Single source of truth for the track ("program"/"patch") grammar, which was
implemented by hand in src/engine.js and pico-cp/app.py with no cross-check and
had quietly drifted.
- docs/track-format.md: formal grammar, container (programs.json) schema with a
version field, the new per-track playback-flow model (rep/end + relative goto;
default = loop forever), normalization rules, and a list of known divergences.
- tests/: golden vectors + a runner that loads the REAL engine.js and app.py
grammar (no copies; app.py via ast extraction) and compares both against the
spec. Exit non-zero on unexpected mismatch or round-trip break -> usable as CI.
Surfaces real divergences for follow-up: default accent pattern (no =pattern)
differs web vs device and affects shipped presets; euclid not parsed on device;
vol/cd dropped on device; unknown-sound fallback; tempo clamp; empty patch.
The rep/end playback-flow vectors are the acceptance test for building that.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
