improved performance and battery usage on older devices

lib/api/cache_store.dart

@@ -0,0 +1,185 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:flutter/foundation.dart';
+import 'package:path_provider/path_provider.dart';
+
+/// One cached response: the raw JSON payload and when it was stored.
+class CacheEntry {
+  final String json;
+  final int lastUpdate;
+
+  const CacheEntry({required this.json, required this.lastUpdate});
+}
+
+/// File-per-key store behind [RequestCache] and friends.
+///
+/// Replaces `localstore` for response caching: localstore reads and decodes
+/// the entire collection synchronously on first access, keeps every document
+/// in memory for the whole session and JSON-encodes payloads a second time.
+/// Here every access is async and touches exactly one file, and the payload is
+/// stored verbatim behind a one-line header (`<lastUpdate>\n<json>`).
+class CacheStore {
+  CacheStore._();
+
+  static final CacheStore instance = CacheStore._();
+
+  /// Payloads above this size are decoded on a background isolate.
+  static const int isolateDecodeThreshold = 64 * 1024;
+
+  Future<Directory>? _dir;
+  final Map<String, Future<void>> _writes = {};
+
+  Future<Directory> _directory() => _dir ??= () async {
+    final base = await getApplicationCacheDirectory();
+    final dir = Directory('${base.path}/request_cache');
+    await dir.create(recursive: true);
+    return dir;
+  }();
+
+  Future<File> _file(String key) async =>
+      File('${(await _directory()).path}/${_safeName(key)}');
+
+  /// Keys are internal ids (`nc-chat-<token>`, `wd-folder-<md5>`); only path
+  /// separators would be a problem in a file name.
+  static String _safeName(String key) => key.replaceAll(RegExp(r'[/\\]'), '_');
+
+  Future<CacheEntry?> read(String key) async {
+    try {
+      await _writes[key];
+      return parse(await (await _file(key)).readAsString());
+    } on Object {
+      // Missing (PathNotFoundException) or unreadable: a cache miss.
+      return null;
+    }
+  }
+
+  /// All entries whose key starts with [prefix], read concurrently.
+  Future<Map<String, CacheEntry>> readAll({String prefix = ''}) async {
+    final keys = await this.keys(prefix: prefix);
+    final entries = await Future.wait(keys.map(read));
+    return {for (var i = 0; i < keys.length; i++) keys[i]: ?entries[i]};
+  }
+
+  Future<void> write(String key, String json) {
+    final previous = _writes[key] ?? Future<void>.value();
+    late final Future<void> current;
+    current = previous.then((_) => _write(key, json)).whenComplete(() {
+      if (identical(_writes[key], current)) _writes.remove(key);
+    });
+    return _writes[key] = current;
+  }
+
+  Future<void> _write(String key, String json) async {
+    try {
+      final file = await _file(key);
+      // Write-then-rename so a reader (or the widget background isolate)
+      // never sees a half-written file.
+      final tmp = File('${file.path}.tmp');
+      await tmp.writeAsString(
+        '${DateTime.now().millisecondsSinceEpoch}\n$json',
+        flush: true,
+      );
+      await tmp.rename(file.path);
+    } on Object catch (e) {
+      debugPrint('CacheStore.write($key) failed: $e');
+    }
+  }
+
+  Future<void> delete(String key) async {
+    try {
+      await _writes[key];
+      await (await _file(key)).delete();
+    } on Object {
+      // A missing or locked file is as good as deleted for a cache.
+    }
+  }
+
+  Future<void> clear() async {
+    try {
+      final dir = await _directory();
+      if (dir.existsSync()) await dir.delete(recursive: true);
+    } on Object catch (e) {
+      debugPrint('CacheStore.clear failed: $e');
+    }
+    _dir = null;
+  }
+
+  /// All stored keys, optionally filtered by [prefix].
+  Future<List<String>> keys({String prefix = ''}) async {
+    try {
+      final dir = await _directory();
+      return [
+        await for (final entity in dir.list())
+          if (entity is File && !entity.path.endsWith('.tmp'))
+            if (entity.uri.pathSegments.last case final name
+                when name.startsWith(prefix))
+              name,
+      ];
+    } on Object {
+      return const [];
+    }
+  }
+
+  /// Removes entries not written for [maxAge], judged by file mtime so nothing
+  /// has to be read or decoded.
+  Future<void> deleteOlderThan(Duration maxAge) async {
+    try {
+      final dir = await _directory();
+      final cutoff = DateTime.now().subtract(maxAge);
+      await for (final entity in dir.list()) {
+        if (entity is! File) continue;
+        // ignore: avoid_slow_async_io
+        final modified = (await entity.stat()).modified;
+        if (modified.isBefore(cutoff)) await entity.delete();
+      }
+    } on Object catch (e) {
+      debugPrint('CacheStore.deleteOlderThan failed: $e');
+    }
+  }
+
+  /// Total size of all entries in bytes.
+  Future<int> totalSize() async {
+    try {
+      final dir = await _directory();
+      var sum = 0;
+      await for (final entity in dir.list()) {
+        if (entity is File) sum += await entity.length();
+      }
+      return sum;
+    } on Object {
+      return 0;
+    }
+  }
+
+  /// Parses the stored file format; public for tests.
+  static CacheEntry? parse(String raw) {
+    final newline = raw.indexOf('\n');
+    if (newline < 0) return null;
+    final lastUpdate = int.tryParse(raw.substring(0, newline));
+    if (lastUpdate == null) return null;
+    return CacheEntry(json: raw.substring(newline + 1), lastUpdate: lastUpdate);
+  }
+
+  /// Decodes a cached payload, off the UI isolate when it is large.
+  static Future<Map<String, dynamic>> decode(String json) =>
+      json.length > isolateDecodeThreshold
+      ? compute(_decodeMap, json)
+      : Future.value(_decodeMap(json));
+
+  static Map<String, dynamic> _decodeMap(String json) =>
+      jsonDecode(json) as Map<String, dynamic>;
+
+  /// Deletes the directory the old localstore-based cache lived in. It is
+  /// never read again and would otherwise linger with up to 200 days of data.
+  static Future<void> deleteLegacyLocalstoreCache() async {
+    try {
+      final docs = await getApplicationDocumentsDirectory();
+      final legacy = Directory('${docs.path}/MarianumMobile');
+      if (legacy.existsSync()) await legacy.delete(recursive: true);
+    } on Object catch (e) {
+      debugPrint('Legacy cache cleanup failed: $e');
+    }
+  }
+}

