Scopes the differentiating "record every peer to their own synced track"
feature and lands its pure, isolated core (no live-audio wiring yet).
- docs/multitrack-recording-plan.md: scope contract + locked decisions
(raw stems pre-volume/mute, stems + a mixed track, silence-pad late joiners).
- src/audio/multitrack.rs: MultitrackRecorder over the existing WavWriter.
One master clock = the mixer cycle; every end_cycle() appends exactly
FRAME_SAMPLES to every track (silence where idle) so all stems stay
sample-aligned. add_peer back-pads a late joiner to cycle 0; track_filename
gives fs-safe `<slug>-<shortid>.wav` (reuses sanitize_name). Optional mix
track for "Both" mode.
- +5 unit tests: equal length across tracks, late-joiner leading silence,
stems-only omits mix, fit() pad/truncate, filename slugging/disambiguation.
Stage 2 (wire into the mixer) is next, behind a checkpoint. 168 lib tests,
clippy --all-targets clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
molluskandClaude Opus 4.8
fde6f8a680