Recovery from the 99937c9 audio-device-change commit broadened the
route-change recovery set to "everything except categoryChange /
routeConfigurationChange", which added .override. But .override is
fired by our own applyA2dpSpeakerFallback() -> overrideOutputAudioPort,
which recoverAudio() calls on every recovery. On an A2DP preset
(Stereo Mic / Mono Mic), disconnecting AirPods ping-ponged:
oldDeviceUnavailable -> recoverAudio -> applyA2dpSpeakerFallback
-> overrideOutputAudioPort(.speaker) -> .override routeChange
-> recoverAudio -> applyConfiguration (setCategory resets override)
-> applyA2dpSpeakerFallback -> overrideOutputAudioPort -> .override -> ...
Each iteration also rebuilt the AVAudioEngine via reconfigure() ->
rebuild() -- the audible reinitialize loop + CPU spin. Voice Chat and
Built-in Mic + Speaker were unaffected (applyA2dpSpeakerFallback
early-returns for non-A2DP modes, so no overrideOutputAudioPort call).
Two-part fix (pure Swift iOS-app target; no C ABI / proto / docs changes):
1. AudioSessionManager.handleRouteChange: added .override to the skip
list alongside .categoryChange / .routeConfigurationChange. .override
is only ever fired by our own overrideOutputAudioPort call, so
treating it as a recovery reason is the loop by definition. The
AVAudioEngineConfigurationChange observer in IOSVoiceProcessingEngine
remains as the backstop if an override ever actually stops the engine.
2. IOSAudioRouter.applyA2dpSpeakerFallback: made idempotent via a
lastAppliedOutputOverride tracker that skips the redundant
overrideOutputAudioPort call when the desired state (.none for
external output present, .speaker otherwise) already matches. Reset
to nil at the top of applyConfiguration() (setCategory can reset the
override) and on a failed call. Defense-in-depth on top of fix 1.
Build: xcodebuild -project clients/apple/iOS/VoiceCatiOS.xcodeproj
-scheme VoiceCatiOS -destination 'generic/platform=iOS' build green
(Xcode 26.5 / iOS 18.0).
Talon
9a20953c08