Function start_mic_capture 

pub fn start_mic_capture(
    app: AppHandle,
    state: State<'_, MicCaptureState>,
    pipeline_state: State<'_, MicCaptureHandle>,
    mic_id: String,
) -> Result<(), MicError>

Start the microphone capture worker (M-MIC.1 / AUT-278).

Advances MicLifecycle Idle → Starting and spawns a MicCapturePipeline. Re-entrant calls while a session is running cleanly tear down the previous worker (the handle’s install swap drops the old Pipeline, which drops the gst child) before starting the new one.

Errors

Returns MicError::GstFailed when the worker thread can’t spawn (effectively never happens). gst-side failures (no mic attached, permission denied, etc.) are reported via the mic_status snapshot returning to Idle after the worker thread’s error path runs.