# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [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). 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**.
- **`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).
- **Optional "Ask before leaving a song" confirm (Gameplay tab, default OFF).** A new client-only toggle (`confirmExitSong` in `localStorage`, in the v3 Gameplay settings + the Gameplay "Reset" set) for players who want a guard against an accidental exit. **Off by default — Escape leaves instantly, zero change for everyone else.** When on, a *user-initiated* exit (the player-scope Escape shortcut, or the player's ✕) opens a small true-modal confirm instead of leaving; auto-exit on song-end and a results screen's own Close are unaffected (they call `closeCurrentSong()` directly, which stays the unguarded actual-exit). The confirm honors the team's refined asks: **opening it pauses the song** (so it isn't running or being scored behind the prompt) and **Stay resumes exactly what was paused**; **Escape = Stay** — the dialog's capture-phase handler *dismisses* it (now consistent with every other modal and the generic `_confirmDialog`'s Esc=cancel), so a second Escape returns you to the (resumed) song rather than leaving; **Space/Enter (or click) Leave** by natively activating the default-focused "Leave" button ("just get me out"). Pause/resume run through the canonical `togglePlay()` path (HTML5 + `_juceMode`), guarded so a count-in, an already-paused song, or a teardown/seek/end behind the modal can't mis-resume. It's a real modal (`role="dialog" aria-modal="true"` / `.feedBack-modal`) with **Tab trapped inside it** and a **backdrop click that also Stays**, so the Escape/Space focus carve-outs treat it as a trap and don't fire player-back / play-pause behind it. The player Escape shortcut and the v3 ✕ route through a shared `window.requestExitSong()` gate (the ✕ also becomes origin-aware, matching Escape). Tests: `tests/browser/exit-confirm.spec.ts` (default-off instant exit, confirm-on opens + stays, second-Escape stays, backdrop stays, Stay/Leave, Enter-leaves); the audio pause/resume is verified manually on web + desktop (the mock song has no backing track).
- **Folder Library — a bundled core plugin (`plugins/folder_library/`) that browses the DLC library by its on-disk folder tree.** Surfaces top-level folders → subfolders → songs (root-level songs land in `(Unsorted)`), with in-app folder management (create / rename / delete nested folders), song moves via dialog or drag-and-drop, and sort/filter that mirrors the host library's filter state. Wired into both the classic (v2) library toolbar and the v3 Songs page as a third **Folders** view alongside grid/tree; the plugin's `screen.js` is loaded once by the host and reused (idempotent IIFEs). Supersedes the former standalone "Folder Organizer" community plugin (removed from the README list). Backend (`routes.py`) registers `/api/plugins/folder_library/{tree,folder/create,folder/rename,folder/delete,song/move}`; **all filesystem mutations are confined to `DLC_DIR` and validated against path traversal** (per-segment name validation plus a resolved-containment check on `song/move`), and folder deletion relocates every song — de-duplicating colliding names — so a name clash never destroys a song. A two-level cache keeps re-opening folders fast. Tests: `tests/plugins/folder_library/test_routes.py` (path-safety helpers + move-traversal and delete-no-data-loss end-to-end).
- **Full-screen (immersive) plugin screens — opt-in via `"fullscreen": true` in `plugin.json`.** DAW-style plugin UIs (e.g. a practice studio) need the whole viewport, not a scrolling content page below the topbar — embedded in the v3 shell they get cut off at the bottom with dead space up top. A plugin can now declare a top-level `"fullscreen": true`; `plugins/__init__.py` surfaces it as the `fullscreen` boolean on `/api/plugins` (mirroring the `settings_category` plumbing). When such a plugin's screen is active, `static/v3/shell.js` toggles `html.fb-immersive` from `syncActive()` (so it tracks every navigation incl. deep-link), and `static/v3/v3.css` hides the topbar, collapses the sidebar to a functional **icon rail** (kept reachable — Escape is bound only on player/settings scopes, so a fully-hidden sidebar would trap the user), and lets the active plugin screen fill `#v3-main`. Mirrors the existing `ss-follower-pre` chrome-hide pattern. Additive + opt-in: plugins without the flag are unaffected. Tests: `tests/test_plugins.py::test_fullscreen_flag_parsed_from_manifest`.
- **Achievements wall sync — background drain worker (epic PR3, client side).** The bundled `achievements` plugin gains a dead-letter sync worker that POSTs queued Feat unlocks (and removals) to the hosted **feedback-achievements** wall service (separate repo). Idle unless a wall URL is configured (`FEEDBACK_ACHIEVEMENTS_WALL_URL`); uses `requests` with the baked-in client-token header, mirroring `lib/lyrics_transcribe`'s outbound pattern (explicit timeout, no raise on non-2xx). **Dead-letter, never drop** (pure `engine.drain_decision`): network error / `429` / `5xx` → keep `pending` (retry); other `4xx` → `dead_letter` (diagnosable, replayable); `2xx` → delete on server ack. A row leaves the queue only on ack or a user opt-out. `remove-me` now enqueues a wall removal keyed by the reused `player_hash`. Verified by an end-to-end staging round-trip (earn a Feat → drains onto the wall with name + short hash → `remove-me` → wall empties) with **no IP** in tables or access logs. Tests: `tests/plugins/achievements/test_sync.py` (decision table + ack/retry/dead-letter retention + four-field payload on the wire). The hosted service itself (FastAPI + SQLite-on-disk, Feats-only, hidden-until-first-global-unlock, profanity filter, in-memory rate limit, Render blueprint, migration tool) lives in the new `feedback-achievements` repo.
- **Achievements wall — opt-in, privacy controls & data-minimization gate (epic PR2).** Sharing earned **Feats** on the (forthcoming) public wall is strictly opt-in. A new **onboarding step** (`static/v3/profile.js`, inserted after song-directory / before instrument paths — the wizard is now five steps) presents a plain-language card: it publishes only your display name and the Feats you earn, never songs/skills/scores, and is **off by default**. The bundled plugin's Settings panel (`plugins/achievements/settings.html`, mounted under the **System** tab via `settings.category`) carries the same toggle plus a **"Remove me from the wall"** button (`POST /api/plugins/achievements/remove-me` — wipes local synced state offline + enqueues a wall removal). Core adds `achievements_enabled` (bool, default `false`) to `_default_settings()` + the `/api/settings` validation block + `_RESETTABLE_SETTINGS_KEYS` in `server.py`, mirrored to `localStorage` in `app.js loadSettings()`. **Data-minimization contract (binding, code-enforced):** every outbound payload is built by a single explicit-dict serializer (`engine.build_wall_payload`, never `dict(row)`/`**model`) whose key-set is **exactly** `{display_name, player_hash, achievement_id, unlocked_at}` with `achievement_id` always a **Feat** id — a unit test asserts the four-field set and goes red on a fifth. Enqueue is doubly gated: it happens only when opted-in **and** a profile identity (name + the reused `player_hash`) exists; **competency unlocks never enqueue** (integration law). Tests: `tests/plugins/achievements/test_datamin.py` (key-set, opt-out/identity/competency gating) + `tests/test_settings_api.py` (flag persists/validates/resettable).
- **Achievements & Feats of Power — local engine + tabbed Profile (epic PR1).** The Profile screen (`static/v3/profile.js`) becomes **tabbed** exactly like the v3 Settings page (`.fb-tabbar` / `.fb-tab[data-tab]` / `.fb-tabpanel[data-tab]`, active-tab persisted in `localStorage 'v3-profile-tab'`): a **Profile** (main) tab carrying the existing header + best-scores cards plus a new **Feats of Power** trophy shelf mount (`#v3-profile-feats-slot`, earned-only / hidden-until-earned), and an **Achievements** tab with a plugin mount (`#v3-profile-achievements-mount`) + `[data-empty-for]` empty note. Core dispatches a new **`v3:profile-rendered`** event after every render (mirrors `v3:settings-rendered`) so the plugin re-injects on each profile entry. A new bundled **`plugins/achievements/`** plugin owns the engine: SQLite under `<config_dir>/achievements/achievements.db` (`unlocks` / `counters` / `comp_ledger` / `sync_queue`), pure threshold/criterion math in the testable sibling `engine.py` (P-V), and routes under `/api/plugins/achievements/` (`activity`, `report-unlock`, `report-criterion`, `catalog`, `earned`, `feats`, `remove-me`). **Two surfaces, one engine, structurally separated (integration law):** **Feats** (activity/volume — Note Hunter, Marathon, Untouchable, Road Warrior, Time Served, Encore, two 🥚 secrets) read activity counters only, evaluated from a batched `song:ended` activity POST (notes only when **notedetect** is present — graceful degradation, no fake progress); **competency Achievements** (baseline: First Steps / Ascendant / Steady Hands / Renaissance + per-instrument Apprentice·Journeyman·Master / Personal Best / Challenger) are evaluated from **progression events only** and never re-derived from activity. The Achievements catalogue is always shown (locked = greyed), grouped by a secondary pill row over the **real progression paths** (Global / Guitar / Bass / Drums / Keys — auto-extends to new paths) with a per-category "X / Y earned" badge, defaulting to the player's primary path. Source plugins contribute their own competency defs and report unlocks through a versioned **`window.feedBack.achievements`** API (`register`/`registerAll`/`unlock`/`progress`), load-order-safe via the `window.__feedBackAchievementsPending` queue + an `achievements:ready` event (minigames pending-queue pattern); an absent source contributes nothing (no dead greyed rows). Opt-in publishing to a hosted Feats wall, the Settings privacy toggle, and the data-minimization gate land in epic PR2/PR3. Tests: `tests/plugins/achievements/test_engine.py` + `test_routes.py` (incl. the integration-law assertion that a competency unlock never reaches the Feats shelf).
- **v3 settings page redesigned as a tabbed, card-row layout.** The single long scrolling settings screen becomes a horizontal tab bar (Gameplay / Audio / Graphics / Keybinds / Progression / Mic / Plugins / System) over card rows — each a leading icon + title + description with the control (toggle/dropdown/slider) on the right, plus a per-category "Reset" action. The markup lives in `static/v3/index.html` (so existing element ids keep hydrating through the unchanged `app.js` `loadSettings()`/`persistSetting()` path); a new `static/v3/settings.js` owns tab switching + active-tab persistence (`localStorage 'v3-settings-tab'`), the per-category reset, and a read-only **Keybinds** reference built from the live shortcut registry (`window.getAllShortcuts()`); styling is plain CSS in `static/v3/v3.css` (no Tailwind rebuild). **Plugins choose their settings tab** via a new optional `settings.category` field in `plugin.json` (`plugins/__init__.py` surfaces it as `settings_category`; `app.js` mounts each plugin's `<details>` panel into `#plugin-settings-<category>`, falling back to the generic Plugins tab) — `highway_3d` ships `category: "graphics"`; the out-of-repo notedetect/progression plugins should declare `"mic"` / `"progression"`. **New gameplay settings:** **Countdown before song** (a four-beat count-in before playback, wired end-to-end via the existing count-in engine + the song-start autostart path; key `countdown_before_song`, default off); **Miss penalty** (`miss_penalty`) and **Fail behavior** (`fail_behavior`) are persisted now but not yet consumed by scoring (shown with a "Not yet active" badge). "Note highway speed" surfaces the existing `master_difficulty` and stays in sync with the player-popover difficulty slider. New `POST /api/settings/reset` clears chosen keys back to defaults. Tests: `tests/test_settings_api.py` (new keys + reset), `tests/test_plugins.py::test_settings_category_parsed_from_manifest`, `tests/browser/settings-tabbed.spec.ts`.
