improved performance and battery usage on older devices

lib/app.dart

@@ -10,6 +10,7 @@ import 'api/marianumconnect/marianumconnect_api.dart';
 import 'api/marianumconnect/queries/get_breakers/get_breakers_response.dart';
 import 'api/marianumconnect/queries/telemetry_heartbeat/telemetry_heartbeat.dart';
 import 'main.dart';
+import 'model/account_data.dart';
 import 'model/data_cleaner.dart';
 import 'notification/notification_controller.dart';
 import 'notification/notification_tasks.dart';
@@ -40,7 +41,6 @@ class App extends StatefulWidget {
 }
 
 class _AppState extends State<App> with WidgetsBindingObserver {
-  late Timer _updateTimings;
   StreamSubscription<dynamic>? _timetableWidgetSync;
   StreamSubscription<RemoteMessage>? _onMessageSub;
   StreamSubscription<RemoteMessage>? _onMessageOpenedAppSub;
@@ -74,7 +74,11 @@ class _AppState extends State<App> with WidgetsBindingObserver {
     bloc.setAutoRefreshInterval(
       talkIsActive ? _chatListActiveInterval : _chatListIdleInterval,
     );
-    if (talkIsActive && refresh) bloc.refresh();
+    // The poll keeps the list current; switching back to the tab shortly
+    // after a fetch doesn't need another one mid tab transition.
+    if (talkIsActive && refresh) {
+      bloc.refreshIfOlderThan(_chatListActiveInterval);
+    }
   }
 
   // Wall-clock throttle rather than Debouncer.throttle: a Timer does not tick
@@ -110,6 +114,7 @@ class _AppState extends State<App> with WidgetsBindingObserver {
       _syncChatListPolling(refresh: false);
       _handlePendingWidgetNavigation();
     } else if (mounted) {
+      context.read<SettingsCubit>().flushSilentSave();
       // Stop polling while backgrounded: a silent refresh failing in the
       // background would otherwise leave an error that flashes on the next
       // resume before the foreground refetch replaces it.
@@ -179,26 +184,42 @@ class _AppState extends State<App> with WidgetsBindingObserver {
       final settingsCubit = context.read<SettingsCubit>();
       final capabilitiesCubit = context.read<CapabilitiesCubit>();
       _timetableWidgetSync?.cancel();
+      // Debounced: a refresh or week swipe emits several times in a row, and
+      // only the settled state is worth mirroring.
       _timetableWidgetSync = timetable.stream.listen((state) {
         final data = state.data;
         if (data is TimetableState && !state.isLoading) {
-          unawaited(
-            WidgetPublisher.publishFromBlocState(
-              data,
-              settings: settingsCubit.val(),
-              isTeacher: capabilitiesCubit.isTeacher,
+          final epoch = AccountData().sessionEpoch;
+          Debouncer.debounce(
+            'widgetPublish',
+            const Duration(seconds: 1),
+            () => unawaited(
+              WidgetPublisher.publishFromBlocState(
+                data,
+                settings: settingsCubit.val(),
+                isTeacher: capabilitiesCubit.isTeacher,
+                epoch: epoch,
+              ),
             ),
           );
         }
       });
-      // Initial publish in case hydrated storage already has data.
+      // Initial publish in case hydrated storage already has data. The widget
+      // still shows its last snapshot, so this waits until the cold-start
+      // frames are done (a fresh bloc emit in the meantime supersedes it).
       final initialData = timetable.state.data;
       if (initialData is TimetableState) {
-        unawaited(
-          WidgetPublisher.publishFromBlocState(
-            initialData,
-            settings: settingsCubit.val(),
-            isTeacher: capabilitiesCubit.isTeacher,
+        final epoch = AccountData().sessionEpoch;
+        Debouncer.debounce(
+          'widgetPublish',
+          const Duration(seconds: 3),
+          () => unawaited(
+            WidgetPublisher.publishFromBlocState(
+              initialData,
+              settings: settingsCubit.val(),
+              isTeacher: capabilitiesCubit.isTeacher,
+              epoch: epoch,
+            ),
           ),
         );
       }
@@ -208,10 +229,6 @@ class _AppState extends State<App> with WidgetsBindingObserver {
       _syncChatListPolling();
     });
 
-    _updateTimings = Timer.periodic(const Duration(seconds: 30), (_) {
-      if (mounted) setState(() {});
-    });
-
     _reportTelemetry();
 
     // A refreshed FCM token invalidates the existing push subscription — the
@@ -250,12 +267,15 @@ class _AppState extends State<App> with WidgetsBindingObserver {
       NotificationController.onAppOpenedByNotification(message, context);
     });
 
-    DataCleaner.cleanOldCache();
+    // Housekeeping only; kept out of the cold-start window.
+    Future<void>.delayed(
+      const Duration(seconds: 20),
+      DataCleaner.cleanOldCache,
+    );
   }
 
   @override
   void dispose() {
-    _updateTimings.cancel();
     _timetableWidgetSync?.cancel();
     _onMessageSub?.cancel();
     _onMessageOpenedAppSub?.cancel();
@@ -271,7 +291,18 @@ class _AppState extends State<App> with WidgetsBindingObserver {
   @override
   Widget build(
     BuildContext context,
-  ) => BlocBuilder<SettingsCubit, model.Settings>(
+  ) => BlocSelector<SettingsCubit, model.Settings, Object>(
+    // Only the module layout shapes the shell; copied values because the
+    // settings object is mutated in place.
+    selector: (settings) {
+      final m = settings.modulesSettings;
+      return (
+        m.moduleOrder.join(','),
+        m.hiddenModules.join(','),
+        m.autoFillBottomBar,
+        m.fixedBottomBarSlots,
+      );
+    },
     builder: (context, _) {
       final bottomBarModules = AppModule.getBottomBarModules(context);
       final totalTabs = bottomBarModules.length + 1;