lib/api/marianumcloud/talk/chat/get_chat_cache.dart

@@ -17,7 +17,7 @@ class GetChatCache extends SimpleCache<GetChatResponse> {
              lookIntoFuture: GetChatParamsSwitch.off,
              setReadMarker: GetChatParamsSwitch.on,
              // Small initial page; also the per-chat offline snapshot written to
-             // localstore. Older messages are paged in on scroll-up via
+             // the request cache. Older messages are paged in on scroll-up via
              // GetChatHistory. Keep in sync with ChatBloc's _kInitialPageSize.
              limit: 50,
            ),

lib/api/marianumcloud/talk/chat/get_chat_history.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 
 import '../../../errors/server_exception.dart';
@@ -45,8 +46,10 @@ class GetChatHistory {
     final status = response.statusCode;
     if (status == 304) return null;
     if (status >= 200 && status < 300) {
-      return GetChatResponse.fromJson(NextcloudOcs.decode(response.body))
-        ..headers = response.headers;
+      // A page holds up to 200 messages and lands while the user is scrolling;
+      // decoding it on the UI isolate stalls the fling.
+      final parsed = await compute(_parseChatResponse, response.body);
+      return parsed..headers = response.headers;
     }
     throw ServerException(
       statusCode: status,
@@ -54,3 +57,6 @@ class GetChatHistory {
     );
   }
 }
+
+GetChatResponse _parseChatResponse(String body) =>
+    GetChatResponse.fromJson(NextcloudOcs.decode(body));

lib/api/marianumcloud/talk/room/get_room.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 
 import '../../nextcloud_ocs.dart';
@@ -10,8 +11,12 @@ class GetRoom extends TalkApi<GetRoomResponse> {
   GetRoom(this.params) : super('v4/room', null, getParameters: params.toJson());
 
   @override
-  GetRoomResponse assemble(String raw) =>
-      GetRoomResponse.fromJson(NextcloudOcs.decode(raw));
+  GetRoomResponse assemble(String raw) => _parseRooms(raw);
+
+  // The room list with status is 100–250 KB and polled every 15–60 s.
+  @override
+  Future<GetRoomResponse> assembleAsync(String raw) =>
+      compute(_parseRooms, raw);
 
   @override
   Future<http.Response> request(
@@ -20,3 +25,6 @@ class GetRoom extends TalkApi<GetRoomResponse> {
     Map<String, String>? headers,
   ) => http.get(uri, headers: headers);
 }
+
+GetRoomResponse _parseRooms(String raw) =>
+    GetRoomResponse.fromJson(NextcloudOcs.decode(raw));

lib/api/marianumcloud/talk/talk_api.dart

@@ -30,6 +30,10 @@ abstract class TalkApi<T extends ApiResponse?> {
   );
   T assemble(String raw);
 
+  /// Override to parse large payloads off the UI isolate (e.g. via `compute`
+  /// with a top-level parser); defaults to the synchronous [assemble].
+  Future<T> assembleAsync(String raw) async => assemble(raw);
+
   Future<T> run() async {
     final endpoint = NextcloudOcs.uri(
       'apps/spreed/api/$path',
@@ -69,7 +73,7 @@ abstract class TalkApi<T extends ApiResponse?> {
     }
 
     try {
-      final assembled = assemble(data.body);
+      final assembled = await assembleAsync(data.body);
       assembled?.headers = data.headers;
       return assembled;
     } catch (e) {

lib/api/marianumcloud/webdav/queries/list_files/cacheable_file.dart

@@ -29,6 +29,19 @@ class CacheableFile {
   /// file/folder in the list. Nullable so older cached entries decode fine.
   bool? isSharedWithMe;
 