- **Full-mix audio exposed alongside stems for the stem mixer's auto-switch.** `lib/sloppak.py::load_song` now parses the optional manifest `original_audio:` key (the single pre-separation mixdown, e.g. `original/full.ogg`) into a new `LoadedSloppak.original_audio` field, with the same path-traversal guard and permissive "missing → disabled" posture as the `drum_tab` loader. The highway WS `song_info` frame additively carries three new fields next to `stems`: `original_audio_url` (served by the existing `/api/sloppak/{filename}/file/{rel_path}` endpoint, `None` when the pack ships stems only), `has_original_audio`, and `has_stems` (mirroring the `has_drum_tab`/`has_keys` flag convention). The stems plugin consumes `original_audio_url` to play the untouched single file while every stem slider is at unity and switch to the separate stems the moment one drops below 100%. **Migration notes:** the `song_info` message shape is a stable contract — these are purely additive; all existing fields are unchanged. `audio_url` still points at stem[0] when stems exist (it is only the degraded native fallback); the one behavioural change is that a stem-less, full-mix-only sloppak now sets `audio_url` to the full mix instead of emitting `audio_error`, so it plays natively.
- **Autoplay & auto-exit — a global "click it, it plays; finish, you're back at the menu" option (default ON).** New single Settings toggle (`autoplayExit` in `localStorage`, surfaced in both the v3 and classic settings screens; absence of the key = enabled) that closes the friction at both ends of the play loop. **Autoplay:** `playSong()` previously loaded a chart paused, requiring a Play press; a one-shot flag armed per fresh load is now consumed by the next `song:ready` (highway.js) to auto-start via the existing `togglePlay()` path (HTML5 + `_juceMode` + count-in). Arrangement switches / seeks reuse the same `song:ready` event but never arm the flag, so they don't auto-restart. **Auto-exit:** on `song:ended`, core returns to the launching menu after a short grace delay — unless a visible full-screen results/dialog overlay is on top (detected via `[role=dialog][aria-modal]` / `.fixed.inset-0` with a `getClientRects()` visibility test that works for `position:fixed`), in which case the return is deferred so that score screen's own Close button (calling `window.closeCurrentSong()`) drives the exit. A plugin can also defer explicitly via the new `window.feedBack.holdAutoExit()` (called synchronously from its own `song:ended` handler — core's listener runs first). Both paths mean **no external plugin PR is required** for a results screen to be respected. **Context-aware destination:** the player's remembered origin (`_playerOriginScreen`) now honours any real launch screen instead of clamping to library/home/favorites, and a one-shot `window.feedBack.setReturnScreen(id)` override lets the lessons catalog (`static/v3/lessons.js`) send a finished lesson back to the lessons screen — not the song library — even though the external tutorials plugin owns the `playSong` call. Also exposes a read-only `window.feedBack.autoplayExit` getter for plugins. Songs and lessons share the same `playSong` → highway path, so both inherit the behaviour. Core-only (`static/app.js`, `static/v3/lessons.js`, both `index.html`s); the end-of-song score screen itself remains a plugin. Optional polish (not required — the overlay heuristic already covers it): external scoring/note-detection plugins (e.g. SlopScale) may call `holdAutoExit()` + `closeCurrentSong()` for an exact, heuristic-free handoff.
- **"Song Editor" promoted to a first-class v3 sidebar item.** The editor
  plugin (`id: editor`) now gets its own dedicated sidebar entry — under the
  Library group, just below Songs — via the existing `PROMOTED_PLUGINS`
  mechanism in `static/v3/shell.js`, instead of being reachable only through
  the generic Plugins gallery. Gated on the plugin actually being installed
  (`renderPromotedNav` checks `/api/plugins`), so it appears only when the
  editor is loaded. The displayed label comes from the plugin's manifest
  `nav.label`.
- **Guitar Pro → notation importer (`lib/gp2notation.py`)** (feedBack#825 WS4b, epic #828). Piano/keys tracks imported from Guitar Pro (GPIF: `.gpx` GP6 / `.gp` GP7-8) now produce real Sloppak Notation Format data (sloppak-spec §5.3) alongside the `midi = string*24 + fret` guitar wire encoding. `gp2rs_gpx.convert_file` writes a `<stem>.notation.json` sidecar next to each keys arrangement XML (best-effort — a notation bug never breaks the RS-XML conversion), and `gp2notation.attach_notation_to_sloppak()` is the assembly-side helper that renames it into `notation_<id>.json` + adds the per-arrangement `notation:` manifest sub-key. Voice→staff routing salvages the logic from PR #703 (whose `stf` wire-field approach this supersedes): GP voice position 0 → `rh` staff (`G2`), positions ≥ 1 → `lh` (`F4`); a forced-LH track (the merged `Piano LH` partner from `_find_piano_pairs`, or a standalone track named `… LH`) routes everything to `lh` — preserving authored hand crossings instead of inferring hands from pitch. Emits measures with absolute `t` from the bar-indexed tempo map, change-only `ts`/`tempo`/`ks`, and `beat_groups` for compound/irregular meters (6/8 → `[3,3]`, 9/8 → `[3,3,3]`, 5/8 → `[2,3]`, 7/8 → `[2,2,3]` — cf. the feedBack#261 denominator pitfalls); beats carry `dur`/`dot`/`tu`/`rest` from GP rhythms and notes carry absolute `midi` (String+Fret resolves via the string template's concert pitches, Tone+Octave via `(octave+1)*12 + step`) with `tied` continuations kept as real beats (engraving needs the tied notehead — unlike the RS-XML walk, which drops them and extends sustain). Timing reuses the `gp2rs_gpx` machinery (bar-indexed tempo map, per-beat rhythm durations, `_note_midi`) so notation lines up with the RS XML the highway plays — with one deliberate divergence: double dots advance time ×1.75 (vs. the RS-XML walk's single-dot ×1.5 approximation) so a written `dot: 2` agrees with the emitted beat times; sharing the walk itself stays tracked in feedBack#618. Tests: `tests/test_gp2notation.py`.
- **Legacy keys → notation lifter (`scripts/lift_keys_notation.py`)** (feedBack#825 WS4c, epic #828). One-time batch converter that lifts existing **directory-form** piano/keys sloppaks from the legacy guitar wire encoding (`midi = s*24 + f`) into real Sloppak Notation Format files (sloppak-spec §5.3). Candidates are arrangements whose name matches `\b(keys|piano|keyboard|synth)\b` (case-insensitive); each gets a `notation_<id>.json` plus the per-arrangement `notation:` manifest sub-key. Measures derive from the song-level `beats` downbeats (`measure >= 0`; `song_timeline.json` preferred, first-arrangement fallback), with per-measure tempo from downbeat spacing (emitted only on a > 1 BPM change). Durations come from the wire sustain (`sus`, legacy `l` alias) when present, else the gap to the next onset in the same hand — quantized to the nearest plain/single-dotted `{1,2,4,8,16,32}` denominator at the local tempo, floored at a 32nd. Hands are split heuristically: onsets within 10 ms form a group; a group spanning > 12 semitones splits at its largest internal interval gap (low side → `lh`), otherwise the whole group goes by mean pitch vs middle C — single-staff output when everything lands on one hand. Idempotent (arrangements already carrying `notation:` are skipped; an orphan `notation_<id>.json` without the manifest key is refused, not overwritten) with `--dry-run` support; every payload is checked via `notation.validate_notation` before write. Honest caveat: the manifest is round-tripped through PyYAML (`safe_load` + `safe_dump(sort_keys=False)`) — key order survives, YAML comments/custom formatting do not (the script warns when comments are present). Zip-form `.sloppak` files are reported and skipped. Tests: `tests/test_lift_keys_notation.py`.
- **Notation schema v1 freeze — completeness batch** (feedBack#822, epic #828). Adds the low-hanging-fruit fields ahead of content production: top-level credits `rights`/`lyricist`/`arranger`; measure `pickup` (anacrusis); beat `arp` (arpeggiate), `ferm` (fermata), and **typed grace notes** — `grace: "a"` (acciaccatura, MusicXML `grace/@slash=yes`) / `"p"` (appoggiatura); note `stem` (`"up"`/`"down"` force). Pedal is settled as the existing `spd`/`sph`/`spu` trio with a documented MusicXML `<pedal start|change|stop>` mapping — no separate `ped` field. A new "v1 non-features" spec subsection pins the accepted limitations (microtonal, figured bass, mid-measure key/time/clef changes, `ott`/`barline`/ornaments/`trem`/`glis`) as additive-v1.x territory. `lib/notation.py` gains the `GRACE_TYPES`, `STEM_DIRECTIONS`, and `DYNAMICS` vocabularies; the validator stays permissive by design.
- **Notation format — standard musical notation as a first-class sloppak type.** Promotes keys, piano, violin, and any other staff-notation instrument out of the guitar wire format and into their own data structure, following the same promotion path used for drums (feedBack#344). New `lib/notation.py` defines the canonical vocabulary (`CLEFS`, `DURATIONS`, `SCHEMA_VERSION`), a permissive `validate_notation()` check, and `measures_to_wire()` / `measure_to_wire()` wire helpers. `lib/sloppak.py::load_song` reads a new per-arrangement `notation:` sub-key from each arrangement entry in the manifest (Option B: per-arrangement, not song-wide), applies path-traversal guards, validates the parsed JSON via `validate_notation()`, and surfaces all notation payloads on `LoadedSloppak.notation_by_id` (a `dict[str, dict]` keyed by arrangement id). A failed or missing notation file for one arrangement does not abort or skip the arrangement itself — partial-failure isolation mirrors the drum tab loader. `file:` is now optional when `notation:` is present: the loader creates a minimal stub arrangement so a notation-only arrangement entry does not require a guitar wire format JSON. `/ws/highway/{filename}` gains two new message types — `notation_info` (staves, instrument, total measure count) and chunked `notation_measures` (32 measures per chunk) — streamed after `sections` and before `anchors`; `song_info` carries a new `has_notation: bool` flag so viz pickers can auto-activate the notation plugin regardless of arrangement name. The notation file schema is measure-structured (`measure → staff → voice → beat → note`), uses MIDI for pitch (no string/fret/tuning indirection), and carries the full set of effects that alphaTab can render. See `docs/sloppak-spec.md` §5.3 for the full schema. Open questions resolved per the piano/keys epic (feedBack#828 / #822): Option B (per-arrangement `notation:` sub-key) and `file:`-optional-when-`notation:`-present are the endorsed design.
- **`song_timeline.json` — beats and sections as a top-level file.** A new optional top-level file pointed at by a new manifest key (`song_timeline: song_timeline.json`) provides the correct home for song-wide beats and sections, replacing the legacy convention of embedding them in the first arrangement JSON. The loader in `lib/sloppak.py` reads and validates the file (must be a dict with `beats` and `sections` as lists), clears and repopulates `Song.beats` / `Song.sections` from it when present, and stores the raw dict on `LoadedSloppak.song_timeline`. The existing arrangement-JSON fallback is fully preserved: all existing sloppaks that omit `song_timeline:` continue to load without any change. This is a prerequisite for notation-only sloppaks, which may have no arrangement JSON at all and therefore no carrier for beats/sections data. New sloppaks should put beats/sections in `song_timeline.json` only. See `docs/sloppak-spec.md` §2 and §5.3.
