AudioRecorder: the stream from startStream never ends when the platform's capture ends #632

Package version

record 6.2.1. The same code is in 7.1.1.

Environment

• OS: Linux (Ubuntu 24.04). The code involved is platform-independent.

Describe the bug

_startRecordStream (lib/src/part/record_stream.dart) re-emits the platform stream through its own broadcast controller. It forwards data (7.x also errors) but not the done event: stream.listen(...) has no onDone, and the controller closes only when the app itself calls stop, cancel, dispose or startStream again. So when a capture ends on the platform's side (the capture process dies, the device goes away, or on Linux another recorder stops it: #631), the stream startStream returned goes silent but never completes, and its owner can't tell its capture has ended.

const RecordConfig(encoder: AudioEncoder.pcm16bits, numChannels: 1)

To Reproduce

Steps to reproduce the behavior:

1. On Linux, start a stream and listen with an onDone:

   final a = AudioRecorder();
   final stream = await a.startStream(
     const RecordConfig(encoder: AudioEncoder.pcm16bits, numChannels: 1),
   );
   stream.listen((_) {}, onDone: () => print('done'));

2. End the capture on the platform's side, here with a second recorder (record_linux: every AudioRecorder shares one parecord process, so starting or disposing any recorder kills another's capture #631):

   final other = AudioRecorder();
   await other.listInputDevices();
   await other.dispose();

3. See: the data stops, and done is never printed.

Expected behavior

When the platform stream is done, the stream from startStream closes too, so the caller's onDone runs; for instance onDone: () => _recordStreamCtrl?.close() in _startRecordStream.

Additional context

Measured with flutter test on the machine above, with RecordPlatform.instance = RecordLinux() (record_linux 1.3.1): no data after the second recorder's dispose, and onDone never ran in the following 1.5 s.