+  /// Lower-cased [name] for sorting/filtering, cached because comparators
+  /// call it for every comparison (name is mutable, hence the identity check).
+  String get lowerName {
+    if (!identical(_lowerNameFor, name)) {
+      _lowerNameFor = name;
+      _lowerName = name.toLowerCase();
+    }
+    return _lowerName;
+  }
+
+  String? _lowerNameFor;
+  String _lowerName = '';
+
   CacheableFile({
     required this.path,
     required this.isDirectory,

lib/api/marianumcloud/webdav/queries/list_files/list_files_cache.dart

@@ -1,9 +1,9 @@
 import 'dart:convert';
 
 import 'package:crypto/crypto.dart';
-import 'package:localstore/localstore.dart';
 
 import '../../../../../utils/cache_invalidation_bus.dart';
+import '../../../../cache_store.dart';
 import '../../../../request_cache.dart';
 import 'list_files.dart';
 import 'list_files_params.dart';
@@ -43,14 +43,11 @@ class ListFilesCache extends SimpleCache<ListFilesResponse> {
   /// (slow) root listing is already populated by the time the user
   /// navigates to the Files module.
   ///
-  /// No-ops when a cached root payload is already present in localstore —
+  /// No-ops when a cached root payload is already present in the cache —
   /// the regular TTL handling in [RequestCache] takes over from there.
   static Future<void> prefetchRootListing() async {
     const rootPath = '';
-    final cached = await Localstore.instance
-        .collection(RequestCache.collection)
-        .doc(_documentId(rootPath))
-        .get();
+    final cached = await CacheStore.instance.read(_documentId(rootPath));
     if (cached != null) return;
     // Drive the same code path as a regular fetch so the result lands in
     // the cache; we don't care about the in-memory callback here.
@@ -69,10 +66,7 @@ class ListFilesCache extends SimpleCache<ListFilesResponse> {
   /// `_FilesView` for that path via [CacheInvalidationBus] so it refetches
   /// even while it is sitting in the background of the navigation stack.
   static Future<void> invalidate(String path) async {
-    await Localstore.instance
-        .collection(RequestCache.collection)
-        .doc(_documentId(path))
-        .delete();
+    await CacheStore.instance.delete(_documentId(path));
     CacheInvalidationBus.notifyListFiles(path);
   }
 }

lib/api/marianumconnect/queries/timetable_custom_events/custom_events_migration.dart

@@ -1,6 +1,6 @@
 import 'dart:developer';
 
-import 'package:localstore/localstore.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 
 import '../../../../model/account_data.dart';
 import '../../../demo/demo_mode.dart';
@@ -21,9 +21,7 @@ import 'timetable_custom_events_add.dart';
 /// failure only sees the events that were not yet moved, so nothing is
 /// duplicated. The flag is set only once MHSL reports no remaining events.
 class CustomEventsMigration {
-  static const String _collection = 'MarianumMobile';
-  static const String _document = 'customEventsMigration';
-  static const String _doneKey = 'migratedToMc';
+  static const String _doneKey = 'customEventsMigratedToMc';
 
   const CustomEventsMigration._();
 
@@ -57,17 +55,11 @@ class CustomEventsMigration {
     }
   }
 
-  static Future<bool> _isDone() async {
-    final data = await Localstore.instance
-        .collection(_collection)
-        .doc(_document)
-        .get();
-    return data != null && data[_doneKey] == true;
-  }
+  // SharedPreferences, like the old cache document, is cleared on sign-out,
+  // so the next account runs its own migration.
+  static Future<bool> _isDone() async =>
+      (await SharedPreferences.getInstance()).getBool(_doneKey) ?? false;
 
-  static Future<void> _markDone() async {
-    await Localstore.instance.collection(_collection).doc(_document).set({
-      _doneKey: true,
-    });
-  }
+  static Future<void> _markDone() async =>
+      (await SharedPreferences.getInstance()).setBool(_doneKey, true);
 }

lib/api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart

@@ -76,10 +76,17 @@ class McTimetableEntry {
 
   /// Combines the calendar date with the hour/minute portion of [startTime]
   /// (which carries a 1970 placeholder date) into a real DateTime.
-  DateTime get startDateTime =>
+  DateTime get startDateTime => _startDateTime;
+
+  DateTime get endDateTime => _endDateTime;
+
+  // Cached (private, so json_serializable ignores them): sorting and lesson
+  // merging read these per comparison, and every local DateTime construction
+  // does a timezone lookup.
+  late final DateTime _startDateTime =
       DateTime(date.year, date.month, date.day, startTime.hour, startTime.minute);
 
-  DateTime get endDateTime =>
+  late final DateTime _endDateTime =
       DateTime(date.year, date.month, date.day, endTime.hour, endTime.minute);
 
   static DateTime _dateFromJson(String raw) => DateTime.parse(raw);

lib/api/request_cache.dart

@@ -1,10 +1,9 @@
 import 'dart:async';
 import 'dart:convert';
 
-import 'package:localstore/localstore.dart';
-
 import '../model/account_data.dart';
 import 'api_response.dart';
+import 'cache_store.dart';
 import 'errors/parse_exception.dart';
 import 'errors/stale_session_exception.dart';
 
@@ -14,12 +13,10 @@ abstract class RequestCache<T extends ApiResponse?> {
   static const int cacheHour = 60 * 60;
   static const int cacheDay = 60 * 60 * 24;
 
-  static String collection = 'MarianumMobile';
-
   int maxCacheTime;
   void Function(T)? onUpdate;
 
