
@@ -209,6 +481,12 @@
             const sc = (typeof window.feedBack?.effectiveStringCount === 'function')
                 ? window.feedBack.effectiveStringCount(songInfo.tuning, ctx)
                 : (songInfo.stringCount || songInfo.tuning.length);
+            // A tuning change invalidates an in-flight mic-verify — its captured targets
+            // and offsets are now stale, so it must not complete against the old tuning.
+            if (_verify && String(songInfo.tuning.slice(0, sc)) !== String(_verify.offsets)) {
+                verifyCancel();
+                _tunerUIApi?.resetVerify?.();
+            }
             _state.currentSongOffsets = songInfo.tuning.slice(0, sc);
             _state.currentSongIsBass = isBass;
             _state.currentSongStringCount = sc;
@@ -267,7 +545,6 @@
             _state._serverConfig = config;
             _state._allTunings = tuningsData.tunings || {};
             _state.referencePitch = tuningsData.referencePitch || 440;
-            _state.showFloatingButton = config.showFloatingButton !== false;
             _state.visualizationMode = config.visualizationMode || 'default';
             _state.audioInputMode = config.audioInputMode || 'auto';
 
@@ -341,8 +618,16 @@
         }
     }
 
-    async function enable() {
+    async function enable(opts) {
         if (_state.enabled) return;
+        const myOpen = ++_openGen;   // this open's token; a disable()/newer open invalidates it
+        // An AUTO-open (the "this song needs a different tuning" nudge) must
+        // PERSIST: it is NOT dismissed by the autoplay song:play that follows
+        // song entry, a stray click, or a same-screen re-emit — only by the
+        // Skip/× buttons or leaving the song. A manual open keeps the classic
+        // click-away / play-to-close behaviour.
+        const auto = !!(opts && opts.auto);
+        _state.autoOpened = auto;
         await _loadScript('/api/plugins/tuner/utils/tuning-utils.js');
         await _loadScript('/api/plugins/tuner/utils/audio.js');
         await _loadScript('/api/plugins/tuner/utils/ui.js');
@@ -371,15 +656,33 @@
         _state.uiContainer.classList.add('flex');
         _tunerUIApi.positionPanel();
         _tunerUIApi.updateFreeTuneUI();
+        // "Skip" is the auto-open nudge's explicit dismiss; hidden for a manual
+        // open (the × / click-away already close those).
+        if (_state.skipBtn) _state.skipBtn.classList.toggle('hidden', !auto);
+        // Auto-open shows the "Back to library" escape hatch and hides the ×:
+        // the Skip / Back buttons + Esc are the auto-open's dismiss surface, so a
+        // gated retune always offers a way forward AND a way out.
+        if (_state.backBtn) _state.backBtn.classList.toggle('hidden', !auto);
+        if (_state.closeBtn) _state.closeBtn.classList.toggle('hidden', !!auto);
 
-        // Close when clicking outside the panel. Deferred so the badge's
-        // opening click doesn't bubble up to the document and fire immediately.
-        if (_outsideClickClose) document.removeEventListener('click', _outsideClickClose);
-        _outsideClickClose = () => { if (_state.enabled) disable(); };
-        setTimeout(() => { if (_outsideClickClose) document.addEventListener('click', _outsideClickClose, { once: true }); }, 0);
+        // Close when clicking outside the panel. Deferred so the badge's opening
+        // click doesn't bubble up to the document and fire immediately. Skipped
+        // for an auto-open: the user never clicked to open it, so their first
+        // unrelated click must not dismiss it (it persists until Skip / Back to
+        // library / Esc).
+        if (!auto) {
+            if (_outsideClickClose) document.removeEventListener('click', _outsideClickClose);
+            _outsideClickClose = () => { if (_state.enabled) disable(); };
+            setTimeout(() => { if (_outsideClickClose) document.addEventListener('click', _outsideClickClose, { once: true }); }, 0);
+        }
 
         if (window.feedBack && !_onScreenChanged) {
-            _onScreenChanged = () => { disable(); };
+            // Auto-opened: close only when we actually LEAVE the song — a player
+            // re-emit while staying put must not tear down the nudge. Manual:
+            // unchanged (any screen change closes it).
+            _onScreenChanged = () => {
+                if (!_state.autoOpened || !document.getElementById('player')?.classList.contains('active')) disable();
+            };
             _onSongReady = () => {
                 _tunerUIApi.renderTuningOptions();
                 if (_state.selectedTuningName === '_current') _syncCurrentTuning();
@@ -396,6 +699,10 @@
                 { deviceId: _state.selectedDeviceId, channel: _state.selectedChannel, audioInputMode: _state.audioInputMode },
                 _tunerUIApi.updateUI
             );
+            // The panel is visible (with ×/Skip) across the audio-start await above, so a
+            // dismiss can land here. If so, disable() already tore the panel down and
+            // bumped _openGen — do NOT flip enabled on (that would leave enabled-but-hidden).
+            if (myOpen !== _openGen) return;
             _state.enabled = true;
             if (window.tuner?.updateButtons) window.tuner.updateButtons();
         } catch (e) {
@@ -406,10 +713,16 @@
     }
 
     function disable() {
+        _openGen++;   // invalidate any in-flight enable() so it won't re-enable after this teardown
         const wasEnabled = _state.enabled;
+        const wasAutoOpened = _state.autoOpened;
         const onPlayer = document.getElementById('player')?.classList.contains('active');
         _state.enabled = false;
+        _state.autoOpened = false;
+        _releaseGate();   // dismissing a gated auto-open releases playback (it starts now)
         _state.manualTargetFreq = null;
+        verifyCancel();                       // a running mic-verify ends when the panel closes
+        _tunerUIApi?.resetVerify?.();
         if (_outsideClickClose) { document.removeEventListener('click', _outsideClickClose); _outsideClickClose = null; }
         if (_state.activeViz) { _state.activeViz.destroy(); _state.activeViz = null; }
         if (_state.uiContainer) { _state.uiContainer.classList.add('hidden'); _state.uiContainer.classList.remove('flex'); }
@@ -427,8 +740,17 @@
         }
         if (wasEnabled && onPlayer) {
             const songInfo = window.highway?.getSongInfo?.() || window.feedBack?.currentSong;
-            if (songInfo) _autoOpenDismissedSessionKey = _autoOpenSessionKey(songInfo);
+            if (songInfo) {
+                _autoOpenDismissedSessionKey = _autoOpenSessionKey(songInfo);
+                // Clearing an auto-opened tuner = the player tuned to this song:
+                // publish the song's tuning as their instrument's live working tuning
+                // so coverage stops nagging for it (and prompts on the way back). But
+                // if a mic-verify already wrote 'verified' this session, a plain
+                // 'assumed' publish would immediately clobber it — leave it verified.
+                if (wasAutoOpened && !_verifiedPublished) _publishWorkingTuning(songInfo);
+            }
         }
+        _verifiedPublished = false;   // consumed — fresh for the next tuner session
     }
 
