watchSyncStatus method

@override Stream<SyncStatus> watchSyncStatus()

The live SyncStatus stream (spec §3.3). Emits the CURRENT status immediately on subscribe (so a re-subscribe after a background gap re-renders at once), then every change coalesced latest-wins. It NEVER completes on a transient fault — a stall is a SyncStatus.stalled EVENT, not an error or EOF.

Implementation

@override
Stream<SyncStatus> watchSyncStatus() {
  subscribeCount++;
  final controller = StreamController<SyncStatus>();
  controller.onListen = () {
    if (failOnSubscribe) {
      controller.addError('fake subscribe failure');
    } else {
      controller.add(_current);
      if (dropAfterReplay) controller.addError('fake post-replay drop');
    }
  };
  controller.onCancel = () {
    cancelCount++;
    if (identical(_active, controller)) _active = null;
  };
  _active = controller;
  return controller.stream;
}