- Built-in Song playlist: every section is now b4 (~4 bars) so Continue rolls one into
the next quickly.
- On-screen timer now counts WITHIN the current segment and resets every time the bar
counter wraps (new _seg_start, reset at each b<n> boundary + on _reset_clock). The
practice-log duration still uses play_start (total). Unified the segment-boundary
handling (timer reset + ramp restart + Continue advance) in _on_new_bar.
- MIDI stutter: display.refresh() BLOCKS on the SPI stream and was delaying the next
beat's note. Cap refresh to ~30Hz and poll the GT911 touch ~30Hz (was every loop) so
the scheduler fires notes on time; visuals lag a few ms (imperceptible).
Verified in harness: Build(b4,rmp92/4/2) bpm 92->96->reset@bar4, seg_start resets only at
the boundary, Continue arms there; edit tests pass; app.mpy builds (C/v6).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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