- **`note-detection` capability domain promoted — control plane (spec 009)** (feedBack#727/#728, epic #828). New core host `static/capabilities/note-detection.js`: provider registry (kinds `midi`/`engine`/`js`, primitives `pitch.estimate`/`verify.target`), requester-owned context-scoped detection bindings (`open-binding`/`close-binding`/`set-target`/`clear-target` — each binding carries its own redacted tuning context, independent of the host's loaded song, per spec-009 FR-003), and hit/miss/verdict observability events (consumers own judgment). The legacy chart-coupled `highway.setNoteStateProvider` surface keeps working and is wrapped for compatibility-shim hit accounting. Diagnostics (`feedBack.note_detection_capability.v1`) carry provider/binding summaries and bounded outcomes — no raw audio, device labels, or song identity. Migrating the chart path, Step Mode verify, minigames YIN, and the engine verifier onto bindings is the remainder of the spec-009 slice.
- **`visualization` capability domain promoted (cap:6)** (feedBack#828). New core host `static/capabilities/visualization.js` registers a provider-coordinator owning the highway renderer surface: commands `inspect` / `list-providers` / `select-renderer` / `clear-renderer` (selection delegates to the existing picker so persistence, WebGL2 gating, and fallback stay single-sourced), events `providers-refreshed` / `renderer-changed` / `renderer-ready` / `renderer-failed`. Legacy discovery (`type: "visualization"` manifests, `window.feedBackViz_*` globals) keeps working unchanged and is accounted as compatibility shims with hit counts. `static/app.js` attributes every renderer change (auto-match / user-select / fallback) and auto-match outcomes into the domain. Diagnostics (`feedBack.visualization_capability.v1`) carry provider ids/labels/context types, active renderer + selection source, last auto-match outcome, and last failure — no song filenames/titles. Per-panel (splitscreen) selection is a tracked follow-up.
- **Viz picker routes notation arrangements** (feedBack#826, epic #828). `window.feedBack.currentSong` gains `hasNotation` (sibling of `hasDrumTab`) from the `song_info` frame's `has_notation` flag, so notation viz plugins (Staff View, Keys Highway 3D) can gate `matchesArrangement` on data presence instead of arrangement-name heuristics. When a notation-only arrangement (no wire notes — `file:` omitted per sloppak-spec §5.3) falls through Auto with no notation plugin installed, the built-in highway still takes the canvas but the Auto label reads "no notation view installed" and a one-shot dismissable hint points at the visualization picker — never a silently blank board.
- **Keys instrument path in progression** (feedBack#828). New `data/progression/paths/keys.json` (5 levels / 15 challenges at parity with the guitar path) plus keys-flavoured daily/weekly quest pool entries (`d.keys-one` "Ivory Tower", `w.keys-three` "Grand Recital"). `lib/progression.py::instrument_for_arrangement()` now attributes `type: piano|keys` arrangements — and names matching `keys`/`piano`/`keyboard`/`synth` on a word boundary — to the new `keys` instrument, so scored keys runs advance the path automatically. Purely content + attribution: no schema or API changes.
- **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).
- **Built-in diagnostic sloppak rebranded "Slopsmith" → "FeedBack" in the song name.** PR #586 renamed the file to `feedBack-diagnostic-basic-guitar.sloppak` but never regenerated the archive, so the manifest inside still carried `title: Slopsmith Diagnostic — Basic Guitar` / `artist: Slopsmith` (and the same heading in `DIAGNOSTIC.md`) — the stale name testers saw in the library/player and the onboarding calibration step, even though the build script, server, and docs all already say "FeedBack Diagnostic — Basic Guitar". Regenerated `docs/diagnostics/feedBack-diagnostic-basic-guitar.sloppak` from `docs/diagnostics/build_diagnostic_basic_guitar.py` so the committed artifact matches its source generator (title/artist/heading now "FeedBack"; chart, stem, and `diagnostic:` metadata unchanged). No code change — the rename in #586 just needed the rebuild.
- **v3 song/lesson accuracy badges now refresh on the first return from a song — no restart needed.** PR #574 added a `stats:recorded` → in-place badge repaint, but the repaint never matched a card. The event (like `song:loading`) carries the filename **`encodeURIComponent`'d** — exactly as `playCard` hands it to `playSong` (the highway WS `decodeURIComponent`s it back) — whereas library cards key on the **decoded** `localFilename` (`data-fn`), and `/api/stats/best` is server-canonicalized to that same decoded key (`server.py` `_canonical_song_filename`). So `repaintAccuracy`'s `data-fn !== key` check rejected every card and `state.accuracy[encoded]` was `undefined`, leaving the just-earned badge stale until a full `render()` (app restart / search / re-enter the screen) — which is why it "came back after a restart." `static/v3/songs.js` now decodes the `stats:recorded` filename back into the card / `state.accuracy` key space via a small `decFn` helper before marking dirty and repainting (idempotent for already-decoded names; falls back to the original on malformed input so a real filename containing a literal `%` is never corrupted), so both the immediate repaint and the `onV3SongsScreenEnter` deferred path land on the right card. Tests: `tests/js/v3_songs_score_badge_refresh.test.js`.
- **Escape now exits a song (and leaves Settings) even when a transport/rail control button holds keyboard focus.** Clicking a player control (Play / FF / RW / Restart) left that `<button>` focused, and `_shortcutDispatchBlocked()` in `static/app.js` treats any focused `INPUT/SELECT/TEXTAREA/BUTTON` as an "interactive control" and bails before the shortcut registry runs — so the player-scope `Escape → Back` shortcut never fired until the user clicked empty canvas to blur the control ("Escape in song not consistent"). Space already had a player-screen carve-out (#593) that let it fire through a focused control; Escape did not. Generalized that carve-out to Escape, scoped to the player **and** settings screens (both register an `Escape = Back` shortcut, and settings had the identical latent bug). The earlier guards are preserved and still win: text inputs are exempted first (Escape there clears/blurs the field), the Section Practice popover already claims Escape before the carve-out, and a true modal layered over the screen (`[role="dialog"][aria-modal="true"]` / `.feedBack-modal`) still traps Escape so it closes the modal rather than ejecting past it. Escape becomes a reliable, focus-independent "Back" — making it monotonic groundwork for an optional exit-confirm. Plugins that register a player-scope `Escape` shortcut benefit identically (they were broken the same way). Tests: `tests/browser/keyboard-shortcuts.spec.ts` (focused-button repro, text-input no-exit, no-escape-past-modal, Section Practice popover, settings twin-bug).
- **The v3 "Up Next" pill can now be turned off — new "Show 'Up Next'" gameplay toggle (default ON).** The v0.3.0 player chrome's persistent upcoming-section pill (`#v3-upnext`, drawn by `static/v3/player-chrome.js`'s `updateUpNext()`) shipped with no off switch, so it always showed during playback whenever a section was upcoming — overlapping the top-right FPS HUD and ignoring the 3D-highway "Show 'Up Next' section card" checkbox (a *different*, in-canvas widget that was demoted to default-off precisely because this pill is the canonical readout). Users reading the pill as the same setting saw "disabled in settings but still there." Adds a real core toggle following the `autoplayExit` idiom: a client-only `showUpNext` `localStorage` pref (absence = enabled), a **Show "Up Next"** switch in the Gameplay settings tab (`static/v3/index.html`), reader/writer + `loadSettings()` hydration + a read-only `window.feedBack.showUpNext` getter in `static/app.js`, and a gate at the top of `updateUpNext()` that hides the pill when off. Disabling mid-playback hides it immediately; re-enabling re-shows it on the next chrome tick (~6 Hz). Added to `RESET_MAP.gameplay.local` in `static/v3/settings.js` so the Gameplay "Reset" restores the default-on state. Default ON = zero change for existing users. No Tailwind rebuild (plain markup + existing classes).
- **v3 list/tree view brought to parity with the grid: select mode, parts chips, and song actions — plus a stale-CSS Docker fix.** Re-lands a previously-reverted change. **Frontend (`static/v3/songs.js`):** entering select mode no longer collapses the tree — `loadTree()` now captures the expanded artist groups (`details[open]` keyed by `data-artist`) before the "Loading…" wipe and restores them on rebuild, so toggling select mode (which re-renders via `reload()`) keeps groups open and selection usable; tree rows gain a display-only checkbox + selection ring, the same fav / save-for-later / overflow-menu cluster as the grid card (always shown, all bound by `wireCards()`), and a capture-phase select guard mirroring the grid so clicking a row or arrangement chip in select mode selects instead of playing (`<summary>` headers sit outside `[data-fn]`, so native expand/collapse is untouched). **Docker fix (`static/tailwind.min.css`):** the committed Tailwind stylesheet was stale — `.sm\:flex` (and the other utilities behind #582's `hidden sm:flex` arrangement chips and the new action cluster) were never compiled in, so they rendered `display:none` on the Docker build (which serves the committed CSS as-is; Desktop rebuilds from source so it looked fine). Regenerated with the pinned `tailwindcss@3.4.19` via `scripts/build-tailwind.sh` so Docker matches Desktop and #582's chips render on every Docker deploy. Regression tests: `tests/browser/v3-tree-select.spec.ts`.
- **Space bar now plays/pauses on the player screen even when a sidebar nav link or rail button has focus.** When any `<button>` in the player rail (viz, audio, mixer, lyrics, plugins, advanced), a sidebar nav link, or a popover control held keyboard focus, pressing Space was swallowed by `_shortcutDispatchBlocked` → `_isInsideInteractiveControl` (which treats `BUTTON`/`A` as interactive), so the Space shortcut never reached the dispatcher and `togglePlay()` never ran. `_shortcutDispatchBlocked` (`static/app.js`) now extends the same carve-out already used for the Section Practice bar: while the player screen is active, Space is always routed through the shortcut system — the dispatcher calls `e.preventDefault()` before invoking the handler, so the focused element does not also activate. Text inputs (`_isTextInput`) remain exempted first, so typing space in a search/input field still works normally, and focus inside a true modal dialog (`role="dialog" aria-modal="true"` / `.feedBack-modal`) layered over the player is also exempted so Space reaches the modal's focused control (e.g. its Close button) instead of toggling playback behind it — non-modal player popovers/toasts (loop A/B, arrangement pin) stay covered. Regression tests in `tests/browser/keyboard-shortcuts.spec.ts` cover the focused-rail-button play/pause, the text-input exemption, and the modal-dialog exemption.
- **A song's accuracy badge now updates on its library card right after you play it — no restart needed.** The v3 library (`static/v3/songs.js`) loaded the best-accuracy map (`/api/stats/best`) once into `state.accuracy` at render time and only ever refreshed it on a full re-render; the play→return flow takes the screen-entry fast-path that restores the cached grid DOM without re-fetching, so a just-earned score stayed invisible until the next restart re-ran `render()`. The `stats-recorder` now emits a `stats:recorded` event (carrying `filename`/`arrangement`) once the scored `POST /api/stats` resolves on the server — the correct moment, since `song:stop` fires before the POST completes. `songs.js` listens: if the library is the active screen it re-fetches `/api/stats/best` and patches the affected card/row badge in place; otherwise it marks the filename dirty and `onV3SongsScreenEnter` applies it on return (a failed fetch keeps the entry dirty to retry). Badge markup was factored into a shared `accuracyBadge(filename, variant)` (grid pill + tree-row percentage, both tagged `.fb-acc-badge`) so the in-place `repaintAccuracy` can find and replace them without a full list re-render (scroll/pagination preserved). The old empty `song:stop` "refresh lazily next render" placeholder is replaced.