-  /// Called only when [start] finds a cached payload in localstore. Use this
+  /// Called only when [start] finds a cached payload in the [CacheStore]. Use this
   /// (instead of [onUpdate]) when callers need to distinguish stale-but-fast
   /// cache hits from authoritative network responses.
   void Function(T)? onCacheData;
@@ -52,17 +49,33 @@ abstract class RequestCache<T extends ApiResponse?> {
   Future<void> start(String document) async {
     final epoch = AccountData().sessionEpoch;
     try {
-      final tableData = await Localstore.instance
-          .collection(collection)
-          .doc(document)
-          .get();
-      if (tableData != null) {
-        final cached = onLocalData(tableData['json'] as String);
+      final entry = await CacheStore.instance.read(document);
+      var lastUpdate = entry?.lastUpdate ?? 0;
+      T? cached;
+      if (entry != null) {
+        try {
+          cached = fromCacheJson(await CacheStore.decode(entry.json));
+        } on Object {
+          // A payload from an older model version: treat it as a miss.
+          await CacheStore.instance.delete(document);
+          lastUpdate = 0;
+        }
+      }
+      if (cached != null) {
         onUpdate?.call(cached);
         onCacheData?.call(cached);
       }
+      await _load(document, epoch, lastUpdate: lastUpdate);
+    } finally {
+      if (!_ready.isCompleted) _ready.complete();
+    }
+  }
 
-      final lastUpdate = (tableData?['lastupdate'] as num?) ?? 0;
+  Future<void> _load(
+    String document,
+    int epoch, {
+    required int lastUpdate,
+  }) async {
     if (DateTime.now().millisecondsSinceEpoch - (maxCacheTime * 1000) <
         lastUpdate) {
       if (renew == null || !renew!) return;
@@ -70,7 +83,7 @@ abstract class RequestCache<T extends ApiResponse?> {
 
     try {
       final newValue = await onLoad();
-        // The collection is shared, so a late response of a signed-out
+      // The cache is shared, so a late response of a signed-out
       // account would otherwise be cached for the next one.
       if (!AccountData().isCurrentSession(epoch)) {
         onError(const StaleSessionException());
@@ -78,21 +91,13 @@ abstract class RequestCache<T extends ApiResponse?> {
       }
       onUpdate?.call(newValue);
       onNetworkData?.call(newValue);
-        unawaited(
-          Localstore.instance.collection(collection).doc(document).set({
-            'json': jsonEncode(newValue),
-            'lastupdate': DateTime.now().millisecondsSinceEpoch,
-          }),
-        );
+      unawaited(CacheStore.instance.write(document, jsonEncode(newValue)));
     } on Exception catch (e) {
       onError(e);
     }
-    } finally {
-      if (!_ready.isCompleted) _ready.complete();
-    }
   }
 
-  T onLocalData(String json);
+  T fromCacheJson(Map<String, dynamic> json);
   Future<T> onLoad();
 }
 
@@ -126,8 +131,7 @@ class SimpleCache<T extends ApiResponse?> extends RequestCache<T> {
   Future<T> onLoad() => _loader();
 
   @override
-  T onLocalData(String json) =>
-      _fromJson(jsonDecode(json) as Map<String, dynamic>);
+  T fromCacheJson(Map<String, dynamic> json) => _fromJson(json);
 }
 
 /// Captures the latest cache payload (cached or network) and rethrows the

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(
+          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(
+        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;

lib/extensions/text.dart

@@ -1,16 +1,29 @@
 import 'package:flutter/material.dart';
 
 extension TextExt on Text {
-  Size get size {
-    final textPainter = TextPainter(
+  /// Single-line width as rendered in [context] (honours the text scaler).
+  /// Memoised: chat bubbles measure the same few names and times over and
+  /// over, and every measurement is a full paragraph layout.
+  double measuredWidth(BuildContext context) {
+    final scaler = MediaQuery.textScalerOf(context);
+    final key = (data, style, scaler);
+    final cached = _widthCache[key];
+    if (cached != null) return cached;
+    final painter = TextPainter(
       text: TextSpan(text: data, style: style),
       maxLines: 1,
       textDirection: TextDirection.ltr,
-    )..layout(minWidth: 0, maxWidth: double.infinity);
-    return textPainter.size;
+      textScaler: scaler,
+    )..layout();
+    final width = painter.width;
+    painter.dispose();
+    if (_widthCache.length >= 512) _widthCache.clear();
+    return _widthCache[key] = width;
   }
 }
 
+final Map<(String?, TextStyle?, TextScaler), double> _widthCache = {};
+
 /// Returns the first non-empty (after trim) entry, or '' if none match.
 String firstNonEmpty(List<String?> values) {
   for (final v in values) {

lib/main.dart

@@ -167,6 +167,12 @@ Future<void> main() async {
   await Future.wait(initialisationTasks);
   log('app initialisation done!');
 
+  // Independent of the notification setup below, so it runs alongside it.
+  final widgetSyncInit = _startupStep(
+    'widget sync',
+    WidgetSync.ensureInitialized,
+  );
+
   // Local notifications: init the plugin (with tap/action callbacks) and the
   // Android channels, then register the FCM background isolate handler that
   // decrypts and renders Nextcloud pushes while the app is not in foreground.
@@ -186,9 +192,9 @@ Future<void> main() async {
     ),
   );
 
