Relocate the playback/queue/transport/audio-output engine out of the type-first
store/ + utils/playback/ + utils/audio/ dirs into a cohesive src/features/playback/,
structure-preserving:
store/<x> -> features/playback/store/<x>
store/audioListenerSetup/<x> -> features/playback/store/audioListenerSetup/<x>
utils/playback/<x> -> features/playback/utils/playback/<x>
utils/audio/<x> -> features/playback/utils/audio/<x>
184 files moved (107 source + 77 tests), 365 consumers rewritten. Pure move — no
behavior change, no state-split (the playerStore state-split stays a separate M5
question). Enabled by this session's decouple seams (artist/offline/orbit/auth →
core registries), so the engine carries no inbound core->feature inversion: store/
now holds only the 50 cross-cutting global stores (auth family, the seams, library
index, UI/settings stores).
KEPT OUT of the move (would re-create global->engine edges): the 3 pure config
helpers utils/audio/{loudnessPreAnalysisSlider,hiResCrossfadeResample} +
utils/playback/autodjOverlapCap (authStore + settings UI read them — they stay in
utils/). Ambiguous view-state stores (eqStore, queueToolbarStore,
playerBarLayoutStore) stay global (no engine imports).
Consumers use DEEP paths (@/features/playback/...), no barrel — matches the lib/
approach and avoids barrel-mock-collapse across the 140 usePlayerStore consumers.
Two tolerated type-only core->feature edges remain (localPlaybackStore->QueueItemRef,
localPlaybackMigration->HotCacheEntry, both erased).
tsc 0, lint 0, full suite 319/2353 green, iron-rule clean (no runtime store->feature
import). Behavior-touching only via the prerequisite bridge seam (already QA-flagged);
the move itself is pure.
Move the Subsonic + Navidrome protocol clients and the library IPC facade
(subsonic*, navidrome*, library.ts + tests) from src/api/ into src/lib/api/,
the feature-free infra layer (plan M4, decision §10.3: shared client core → lib/).
Pure move: deep-path import specifiers @/api/* -> @/lib/api/* across ~150
consumers; no behaviour change. Domain REST (lyrics/events) and cover/analysis
infra stay in src/api/ pending their own M4 placement.
tsc 0, lint 0/0, full suite 319 files / 2353 tests green.
The M0 pilot mis-membered the waveform data pipeline into features/waveform,
creating a core->feature inversion: ~12 audio-core files in store/ imported
refreshWaveformForTrack / fetchWaveformBins / bumpWaveformRefreshGen from the
feature barrel. These are playback coordination (write waveformBins into
playerStore on track change, last-write-wins gen guard), not seekbar rendering.
Move waveformRefresh + waveformRefreshGen (+ tests) to src/store/ and
waveformParse (+ test) to src/utils/waveform/ (beside waveformSilence). The
feature now holds only the seekbar UI (WaveformSeek/SeekbarPreview + their
hooks/render utils); its barrel exports UI only. Core consumers import the
pipeline directly from @/store/*. Restores the no-core->feature-inversion rule.
Psychotoxical