- **Changing Settings → 3D Highway → Fret spacing no longer ejects you to the home screen.** The `highway_3d` plugin's `h3dSetFretSpacing` was the lone 3D-highway setting that called `location.reload()` to apply — and since the SPA boots with `#home` as the active screen (`index.html` `.screen.active`), the reload dropped the user out of Settings onto the homescreen. It now applies live like every other 3D-highway setting: it rebinds the module-scope `_h3dFretUniform` flag (so panels mounted later this session pick up the new mode), recomputes the two `fretX`-derived scalars that were baked at init (`_fretLabelScaleRefW` for fret-label sprite scaling, `FRET_WIDTH_MID` for camera hysteresis), and broadcasts a `fretSpacing` change over the existing `_bgEmitChange` pub-sub so every mounted panel rebuilds its board via `buildBoard()`. Per-frame note geometry already reads `fretX` live and needs no rebuild. No page reload, so the Settings screen stays put. Source-level regression tests in `tests/js/highway_3d_fret_spacing.test.js` now pin the no-reload / live-rebuild behavior.
- **v3 library scroll-restore no longer breaks the classic v2 UI or drops off-screen searches** (feedBack#857). Two regressions in the scroll-restore work above: (1) `playSong` remapped `home`-launched songs to return to the `#v3-songs` screen unconditionally, but `static/app.js` is shared with the v2 UI (served at `/v2` / `FEEDBACK_UI=v2`) where that screen does not exist — Esc-from-player then called `showScreen('v3-songs')`, which threw on the missing element and stranded the user on a blank screen with playback still running; the remap now applies only when `#v3-songs` is present. (2) The Songs screen-entry fast-path skips reloading to preserve scroll, but the global topbar search routed through it, so once Songs had been visited, searching from another screen navigated there without applying the new query; the screen now tracks the state hash each fetch reflects and refetches when it has drifted, keeping the scroll-preserving no-op only when nothing changed.
- **An active custom highway renderer is no longer starved of `draw()` when it hides the canvas** (#819). The per-frame draw gate in `static/highway.js` bailed on `if (!_lastVisible) return`, which conflated two different "hidden" states: a genuine off-screen canvas (`offsetParent === null` — navigate-away / `display:none` splitscreen panel, #246) versus a renderer-set *override-hide* (`setVisible(false)`, where an opaque overlay covers the canvas but the active renderer keeps painting its own surface). The gate now only pauses everything for the off-screen case (and still pauses the default 2D renderer on an override-hide); the **active custom renderer** keeps receiving `draw()` through its own override-hide. The `highway:visibility` event still fires before the gate, so sibling overlay renderers (e.g. 3D Highway's `.h3d-wrap`) still pause. This is the core-side root cause behind the Tab View cursor freezing in single-player (feedBack#734; worked around plugin-side in feedBack-plugin-tabview#25).
- **Screensaver no longer kicks in during windowed-mode playback** (#686). While a song is playing, `static/app.js` now holds a [Screen Wake Lock](https://developer.mozilla.org/en-US/docs/Web/API/Screen_Wake_Lock_API) (`navigator.wakeLock.request('screen')`) so the OS display/screensaver stays awake even though only audio + the highway animation are active and the keyboard/mouse are idle. The lock is acquired on `song:play`/`song:resume` and released on `song:pause`/`song:ended`/`song:stop` (kept only while actually playing), and re-acquired on `visibilitychange` when the tab refocuses (the API auto-releases a lock whenever the page is hidden). Both the HTML5 `<audio>` and JUCE desktop playback paths emit the same `song:*` events, so the fix covers both. In feedBack-desktop (Electron), where `navigator.wakeLock` is unreliable, it also drives a native `powerSaveBlocker` bridge via the optional `window.feedBackDesktop.power.setScreenAwake` hook when present; both calls degrade silently where unsupported. Note: the browser Wake Lock API is secure-context only, so in a plain browser this is active on `localhost` / HTTPS only — a session opened over plain HTTP to a LAN IP (e.g. `http://192.168.1.100:8000`) won't keep the screen awake; front it with HTTPS or use the desktop app (see README → reverse-proxy notes).

### Changed
- **Practice plugin first-class sidebar slot now points at Virtuoso.** The bundled practice plugin was rebranded/re-homed from the SlopScale fork (`id: slopscale`) to `got-feedback/feedBack-plugin-virtuoso` (`id: virtuoso`); the desktop bundle swap is feedBack-desktop#31. `static/v3/shell.js` still promoted `slopscale`, whose id no longer ships — so `renderPromotedNav()` (gated on the plugin appearing in `/api/plugins`) would have found no match and the dedicated sidebar slot would have gone dark, dropping Virtuoso to the generic Plugins gallery. Update the NAV entry + `PROMOTED_PLUGINS` slot `slopscale` → `virtuoso` (`screen: plugin-virtuoso`, label "Virtuoso - Practice", same FeedBarcade anchor + `target` icon) so the practice plugin keeps its first-class entry. Also clear the now-dead `slopscale` id from the Plugins-gallery curated category map (`static/v3/plugins-page.js`) and add `virtuoso: 'practice'` as a defensive fallback (the manifest's `category: "practice"` is authoritative, so it lands on the practice board regardless), and refresh the stale SlopScale references in `README.md` + `docs/plugin-capability-inventory.md`. Must land with the bundle swap or the practice plugin regresses in the UI.
- **3D highway: realistic curved metal frets.** The fret wires are now bowed `TubeGeometry` (the middle strings push away from the camera so the row of frets reads as wrapping a cylindrical neck — a depth cue) rendered with a lit `MeshStandardMaterial` instead of the old flat, straight `MeshBasicMaterial` boxes, so the scene's ambient + directional light glints across the rounded surface for a polished-steel look. The existing per-frame highlight is preserved unchanged: frets inside the active anchor still turn gold (`0xD8A636`), which under the metallic shading reads as brass. Metalness is kept moderate (0.4, not full-metal) because the scene has no envMap — a PBR full-metal surface would reflect black — with a dim emissive floor so frets stay legible down the fogged neck. Backported from the `highway_babylon` plugin's "hit-zone fret bars". All knobs (`FRET_BOW_DZ`, metalness/roughness/emissive) are tunable constants. `plugins/highway_3d` v3.25.0.
- **3D highway: section + tone HUD cards now default OFF.** The v0.3.0 player chrome carries a persistent "Up Next" pill, making the in-canvas section card redundant by default (it doubled the readout, feedBack feedback); the tone HUD follows the same less-is-more default. Both remain available in Settings → 3D Highway (visibility/position/size unchanged); users who previously toggled either explicitly keep their stored preference — only the untouched default flips. `plugins/highway_3d` v3.24.1.
- **Perf**: replace runtime Tailwind Play CDN with a prebuilt static stylesheet (`static/tailwind.min.css`). The Play CDN's runtime JIT scanned the DOM ~1.8x/sec on the main thread (~37 ms blocking spans), dropping ~26% of frames in long playback sessions with the 3D highway as default. Theme extensions (dark/accent/gold colors, Inter font) move to `tailwind.config.js`; regen via `bash scripts/build-tailwind.sh`. No runtime build step — the generated CSS is committed. Fixes feedBack-desktop#110.
- **Perf**: reduce per-frame allocations in the 2D highway chord + lyric render paths. `_ensureChordRenderCache` now also caches `sortedNotes` / `nonZeroNotes` / `nonZeroFrets` / `allMuted` / `hasMultipleNotes` (computed once per chord, invalidated on `src` / `_inverted` / `chordTemplates` change — the third key catches a stale `isOpen`-derived classification when the WS `chord_templates` message lands after the final `chords` chunk), so `drawChords` no longer re-sorts / re-filters / spreads min-max per visible chord per frame. The in-chord unison bend classification is folded inline (no `chordPositions.filter` × 2 per frame). `drawLyrics` memoizes `ctx.measureText` results in a two-level `Map<fontSize, Map<text, width>>` so cache hits don't allocate a composite string key. Lit-sustain shimmer in `drawSustains` swaps the 4 per-note-per-frame `Math.random()` calls for a 64-entry precomputed jitter LUT (xorshift32-seeded — the LUT contents are reload-stable and test-reproducible; rendered shimmer is deterministic per `createHighway()` instance, since the seed includes that instance's `_frameIdx`) indexed by `(frameIdx + n.s + ⌊n.t·60⌋)`, visually indistinguishable and allocation-free.
- **Perf**: the load-adaptive render scale (`_adaptRenderScale`, #654) no longer visibly hunts up/down on passages that hover near the frame budget (testers saw "quality going up and down" with the 3D highway). Downscaling stays prompt to protect the frame rate, but **upscaling is now lazy**: a smaller step (×1.06 vs ×1.1) on a longer cooldown (`_AUTO_UPSCALE_COOLDOWN_MS` 2500 ms vs the 600 ms adjust cooldown), reset on any downscale, and gated by a predictive guard — it only upscales when the projected cost *after* the step (≈ cost × step², since draw cost tracks the pixel count) still clears the high budget. The scale therefore settles just inside the 7–12 ms deadband instead of oscillating across it. No new public API; the `_autoScaleMin` "Min res" floor is unchanged.

### Removed
- **`c` library hotkey ("Convert to .sloppak") removed from core.** Core hardcoded a plugin-specific shortcut: a documentation-only `registerShortcut({ key: 'c', scope: 'library' })` no-op plus a `c → button.sloppak-convert-btn` entry in the library keydown handler that fired the Sloppak Converter plugin's button. Per the plugins-own-their-behavior principle, core no longer ships this hotkey — the convert button still works by click, and the Sloppak Converter plugin can register its own `c` shortcut via `window.registerShortcut()` if keyboard access is wanted. The `f` (favorite) and `e` (edit) library hotkeys, which drive core buttons, are unchanged. Help-modal/registry tests in `tests/browser/keyboard-shortcuts.spec.ts` updated to drop the `c` assertions.

### Added
- **Player progression: Mastery Rank, instrument-path challenges, daily/weekly quests, Decibels currency, cosmetics shop (spec 010).** Onboarding gains two steps: pick one or more **instrument paths** (Guitar / Bass / Drums — data-driven, more can ship as content) and a **calibration challenge** offer (play the bundled FeedBack Diagnostic with note detection at 100% accuracy — or skip; either way you reach **Mastery Rank 1**, and a skipped calibration can still be completed later from the Progress screen). Each path levels by completing a content-defined number of **challenges** (any order) from that level's set; Mastery Rank = onboarding rank + the sum of path levels, starting at 0 on a fresh install. The existing unified XP backend is untouched but the frontend renames it to **Decibels (dB)** — a spendable currency earned ONLY by playing (songs, FeedBarcade rounds, quest rewards; no real-money path exists or may be added) — with spend tracked in a separate wallet so lifetime earnings stay monotonic. Rotating **daily/weekly quests** (deterministic per period, lazy instantiation, local-midnight / Monday resets) award dB and feed `quest_completed` challenges. A new **Progress** screen (rank hero, per-path checklists, quest countdowns, add-a-path) and **Shop** screen (themes via CSS-variable swaps under `html[data-fb-theme]`, avatar frames; atomic balance-checked purchases — 402 on insufficient dB, 409 on re-buy) join the v3 nav, and the topbar badge now shows Rank + challenge-set progress + dB balance. All definitions live in `data/progression/` JSON (paths/levels/challenges, quest pools, shop catalog) — adding a rank, challenge, quest, or cosmetic is a content edit + restart, never code; invalid content degrades to logged warnings. New tables (additive + idempotent): `progression_state`, `player_paths`, `challenge_progress`, `quest_state`, `wallet`, `shop_owned`, `shop_equipped`. New endpoints: `GET /api/progression`, `POST /api/progression/paths|onboarding|events` (events whitelists `minigame_run`; `song_completed` stays server-derived inside `POST /api/stats`, which now resolves the instrument server-side and reports an additive `progression` outcome key), `GET /api/shop`, `POST /api/shop/buy|equip`; equipped cosmetics ride along on `GET /api/profile`. A new **`progression` capability domain** (core-owned, kind: command, safety: safe — `inspect`, `record-event`, `list-shop`, `buy-item`/`equip-item` gated on user action) emits `challenge-completed`/`quest-completed`/`path-level-up`/`rank-changed`/`db-changed`/`calibration-completed`/`cosmetic-equipped`, mirrored as `progression:*` window events, with a redaction-safe diagnostics contributor; backend plugins get the symmetric `record_progression_event` context hook (the bundled minigames hub reports runs through it, guarded for standalone). Spec: `specs/010-progression-domain/`. Tests: `tests/test_progression.py`, `tests/test_progression_api.py`. **Migration notes:** existing XP totals carry over as lifetime dB (balance = lifetime − spent); resetting a per-source XP contribution (e.g. a minigames profile reset) after spending can clamp the spendable balance to 0 until new dB is earned; drums-path v1 content uses currently-satisfiable goals (arcade rounds, quests, any-instrument plays) until drums scoring lands.