     window.tuner = {
@@ -472,10 +794,110 @@
         _installAutoOpenListeners();
     }).catch(e => console.error(e));
     _installAutoOpenListeners();
+
+    // ── Mic-verify (working-tuning PR 9b) ──────────────────────────────────────
+    // A choreographed per-string check that promotes the current working tuning
+    // from 'assumed' to 'verified' — the ONLY thing that may ever claim 'verified'
+    // (audio-engine's honesty rule). The player plays each string; once every one
+    // reads in-tune (±VERIFY_TOL_CENTS) and holds for VERIFY_STABLE frames we stamp
+    // provenance:'verified' + verifiedStrings. Cancels on tuner close / tuning change.
+    const VERIFY_TOL_CENTS = 6;
+    const VERIFY_STABLE = 8;
+    let _verify = null;
+    let _verifiedPublished = false;   // set when a mic-verify wrote 'verified' this session
+
+    function verifyState() {
+        if (!_verify) return null;
+        return {
+            complete: _verify.complete,
+            done: _verify.targets.map((t) => t.done),
+            remaining: _verify.targets.filter((t) => !t.done).length,
+        };
+    }
+    // Start a verify session for `targets` (freqs; defaults to the selected tuning).
+    // Captures the tuning's OFFSETS now (explicit arg, else the current song's) so that
+    // when it completes we stamp 'verified' onto the exact tuning that was confirmed.
+    // Per-string semitone offsets (from standard) of the tuning we're verifying, derived
+    // from its target freqs. This is authoritative for BOTH the song ('_current') tuning
+    // and a manually-selected tuning — unlike _state.currentSongOffsets, which for a manual
+    // tuning is a stale/different song's tuning that must NOT be stamped 'verified'. The
+    // player's reference pitch scales both the targets and the standard, so it cancels.
+    function _tuningOffsetsFromFreqs(freqs) {
+        const u = window._tunerUtils;
+        if (!u || typeof u.offsetsToFreqs !== 'function' || typeof u.freqToMidi !== 'function') return null;
+        const isBass = /^bass/.test(_state.selectedInstrument || '');   // the selected instrument, not the song's
+        const refScale = (Number(_state.referencePitch) || 440) / 440;
+        const std = u.offsetsToFreqs(new Array(freqs.length).fill(0), isBass);
+        if (!Array.isArray(std) || std.length !== freqs.length) return null;
+        const out = [];
+        for (let i = 0; i < freqs.length; i++) {
+            const f = Number(freqs[i]);
+            const s = Number(std[i]) * refScale;
+            if (!(f > 0) || !(s > 0)) return null;
+            out.push(Math.round(u.freqToMidi(f) - u.freqToMidi(s)) || 0);   // normalize -0 → 0
+        }
+        return out;
+    }
+    function verifyStart(targets, offsets) {
+        const freqs = (Array.isArray(targets) && targets.length) ? targets : _state.selectedTuning;
+        if (!Array.isArray(freqs) || !freqs.length) return null;
+        // Explicit offsets win (callers/tests that already have them); otherwise derive
+        // them from the tuning actually being verified.
+        const offs = (Array.isArray(offsets) && offsets.length) ? offsets.slice() : _tuningOffsetsFromFreqs(freqs);
+        _verify = { targets: freqs.map((f) => ({ freq: f, streak: 0, done: false })), complete: false, offsets: offs };
+        _verifiedPublished = false;
+        return verifyState();
+    }
+    function verifyCancel() { _verify = null; }
+    // Feed one processed frame (its matched target freq + cents-off). Requires
+    // CONSECUTIVE in-tune frames per string: the one confirmed string advances, and
+    // every other not-yet-done string's streak resets — so a run can't accumulate across
+    // silence / wrong-string / out-of-tune frames. Completes + stamps 'verified' when all pass.
+    function verifyFeed(targetFreq, cents) {
+        if (!_verify || _verify.complete) return verifyState();
+        let hit = null;
+        if (targetFreq != null) {
+            const t = _verify.targets.find((x) => Math.abs(x.freq - targetFreq) < 0.5);
+            if (t && !t.done && isFinite(cents) && Math.abs(cents) <= VERIFY_TOL_CENTS) hit = t;
+        }
+        for (const t of _verify.targets) {
+            if (t.done) continue;
+            if (t === hit) { if (++t.streak >= VERIFY_STABLE) t.done = true; }
+            else t.streak = 0;
+        }
+        if (_verify.targets.every((x) => x.done)) {
+            _verify.complete = true;
+            _publishVerified();
+        }
+        return verifyState();
+    }
+    // Promote the working tuning to 'verified'. Write the CONFIRMED tuning's offsets
+    // atomically with provenance + verifiedStrings (into the selected instrument's slot),
+    // so 'verified' can never attach to stale offsets the slot happened to hold.
+    function _publishVerified() {
+        const wt = window.feedBack && window.feedBack.workingTuning;
+        if (!wt || typeof wt.set !== 'function') return;
+        const offsets = (_verify && Array.isArray(_verify.offsets)) ? _verify.offsets.slice() : null;
+        if (!offsets || !offsets.length) return;   // nothing concrete to claim verified
+        const sel = _state._playerSelected;
+        const next = { offsets: offsets, stringCount: offsets.length, verifiedStrings: offsets.map(() => true) };
+        if (sel && sel.key) { next.instrument = sel.isBass ? 'bass' : 'guitar'; next.referencePitch = sel.refPitch; }
+        const opts = (sel && sel.key) ? { instrument: sel.key, provenance: 'verified' } : { provenance: 'verified' };
+        try { wt.set(next, opts); _verifiedPublished = true; } catch (_) { /* noop */ }
+    }
+
     window._tunerAutoOpen = {
         tuningIdentityKey: _tuningIdentityKey,
         sessionKey: _autoOpenSessionKey,
         maybeAutoOpenOnTuningChange: _maybeAutoOpenOnTuningChange,
+        coveredByPlayerInstrument: _coveredByPlayerInstrument,
+        coverageReport: _coverageReport,
+        playerTuning: _playerTuning,
+        publishWorkingTuning: _publishWorkingTuning,
+        verifyStart: verifyStart,
+        verifyFeed: verifyFeed,
+        verifyCancel: verifyCancel,
+        verifyState: verifyState,
         onSongLoading: _onAutoOpenSongLoadingHandler,
         getState() {
             return {

plugins/tuner/settings.html

@@ -1,11 +1,11 @@
 <div class="space-y-6 py-2">
     <div class="flex items-center justify-between bg-dark-900/50 p-3 rounded-xl border border-gray-800/50">
         <div>
-            <h3 class="text-sm font-medium text-gray-200">Floating Button</h3>
-            <p class="text-[11px] text-gray-500">Show the tuner button on the main interface.</p>
+            <h3 class="text-sm font-medium text-gray-200">Auto-open on tuning change</h3>
+            <p class="text-[11px] text-gray-500">When a song (or arrangement) needs a different tuning, pop the tuner open automatically. It stays open until you Skip or close it.</p>
         </div>
         <label class="relative inline-flex items-center cursor-pointer">
-            <input type="checkbox" id="tuner-show-floating" class="sr-only peer" onchange="window._tunerToggleFloating(this.checked)">
+            <input type="checkbox" id="tuner-auto-open" class="sr-only peer" onchange="window._tunerToggleAutoOpen(this.checked)">
             <div class="w-9 h-5 bg-gray-700 peer-focus:outline-none rounded-full peer peer-checked:after:translate-x-full peer-checked:after:border-white after:content-[''] after:absolute after:top-[2px] after:left-[2px] after:bg-white after:border-gray-300 after:border after:rounded-full after:h-4 after:w-4 after:transition-all peer-checked:bg-accent"></div>
         </label>
     </div>
@@ -27,14 +27,6 @@
     </script>
 