-  // Wire up the home-screen widget bridge before runApp so any widget render
-  // triggered during startup hits initialised native storage.
-  await _startupStep('widget sync', WidgetSync.ensureInitialized);
+  // The home-screen widget bridge must be ready before runApp so any widget
+  // render triggered during startup hits initialised native storage.
+  await widgetSyncInit;
   unawaited(
     WidgetBackgroundTask.initialize().onError(
       (e, _) => log('Workmanager init failed: $e'),
@@ -271,6 +277,10 @@ class Main extends StatefulWidget {
 }
 
 class _MainState extends State<Main> {
+  final List<NavigatorObserver> _navigatorObservers = [
+    AppRoutes.chatRouteObserver,
+    DownloadRouteObserver(),
+  ];
   bool _showPostLoginSplash = false;
   bool _appMounted = true;
   late AccountStatus _lastStatus;
@@ -364,39 +374,45 @@ class _MainState extends State<Main> {
   @override
   Widget build(BuildContext context) => Directionality(
     textDirection: TextDirection.ltr,
-    child: BlocBuilder<SettingsCubit, Settings>(
-      builder: (context, settings) {
-        final devToolsSettings = settings.devToolsSettings;
+    // Selects only what the root uses: Settings is mutated in place and
+    // re-emitted as a fresh instance on every write, so a plain BlocBuilder
+    // would rebuild MaterialApp (and every route) for unrelated settings.
+    child: BlocSelector<SettingsCubit, Settings, _RootSettings>(
+      selector: (settings) => (
+        appTheme: settings.appTheme,
+        mcBaseUrl: settings.devToolsSettings.resolveMarianumConnectBaseUrl(),
+        notificationsEnabled: settings.notificationSettings.enabled,
+        showPerformanceOverlay:
+            settings.devToolsSettings.showPerformanceOverlay,
+        checkerboardOffscreenLayers:
+            settings.devToolsSettings.checkerboardOffscreenLayers,
+        checkerboardRasterCacheImages:
+            settings.devToolsSettings.checkerboardRasterCacheImages,
+      ),
+      builder: (context, root) {
         // Keep the MC dio singleton aligned with the currently selected
         // endpoint (live / beta / custom). Idempotent when the URL is
-        // unchanged so it's safe to call on every rebuild. Mirrored into
-        // WidgetSync so the background isolate refreshes against the same
-        // endpoint.
-        final mcBaseUrl = devToolsSettings.resolveMarianumConnectBaseUrl();
-        MarianumConnectEndpoint.update(mcBaseUrl);
-        unawaited(WidgetSync.setMarianumConnectBaseUrl(mcBaseUrl));
+        // unchanged. Mirrored into WidgetSync so the background isolate
+        // refreshes against the same endpoint.
+        MarianumConnectEndpoint.update(root.mcBaseUrl);
+        unawaited(WidgetSync.setMarianumConnectBaseUrl(root.mcBaseUrl));
         // Mirror the notification toggle into group-scoped storage so the FCM
         // background isolate and the iOS NSE can suppress rendering when off.
         unawaited(
           const PushRegistrationStore().setNotificationsEnabled(
-            settings.notificationSettings.enabled,
+            root.notificationsEnabled,
           ),
         );
         return MaterialApp(
-          showPerformanceOverlay: devToolsSettings.showPerformanceOverlay,
-          checkerboardOffscreenLayers:
-              devToolsSettings.checkerboardOffscreenLayers,
-          checkerboardRasterCacheImages:
-              devToolsSettings.checkerboardRasterCacheImages,
+          showPerformanceOverlay: root.showPerformanceOverlay,
+          checkerboardOffscreenLayers: root.checkerboardOffscreenLayers,
+          checkerboardRasterCacheImages: root.checkerboardRasterCacheImages,
           debugShowCheckedModeBanner: false,
           navigatorKey: AppRoutes.rootNavigatorKey,
           // Used by ChatView.didPopNext to reclaim the global ChatBloc.
           // DownloadRouteObserver tracks full-page navigations so the downloads
           // chip only surfaces once the user leaves the screen they started on.
-          navigatorObservers: [
-            AppRoutes.chatRouteObserver,
-            DownloadRouteObserver(),
-          ],
+          navigatorObservers: _navigatorObservers,
           localizationsDelegates: const [
             ...GlobalMaterialLocalizations.delegates,
             GlobalWidgetsLocalizations.delegate,
@@ -404,7 +420,7 @@ class _MainState extends State<Main> {
           supportedLocales: const [Locale('de'), Locale('en')],
           locale: const Locale('de'),
           title: 'Marianum Fulda',
-          themeMode: settings.appTheme,
+          themeMode: root.appTheme,
           theme: LightAppTheme.theme,
           darkTheme: DarkAppTheme.theme,
           // Brand-colored backdrop behind every route. During the logout
@@ -527,3 +543,12 @@ class _MainState extends State<Main> {
     ),
   );
 }
+
+typedef _RootSettings = ({
+  ThemeMode appTheme,
+  String mcBaseUrl,
+  bool notificationsEnabled,
+  bool showPerformanceOverlay,
+  bool checkerboardOffscreenLayers,
+  bool checkerboardRasterCacheImages,
+});

