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Fix SIGABRT on audio interruptions: reject stale render clocks in Deck.play #93

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Merged
sanylax0 merged 1 commit into from
Jul 18, 2026
Merged

Fix SIGABRT on audio interruptions: reject stale render clocks in Deck.play #93

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24 changes: 17 additions & 7 deletions Packages/ContinuityKit/Sources/Playback/Deck.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -136,13 +136,23 @@ final class Deck {
// several ms apart — and nothing ever re-aligns them. Anchor both to one shared
// host-clock start just far enough out to cover the second call.
//
// Only when the node already has a render clock: play(at:) on a node that hasn't
// seen an IO cycle yet (first start after engine build) throws the AVFAudio
// start-time exception and crashes on the play button. On that first start the
// two play() calls run back-to-back on a freshly started engine, which in practice
// lands them on the same quantum; every later start (pause/resume, seek) syncs.
if let render = accompPlayer.lastRenderTime, render.isHostTimeValid {
let start = AVAudioTime(hostTime: render.hostTime + AVAudioTime.hostTime(forSeconds: 0.03))
// Only when the render clock is FRESH, not merely host-time-valid. Two traps here:
// - A node that hasn't seen an IO cycle yet (first start after engine build) has no
// render time → play(at:) throws the AVFAudio start-time exception.
// - After a stop → engine-restart (Siri/interruption recovery, route or config
// changes), lastRenderTime can be *valid but stale* — a host timestamp from the
// pre-interruption timeline. Anchoring to it puts the start time in the PAST,
// which raises the same uncatchable exception → SIGABRT mid-song whenever the
// system pokes the audio environment.
// So: require a render cycle within the last second (proof the engine is actively
// rendering) and anchor to NOW, not to the render timestamp. Otherwise fall back to
// two bare play() calls — on a freshly (re)started engine they land on the same
// quantum in practice.
let now = mach_absolute_time()
if let render = accompPlayer.lastRenderTime, render.isHostTimeValid,
render.hostTime <= now,
now - render.hostTime < AVAudioTime.hostTime(forSeconds: 1.0) {
let start = AVAudioTime(hostTime: now + AVAudioTime.hostTime(forSeconds: 0.03))
accompPlayer.play(at: start)
vocalsPlayer.play(at: start)
} else {
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