     <div>
-        <h3 class="text-sm font-medium text-gray-400 mb-3">Tuning Visibility</h3>
-        <p class="text-xs text-gray-500 mb-4">Toggle which built-in tunings appear in the tuner menu.</p>
-        <div id="tuner-visibility-list" class="space-y-2 pr-2">
-            <!-- Populated by JS -->
-        </div>
-    </div>
-
-    <div class="pt-4 border-t border-gray-800">
         <h3 class="text-sm font-medium text-gray-400 mb-3">Custom Tunings</h3>
         <div id="tuner-custom-list" class="space-y-2 mb-4">
             <!-- Populated by JS -->
@@ -77,16 +69,7 @@
 
     <script>
         (function() {
-            let config = { customTunings: {}, disabledTunings: [], defaultTunings: {}, showFloatingButton: true, audioInputMode: 'auto' };
-            let expandedGroups = [];
-
-            var _INSTRUMENT_CAPTIONS = {
-                "guitar-6": "Guitar",
-                "guitar-7": "Guitar 7-string",
-                "guitar-8": "Guitar 8-string",
-                "bass-4": "Bass 4-string",
-                "bass-5": "Bass 5-string"
-            };
+            let config = { customTunings: {}, audioInputMode: 'auto' };
 
             var _instrumentLabels = {
                 "guitar-6": "Guitar 6-string",
@@ -101,23 +84,23 @@
                     const resp = await fetch('/api/plugins/tuner/config');
                     config = await resp.json();
 
-                    const floatingToggle = document.getElementById('tuner-show-floating');
-                    if (floatingToggle) floatingToggle.checked = config.showFloatingButton !== false;
-
                     const browserAudioToggle = document.getElementById('tuner-force-browser-audio');
                     if (browserAudioToggle) browserAudioToggle.checked = config.audioInputMode === 'browser';
 
+                    const autoOpenToggle = document.getElementById('tuner-auto-open');
+                    if (autoOpenToggle) autoOpenToggle.checked = config.autoOpenOnTuningChange === true;
+
                     render();
                 } catch (e) { console.error('Tuner settings: load failed', e); }
             }
 
-            window._tunerToggleFloating = (enabled) => {
-                config.showFloatingButton = enabled;
+            window._tunerToggleBrowserAudio = (forceBrowser) => {
+                config.audioInputMode = forceBrowser ? 'browser' : 'auto';
                 save();
             };
 
-            window._tunerToggleBrowserAudio = (forceBrowser) => {
-                config.audioInputMode = forceBrowser ? 'browser' : 'auto';
+            window._tunerToggleAutoOpen = (enabled) => {
+                config.autoOpenOnTuningChange = enabled;
                 save();
             };
 
@@ -134,115 +117,6 @@
             }
 
             function render() {
-                const visList = document.getElementById('tuner-visibility-list');
-                visList.innerHTML = '';
-
-                const defaultTunings = config.defaultTunings || {};
-
-                Object.keys(defaultTunings).forEach(groupName => {
-                    const group = defaultTunings[groupName];
-                    const groupTunings = Object.keys(group);
-                    const instrument = groupName;
-                    // Compound keys for all tunings in this group
-                    const compoundKeys = groupTunings.map(n => instrument + ':' + n);
-
-                    const groupWrapper = document.createElement('div');
-                    groupWrapper.className = 'mb-4';
-
-                    const header = document.createElement('div');
-                    header.className = 'flex items-center justify-between p-2 mt-2 bg-dark-900/80 rounded-t-lg border-x border-t border-gray-800/50 cursor-pointer hover:bg-dark-900 transition-colors';
-
-                    const left = document.createElement('div');
-                    left.className = 'flex items-center gap-2';
-
-                    const chevron = document.createElement('span');
-                    chevron.innerHTML = '<svg class="w-3 h-3" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7"/></svg>';
-                    chevron.className = 'text-gray-500 transition-transform duration-200 rotate-0';
-
-                    const groupLabel = document.createElement('span');
-                    groupLabel.className = 'text-[11px] font-bold text-gray-400 uppercase tracking-wider';
-                    groupLabel.textContent = _INSTRUMENT_CAPTIONS[groupName] || groupName;
-
-                    left.appendChild(chevron);
-                    left.appendChild(groupLabel);
-
-                    const groupToggle = document.createElement('input');
-                    groupToggle.type = 'checkbox';
-                    const allEnabled = compoundKeys.every(k => !config.disabledTunings.includes(k));
-                    const someEnabled = compoundKeys.some(k => !config.disabledTunings.includes(k));
-                    groupToggle.checked = allEnabled;
-                    groupToggle.indeterminate = someEnabled && !allEnabled;
-                    groupToggle.className = 'accent-accent';
-
-                    groupToggle.onclick = (e) => e.stopPropagation();
-                    groupToggle.onchange = () => {
-                        if (groupToggle.checked) {
-                            config.disabledTunings = config.disabledTunings.filter(k => !compoundKeys.includes(k));
-                        } else {
-                            compoundKeys.forEach(k => {
-                                if (!config.disabledTunings.includes(k)) config.disabledTunings.push(k);
-                            });
-                        }
-                        save();
-                        render();
-                    };
-
-                    header.appendChild(left);
-                    header.appendChild(groupToggle);
-                    groupWrapper.appendChild(header);
-
-                    const groupContainer = document.createElement('div');
-                    groupContainer.className = 'border-x border-b border-gray-800/50 rounded-b-lg overflow-hidden';
-
-                    const isExpanded = expandedGroups.includes(groupName);
-                    if (!isExpanded) {
-                        groupContainer.classList.add('hidden');
-                        chevron.classList.remove('rotate-90');
-                    } else {
-                        chevron.classList.add('rotate-90');
-                    }
-
-                    header.onclick = () => {
-                        const idx = expandedGroups.indexOf(groupName);
-                        if (idx === -1) {
-                            expandedGroups.push(groupName);
-                        } else {
-                            expandedGroups.splice(idx, 1);
-                        }
-                        render();
-                    };
-
-                    groupTunings.forEach((name, idx) => {
-                        const compoundKey = instrument + ':' + name;
-                        const div = document.createElement('div');
-                        div.className = `flex items-center justify-between p-2 bg-dark-800/30 hover:bg-dark-800/50 transition-colors ${idx === 0 ? 'border-t-0' : 'border-t border-gray-800/20'}`;
-
-                        const label = document.createElement('span');
-                        label.className = 'text-xs text-gray-300';
-                        label.textContent = name;
-
-                        const toggle = document.createElement('input');
-                        toggle.type = 'checkbox';
-                        toggle.checked = !config.disabledTunings.includes(compoundKey);
-                        toggle.className = 'accent-accent';
-                        toggle.onchange = () => {
-                            if (toggle.checked) {
-                                config.disabledTunings = config.disabledTunings.filter(k => k !== compoundKey);
-                            } else {
-                                if (!config.disabledTunings.includes(compoundKey)) config.disabledTunings.push(compoundKey);
-                            }
-                            save();
-                            render();
-                        };
-
-                        div.appendChild(label);
-                        div.appendChild(toggle);
-                        groupContainer.appendChild(div);
-                    });
-                    groupWrapper.appendChild(groupContainer);
-                    visList.appendChild(groupWrapper);
-                });
-
                 const customList = document.getElementById('tuner-custom-list');
                 customList.innerHTML = '';
                 const customNames = Object.keys(config.customTunings);

