Initial commit: watch-together phases 0-4 + presence hardening, internet-tested

apps/desktop/test/coord_presence_test.dart

@@ -0,0 +1,59 @@
+import 'dart:async';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:media_kit/media_kit.dart';
+import 'package:sync_relay_core/core.dart';
+import 'package:sync_relay_server/server.dart';
+import 'package:watch_together/src/session/session_coordinator.dart';
+
+Future<void> _poll(
+  FutureOr<bool> Function() cond,
+  String what, {
+  Duration timeout = const Duration(seconds: 15),
+}) async {
+  final deadline = DateTime.now().add(timeout);
+  while (DateTime.now().isBefore(deadline)) {
+    if (await cond()) return;
+    await Future.delayed(const Duration(milliseconds: 200));
+  }
+  fail('timed out waiting for $what');
+}
+
+void main() {
+  test(
+    'dead server clears room state and reconnects instead of freezing',
+    timeout: const Timeout(Duration(minutes: 2)),
+    () async {
+      MediaKit.ensureInitialized();
+      final server = RoomServer(
+          const AppConfig(port: 0, secret: 'presence', name: 'presence'));
+      await server.start();
+      final coord = SessionCoordinator();
+      try {
+        await coord.connect(ConnectParams(
+          host: '127.0.0.1',
+          port: server.boundPort,
+          secret: 'presence',
+          name: 'watcher',
+        ));
+        await coord.playback.player.setVolume(0);
+        await _poll(() => coord.room.peek() != null, 'room state to arrive');
+        expect(coord.reconnecting.peek(), isFalse);
+
+        await server.stop();
+        await _poll(
+          () => coord.reconnecting.peek() == true,
+          'reconnect loop to engage',
+        );
+        await _poll(
+          () => coord.room.peek() == null,
+          'stale room (ghost members) to clear',
+        );
+        coord.cancelReconnect();
+        expect(coord.reconnecting.peek(), isFalse);
+      } finally {
+        await coord.dispose();
+      }
+    },
+  );
+}