- **3D highway score FX (notedetect game-scoring layer).** The bundled `highway_3d` renderer now visualizes the scoring layer shipped in feedBack-plugin-notedetect ≥1.13: floating **"+N" score pops** above each judged gem (sourced from the note-state provider's new `{ points, mult, popKey }` verdict fields — chord members share the chord-level `popKey`, so a chord pops once, not once per string), plus session-level FX from the new `notedetect:fx` event — a particle burst at the strike line on streak milestones (25/50/every 100), an expanding ring pulse on multiplier tier-ups (×2/×3/×4), and a brief red wash when a ≥10 streak breaks. Colors and the pop font follow the user's notedetect scoring-UI skin (`feedBack_notedetect_skin`: neon/esports/metal, refreshed live on the `notedetect:skin` bus event). Everything renders on the existing 2D overlay canvas from fixed-size slot pools — no Three.js geometry, no text-sprite cache traffic, near-zero cost when idle — and degrades to a silent no-op with older notedetect builds (the new fields/events simply never arrive). Splitscreen panels scope FX to their own detector instance via the bubbling per-panel `notedetect:fx` dispatch. `plugins/highway_3d` v3.24.1.
- **3D highway: slide direction arrows + gem-follow animation.** Slide notes now show a ›/‹ arrow indicating which way the slide goes — on the note/gem itself, as an early preview on the neck before the note arrives, and (optionally) chained further ahead for multi-leg slides — each independently toggleable in Settings → 3D Highway (`slideArrowApproachVisible`, `slideArrowNeckVisible`, `slideArrowChainPreviewVisible`). The note gem also now visually glides from its starting fret to the slide's destination over the note's sustain and holds there through the brief post-sustain linger, instead of snapping back to the starting fret — most noticeable on unpitched "slide to nothing" notes. `plugins/highway_3d` v3.25.2.
- **3D highway: up to 3 upcoming-note ghost previews per string, with fade-in/grow.** Each string now previews up to 3 upcoming notes (was 1) on a fixed 0.6 s fade-in/grow ramp, so tight same-string runs no longer pop in at full size right before impact and the player can read note order ahead of time. `isBlocked` (the pre-impact ghost suppression in a note's last 150 ms) is now scoped to chord notes only — for lead notes it had been blinking the ghost out right before each sustained note in dense runs. (Slide notes stay excluded too, per the slide-arrow work above, since their gem glides off the start fret.) `plugins/highway_3d` v3.26.0.
- **Enable/disable plugins from the v3 Pedalboard (footswitch backend).** Every `/api/plugins` entry now carries an `enabled` boolean (default `true`), and a new `POST /api/plugins/{plugin_id}/enabled` endpoint (`{"enabled": <bool>}` → `{"id", "enabled"}`) persists the choice to `CONFIG_DIR/plugin_state.json` (only non-default `enabled:false` entries are stored; a missing/corrupt file is tolerated and never crashes startup). The loader **skips disabled plugins at startup** — no requirements install, no `routes.setup()`, no screen/nav/capabilities — while still surfacing them in `/api/plugins` as a disabled entry (`status:"disabled"`, `enabled:false`) so the UI can show an "off" pedal you can switch back on. Toggling persists immediately and flips the in-memory flag so the next `/api/plugins` reflects it at once (a runtime-disabled plugin's already-mounted routes/screen remain until the next restart; re-enabling a startup-skipped plugin mounts on restart). A disabled plugin is **excluded from the capability pipeline** — its capability metadata is emptied in `/api/plugins`. Guard rails keep `capability_inspector` and `app_tour_*` always enabled (disable → `400`); unknown id → `404`; missing/non-boolean `enabled` → `400`. Backend only; the v3 Pedalboard frontend consumes this contract. Docs: `docs/plugin-v3-ui.md`.
- **fee[dB]ack v0.3.0 rebrand + UI redesign (opt-in, isolated).** The visible product is being renamed from **FeedBack** to **fee[dB]ack** (the `[dB]` is a decibel pun on the practice "feedback" loop) alongside a full dashboard-style UI redesign. **Rebrand scope is the app + docs wordmark only** — the repository, Python package, ghcr Docker image, `CONFIG_DIR`, and `FEEDBACK_*` env vars all keep the `feedBack` name, so existing deployments and data are unaffected. The redesigned UI is additive and served behind a feature flag: `FEEDBACK_UI=v3` flips the `/` route to the new `static/v3/` shell, and `GET /v3` always serves it; the default `/` stays byte-identical to 0.2.9 until 0.3.0 flips the default. This release adds the `static/v3/` scaffold (navy app shell + styled fee[dB]ack wordmark, brand SVG + favicon + PWA manifest with 192/512 icons), an additive `fb` Tailwind color palette (legacy `dark`/`accent`/`gold` retained) with `static/v3/**` in the content globs, and the regenerated `static/tailwind.min.css`. Vanilla JS, prebuilt Tailwind, no Play CDN (Principle II). Shell wiring, screens, profile/scoring backends, and capability-runtime integration land in subsequent v0.3.0 changes.
- **fee[dB]ack v0.3.0 app shell (sidebar + topbar + routing).** The v3 shell (`static/v3/index.html`) is now a re-chromed copy of the legacy app: the new left **sidebar** (HOME / LIBRARY groups) and **topbar** (secondary nav, search, Support, badge-cluster mount points) replace the hidden legacy navbar, and new `#v3-*` screens (dashboard/plugins/profile/playlists/saved) are added — while all legacy screens (`#home` library, `#favorites`, `#settings`, `#player`, `#audio`, plugin nav containers) are kept verbatim so `static/app.js` boots **unmodified** and the whole engine (player/highway, plugin loader, capabilities, audio, library, settings) is reused as-is. Navigation is the shared `window.showScreen` across `#v3-*`, reused legacy, and `#plugin-*` screens, with a responsive hamburger and a `localStorage`/`v3:`-namespaced shell. Plugin nav is mirrored into the sidebar from `/api/plugins` (UI placement is a deferred capability domain, so this uses the legacy loader, not capability dispatch). `static/v3/shell.js` wraps `window.showScreen` via the idempotent rehydration pattern to keep sidebar/topbar active-state in sync.
- **fee[dB]ack v0.3.0 player profile + first-run onboarding + unified XP + streak.** Adds a single-user core **profile** (`profile`/`profile_progress`/`xp_profile` tables in `web_library.db`, additive + idempotent): display name + avatar, a stable `player_hash` (SHA-256 of the first name + a once-generated salt — stable across later renames; a future-leaderboard label, never auth), and a **streak** (any session on a calendar day keeps it; a missed day resets to 1). New endpoints: `GET/POST /api/profile`, `POST /api/profile/avatar` (base64, re-encoded to a ≤512px PNG under `CONFIG_DIR/avatars/`), `GET /api/profile/avatar/{name}` (safe-joined), `GET /api/profile/avatars` (bundled defaults under `static/v3/avatars/`), `GET /api/profile/progress` (one call for the badge), and `POST /api/xp/award`. **Unified XP:** `lib/xp.py` is the single XP curve (same math the minigames plugin shipped); the core `xp_profile` store is the one source of truth the profile badge reads, exposed to plugins via `context["award_xp"]`/`get_xp_progress`/`seed_xp`. The bundled **minigames** plugin now delegates XP to the core store (seeding once from its existing `profile.json` so earned levels carry over) — so song-play, minigames, and tutorials all feed one level. Frontend: a blocking first-run onboarding overlay (name + avatar grid + upload), the topbar profile badge (avatar, 🔥 streak, level + XP bar), and the `#v3-profile` screen. Tests: `tests/test_xp.py`, `tests/test_profile_api.py`.
- **fee[dB]ack v0.3.0 song-stats store (best score + accuracy, plays, resume position).** A core `song_stats` table (`web_library.db`, additive + idempotent, PK `(filename, arrangement)`) records per-song/arrangement best/last score + accuracy, play count, and last position. Endpoints: `POST /api/stats` (scored session → `plays += 1`, `best_*` = max, `last_*` = new, plus **unified-XP award** `xp_for_run(score)` and a **streak** bump, both behind try/except so a side-effect failure never drops the stat write; or position-only `lastPlayPosition` → resume touch with no `plays` change), `GET /api/stats/{filename}` (aggregated across arrangements), `GET /api/stats/recent` (joined to song title/artist/art for "Jump back in"). Scoring stays frontend-driven: `static/v3/stats-recorder.js` tallies the `note:hit`/`note:miss` events the optional `feedBack-plugin-notedetect` already emits (and also accepts an explicit `note_detect:session-ended` summary), then POSTs on song end; it also persists resume position on pause/stop. No note-detect edit required — note-detection is a deferred capability domain, so the recorder uses those legacy events and degrades to "no accuracy" when the plugin isn't installed. Score/accuracy math is shared with the server via `lib/song_score.py`. Tests: `tests/test_song_score.py`, `tests/test_song_stats_api.py`.
- **fee[dB]ack v0.3.0 playlists, Saved for Later, and Continue-Playing.** Core playlist management (`playlists` + `playlist_songs` tables in `web_library.db`, additive + idempotent): create/rename/delete, add/remove/reorder songs, plus a reserved **Saved for Later** system playlist (created on first use; protected from rename/delete). Endpoints: `GET/POST /api/playlists`, `GET/PATCH/DELETE /api/playlists/{id}`, `POST /api/playlists/{id}/songs`, `DELETE /api/playlists/{id}/songs/{filename}`, `POST /api/playlists/{id}/reorder`, `POST /api/saved/toggle`, and `GET /api/session/continue` (derives the resume song + last position from `song_stats`, no new table). Frontend `static/v3/playlists.js` renders the `#v3-playlists` list + detail (drag-reorder, play, remove) and `#v3-saved`, and exposes `window.v3Saved.toggle()` for a "Save for later" affordance on song cards. Favorites reuse the existing favorites screen/API. Core REST, no capability domain. Tests: `tests/test_playlists_api.py`.
- **fee[dB]ack v0.3.0 Dashboard / Home.** The `#v3-home` dashboard (matching the v0.3.0 design target) composes the new backends: a "Welcome back, {name}!" banner with a patch-notes link (`/api/version`), a hero card (Start Playing / Create Lobby), a **Continue-Playing** card (`/api/session/continue` → art, tuning chip, 4-segment progress; click resumes via `playSong` + best-effort seek), a stats row (audio-routing widget placeholder until prompt 18, library count from `/api/library/stats`, plugins count from `/api/plugins` where `status==="ready"`), and a **Recently Played** grid (`/api/stats/recent`) with per-song accuracy badges (good/mid/low ramp). Each widget fetches + renders independently and degrades gracefully (missing/empty endpoint → placeholder, never blocks first paint). `static/v3/dashboard.js`; re-renders on return to Home and on profile update.