plugins/tuner/utils/ui.js

@@ -305,6 +305,12 @@ window._tunerUI = function(state, actions) {
     function renderStringNotes() {
         if (!state.stringNoteContainer) return;
         state.stringNoteContainer.innerHTML = '';
+        // Show the mic-verify control only for a selected (non-free) tuning.
+        if (state.verifyRow) {
+            const hasTuning = !!(state.selectedTuning && state.selectedTuning.length && !state.freeTune);
+            state.verifyRow.classList.toggle('hidden', !hasTuning);
+            if (!hasTuning) resetVerifyUI();
+        }
         if (!state.selectedTuning || state.selectedTuning.length === 0) {
             _syncStringOrderHelp(0);
             return;
@@ -327,6 +333,41 @@ window._tunerUI = function(state, actions) {
         _syncStringOrderHelp(total);
     }
 
+    // ── Mic-verify UI (working-tuning PR 9b) ───────────────────────────────────
+    function _markVerifiedStrings(done) {
+        if (!state.stringNoteContainer) return;
+        state.stringNoteContainer.querySelectorAll('[data-freq]').forEach((btn, i) => {
+            btn.classList.toggle('ring-2', !!done[i]);
+            btn.classList.toggle('ring-emerald-400', !!done[i]);
+        });
+    }
+    function _syncVerifyProgress(vs) {
+        if (!vs || !state.verifyStatus) return;
+        const total = vs.done.length;
+        const done = vs.done.filter(Boolean).length;
+        state.verifyStatus.classList.remove('hidden');
+        state.verifyStatus.textContent = vs.complete
+            ? '✓ In tune — tuning verified'
+            : (done + ' of ' + total + ' strings in tune');
+        _markVerifiedStrings(vs.done);
+        if (vs.complete && state.verifyBtn) state.verifyBtn.textContent = 'Verify tuning';
+    }
+    function _startVerify() {
+        if (!window._tunerAutoOpen || typeof window._tunerAutoOpen.verifyStart !== 'function') return;
+        const vs = window._tunerAutoOpen.verifyStart();
+        if (!vs) return;
+        if (state.verifyBtn) state.verifyBtn.textContent = 'Verifying — play each string…';
+        _syncVerifyProgress(vs);
+    }
+    function resetVerifyUI() {
+        if (window._tunerAutoOpen && typeof window._tunerAutoOpen.verifyCancel === 'function') {
+            window._tunerAutoOpen.verifyCancel();
+        }
+        if (state.verifyBtn) state.verifyBtn.textContent = 'Verify tuning';
+        if (state.verifyStatus) { state.verifyStatus.classList.add('hidden'); state.verifyStatus.textContent = ''; }
+        _markVerifiedStrings([]);
+    }
+
     function updateUI(result) {
         const { smoothedFreq, rms, hasSignal } = result;
         const vizMode = state.manualTargetFreq ? 'manual'
@@ -387,13 +428,20 @@ window._tunerUI = function(state, actions) {
         if (window.feedBack && window.feedBack.emit) {
             window.feedBack.emit('tuner:frame', { note, cents, freq: displayFreq, hasSignal: true });
         }
+        // Mic-verify: feed the matched string + cents to a running verify session
+        // and reflect per-string progress on the panel.
+        if (!isManual && !state.freeTune && window._tunerAutoOpen
+            && typeof window._tunerAutoOpen.verifyFeed === 'function') {
+            const vs = window._tunerAutoOpen.verifyFeed(targetFreq, Math.round(cents));
+            if (vs) _syncVerifyProgress(vs);
+        }
     }
 
     function updateFloatingButtonVisibility() {
         const btn = document.getElementById('tuner-toggle-btn');
         if (!btn) return;
         const isPlayer = document.querySelector('.screen.active')?.id === 'player';
-        if (!state.showFloatingButton || isPlayer || window.feedBack?.isPlaying) {
+        if (isPlayer || window.feedBack?.isPlaying) {
             btn.classList.add('hidden');
         } else {
             btn.classList.remove('hidden');
@@ -565,6 +613,17 @@ window._tunerUI = function(state, actions) {
         title.textContent = 'TUNER';
         header.appendChild(title);
 
+        // Explicit close (the panel had no in-box dismiss before; persist mode
+        // needs one). Mirrors the settings gear on the opposite side.
+        const closeBtn = document.createElement('button');
+        closeBtn.className = 'absolute left-0 text-fb-textDim hover:text-fb-text transition-colors text-lg leading-none';
+        closeBtn.setAttribute('aria-label', 'Close tuner');
+        closeBtn.title = 'Close';
+        closeBtn.textContent = '×';
+        closeBtn.onclick = () => actions.disable();
+        state.closeBtn = closeBtn;
+        header.appendChild(closeBtn);
+
         const settingsBtn = document.createElement('button');
         settingsBtn.className = 'absolute right-0 text-fb-textDim hover:text-fb-text transition-colors';
         settingsBtn.innerHTML = `<svg xmlns="http://www.w3.org/2000/svg" class="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M10.325 4.317c.426-1.756 2.924-1.756 3.35 0a1.724 1.724 0 002.573 1.066c1.543-.94 3.31.826 2.37 2.37a1.724 1.724 0 001.065 2.572c1.756.426 1.756 2.924 0 3.35a1.724 1.724 0 00-1.066 2.573c.94 1.543-.826 3.31-2.37 2.37a1.724 1.724 0 00-2.572 1.065c-.426 1.756-2.924 1.756-3.35 0a1.724 1.724 0 00-2.573-1.066c-1.543.94-3.31-.826-2.37-2.37a1.724 1.724 0 00-1.065-2.572c-1.756-.426-1.756-2.924 0-3.35a1.724 1.724 0 001.066-2.573c-.94-1.543.826-3.31 2.37-2.37.996.608 2.296.07 2.572-1.065z"/><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M15 12a3 3 0 11-6 0 3 3 0 016 0z"/></svg>`;
@@ -624,8 +683,77 @@ window._tunerUI = function(state, actions) {
         state.vizContainer.className = 'w-full';
         state.uiContainer.appendChild(state.vizContainer);
 
