fix(audio): audioFramesForTick counts frames at the realm's declared rate - #275
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fix(audio): audioFramesForTick counts frames at the realm's declared rate#275NathanWalker wants to merge 1 commit into
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…rate The Bresenham floor difference takes the realm's ticks-per-second (default 60, so every existing callsite and tape is byte-identical); the sim sink is constructed at the runner's declared rate. The zero-drift property is now stated and tested over any ticksPerSecond window, and gen-rust pins the formula at a declared 120 alongside the 60 pins. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This was referenced Aug 14, 2026
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The audio deferral from #257, closed before any audio-capable host grows a declared rate:
audioFramesForTickdivided by a literal 60, so a 120 realm would consume PCM at 2x and the zero-drift statement went false.What changed
contracts/spec/audio.ts:audioFramesForTick(rate, tick, ticksPerSecond = 60). The default keeps every existing callsite byte-identical — the 60-window tests now pin the default path. The doc states the generalized property (sum over anyticksPerSecondconsecutive ticks is exactlyrate) and the reachability argument: the pairing invariant refuses a mismatched mount, so formula and realm can only disagree through a host bug, never through a bundle.hosts/sim/audio.ts:createSimAudioSink(ticksPerSecond = 60)— a runner driving a non-60 realm constructs the sink at that rate, keeping one-tick-one-sink.tick()pairing intact.contracts/spec/gen-rust.ts+ regeneratedengine/core/src/spec.rs: the pin now also asserts the formula at a declared 120 (22050 -> 183, 184), and the emitted doc states the rate-parameterized form.Tests
AUDIO_RATESentry, window starts 0/1/59/600, plus the ±1-frame bound.Verification
bun run test11/11 stages green (38.5 s);bunx tsc --noEmitclean;bun tests/contract.tsgreen against the regenerated spec.rs;cargo check -p pocketjs-coreclean (the spec.rs delta is doc text).Deliberately not here: nothing calls this with a non-60 rate yet — the sim can't reach a non-60 realm until
engine/wasmexportsui_set_tick_rate(next PR in this follow-up series).🤖 Generated with Claude Code