- **fee[dB]ack v0.3.0 tuner + instrument topbar badges.** The topbar gains an **instrument selector** (guitar/bass + string count + tuning + reference pitch) persisted via additive `/api/settings` fields (`reference_pitch` clamped 430–450, `instrument`, `string_count` 4–8, `tuning` name or semitone offsets); changing it emits `instrument:changed` so the note_detect scorer can re-tune (consumed once the external plugin adopts it). A **live tuner badge** stays idle until the user enables the mic (explicit gesture; `getUserMedia`), then shows a YIN note readout with a cents needle (green within ±5¢) using a new dependency-free `static/v3/tuner-core.js` (YIN + frequency→note/cents, honoring the reference pitch); clicking opens the full `feedBack-plugin-tuner` screen when installed. CPU-friendly (~20 Hz, paused when the tab is hidden, respects `prefers-reduced-motion`). Tests: `tests/test_settings_instrument.py`, `tests/js/tuner_core.test.js`.
- **fee[dB]ack v0.3.0 audio-routing widget (dashboard).** The dashboard's audio stat tile now reads the live audio session **through the capability runtime** — `audio-mix inspect` (route + faders + required kinds), `audio-input list-sources` (selected/available input), `audio-monitoring inspect` — and renders **Audio Input → VST/NAM/IR → Audio Output** with per-node state dots and a Connected/Not Connected line. It never touches `audio-mixer.js` internals or `nam_tone` routes directly; "Not Connected" is the honest browser default (no native route), and it degrades on `no-owner`/`no-handler`/`failed` or absent capabilities. Refreshes on `instrument:changed`, play/stop, capability audio events, and each Home visit. `static/v3/audio-routing.js`.
- **fee[dB]ack v0.3.0 Plugins page.** The `#v3-plugins` screen renders the enriched `/api/plugins`: a "{N} active" header (`status==="ready"`), a card grid per plugin (icon, name, version, status pill with the error on failed, capability summary badges — declared domains / validation warnings / unsupported versions / shim hits / bundled / type), an **Open →** action that navigates to the plugin's injected `#plugin-<id>` screen, and All/Bundled/Visualizations filters. Surfaces a deep-link to the bundled **Capability Inspector** rather than re-implementing the graph. No new backend. `static/v3/plugins-page.js`.
- **fee[dB]ack v0.3.0 Songs / Library screen (`#v3-songs`).** A native vanilla-JS library browser over the existing `/api/library*` endpoints: provider selector (via the `library` capability, not DOM scraping), grid + tree views, sort, format filter, a tri-state filter drawer (arrangements / stems / lyrics / tunings), topbar-driven search (debounced), infinite scroll, fb song cards with **accuracy badges** (good/mid/low ramp, batched via a new `GET /api/stats/best`), favorite + save-for-later affordances, and upload (reuses the existing uploader). The "Songs" sidebar nav now opens this screen. No regression to `/api/library*`. `static/v3/songs.js`.
- **`ui.library-card-injection` capability + native song-card actions (fee[dB]ack v0.3.0).** New core capability (`static/capabilities/library-card-actions.js`, owner `core.ui.library-card-injection`, exposed as `window.feedBack.libraryCardActions`) lets plugins **register** per-song library-card actions (id, label, placement, applicability, enabled state, run handler) with `action-registered`/`action-result` events — replacing the legacy `.song-card` DOM-injection pattern (roadmap domain #9, now delivered as a frontend host). The native Songs grid renders registered actions in each card's "⋮" menu; the built-in **Edit metadata** and **Convert to E Standard (retune)** actions ship through it (`static/v3/card-actions-core.js`, calling the existing `openEditModal`/`retuneSong` globals). Songs cards also gain **arrangement chips** (play a specific arrangement) and a **multi-select** mode with batch **Add to playlist** / **Save for Later**. Recipe in `docs/capability-recipes.md`; tests in `tests/js/library_card_actions.test.js`. Migrating the external card-action plugins (Sloppak Converter, Find More, editor) onto `register(...)` is a follow-up.
- **`centOffset` exposed via `getSongInfo()`** — the arrangement `<centOffset>` field (float, cents) is now parsed from all chart sources (loose folder XML, sloppak wire format) and sent as `centOffset` in the `song_info` WebSocket message. Plugins can read `getSongInfo().centOffset` to obtain the arrangement's pitch-shift offset — commonly `-1200.0` for extended-range bass (one octave down) or a small non-zero value for true-tuned content (e.g. A443 ≈ +11.8 cents). Defaults to `0.0` when absent.
- **`highway.getPhrases()` and `highway.getMastery()` public plugin API** — exposes phrase timing windows (`[{ index, start_time, end_time, max_difficulty }]`) and the current mastery slider value (`0..1`) as documented, stable plugin API. Both values were already in memory and reachable via internal names; this surfaces them with intent so plugins can implement section-aware logic (e.g. tracking accuracy per phrase, suppressing difficulty changes during a hard solo) without reaching into undocumented internals. Returns `null` when the song has no phrase data (GP imports, single-difficulty charts). Pair with the existing `hasPhraseData()` to gate phrase-aware code paths.
- **Tailwind freshness guard + wider plugin scan.** A new `tailwind-fresh` CI job (`.github/workflows/tests.yml`) rebuilds `static/tailwind.min.css` with the pinned `tailwindcss@3.4.19` and hard-fails on any diff, so the committed prebuilt stylesheet can no longer silently lag source (after PR #411 removed the runtime Play CDN, a stale file shipped unstyled elements with no guard). The `tailwind.config.js` plugin content glob is widened to `./plugins/**/*.{js,html}`, which also scans non-`screen.js` plugin JS (e.g. `plugins/app_tour_*/script.js`) that was previously invisible to the build. Regenerating under the wider glob is a no-op for runtime behaviour — it only adds classes that were already used in source. Groundwork for the plugin `styles` capability (constitution 1.1.0, Principle II): runtime-installed plugins ship their own compiled CSS rather than relying on core's build-time scan.
- **Plugin capability pipelines** — adds the first versioned capability coordination layer for plugin authors and support tooling. `/api/plugins` now exposes validated capability declarations, validation warnings, unsupported-version metadata, UI/runtime domain declarations, and compatibility shim summaries for legacy `nav` / `screen` / `settings` / `routes` / visualization surfaces. The browser runtime now tracks manifest participants separately from live handlers, explicit dispatch outcomes (`no-owner`, `no-handler`, `unsupported-command`, `incompatible-version`), claim lifecycle cleanup, manual override precedence, deterministic ownership conflicts, multi-provider ordering, shim hit counts, and a redaction-safe diagnostics snapshot capped at 64 KB. A bundled Capability Inspector plugin shows the live graph, and new docs cover the manifest schema, recipes, safety matrix, lifecycle cleanup, and diagnostics contract.
- **Audio graph/session capability slice** — promotes `audio-mix`, `audio-input`, `audio-monitoring`, and coordinated `stems` diagnostics into the capability runtime. The new audio session host records song route/fader state, redaction-safe input sources, monitoring lifecycle outcomes, stem automation claims/overrides/orphans, and compatibility bridge hits for legacy faders, song volume, Stems master volume, 3D Highway analyser taps, audio startup barriers, and input source handoffs. `core.audio.session` coordinates `stems` without replacing the Stems plugin as the owner of actual stem playback/state.
- **Audio-mix control plane** — makes `audio-mix` the player mixer source of truth. Core now exposes `list-faders`, `get-fader-value`, `set-fader-value`, `inspect-route`, and `inspect-analyser` through the capability runtime, routes native and compatibility-backed fader provider operations with a 2-second timeout, reports committed values back to the mixer UI, suppresses matching legacy faders when a native participant owns the same logical control, and expands audio-session diagnostics/Capability Inspector rendering for fader availability, source modes, bridge hits, route/analyser summaries, and timeout failures.
- **Audio-input control plane** — makes `audio-input` the redaction-safe source of truth for instrument input discovery and lifecycle. Core now exposes `list-sources`, `select-source`, `open-source`, and `close-source` through the capability runtime, persists selected logical sources, keeps inspect/list/select prompt-free, routes provider `source.open`/`source.close` operations with bounded outcomes, shares compatible open sessions across requesters, suppresses compatibility-backed duplicate sources when a native provider owns the same logical key, and expands audio-session diagnostics/Capability Inspector rendering for selected input, open sessions, bridge hits, storage status, and permission/device failures without exposing raw device labels or live audio handles.
- **Audio-monitoring control plane** — makes `audio-monitoring` the shared live-monitoring coordinator. Core now exposes provider registration/list/selection, explicit user-action `start`, requester-counted `stop`, prompt-free `inspect`/`monitoring.status`, and `set-direct-monitor` through the capability runtime. Monitoring starts integrate with selected `audio-input` readiness, background requesters can only attach to active compatible sessions, active sessions survive song/playback stops without auto-resuming after reload, native providers suppress compatibility-backed legacy monitor paths, and diagnostics/Capability Inspector now show providers, sessions, requesters, direct-monitor state, bridge hits, and distinct safe outcomes (`provider-selection-required`, `user-action-required`, `incompatible`, `unavailable`, `stopped`, etc.) without exposing raw audio/device data.
- **Playback control plane** — promotes `playback` to an active core capability domain for song transport, timing, loop, route, requester/observer, bridge, and diagnostics state. Core now exposes `inspect`, user-authorized `start`, `pause`, `resume`, `stop`, `seek`, `set-loop`, and `clear-loop` through the capability runtime while `static/app.js` keeps raw `<audio>`/JUCE handles private behind a redaction-safe adapter. Playback diagnostics use pseudonymous targets in exported bundles, local display labels only in the Capability Inspector, bounded recent outcomes/events, and bridge accounting for `window.playSong`, legacy `song:*` events, `window.feedBack` transport helpers, loop helpers, and browser/native route handoff.
- **3D highway — Tone HUD, fret dividers, chord-diagram toggle, FPS counter.** The bundled `plugins/highway_3d` gains an amber **Tone-change HUD** (shows the active tone and the next scheduled tone change; position / size / visibility configurable in settings), a **fret-dividers** toggle (vertical dividers on the highway, on by default, via `h3dBgSetFretDividersVisible`), a **chord-diagram visibility** toggle (`h3dBgSetChordDiagramVisible`), and an **FPS counter** setting migrated to `BG_DEFAULTS.fpsVisible` (drops the legacy `h3d_showFps` localStorage key). Chord-diagram position is restricted to `tl`/`tr`; legacy `bl`/`br` values are coerced on load. Perf: accent-halo shell descriptors are pre-built per string in `initScene()` and the chord-verdict cache key is encoded as a number, eliminating per-frame allocations in the `drawNote()` and chord hot paths.
- **Sloppak assembly preserves a short preview clip.** When a source chart carries a separate short browser-preview audio clip alongside the full song, the sloppak assembler now decodes it to `preview.ogg` at the sloppak root and records it under a new top-level `preview:` manifest key (POSIX relpath, same shape as `lyrics`/`cover`). A failed preview decode is logged at debug and skipped without aborting the overall build. Sources with no separate preview are unaffected. Older sloppak readers ignore the unknown `preview` key, so the change is purely additive (sloppak-spec.md §5.5 backward-compat). Documented in `docs/sloppak-spec.md` §2 alongside the other optional top-level keys. Enables [`feedBack-plugin-song-preview`](https://github.com/got-feedback/feedBack-plugin-song-preview) to render hover-to-listen previews for sloppaks without seeking into the full audio.