+        // Mic-verify control (working-tuning PR 9b): play each string in tune to
+        // confirm your tuning — promotes 'assumed' → 'verified'. Shown only for a
+        // selected (non-free) tuning; visibility managed in renderStringNotes().
+        state.verifyRow = document.createElement('div');
+        state.verifyRow.className = 'w-full mt-2 hidden';
+        state.verifyBtn = document.createElement('button');
+        state.verifyBtn.className = 'tuner-verify-btn w-full text-[11px] text-fb-textDim hover:text-fb-text border border-fb-border/40 hover:border-fb-border/70 rounded-lg py-1.5 transition-colors';
+        state.verifyBtn.textContent = 'Verify tuning';
+        state.verifyBtn.title = 'Play each string in tune to confirm — marks your tuning verified';
+        state.verifyBtn.onclick = () => _startVerify();
+        state.verifyRow.appendChild(state.verifyBtn);
+        state.verifyStatus = document.createElement('div');
+        state.verifyStatus.className = 'text-[10px] text-fb-textDim text-center mt-1 hidden';
+        state.verifyRow.appendChild(state.verifyStatus);
+        state.uiContainer.appendChild(state.verifyRow);
+
+        // Auto-open nudge's explicit dismiss (hidden unless auto-opened; enable()
+        // toggles it). Closes the same way as the × — disable().
+        const skipBtn = document.createElement('button');
+        skipBtn.className = 'tuner-skip-btn hidden w-full mt-3 text-[11px] text-fb-textDim hover:text-fb-text border border-fb-border/40 hover:border-fb-border/70 rounded-lg py-1.5 transition-colors';
+        skipBtn.textContent = 'Skip';
+        skipBtn.title = "I've tuned — play the song";
+        skipBtn.onclick = () => actions.disable();
+        state.skipBtn = skipBtn;
+        state.uiContainer.appendChild(skipBtn);
+
+        // Auto-open escape hatch: leave the song entirely instead of committing to
+        // the play-now choice — so a gated retune is never a one-way trap. Mirrors
+        // Escape (the player's "Back to library" shortcut) and, like Escape, does
+        // NOT record a tuning (you're leaving, not asserting you tuned).
+        const backBtn = document.createElement('button');
+        backBtn.className = 'tuner-back-btn hidden w-full mt-2 text-[11px] text-fb-textDim hover:text-fb-text border border-fb-border/40 hover:border-fb-border/70 rounded-lg py-1.5 transition-colors';
+        backBtn.textContent = 'Back to library';
+        backBtn.title = 'Leave the song (Esc)';
+        backBtn.onclick = () => {
+            const exit = window.feedBack && window.feedBack.requestExitSong;
+            if (typeof exit === 'function') exit();
+            else if (typeof window.requestExitSong === 'function') window.requestExitSong();
+        };
+        state.backBtn = backBtn;
+        state.uiContainer.appendChild(backBtn);
+
         document.body.appendChild(state.uiContainer);
         state.uiContainer.addEventListener('click', (e) => e.stopPropagation());
+
+        // Re-anchor while the panel is open: the popover it hugs is
+        // vertically centered, so its rect shifts with viewport height.
+        // initUI() runs once (guarded above), so this binds a single listener.
+        window.addEventListener('resize', () => {
+            if (state.uiContainer && !state.uiContainer.classList.contains('hidden')) positionPanel();
+        });
+    }
+
+    // Resolve the sidebar Plugins popover to anchor the panel beside it.
+    // Prefer the host's stable plugin-control slot API and derive its popover
+    // container; fall back to the known popover id only if that's unavailable.
+    // Returns a visible rect, or null (→ caller uses the fixed fallback slot).
+    function _pluginsPopoverRect() {
+        let pop = null;
+        try {
+            if (window.feedBack?.ui && typeof window.feedBack.ui.playerControlSlot === 'function') {
+                const slot = window.feedBack.ui.playerControlSlot();
+                if (slot instanceof Element) pop = slot.closest('.v3-rail-pop') || slot;
+            }
+        } catch (_e) { /* host slot API failure → fall back to id lookup */ }
+        if (!pop) pop = document.getElementById('v3-rail-pop-plugins');
+        // offsetParent === null covers display:none on the element or any
+        // ancestor (more robust than testing a specific `hidden` class).
+        if (!pop || pop.offsetParent === null) return null;
+        const rect = pop.getBoundingClientRect();
+        return (rect.width || rect.height) ? rect : null;
     }
 
     function positionPanel() {
@@ -645,7 +773,20 @@ window._tunerUI = function(state, actions) {
                 .replace('right-0', '')
                 .replace('top-full', '')
                 .trim();
-            state.uiContainer.style.cssText = 'top:5rem;right:11rem';
+            const anchor = _pluginsPopoverRect();
+            if (anchor) {
+                // Anchor to the right of the Plugins popover, clamped to the
+                // viewport so the panel never opens off-screen (right/bottom)
+                // on a narrow or short window.
+                const GAP = 8, MARGIN = 8;
+                const pw = state.uiContainer.offsetWidth || 288;   // w-72
+                const ph = state.uiContainer.offsetHeight || 0;
+                const left = Math.max(MARGIN, Math.min(anchor.right + GAP, window.innerWidth - pw - MARGIN));
+                const top = Math.max(MARGIN, Math.min(anchor.top, window.innerHeight - ph - MARGIN));
+                state.uiContainer.style.cssText = `top:${top}px;left:${left}px`;
+            } else {
+                state.uiContainer.style.cssText = 'top:5rem;right:11rem';
+            }
             return;
         }
 
@@ -683,7 +824,11 @@ window._tunerUI = function(state, actions) {
 
         const handlePlay = () => {
             updateFloatingButtonVisibility();
-            if (state.enabled) actions.disable();
+            // A manually-opened tuner closes when playback starts (you don't tune
+            // while playing). An AUTO-opened tuner PERSISTS through the autoplay
+            // song:play that immediately follows song entry — that auto-close was
+            // the "opens then vanishes ~1s later" flash. It closes via Skip/×/leave.
+            if (state.enabled && !state.autoOpened) actions.disable();
         };
         const handleStop = () => updateFloatingButtonVisibility();
 
