feedBack/docs/size-exemptions.md

Size-exemption register

The working norm (constitution Principle II; enforced by the max-lines lint gate) is no source file over 1,500 lines. A few files are allowed to exceed it because splitting them would do more harm than good — hot per-frame renderers, C++, offline generators, cohesive registries. This register is the list of those exceptions: each row is a deliberate, signed decision with a ceiling, a rationale, and a review trigger. Without it, "no file over 1,500 without a signed exemption" is unenforceable.

Rules

• One row per file: a ceiling, a rationale, a signer, a review trigger.
• The max-lines per-file ceilings in eslint.config.js mirror this table — keep them in sync (this register is canonical).
• Files with a scheduled split plan are not exempt — they live in "Planned, not exempt" at the bottom so nothing falls between the two states.
• Signers (decided 2026-07-08): Byron signs core + bundled rows; Christian signs the authored-plugin row (virtuoso, its own repo/track).

Permanent exemptions (structural rationale)

Repo / file	Lines (7-07)	Ceiling	Rationale	Signer	Review
core static/highway.js → residual renderer-2d.js (post-split)	~2,400–2,900 est.	3,000	60 fps hot path; no module boundary inside the per-frame loop	Byron	after the highway.js split
core plugins/highway_3d/ → residual renderer	sized at split; likely >3,000	set at split, flagged now	same hot-path rule; the draw core can't be cut without behavior risk	Byron	after the highway_3d split
core static/capabilities.js	1,538	1,600	cohesive registry + window.feedBack bus, 38 lines over; a split spends credibility for nothing	Byron	R4
tutorials builtin/reading-the-highway/generate.py	1,818	2,000	offline content generator, never imported at runtime, deps not in runtime requirements	Byron	if a 3rd builtin pack appears
desktop src/audio/NodeAddon.cpp	3,542	as-is	C++, outside the ESM/routes playbooks; under active use-after-free crash work — do not churn	Byron	after crash-class work settles
desktop src/audio/AudioEngine.cpp	2,977	as-is	same	Byron	same
desktop src/vst-host/main.cpp	1,928	as-is	same	Byron	same
virtuoso screen.js (authored, own track)	25,741	as-is until its own split	authored plugin on a separate roadmap; migrates on its own schedule	Christian	virtuoso split kickoff

Split-when-touched (no scheduled train; row retires when split)

Repo / file	Lines	Ceiling	Rationale	Signer	Review
core lib/gp2rs_gpx.py	2,540	as-is	import converter, off the serve-path hot loop	Byron	when next touched
core lib/gp2rs.py	2,055	as-is	same	Byron	when next touched
core lib/song.py	1,689	as-is	data models + wire format; cohesive	Byron	when next touched
core lib/gp_autosync.py	1,572	as-is	under active dev (#787/#791) — don't collide	Byron	after in-flight work lands
core plugins/capability_inspector/screen.js	1,752	as-is	bundled diagnostics plugin, low churn	Byron	when next touched
core plugins/folder_library/screen.js	1,672	as-is	bundled plugin, low churn	Byron	when next touched

Temporary rows (cleared by a scheduled PR)

Repo / file	Lines	Cleared by
core plugins/__init__.py	~2,470 (grew under R0)	the plugins/_routes.py + plugins/_registry.py split (rides the server.py router work)

Watch list (under the norm — no row needed, re-census each phase)

musicxml-import/mxml2notation.py (1,456) · core static/capabilities/audio-effects.js (1,436) · studio routes.py (1,399) · update-manager screen.js (1,492 — zero headroom).

Planned, NOT exempt (owned by split plans — listed so nothing falls between states)

core static/app.js (11,852) · static/highway.js (4,168, whole file) · server.py (9,085 — was 14,037; ratcheted by the R3 MetadataDB + AudioEffectsMappingDB extractions and four routers/ modules) · lib/metadata_db.py (4,373 — new in R3; the MetadataDB class alone is 4,018 lines and is a monolith in its own right, to be split per-table once the router train lands) · static/v3/songs.js (4,134) · static/capabilities/audio-session.js (2,974) · plugins/highway_3d/screen.js (15,656) · plugins/keys_highway_3d/screen.js (3,780) · plugins/drum_highway_3d/screen.js (3,597) — and every monolith with a PR train in the refactor plan. Test files (e.g. tests/test_plugins.py) are out of scope by policy — the norm governs source files.