- **Generic plugin asset route** — `GET /api/plugins/{plugin_id}/assets/{path}` serves arbitrary static files a plugin bundles under its own `assets/` directory (AudioWorklet modules, WASM, images, etc.), so plugins can self-host browser-fetchable assets without a CDN (Principle II). Containment is enforced by `lib/safepath.safe_join` against `<plugin>/assets/`, so `..` traversal, absolute paths, and NUL bytes cannot escape `assets/` to reach a plugin's Python modules. `.js` is served as `application/javascript`. First consumer: the stems plugin's pitch-preserving time-stretch worklet.
- **Minigames framework — bundled as a core plugin (`plugins/minigames/`).** Promotes the upstream [`feedBack-plugin-minigames`](https://github.com/got-feedback/feedBack-plugin-minigames) repo into the core bundle so every FeedBack install gets the framework out of the box (same promotion path used for `highway_3d`). The plugin adds a top-level **Minigames** nav link (alongside Library / Favorites / Upload — not buried in the Plugins dropdown), a library-style card grid of installed minigame plugins, and a shared profile layer (XP, level, per-game leaderboards, cross-minigame unlocks) persisted under `CONFIG_DIR/minigames/` and opted into the settings export. Other plugins that want to ship a minigame add a `minigame` block to their `plugin.json` and call `window.feedBackMinigames.register(spec)`; the SDK exposes scoring (`createContinuous` runs a self-contained YIN tracker; `createDiscrete` / `createChord` wrap `note_detect`'s `createNoteDetector`), HUD primitives, run persistence, and a scheduler so individual minigames don't need their own DSP or backend. Backend endpoints live under `/api/plugins/minigames/{runs,profile,registry}`. The framework is plugin-shaped (not core code) per Principle III, but bundled so it ships with every install. First consumer: [`feedBack-plugin-flappy-bend`](https://github.com/got-feedback/feedBack-plugin-flappy-bend), shipped separately.
- **Alpha-build heads-up banner** — when `/api/version` reports a version string containing "alpha" (case-insensitive), an amber banner appears at the top of the library section warning users that the build is in active development and may have bugs or breaking changes. The banner stays hidden on stable / beta / RC builds. No persistence or dismiss state — it's a passive notice, not a modal.
- **Drum vocabulary expanded to 18 pieces** — adds `stack` (MIDI 30, from GM's extended-percussion range, unused by real drum-kit MIDIs) and `bell` (MIDI 80 "Mute Triangle", also unused in real drum-kit MIDIs) to `lib/drums.py` PIECES. Inserted in the iteration order so the editor / highway lane ordering is *hi-hat → stack → crash → … → ride bell → bell*. Both are cymbals; default shape `circle_jagged` (stack) / `circle_dot` (bell). Old drum tabs round-trip unchanged — the schema is permissive and existing piece-ids are untouched.
- **GP / MIDI drum import surfaces unmapped notes** — `convert_drum_track_to_drumtab` (`lib/gp2rs.py`) and `convert_drum_track_from_midi` (`lib/midi_import.py`) gain an optional keyword-only `out_unmapped` parameter. Callers that pass an empty dict receive a per-MIDI record of every silently-skipped percussion note (`{midi: {"count": int, "times": [float, ...]}}`, times capped at 100 samples per note). This lets the editor plugin show a warning + manual-mapping UI on import instead of silently dropping unmapped notes. Default behavior unchanged for callers that don't opt in.

- **Drum support from scratch** — drums are now a first-class arrangement type with their own JSON payload on disk and their own WS stream to the highway. New `lib/drums.py` defines the closed piece-id vocabulary (kick, snare, snare_xstick, hh_closed/open/pedal, tom_hi/mid/low/floor, crash_l/r, splash, china, ride, ride_bell), default GM-MIDI mappings, three preset lane configurations, and a permissive `drum_tab.json` validator. `lib/sloppak.py::load_song` reads the manifest's optional top-level `drum_tab:` key, parses + validates the JSON, and surfaces it on `LoadedSloppak.drum_tab`; the load stays permissive so a missing or malformed tab silently disables drums rather than failing the sloppak load. `/ws/highway/{filename}` gains two new message types — `drum_tab` (metadata + kit legend) and chunked `drum_hits` (500 hits per frame, same chunking as notes) — exposed to renderers via `bundle.drumTab`. `song_info` carries a `has_drum_tab` flag so viz pickers can auto-activate the drums highway regardless of which guitar arrangement is selected. `lib/gp2rs.py::convert_drum_track_to_drumtab` converts a Guitar Pro drum track to a `drum_tab.json` dict, preserving velocity verbatim, mapping hi-hat openness through the canonical piece-ids, and flagging flam / ghost / cymbal-choke articulations from GP effects. `lib/midi_import.py` gains `list_drum_tracks` + `convert_drum_track_from_midi` (channel-9 only) with heuristic flam-collapse (≤30 ms same-piece) and choke detection (cymbal note-off ≤120 ms). `docs/sloppak-spec.md` §5.3 promotes drum_tab from worked-example to canonical with the closed piece-id table and wire format. Sloppaks without a drum_tab are unaffected; legacy drums-as-guitar-notes sloppaks keep playing via the drums plugin's fallback decoder.
- **Loose folder support** — a directory containing an audio file + arrangement XMLs, with optional `manifest.json` and album art, is now discovered, indexed, and playable as a first-class library format alongside Sloppak. The scanner walks `DLC_DIR` for non-preview audio files and treats each parent directory that also contains XMLs as a loose song. Metadata follows a `manifest.json` → XML tags → folder-name priority chain (see `lib/loosefolder.py`). Songs are tagged `format: "loose"`, render an amber `FOLDER` badge in the library, and are filterable via the new "Folder" option in the format dropdown. Audio uses the shared vgmstream/`convert_wem` pipeline, cached under `AUDIO_CACHE_DIR`. The chart `<offset>` from the first non-vocals XML is now propagated to the frontend via `song_info.offset` and applied in `highway.setTime()` so loose folders authored against non-silence-padded audio stay in sync. Pairs with the companion `feedBack-plugin-loosefolder` plugin which adds an in-player Fix Sync UI for nudging and saving offset corrections.
- Highway note-state hook (#254). New `highway.setNoteStateProvider(fn)` lets a scorer plugin publish a per-note judgment (`'hit'` / `'active'` for a sustain currently held correctly / `'miss'`, or `{ state, alpha, color }`) so the renderer lights up the **gem itself** on a correct hit and keeps a sustain trail glowing while it's still being played right — instead of a separate overlay ring near the note. The built-in 2D highway honors it in `drawNote` / `drawSustains` / the chord-frame path (bright string colour + additive halo on hits, bright vs dim sustain trail, faint red wash on misses); the bundled 3D highway reads the same data via `bundle.getNoteState` (bright string-tinted outline + bright body + glowing sustain on hit/active, red outline + suppressed body on miss). Custom renderers opt in by calling `bundle.getNoteState(note, chartTime)`. note_detect registers the provider (and still owns its HUD / diagnostic miss markers / "currently detected" indicator); renderers that ignore the hook simply don't light gems. On a confirmed hit/active the renderers add a contained "sparkle/sizzle" on the note — the 2D highway: additive throbbing halo + flickering hot core + crackling spark lines (+ an expanding shockwave ring on a fresh strike) on the gem and a glowing/jittery sustain trail; the 3D highway: a few twinkling bright dots and short crackling arc segments hugging the note's rectangle (no bloom past the note), drawn on its overlay and projected through the camera so they ride the note. Also adds `highway.isDefaultRenderer()` so overlays that position with the 2D-highway helpers (`project` / `fretX`) can skip rendering when a custom renderer is active — fixes note_detect's miss markers appearing in random places over the 3D highway. New 3D-highway setting **Show note preview on the fretboard** (on by default) toggles the board-projection ghost — the translucent preview of the upcoming note on the fretboard surface. (Note: the companion change in the **note_detect plugin repo** turns its full-screen green/red edge flash off by default and adds a toggle to re-enable it — ships separately with note_detect, not in this feedBack release.)
- Diagnostic bundle export (#166). New "Export Diagnostics" + "Preview Bundle" buttons in Settings produce a single redacted zip combining server logs (tail of `LOG_FILE`), system info (Python/OS/version), hardware probe (CPU model + cores + freq + RAM, GPU via `nvidia-smi`/`rocm-smi`/`system_profiler`, container/Electron/bare runtime detection), full plugin inventory with git SHA + remote URL (read directly from `.git/HEAD` so it works in minimal runtime images without `git` installed) + orphan/failed-to-load detection, the browser console transcript (all levels: log/info/warn/error/debug + window.onerror + unhandledrejection, 500-entry ring buffer), browser hardware (WebGL/WebGPU adapter info, navigator + userAgentData), filtered localStorage, and per-plugin contributed diagnostics. Top-level `manifest.json` lists every file with its versioned schema id (`system.hardware.v1`, `client.console.v1`, etc.) so AI agents can dispatch by schema. Redaction is on by default: DLC paths, song filenames (`<song:HASH8>` stable per-bundle), IPv4/IPv6 addresses, bearer tokens, and `key=`/`token=` query strings are replaced. Plugins opt their backend diagnostics in via a new `diagnostics` manifest field (`server_files` allowlist mirroring `settings.server_files` semantics, plus an optional `callable: "<module>:<function>"` resolved lazily via `load_sibling`). Frontend plugins push diagnostics via `window.feedBack.diagnostics.contribute(plugin_id, payload)`. Three new endpoints: `POST /api/diagnostics/export`, `GET /api/diagnostics/preview`, `GET /api/diagnostics/hardware`. Full bundle format spec in `docs/diagnostics-bundle-spec.md`.
- Structured logging bootstrap (phase 1 of #155). Three new environment variables control server log output: `LOG_LEVEL` (default `INFO`), `LOG_FORMAT` (`text` for coloured console, `json` for one-JSON-object-per-line suitable for Loki/ELK/Promtail), and `LOG_FILE` (optional path, rotated at 10 MB with 5 backups). HTTP responses now include a `X-Request-ID` correlation header (via `CorrelationIdMiddleware`); the same request ID appears as `request_id` in structured log lines emitted via the stdlib `logging` / `structlog` APIs during that request.
- Structured logging migration completed (phase 2 of #155, #159, #242). The 42 `print()` calls and 6 `traceback.print_exc()` calls across `server.py` and `lib/` have been migrated to levelled `feedBack.*` loggers. Silent `except: pass` blocks in `lib/sloppak.py` and `lib/sloppak_convert.py` now surface as `log.warning` / `log.debug` with the exception attached. WebSocket handlers (`highway_ws`, `ws_retune`) bind a `ws_conn_id` contextvar at accept time so every log line within a session carries a connection ID. A CI grep guard in `.github/workflows/tests.yml` fails the build if either `print(` or `traceback.print_exc(` reappears in `server.py` or `lib/`.
- **Lyrics Karaoke plugin** — end-to-end karaoke setup for Sloppak songs in one workflow. The setup screen shows a per-song checklist (vocals stem / synced lyrics / per-syllable pitch) and a single "Build Karaoke" button that runs whatever's missing: Whisper alignment of pasted lyric text against the vocals stem, then `librosa.pyin` pitch extraction. Both artifacts persist inside the Sloppak (`lyrics.json`, `vocal_pitch.json`). In the player, a "Karaoke" toggle swaps the text-lyrics overlay for a horizontal pitch ribbon (one bar per syllable, vertically positioned by pitch, sweeping playhead).