@@ -724,8 +869,15 @@ window._tunerUI = function(state, actions) {
         btn.textContent = 'Tuner';
         btn.title = 'Open Tuner';
         btn.onclick = window.tuner.toggle;
-        const closeBtn = isV3 ? null : controls.querySelector('button:last-child');
-        if (closeBtn) controls.insertBefore(btn, closeBtn);
+        // Anchor to the last DIRECT-child button of `controls` (the classic
+        // transport's close/exit button). A bare `button:last-child` can match
+        // a NESTED button that is not a direct child of `controls`, and
+        // `insertBefore()` then throws NotFoundError — which propagated out of
+        // the player-screen transition and aborted its render (feedBack#800).
+        // `:scope > button:last-of-type` restricts the anchor to a direct child;
+        // the parentNode check is a belt-and-suspenders guard before insertBefore.
+        const closeBtn = isV3 ? null : controls.querySelector(':scope > button:last-of-type');
+        if (closeBtn && closeBtn.parentNode === controls) controls.insertBefore(btn, closeBtn);
         else controls.appendChild(btn);
         updatePlayerButton();
     }
@@ -737,6 +889,7 @@ window._tunerUI = function(state, actions) {
         renderTuningOptions,
         renderStringNotes,
         updateUI,
+        resetVerify: resetVerifyUI,
         updateInstrumentDisplay: _updateInstrumentDisplay,
         updateSaveAsCustomVisibility: _updateSaveAsCustomVisibility,
         updateFreeTuneUI,

plugins/tuner/visualization/analogue-gauge.js

@@ -18,6 +18,8 @@
     // ── Constants ─────────────────────────────────────────────────────
     var _TUNER_LABEL_H = 12;           // px height of each drum label
     var _TUNER_NEEDLE_HALF_SWEEP = 90; // degrees — ±50 cents = horizontal (180° apart)
+    var _SETTLE_A = 0.05;              // deg — needle "settled" threshold (sub-visible)
+    var _SETTLE_Y = 0.1;               // px — drum-strip "settled" threshold
     var _TUNER_IN_TUNE_THRESHOLD = 2;
     var _TUNER_STRIP_START_MIDI = 14;  // ~18 Hz — covers 20 Hz minimum
     var _TUNER_STRIP_END_MIDI = 84;    // ~1047 Hz C6
@@ -321,9 +323,34 @@
             currentAngle += (targetAngle - currentAngle) * lf;
             _setNeedle(currentAngle);
 
+            // Stop once the needle has settled on its target — a static needle
+            // needs no repaint. update() re-kicks the loop when a new reading
+            // moves the target, so this idles the always-on tuner (no signal /
+            // steady pitch) instead of pinning a core at 60 fps forever.
+            if (Math.abs(targetDrumY - currentDrumY) <= _SETTLE_Y
+                    && Math.abs(targetAngle - currentAngle) <= _SETTLE_A) {
+                currentDrumY = targetDrumY; currentAngle = targetAngle;
+                freqStrip.style.transform = 'translateY(' + currentDrumY + 'px)';
+                noteStrip.style.transform = 'translateY(' + currentDrumY + 'px)';
+                _setNeedle(currentAngle);
+                rafId = null;
+                return;
+            }
             rafId = requestAnimationFrame(_animate);
         }
 
+        // Restart the loop only when there's actually something to animate toward
+        // (a new target). Reset lastTime so the first frame after an idle gap
+        // doesn't take one big easing step.
+        function _kick() {
+            if (rafId === null
+                    && (Math.abs(targetDrumY - currentDrumY) > _SETTLE_Y
+                        || Math.abs(targetAngle - currentAngle) > _SETTLE_A)) {
+                lastTime = performance.now();
+                rafId = requestAnimationFrame(_animate);
+            }
+        }
+
         rafId = requestAnimationFrame(_animate);
 
         // ── Public API ────────────────────────────────────────────────
@@ -360,6 +387,7 @@
                 bulbEl.style.backgroundColor = '#2a1010';
                 bulbEl.style.border = '2px solid #4a2020';
                 bulbEl.style.boxShadow = 'none';
+                _kick();   // animate back to rest, then the loop self-stops
                 return;
             }
 
@@ -376,6 +404,7 @@
                 bulbEl.style.border = '2px solid #4a2020';
                 bulbEl.style.boxShadow = 'none';
             }
+            _kick();   // a new reading moved the target → run until it settles
         }
 
         function destroy() {

plugins/tuner/visualization/chef-mt3.js

@@ -620,8 +620,20 @@
             if (_mt3Mode === 'strobe') { _computeStrobeStates(); }
 
             _applyTickStates();
+
+            // No signal and both the glow and strobe drift have fully settled →
+            // idle the loop. update() re-kicks it on the next note.
+            if (!_mt3HasSignal && _mt3GlowOpacity < 0.004
+                    && Math.abs(_mt3SmoothedCents) <= 0.1) {
+                _mt3RafId = null;
+                _mt3LastTime = null;
+                return;
+            }
             _mt3RafId = requestAnimationFrame(_animateStrobe);
         }
+        function _kick() {
+            if (_mt3RafId === null) { _mt3LastTime = null; _mt3RafId = requestAnimationFrame(_animateStrobe); }
+        }
         _mt3RafId = requestAnimationFrame(_animateStrobe);
 
         // ── MODE button ───────────────────────────────────────────────
@@ -677,6 +689,7 @@
                 _renderNote(' ');
                 _applyAccidental();
             }
+            if (hasNote) { _kick(); }   // new signal → restart the strobe loop if idled
         }
 
         // ── Public: destroy ───────────────────────────────────────────

plugins/tuner/visualization/mace-fx-iii.js

@@ -354,10 +354,19 @@
                 if (_smoothedCents > 0) { speed = -speed; }
                 _strobeOffset = ((_strobeOffset + speed * dt) % _totalDash + _totalDash) % _totalDash;
                 arcPath.setAttribute('stroke-dashoffset', String(_strobeOffset));
+            } else if (_currentCents === 0) {
+                // Fully decelerated and no live signal → idle the loop instead of
+                // rescheduling forever. update() re-kicks it on the next note.
+                _rafId = null;
+                _lastTime = null;
+                return;
             }
 
             _rafId = requestAnimationFrame(_animateStrobe);
         }
+        function _kick() {
+            if (_rafId === null) { _lastTime = null; _rafId = requestAnimationFrame(_animateStrobe); }
+        }
         _rafId = requestAnimationFrame(_animateStrobe);
 
         // ── Helper: derive octave number from frequency ───────────────
@@ -439,6 +448,7 @@
 
             // Strobe state — smoothed animation decelerates naturally when _currentCents → 0
             _currentCents = hasNote ? cents : 0;
+            if (hasNote) { _kick(); }   // new signal → restart the decel loop if idled
         }
 
         // ── Public: destroy ───────────────────────────────────────────

plugins/tuner/visualization/strobe.js

@@ -142,9 +142,20 @@ window._tunerViz_strobe = function (container) {
             strobeEl.style.opacity = '0';
         }
 
+        // Idle the loop when there's no live signal — the strobe only needs to
+        // paint while a note is sounding. update() re-kicks it on the next note,
+        // so a silent tuner stops repainting instead of spinning at 60 fps.
+        if (!strobeActive) { rafId = null; return; }
         rafId = requestAnimationFrame(_animate);
     }
 
+    function _kick() {
+        if (rafId === null) {
+            lastAnimateTime = performance.now();
+            rafId = requestAnimationFrame(_animate);
+        }
+    }
+
     rafId = requestAnimationFrame(_animate);
 
