A lane with no =pattern produced different defaults on web vs device — a real,
shipped divergence the new conformance suite caught (e.g. hatClosed:4/2 in
"Four-on-the-floor" played steady 8ths in the browser but quarter-notes on the
device). Adopt one rule everywhere: every subdivision sounds at normal level,
accents fall ONLY on group starts (the grouping is the accent map).
- pico-cp/app.py, pico-explorer/app.py: off-beat subdivisions sound at normal (1)
instead of resting (0); group-start accenting was already correct.
- src/engine.js: default beatsOn accents group starts only (was: every beat);
laneCfgToStr isDefault check updated to match so round-trips stay idempotent.
- docs + fixtures: document the rule; default-pattern vectors now pass on both.
Audible effect (intended): device subdivided hat/ride lanes gain their off-beat
strokes (now match the web); web stops over-accenting every beat. Lanes with an
explicit =pattern are unchanged. Verified green via node tests/run.mjs.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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>