lib/model/account_data.dart

@@ -228,16 +228,25 @@ class AccountData {
   Future<void> _migrateAndLoad() async {
     await _migrateFromLegacyStorage();
     await _migrateKeychainAccessibility();
-    _username = await _secureStorage.read(key: _usernameField);
-    _password = await _secureStorage.read(key: _passwordField);
-    _isDemo = (await _secureStorage.read(key: _demoField)) == 'true';
-    _usesLoginFlow =
-        (await _secureStorage.read(key: _loginFlowField)) == 'true';
+    // Independent keystore reads, each a platform-channel round trip with
+    // decryption: issued together since this gates the first frame.
+    final (username, password, demo, loginFlow) = await (
+      _secureStorage.read(key: _usernameField),
+      _secureStorage.read(key: _passwordField),
+      _secureStorage.read(key: _demoField),
+      _secureStorage.read(key: _loginFlowField),
+    ).wait;
+    _username = username;
+    _password = password;
+    _isDemo = demo == 'true';
+    _usesLoginFlow = loginFlow == 'true';
     try {
-      _appPassword = await pushSecureStorage.read(key: _appPasswordField);
-      _appPasswordTalk = await pushSecureStorage.read(
-        key: _appPasswordTalkField,
-      );
+      final (appPassword, appPasswordTalk) = await (
+        pushSecureStorage.read(key: _appPasswordField),
+        pushSecureStorage.read(key: _appPasswordTalkField),
+      ).wait;
+      _appPassword = appPassword;
+      _appPasswordTalk = appPasswordTalk;
     } on Object {
       _appPassword = null;
       _appPasswordTalk = null;

lib/model/data_cleaner.dart

@@ -1,24 +1,8 @@
-import 'package:localstore/localstore.dart';
-
-import '../api/request_cache.dart';
+import '../api/cache_store.dart';
 
 class DataCleaner {
   static Future<void> cleanOldCache() async {
-    final cacheData = await Localstore.instance
-        .collection(RequestCache.collection)
-        .get();
-    cacheData?.forEach((key, value) async {
-      final lastUpdate = DateTime.fromMillisecondsSinceEpoch(
-        ((value['lastupdate'] as num?) ?? 0).toInt(),
-      );
-      if (DateTime.now()
-          .subtract(const Duration(days: 200))
-          .isAfter(lastUpdate)) {
-        await Localstore.instance
-            .collection(RequestCache.collection)
-            .doc(key.split('/').last)
-            .delete();
-      }
-    });
+    await CacheStore.deleteLegacyLocalstoreCache();
+    await CacheStore.instance.deleteOlderThan(const Duration(days: 200));
   }
 }

lib/model/session_wipe.dart

@@ -8,6 +8,7 @@ import 'package:hydrated_bloc/hydrated_bloc.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
+import '../api/cache_store.dart';
 import '../api/marianumcloud/talk/share_files_to_chat.dart';
 import '../background/widget_background_task.dart';
 import '../notification/notification_service.dart';
@@ -26,7 +27,6 @@ import '../state/app/modules/timetable/bloc/timetable_bloc.dart';
 import '../utils/app_paths.dart';
 import '../utils/downloads/download_manager.dart';
 import '../utils/file_clipboard.dart';
-import '../widget/debug/cache_view.dart';
 import '../widget_data/widget_sync.dart';
 
 /// Removes everything the signed-out account left on the device. Every step
@@ -98,7 +98,7 @@ abstract final class SessionWipe {
       await (await SharedPreferences.getInstance()).clear();
     });
     await _stepAsync('hydrated storage', HydratedBloc.storage.clear);
-    await _stepAsync('request cache', const CacheView().clear);
+    await _stepAsync('request cache', CacheStore.instance.clear);
     await _stepAsync('chat background', () async {
       final image = File(AppPaths.chatBackgroundImage);
       if (image.existsSync()) await image.delete();

lib/notification/notification_controller.dart

@@ -7,6 +7,8 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import '../push/push_message_handler.dart';
 import '../routing/app_routes.dart';
 import '../state/app/modules/chat/bloc/chat_bloc.dart';
+import '../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
+import '../utils/debouncer.dart';
 import '../widget/debug/debug_tile.dart';
 import '../widget/debug/json_viewer.dart';
 import '../widget/info_dialog.dart';
@@ -35,7 +37,14 @@ class NotificationController {
     );
     await NotificationTasks.refreshBadge();
     if (!context.mounted) return;
-    NotificationTasks.updateProviders(context);
+    // A busy group chat delivers pushes in bursts; one silent refresh after
+    // the burst replaces a full room-list fetch per message.
+    final chatList = context.read<ChatListBloc>();
+    Debouncer.debounce(
+      'pushChatListRefresh',
+      const Duration(seconds: 1),
+      () => chatList.refresh(silent: true),
+    );
   }
 
   static Future<void> onAppOpenedByNotification(

lib/push/push_decryptor.dart

@@ -1,7 +1,7 @@
 import 'dart:convert';
-import 'dart:typed_data';
 
 import 'package:crypton/crypton.dart';
+import 'package:flutter/foundation.dart';
 import 'package:pointycastle/export.dart' as pc;
 
 import 'push_subject.dart';
@@ -25,6 +25,14 @@ class PushDecryptor {
 
   const PushDecryptor({required this.devicePrivateKey, this.serverPublicKey});
 