     // ── Public API ────────────────────────────────────────────────────
@@ -188,6 +199,7 @@ window._tunerViz_strobe = function (container) {
         const inTune = Math.abs(cents) < 5;
         strobeEl.style.opacity = inTune ? '1' : '0.6';
         strobeEl.style.filter = inTune ? _STROBE_GLOW_IN_TUNE : _STROBE_GLOW_OUT;
+        _kick();
     }
 
     function destroy() {

plugins/tuner/visualization/toilet-tuner.js

@@ -122,6 +122,26 @@
             plungerEl.style.left = _leftPct.toFixed(2) + '%';
             plungerEl.style.top  = _topPct.toFixed(2)  + '%';
 
+            // No live signal and the plunger has eased back to its resting centre
+            // → idle the loop. update() re-kicks it on the next note.
+            if (_currentNote === null && !_plungerDipped
+                    && Math.abs(targetLeft - _leftPct) < 0.05) {
+                _leftPct = targetLeft;
+                plungerEl.style.left = _leftPct.toFixed(2) + '%';
+                _rafId = null;
+                _lastTime = null;
+                return;
+            }
+
+            _rafId = requestAnimationFrame(_animate);
+        }
+
+        function _kick() {
+            if (_rafId !== null) return;
+            // Already parked at rest with no signal → nothing to animate, stay idle.
+            if (_currentNote === null && !_plungerDipped
+                    && Math.abs(_TUNER_TT_CENTRE_PCT - _leftPct) < 0.05) return;
+            _lastTime = null;
             _rafId = requestAnimationFrame(_animate);
         }
 
@@ -130,6 +150,7 @@
             _currentNote  = note;
             _currentCents = note === null ? 0 : cents;
             if (!_plungerDipped) { noteEl.textContent = note || '–'; }
+            _kick();   // a new reading may move the plunger → ensure the loop runs
         }
 
         function destroy() {

scripts/lift_keys_notation.py

@@ -60,6 +60,8 @@ import yaml  # noqa: E402
 
 import notation as notation_mod  # noqa: E402, F401  (re-exported for tests)
 
+from jsonc import load_json  # noqa: E402
+
 # The wire→notation heuristic core lives in ``lib/notation_lift.py`` so it can
 # be reused in-process (e.g. by the Arrangement Editor's notation save path)
 # rather than being copy-pasted out of this one-time CLI. Re-exported here so
@@ -106,15 +108,16 @@ def _parse_time_signature(raw: object) -> tuple[int, int]:
 
 
 def _load_song_beats(pak: Path, manifest: dict) -> list[dict]:
-    """Song-level beats: ``song_timeline.json`` when present, else the first
+    """Song-level beats: the ``song_timeline`` file when present, else the first
     arrangement JSON that carries a non-empty ``beats`` array (the loader's
-    legacy convention)."""
+    legacy convention). Both the timeline and arrangement files are read via
+    ``load_json``, so either may be ``.json`` or ``.jsonc``."""
     st_rel = manifest.get("song_timeline")
     if isinstance(st_rel, str) and st_rel:
         st_path = _safe_child(pak, st_rel)
         if st_path is not None and st_path.is_file():
             try:
-                data = json.loads(st_path.read_text(encoding="utf-8"))
+                data = load_json(st_path)
                 # An empty beats list is not an authoritative timeline — fall
                 # through to the arrangement JSONs rather than ending up with
                 # zero downbeats and skipping the whole sloppak.
@@ -134,7 +137,7 @@ def _load_song_beats(pak: Path, manifest: dict) -> list[dict]:
         if arr_path is None or not arr_path.is_file():
             continue
         try:
-            data = json.loads(arr_path.read_text(encoding="utf-8"))
+            data = load_json(arr_path)
         except (OSError, ValueError):
             continue
         if isinstance(data, dict):
@@ -219,7 +222,7 @@ def lift_sloppak(pak: Path, *, dry_run: bool = False) -> list[str]:
             continue
 
         try:
-            arr_data = json.loads(arr_path.read_text(encoding="utf-8"))
+            arr_data = load_json(arr_path)
         except (OSError, ValueError) as e:
             log.warning("%s/%s: unreadable arrangement JSON (%s) — skipped",
                         pak.name, arr_id, e)

