fix(tugboat): dedupe hidden/paused into single app_backgrounded

Author: Chinmay-KB

sdks/flutter/packages/tugboat/lib/src/controller.dart

@@ -1090,6 +1090,8 @@ class TugboatReplayController extends ChangeNotifier {
   bool _skipCapture = false;
   bool _captureLifecycleActive = true;
   int _captureLifecycleEpoch = 0;
+  AppLifecycleState? _lastLifecycleState;
+  String? _lastLifecycleEventType;
   int _routeEpoch = 0;
   final Map<String, _RouteCaptureWork> _activeRouteCaptures =
       <String, _RouteCaptureWork>{};
@@ -1655,6 +1657,8 @@ class TugboatReplayController extends ChangeNotifier {
     _clearReleasedInteractions(reason: InteractionRejectionReason.sessionEnd);
     _captureLifecycleActive = true;
     _captureLifecycleEpoch++;
+    _lastLifecycleState = null;
+    _lastLifecycleEventType = null;
     _endSessionFuture = null;
     _clock
       ..reset()
@@ -5151,6 +5155,17 @@ class TugboatReplayController extends ChangeNotifier {
   }
 
   void recordAppLifecycleState(AppLifecycleState state) {
+    final eventType = _appLifecycleEventType(state);
+    // Flutter emits hidden + paused back-to-back on every background
+    // transition (inactive -> hidden -> paused). Both map to
+    // app_backgrounded, so without dedup each background produces two
+    // identical events at the same atMs (see pmkit.raw_events). Drop exact
+    // repeats and consecutive same-type events; a new event is only emitted
+    // on an effective transition (e.g. backgrounded -> foregrounded ->
+    // backgrounded still emits twice, correctly).
+    final isDuplicate =
+        state == _lastLifecycleState ||
+        eventType == _lastLifecycleEventType;
     switch (state) {
       case AppLifecycleState.paused:
       case AppLifecycleState.hidden:
@@ -5186,11 +5201,17 @@ class TugboatReplayController extends ChangeNotifier {
       case AppLifecycleState.inactive:
         break;
     }
+    _lastLifecycleState = state;
+    if (isDuplicate) {
+      _lastLifecycleEventType = eventType;
+      return;
+    }
+    _lastLifecycleEventType = eventType;
     _addEvent(
       TugboatEvent(
         id: _nextId('event'),
         atMs: atMs,
-        type: _appLifecycleEventType(state),
+        type: eventType,
         data: {'state': state.name},
       ),
     );

sdks/flutter/packages/tugboat/test/tugboat_replay_test.dart

@@ -183,6 +183,39 @@ void main() {
     );
   });
 
+  testWidgets('hidden plus paused emits a single app_backgrounded', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        builder: (context, child) =>
+            TugboatReplay.wrapApp(config: _testConfig, child: child!),
+        home: const SizedBox.expand(),
+      ),
+    );
+    await tester.pump();
+
+    final session = TugboatReplay.controller!.session!;
+    final baseline = session.events
+        .where((event) => event.type == 'app_backgrounded')
+        .length;
+    // Flutter delivers hidden + paused back-to-back on every background
+    // transition; both map to app_backgrounded and must coalesce.
+    tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.hidden);
+    await tester.pump();
+    tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.paused);
+    await tester.pump();
+    tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.paused);
+    await tester.pump();
+
+    expect(
+      session.events.where((event) => event.type == 'app_backgrounded'),
+      hasLength(baseline + 1),
+    );
+    tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.resumed);
+    await tester.pump();
+  });
+
   testWidgets('captures initial screenshot and tap interaction anchors', (
     tester,
   ) async {