+  /// [verify] + [decrypt] on a background isolate: pure-Dart RSA-2048 (with
+  /// the OAEP → PKCS#1 fallback) takes tens of ms up to >100 ms on older
+  /// phones, which would otherwise land on the UI thread for every push.
+  Future<({bool verified, PushSubject? subject})> verifyAndDecryptInBackground(
+    String subjectBase64,
+    String signatureBase64,
+  ) => compute(_verifyAndDecrypt, (this, subjectBase64, signatureBase64));
+
   /// Returns true when [signatureBase64] is a valid server signature over the
   /// encrypted subject. Returns true when no server key is configured (the
   /// proxy already verified the signature before forwarding).
@@ -75,3 +83,13 @@ class PushDecryptor {
     }
   }
 }
+
+({bool verified, PushSubject? subject}) _verifyAndDecrypt(
+  (PushDecryptor, String, String) args,
+) {
+  final (decryptor, subject, signature) = args;
+  if (!decryptor.verify(subject, signature)) {
+    return (verified: false, subject: null);
+  }
+  return (verified: true, subject: decryptor.decrypt(subject));
+}

lib/push/push_message_handler.dart

@@ -178,11 +178,15 @@ class PushMessageHandler {
       devicePrivateKey: privateKey,
       serverPublicKey: serverPublicKey,
     );
-    if (!decryptor.verify(subjectBase64, signatureBase64)) {
+    final result = await decryptor.verifyAndDecryptInBackground(
+      subjectBase64,
+      signatureBase64,
+    );
+    if (!result.verified) {
       log('Push: signature verification failed');
       return;
     }
-    final subject = decryptor.decrypt(subjectBase64);
+    final subject = result.subject;
     if (subject == null) {
       log('Push: could not decrypt subject');
       return;

lib/state/app/infrastructure/loadable_state/bloc/loadable_state_bloc.dart

@@ -20,10 +20,15 @@ class LoadableStateBloc extends Bloc<LoadableStateEvent, LoadableStateState>
 
   LoadableStateBloc() : super(const LoadableStateState(connections: null)) {
     on<ConnectivityChanged>((event, emit) {
+      // Only a real reconnect (or a resume) warrants a refetch: the initial
+      // status after mount and Wi-Fi ↔ mobile handovers would otherwise
+      // reload an already loaded page for nothing.
+      final wasOffline = connectivityStatusKnown() && !isConnected();
       emit(event.state);
-      if (connectivityStatusKnown() && isConnected()) {
-        if (reFetch == null) return;
-        reFetch!();
+      if ((wasOffline || event.fromResume) &&
+          connectivityStatusKnown() &&
+          isConnected()) {
+        reFetch?.call();
       }
     });
 
@@ -54,7 +59,12 @@ class LoadableStateBloc extends Bloc<LoadableStateEvent, LoadableStateState>
     unawaited(
       Connectivity().checkConnectivity().then((result) {
         if (isClosed) return;
-        add(ConnectivityChanged(LoadableStateState(connections: result)));
+        add(
+          ConnectivityChanged(
+            LoadableStateState(connections: result),
+            fromResume: true,
+          ),
+        );
       }),
     );
   }

lib/state/app/infrastructure/loadable_state/bloc/loadable_state_event.dart

@@ -4,5 +4,10 @@ sealed class LoadableStateEvent {}
 
 final class ConnectivityChanged extends LoadableStateEvent {
   final LoadableStateState state;
-  ConnectivityChanged(this.state);
+
+  /// Re-check after the app came back to the foreground: refetches whenever
+  /// online, not only on an offline → online transition.
+  final bool fromResume;
+
+  ConnectivityChanged(this.state, {this.fromResume = false});
 }

lib/state/app/infrastructure/loadable_state/view/loadable_state_consumer.dart

@@ -69,7 +69,7 @@ class LoadableStateConsumer<
     // null mid-refetch, and toggling the RefreshIndicator on that signal would
     // rebuild the tree under the ListView and reset its scroll position.
     final content = SizedBox(
-      height: MediaQuery.of(context).size.height,
+      height: MediaQuery.sizeOf(context).height,
       child: hasContent
           ? child(typedData as TState, isLoading)
           : const SizedBox.shrink(),

lib/state/app/infrastructure/loadable_state/view/loadable_state_error_bar.dart

@@ -95,10 +95,12 @@ class _LoadableStateErrorBarTextState extends State<LoadableStateErrorBarText> {
   late Timer _rebuildTimer;
   @override
   void initState() {
-    _rebuildTimer = Timer.periodic(
-      const Duration(seconds: 10),
-      (timer) => setState(() {}),
-    );
+    // Only refresh the relative "last updated" text while this page is the
+    // visible one; offstage tabs and covered routes have tickers disabled.
+    _rebuildTimer = Timer.periodic(const Duration(seconds: 10), (timer) {
+      if (!mounted) return;
+      if (TickerMode.getValuesNotifier(context).value.enabled) setState(() {});
+    });
     super.initState();
   }
 

lib/state/app/infrastructure/loadable_state/view/loadable_state_primary_loading.dart