- Settings export/import (#113). Two buttons on the Settings page bundle server config, browser localStorage, and opted-in plugin server-side files into a single versioned JSON file for backup, migration, or sharing a calibrated setup. Server-side import is all-or-nothing for safety-critical failures: phase-1 validates the entire bundle (schema, path-traversal, encoding) before any disk writes; phase-2 commits each file via temp+rename. Plugin-state mismatches between export and import are handled leniently: files referenced for a plugin that isn't loaded are skipped with a warning, files referenced for a plugin whose manifest no longer declares them are skipped with a warning, and localStorage is merged (not cleared) so first-run defaults from plugins installed after the export are preserved. Path-traversal, absolute paths, schema mismatch, and decode failures remain hard refusals. Plugins opt their server-side files in by declaring `settings.server_files` in `plugin.json` (list of relpaths under `CONFIG_DIR`; trailing `/` denotes a directory).
- Library filtering by parts present or missing (#129, #69). New right-side Filters drawer (single button next to the format/sort row, with active-filter count badge and dismissible chips below) lets you require or exclude arrangements (Lead/Rhythm/Bass/Combo), specific stems on Sloppaks (drums/bass/vocals/piano/other), lyrics, and tuning. Multi-select within an axis is OR (Lead OR Rhythm); cross-axis is AND. State persists across reloads. New endpoint `GET /api/library/tuning-names` returns distinct tunings present in the library, ordered by musical distance.
- Sort library by year (#128). Two new options in the sort dropdown: "Year (newest)" and "Year (oldest)". Songs without a year are pushed to the bottom for both directions.
- **`highway.getLyrics()` accessor.** `createHighway()` now exposes the parsed timed lyric syllables (`[{t, d, w}]`) via `getLyrics()`, mirroring `getBeats()`/`getSections()`, so overlay plugins can render karaoke without opening a second highway WebSocket. Pure accessor; no behavior change.

### Changed
- **Perf (3D highway, feedBack#226)**: pre-warm `plugins/highway_3d/screen.js` object pools at board init. Previously the pool factory grew lazily on first `.get()` past the high-water mark, allocating a fresh `T.Mesh` mid-rAF on dense 7/8-string charts and stalling those frames; the meshes were then permanently added to `noteG` (the pool only hides on `reset()`, never removes), bloating the scene graph for the rest of the session. Pre-warming spends the cost up front. Fold the per-frame `updateStringHighlights()` per-string loop with the post-call `mGlow`/`mAccentCore` emissive writes — one walk over the per-string scratch arrays instead of two. Replace `longestConsecutiveRun`'s per-call array allocations with a `{start, len}` index pair (trades two per-call sub-array allocations for one small 2-key object — net reduction in per-visible-chord allocation churn). Opt-in perf bench harness via `?h3dbench=1` URL param: `console.log` p50/p95/max for six update() segments every 5 seconds; when the URL flag is absent the mark helpers are bound to empty functions at renderer-instance init (each `createHighway()` panel re-checks the flag), so the hot-path calls are no-ops with negligible overhead (typically JIT-inlined).
- **License**: Relicensed to AGPL-3.0-only. Prior versions claimed MIT in the README, but the bundled desktop build statically links JUCE 8 (AGPL-3.0), so AGPL terms have effectively governed the desktop distribution since JUCE was added. AGPL-3.0-only is now the canonical license for the project — see [LICENSE](LICENSE) and [CONTRIBUTING.md](CONTRIBUTING.md) (DCO sign-off + plugin licensing policy). Bundled and vendored third-party code keeps its original license.
- Tuning sort is now ordered by musical distance from E Standard (#22) instead of alphabetical: E Standard first, then Drop D / F Standard at distance 2, then Eb Standard / F# Standard at distance 6, etc. Within a magnitude tier, down-tuned variants come before up-tuned, then alphabetical.
- Settings page restructured into separate "FeedBack" (core) and "Plugins" sections, with each plugin's settings rendered as a collapsible panel (collapsed by default). "Plugin Updates" moved into the Plugins section.
- **Lyrics Sync** is now a redirect stub. Its alignment + save endpoints moved into the new Lyrics Karaoke plugin alongside the pitch extraction. Existing nav entries and bookmarks land on a "moved" page that auto-redirects to the merged plugin.

### Security
- **Path traversal in archive extractors and library path resolution.** `lib/sloppak.py::_unpack_zip` and `server.py::_resolve_dlc_path` previously concatenated attacker-controlled entry names or filenames directly onto the extraction or library directory, so a crafted sloppak zip member or library filename with `..` segments, an absolute path, or backslash separators could write or read outside the intended directory. Any code path that unpacks a user-supplied archive (library upload, click-to-play, retune) or resolves a library path was reachable. Both locations now delegate to a new `lib/safepath.py::safe_join` helper that resolves each destination once and rejects entries that don't fall under the target directory; rejected entries are logged and skipped, the rest of the archive still extracts. The stem-split paths in `lib/sloppak_convert.py::split_stems` and `scripts/split_stems.py` previously called `ZipFile.extractall()` directly on user-supplied sloppaks; both now delegate to the same hardened `lib/sloppak.py::_unpack_zip` so every sloppak-unzip site in the codebase shares one containment guarantee. Tests in `tests/test_archive_traversal.py` and `tests/test_safepath.py` pin the contract for `../`, deep traversal, absolute paths, mixed `subdir/../../` forms, Windows-style separators, NUL bytes, names that resolve to the unpack root, and symlinked roots.

### Fixed
- E Standard retune now stays metadata-consistent across a chart's arrangement files (feedBack-plugin-notedetect#50). Previously the retune path could shift the audio and update manifests while leaving some arrangement metadata untouched, so `load_song()` later exposed the *original* tuning at runtime. `lib/retune.py` now updates every arrangement's tuning metadata consistently before applying the E Standard tuning, and raises on a partial update instead of silently packing split tuning metadata. EStd files generated before this fix should be re-converted so their metadata is consistent.
- Keyboard shortcut help now opens from the Player/3D Highway context when Linux/Electron reports Shift+Slash as `key="/"`, including while player controls such as the visualization picker are focused (#598).
- 3D Highway left-handed mode now has regression coverage for fret-axis mirroring, board rebuilds on runtime lefty changes, and mirrored camera state including the lookahead target and shoulder offset; the maintainer guide no longer claims the renderer ignores `bundle.lefty` (#321).
- Chord-level `fretHandMute` is now parsed into each note's `fret_hand_mute` (wire `fhm`) instead of being folded into `mute` (`mt`), matching `_parse_note` and preserving wire-format fidelity for both the template-expanded (synthetic-note) and explicit-`chordNote` paths. The 3D highway renders the fret-hand-mute X for `mt` *or* `fhm` notes, so the muted-chord overlay still shows. Also fixes the per-note fret-connector label vanishing exactly at the hit line (the fade now holds full opacity through `dt = 0`).
- `gp2rs` now respects the time-signature denominator when emitting ebeat subdivisions, fixing misaligned beat grids in 6/8 and other non-quarter-note meters.
- Settings dropdowns (Default Arrangement, Platform Filter) now persist immediately when changed. Previously a dropdown selection was only written to `config.json` when an unrelated "Save" button (Library Folder or Demucs Server) was clicked, so picking a default arrangement and navigating away silently discarded it. Both `<select>` controls now POST the single changed field on `change` via the partial-merge `/api/settings` endpoint, matching the auto-save behaviour of the A/V Sync Offset and mastery sliders. The text inputs (Library Folder Path, Demucs Server URL) keep their explicit Save buttons. Autosaves are sent through a single client-side queue (one request in flight at a time, in selection order), and the `POST /api/settings` handler now serializes its read-modify-write of `config.json` under a lock so concurrent partial updates can no longer overwrite each other and drop a key. The config write is also atomic (temp + rename) and `/api/settings/import` shares the same lock, so readers never observe a half-written file and a settings import can't race a concurrent partial save.
- Demucs stem split failing on Windows desktop with `OSError: Could not load this library: libtorchcodec_core4.dll` or `ImportError: TorchCodec is required for save_with_torchcodec`. The demucs subprocess now bootstraps a `torchaudio.save` → `soundfile.write` shim before importing demucs, sidestepping the torchcodec dependency entirely. The override stays in place across torchaudio versions — soundfile's WAV writes are behaviorally equivalent for demucs's float32 outputs.
- Splitscreen pop-out windows briefly flashed the library/song grid before showing the popped panel. A popup loads the full app (whose default screen, `#home`, is the library) and only swaps to the player once the splitscreen plugin loads; app init now detects `?ssFollower=1` and switches to the player screen up front, so the popup shows player chrome the whole time.
- Sloppak assembly dropped all tone data — affected sloppaks showed no signal chain in the Tones plugin and no tone-change markers on the highway. The assembler (`lib/sloppak_convert.py`) now lifts each arrangement's tones from the source chart via the new `lib/tones.py` helper and embeds them inline in the arrangement JSON under a `tones` key (`base`, `changes`, `definitions` — see `docs/sloppak-spec.md` §3.9). The highway WebSocket reads `base`/`changes` for sloppaks, and the Tones plugin (≥ 1.1.0) reads `definitions` to render the gear chain. Sloppaks built before this release carry no tone data and must be rebuilt from their source chart to gain it.
- Tab View (feedBack-plugin-tabview ≥ 3.0.1): the bottom row of tablature was permanently hidden behind the player controls bar (#336). The overlay reserved 60px at the *top* (clearing the transparent HUD) and extended all the way to the bottom of `#player`, where the opaque `#player-controls` (z-index 10) drew over the last row. The overlay now measures `#player-hud` and `#player-controls` dynamically and insets both edges; a `ResizeObserver` on the controls bar re-runs the inset when it wraps to a second row on narrow viewports.
- Tab View (feedBack-plugin-tabview ≥ 3.0.1): the cursor highlight led playback by roughly one beat (#336). alphaTab snaps `tickPosition` to the start of the *next* beat, so the cursor would race ahead by 500ms+ at typical tempos. The plugin now sends `tickPosition` one beat earlier so the snap lands on the current beat, and the highlight overlay tracks the bar cursor (`.at-cursor-bar`) instead of the next-beat cursor (`.at-cursor-beat`).

### Migration notes
- **Constitution amended to 1.1.0 (Principle II — Vanilla Frontend).** Prebuilt Tailwind (`static/tailwind.min.css`) is now codified as non-negotiable: no Play CDN / runtime CSS JIT anywhere, core or plugin. Plugin authors: a plugin that uses Tailwind classes not guaranteed in core — especially arbitrary values like `w-[37px]` — MUST ship its own compiled stylesheet via the new `styles` manifest key, built with `corePlugins.preflight = false`. Plugins that use only core-guaranteed utilities, or that ship no Tailwind at all, need no change. Contributors: after adding any Tailwind class to core or a bundled plugin, run `bash scripts/build-tailwind.sh` and commit the regenerated CSS, or the `tailwind-fresh` CI job fails.
- The library filters depend on three new columns (`stem_ids`, `tuning_name`, `tuning_sort_key`) that are populated as songs are scanned. If filters look empty after upgrading, run **Settings → Full Rescan** to repopulate; alternatively the periodic background rescan picks them up over time.

## [0.2.4] - 2026-04-22

### Added
- Version badge in navbar (`/api/version` endpoint + `VERSION` file)
- `CHANGELOG.md` and semantic versioning
- Step Mode plugin
- `gp2midi` improvements and expanded test coverage
- Note Detection plugin factory-pattern refactor with multi-instance/splitscreen support
- Per-panel note detection in Split Screen plugin with M/L/R channel routing for multi-input interfaces

### Fixed
- `SLOPPAK_CACHE_DIR` moved to `CONFIG_DIR` for AppImage compatibility
- Improved error message when plugin requirements fail to install