A melody / continuous tone (consecutive tone() with no noTone() between) is
back-to-back nonzero-OCR PWM writes with no note-off, so startTone() overwrote
activeOsc without stopping the previous node — oscillators stacked and were
never stopped (reported: created 6, started 6, never stopped 6).
Add a monophonic guard at the top of startTone(): release the live note
(gain ramp + stop) before starting the new one, so a pitch change REPLACES
rather than STACKS. Extract a shared releaseActive(off) helper (also used by
stopTone). Add two melody tests: one asserts starts === stops (no orphans),
monotonic onsets and per-note pitch; one asserts a melody ending without a
trailing noTone() leaves only the final note ringing (stops === starts - 1).
The metronome path is unaffected (each click is an onset→note-off pair, so the
guard never fires there); the three existing metronome tests stay green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Builds on the previous commit; reworks the buzzer audio for glitch-free,
cross-browser playback and adds a metronome quality suite.
- Per-note oscillators with short attack/release ramps, instead of one
long-lived oscillator gated by gain: a fresh fixed frequency per note and no
gain/frequency automation on a persistent node — Firefox in particular clicks
and glitches the pitch otherwise.
- Schedule onsets by their SIMULATED inter-onset spacing (exact, even) with a
light latency hold, instead of a wall-clock average. Turning a control (BPM,
K…) re-locks immediately and the rhythm stays even — no bursts, no overlaps,
no audio drifting away from the display.
- Place each note-off relative to its own onset, preserving the exact click
length from the simulation (the onset scheduler now tracks onsets only).
- Poll PWM every 256 cycles (was 64): finer than any audible pulse, lighter on
the frame loop.
- New src/__tests__/buzzer-metronome.test.ts: drives the buzzer as a metronome
against a controllable audio clock and asserts even spacing, one oscillator
per click with no overlap, correct pitch per metric level, burst absorption,
and a clean re-lock on tempo change.
All simulation-parts + metronome tests pass (57).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>