scripts/perf-baseline.mjs

@@ -0,0 +1,177 @@
+// Perf-baseline harness for the module-migration refactor (R0).
+//
+// Rerun this after every phase (R0 → R3c) to prove the split does not regress
+// screen-entry, frame-time, memory, or server latency. It writes a markdown
+// results block to stdout; paste it into docs/perf-baseline.md (or redirect).
+//
+// Usage:
+//   node scripts/perf-baseline.mjs --base http://127.0.0.1:8000 [--n 60] [--soak 30]
+//   node scripts/perf-baseline.mjs --base http://127.0.0.1:8300 --song "Arcturus ….feedpak"
+//
+// With --song, it additionally measures the 2D highway's PER-FRAME DRAW cost:
+// it wraps requestAnimationFrame before any page script runs, tags the frames
+// in which the highway actually painted (via highway.addDrawHook), starts
+// playback, and reports draw-frame p50/p95/p99 over --frames seconds. Tagging
+// matters — roughly half the rAF callbacks belong to other cheap loops, and
+// averaging them in hides a renderer regression behind ~0.1 ms no-op frames.
+// This is the metric that gates the highway.js split (R3c); run it before AND
+// after each highway change on the same machine.
+//
+// Maintainer/CI-only dev tooling (uses the committed @playwright/test browser);
+// never part of the serve or Docker path. Metrics that need a seeded library
+// with charts (playback frame-time, screen-entry into a live highway) are
+// clearly labelled — run those against an environment with real songs.
+
+import { createRequire } from 'module';
+const require = createRequire(import.meta.url);
+const { chromium } = require('@playwright/test');
+
+const args = new Map();
+for (let i = 2; i < process.argv.length; i += 2) args.set(process.argv[i].replace(/^--/, ''), process.argv[i + 1]);
+const BASE = args.get('base') || 'http://127.0.0.1:8000';
+const N = parseInt(args.get('n') || '60', 10);
+const SOAK_S = parseInt(args.get('soak') || '30', 10);
+const SONG = args.get('song') || null;
+const FRAME_S = parseInt(args.get('frames') || '10', 10);
+const RUNS = parseInt(args.get('runs') || '3', 10);   // repeat frame sampling to show spread
+
+const pct = (xs, p) => {
+    if (!xs.length) return null;
+    const s = [...xs].sort((a, b) => a - b);
+    return s[Math.min(s.length - 1, Math.floor((p / 100) * s.length))];
+};
+const ms = (x) => (x == null ? '—' : `${x.toFixed(1)}`);
+
+// ── Server latency: p50/p95/p99 over N requests per endpoint ──────────────────
+async function serverLatency(paths) {
+    const rows = [];
+    for (const path of paths) {
+        const t = [];
+        let status = 0;
+        for (let i = 0; i < N; i++) {
+            const t0 = performance.now();
+            try {
+                const r = await fetch(BASE + path);
+                status = r.status;
+                await r.arrayBuffer();
+            } catch { status = -1; }
+            t.push(performance.now() - t0);
+        }
+        rows.push({ path, status, p50: pct(t, 50), p95: pct(t, 95), p99: pct(t, 99) });
+    }
+    return rows;
+}
+
+// ── Client: cold boot-to-interactive + idle memory after a soak ───────────────
+async function clientMetrics() {
+    const browser = await chromium.launch();
+    const page = await browser.newPage();
+    const t0 = Date.now();
+    await page.goto(BASE, { waitUntil: 'networkidle', timeout: 60000 });
+    const bootMs = Date.now() - t0;
+
+    // performance.memory is Chromium-only; JS heap after settle.
+    const mem0 = await page.evaluate(() => (performance.memory ? performance.memory.usedJSHeapSize : null));
+    await page.waitForTimeout(SOAK_S * 1000);
+    const mem1 = await page.evaluate(() => (performance.memory ? performance.memory.usedJSHeapSize : null));
+
+    const scripts = await page.evaluate(() =>
+        document.querySelectorAll('script[data-plugin-id]').length);
+
+    await browser.close();
+    return { bootMs, memStartMB: mem0 && mem0 / 1048576, memSoakMB: mem1 && mem1 / 1048576, scripts };
+}
+
+// ── 2D highway per-frame draw cost (needs --song + a seeded library) ──────────
+async function frameTimeOnce(browser) {
+    const page = await browser.newPage();
+    let f, t2, notes;
+    try {
+        // Wrap rAF before any page script; mark frames the highway actually drew.
+        await page.addInitScript(() => {
+            window.__f = [];
+            window.__drew = false;
+            const raf = window.requestAnimationFrame.bind(window);
+            window.requestAnimationFrame = (cb) => raf((t) => {
+                window.__drew = false;
+                const t0 = performance.now();
+                try { cb(t); } finally { window.__f.push({ ms: performance.now() - t0, drew: window.__drew }); }
+            });
+        });
+        await page.goto(BASE, { waitUntil: 'networkidle', timeout: 60000 });
+        await page.evaluate(() => document.getElementById('v3-onboarding')?.remove());
+        await page.evaluate((s) => window.playSong(s), SONG);
+        await page.waitForFunction(() => (window.highway?.getNotes?.() || []).length >= 0 && window.highway?.getSongInfo?.(),
+            null, { timeout: 45000 }).catch(() => {});
+        await page.waitForFunction(() => (window.highway?.getNotes?.() || []).length > 0, null, { timeout: 45000 });
+        await page.evaluate(() => window.highway.addDrawHook(() => { window.__drew = true; }));
+        // Start playback so draw() leaves its paused-throttle path; confirm the clock advances.
+        await page.evaluate(async () => { const a = window.highway.getAudioElement?.(); if (a) a.muted = true; await a?.play?.(); });
+        await page.waitForTimeout(1500);
+        const t1 = await page.evaluate(() => window.highway.getTime());
+        await page.evaluate(() => { window.__f.length = 0; });
+        await page.waitForTimeout(FRAME_S * 1000);
+        ({ f, t2, notes } = await page.evaluate(() => ({
+            f: window.__f.slice(), t2: window.highway.getTime(), notes: window.highway.getNotes().length,
+        })));
+        if (!(t2 > t1 + 1)) throw new Error(`clock did not advance (${t1}→${t2}) — measured the paused path`);
+    } finally {
+        // Always close, even when an await above throws — otherwise a failing
+        // run leaks its page until the final browser.close().
+        await page.close();
+    }
+    const drew = f.filter((x) => x.drew).map((x) => x.ms);
+    return { drew, total: f.length, notes };
+}
+
+async function frameTime() {
+    const browser = await chromium.launch({ args: ['--autoplay-policy=no-user-gesture-required'] });
+    const rows = [];
+    for (let i = 0; i < RUNS; i++) {
+        try {
+            const r = await frameTimeOnce(browser);
+            rows.push({
+                p50: pct(r.drew, 50), p95: pct(r.drew, 95), p99: pct(r.drew, 99),
+                max: Math.max(...r.drew), n: r.drew.length, total: r.total, notes: r.notes,
+            });
+        } catch (e) { rows.push({ error: String(e.message || e) }); }
+    }
+    await browser.close();
+    return rows;
+}
+
+const server = await serverLatency([
+    '/api/version',
+    '/api/plugins',
+    '/api/library?limit=60',
+    '/api/library/artists',
+]);
+const client = await clientMetrics();
+
+const now = new Date().toISOString();
+let out = `\n<!-- generated by scripts/perf-baseline.mjs @ ${now} against ${BASE} (n=${N}, soak=${SOAK_S}s) -->\n\n`;
+out += `### Server latency (ms)\n\n| Endpoint | status | p50 | p95 | p99 |\n|---|---|---|---|---|\n`;
+for (const r of server) out += `| \`${r.path}\` | ${r.status} | ${ms(r.p50)} | ${ms(r.p95)} | ${ms(r.p99)} |\n`;
+out += `\n### Client\n\n| Metric | Value |\n|---|---|\n`;
+out += `| Cold boot → networkidle | ${client.bootMs} ms |\n`;
+out += `| JS heap after load | ${client.memStartMB ? client.memStartMB.toFixed(1) + ' MB' : '—'} |\n`;
+out += `| JS heap after ${SOAK_S}s idle soak | ${client.memSoakMB ? client.memSoakMB.toFixed(1) + ' MB' : '—'} |\n`;
+out += `| Plugin scripts injected | ${client.scripts} |\n`;
+if (SONG) {
+    const frames = await frameTime();
+    out += `\n### 2D highway per-frame draw cost — \`${SONG}\` (${RUNS} runs × ${FRAME_S}s)\n\n`;
+    out += `| run | draw frames | p50 | p95 | p99 | max |\n|---|---|---|---|---|---|\n`;
+    for (let i = 0; i < frames.length; i++) {
+        const r = frames[i];
+        if (r.error) { out += `| ${i + 1} | — | \`${r.error}\` | | | |\n`; continue; }
+        out += `| ${i + 1} | ${r.n}/${r.total} | ${ms(r.p50)} | ${ms(r.p95)} | ${ms(r.p99)} | ${ms(r.max)} |\n`;
+    }
+    const p95s = frames.filter((r) => !r.error).map((r) => r.p95);
+    if (p95s.length) out += `\n**p95 spread across runs: ${ms(Math.min(...p95s))}–${ms(Math.max(...p95s))} ms**\n`;
+} else {
+    out += `\n> **Requires a seeded library** (not captured by this run): playback frame-time p95\n`;
+    out += `> on the 2D highway — pass \`--song "<filename in DLC_DIR>"\` to capture it.\n`;
+    out += `> (3D highway_3d + screen-entry timings are a separate R4 concern.)\n`;
+}
+
+console.log(out);