The shared JitterPolicy grew an adaptive target floor — clustered genuine
underruns raise the live target a step at a time up to max_target_ms, a long
quiet spell relaxes it back — and the three Rust rings all run it via
note_read. The Apple ring is the one hand-written mirror, and it mirrored the
shed half but not the growth half: its target was pinned at the 20 ms base
forever. On Wi-Fi that bunches arrivals (power-save is the classic; the field
MacBook report is the symptom), 20 ms is regularly shorter than one delivery
stall, so the ring re-primed through every stall for the whole session —
crackle that never got better, on exactly the client where a Moonlight with a
deeper buffer sounds fine on the same host and network.
The ring now carries the full mirror of note_read: 3 underruns inside a 5 s
window grow the target 10 ms (capped at COREAUDIO's 70), 30 s of quiet gives a
step back, and the write-side hard trim follows the grown target (including
the Rust policy's target+quantum guard, which the mirror also lacked). New
tests pin the mirror to the Rust suite's expectations — growth, relax, the
cap — plus the field scenario end to end: bunched 60 ms deliveries with every
fourth burst 30 ms late converge to a silence-free tail instead of crackling
forever.
enricobuehler
64c92da356