Local microphone capture

SDK revision 111 adds mic_capture_start, mic_capture_stop and mic_capture_is_active. A watchapp receives signed 16-bit mono PCM at 16 kHz on its app task, in 320-sample (20 ms) callbacks. No audio is sent to the phone by this API. The sample pointer is valid only for the callback. A slow app drops frames once the two-frame kernel queue fills.

static void on_audio(const int16_t *samples, size_t count, void *context) {
  // Consume or copy samples here.
}

static void on_stopped(MicCaptureStopReason reason, void *context) {
  // Capture has ended; a new start is required.
}

MicCaptureStartResult result = mic_capture_start((MicCaptureHandlers) {
  .data = on_audio,
  .stopped = on_stopped,
}, NULL);
// Later: mic_capture_stop();

Declare manifestVersion: 2 and usesPermissions: ["Microphone"] in the pebble block of package.json. The updated phone app syncs only explicitly allowed Microphone decisions for installed apps while its experimental permission system is enabled. Permission granted automatically by a policy does not authorize local capture: enable the permission on the app’s page. Before the first sync, start returns MicCaptureStartErrPermissionDenied and the hardware remains stopped.

The grant is stored on the watch, so capture works after disconnecting the phone or rebooting the watch. An offline watch cannot receive a new grant or revocation until it reconnects. A connected revocation discards queued samples, stops capture and reports MicCaptureStopReasonPermissionRevoked. Disabling the permission system on the phone resyncs app metadata with microphone access denied.

Only foreground watchapps may capture. Watchfaces and workers are rejected. The OS displays its Listening banner; focus loss, app exit and dictation preemption stop capture. Permission updates that retain the current app’s grant do not interrupt it. Local capture and phone streaming share the microphone manager, so only one may run at a time: either start returns busy while the other runs, including while a stream waits for the phone.