@@ -33,6 +33,9 @@ class _LoadableStatePrimaryLoadingState
     extends State<LoadableStatePrimaryLoading> {
   Timer? _slowHintTimer;
   bool _showSlowHint = false;
+  // An indeterminate spinner ticks every frame even at opacity 0, so it is
+  // unmounted once the fade-out finished instead of just being hidden.
+  late bool _spinnerMounted = widget.visible;
 
   @override
   void initState() {
@@ -44,6 +47,7 @@ class _LoadableStatePrimaryLoadingState
   void didUpdateWidget(covariant LoadableStatePrimaryLoading oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.visible != oldWidget.visible) _restartSlowHintTimer();
+    if (widget.visible) _spinnerMounted = true;
   }
 
   void _restartSlowHintTimer() {
@@ -62,16 +66,23 @@ class _LoadableStatePrimaryLoadingState
   }
 
   @override
-  Widget build(BuildContext context) {
-    final status =
-        widget.statusText ??
-        (_showSlowHint ? LoadableStatePrimaryLoading.slowHintText : null);
-
-    return AnimatedOpacity(
+  Widget build(BuildContext context) => AnimatedOpacity(
     opacity: widget.visible ? 1.0 : 0.0,
     duration: LoadableStateConsumer.animationDuration,
     curve: Curves.easeInOut,
-      child: Center(
+    onEnd: () {
+      if (!widget.visible && _spinnerMounted) {
+        setState(() => _spinnerMounted = false);
+      }
+    },
+    child: _spinnerMounted ? _spinner(context) : const SizedBox.shrink(),
+  );
+
+  Widget _spinner(BuildContext context) {
+    final status =
+        widget.statusText ??
+        (_showSlowHint ? LoadableStatePrimaryLoading.slowHintText : null);
+    return Center(
       child: Column(
         mainAxisSize: MainAxisSize.min,
         children: [
@@ -99,7 +110,6 @@ class _LoadableStatePrimaryLoadingState
           ),
         ],
       ),
-      ),
     );
   }
 }

lib/state/app/infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart

@@ -6,6 +6,7 @@ import 'package:hydrated_bloc/hydrated_bloc.dart';
 import '../../../../../api/errors/error_mapper.dart';
 import '../../../../../api/errors/stale_session_exception.dart';
 import '../../../../../model/account_data.dart';
+import '../../../../../utils/session_single_flight.dart';
 import '../../loadable_state/loadable_state.dart';
 import '../../loadable_state/loading_error.dart';
 import '../../repository/repository.dart';
@@ -20,6 +21,12 @@ abstract class LoadableHydratedBloc<
     extends
         HydratedBloc<LoadableHydratedBlocEvent<TState>, LoadableState<TState>> {
   late TRepository _repository;
+
+  // HydratedBloc serialises and writes the full state on every emit; loading
+  // flags, status texts and errors re-emit the very same data, so those
+  // writes are skipped (see [persistenceKey]).
+  Object? _lastPersistedKey;
+  int? _lastPersistedFetch;
   LoadableHydratedBloc()
     : super(
         const LoadableState(
@@ -113,6 +120,8 @@ abstract class LoadableHydratedBloc<
   /// fresh [fetch] (e.g. via [retry] or page-specific refresh) once the user
   /// is authenticated again, otherwise the UI would stay blank.
   Future<void> reset() async {
+    _lastPersistedKey = null;
+    _lastPersistedFetch = null;
     await clear();
     add(Reset<TState>());
   }
@@ -122,10 +131,8 @@ abstract class LoadableHydratedBloc<
   /// Runs [body] tagged with the current session: events it adds, also from
   /// its async continuations, are dropped once the account signed out, so a
   /// late response of the previous account cannot refill the reset bloc.
-  R runInSession<R>(R Function() body) => runZoned(
-    body,
-    zoneValues: {_sessionKey: AccountData().sessionEpoch},
-  );
+  R runInSession<R>(R Function() body) =>
+      runZoned(body, zoneValues: {_sessionKey: AccountData().sessionEpoch});
 
   @override
   void add(LoadableHydratedBlocEvent<TState> event) {
@@ -160,14 +167,23 @@ abstract class LoadableHydratedBloc<
     );
   }
 
+  // The constructor, the app shell and resume/reconnect handlers can all ask
+  // at once; each parallel gather would re-parse, re-emit and re-persist the
+  // same data.
+  final SessionSingleFlight _fetchFlight = SessionSingleFlight();
+
   void fetch() {
+    unawaited(
+      _fetchFlight.run(() {
         log('Fetching data for ${TState.toString()}');
-    runInSession(
+        return runInSession(
           () => gatherData()
               .catchError((Object e) {
-            log('Error while fetching ${TState.toString()}: ${e.toString()}');
-            // The bloc may have been closed before this async error landed;
-            // adding to a closed bloc throws, so swallow that case.
+                log(
+                  'Error while fetching ${TState.toString()}: ${e.toString()}',
+                );
+                // The bloc may have been closed before this async error
+                // landed; adding to a closed bloc throws, so swallow that case.
                 if (isClosed) return;
                 addLoadingError(e);
               })
@@ -175,6 +191,8 @@ abstract class LoadableHydratedBloc<
                 log('Fetch for ${TState.toString()} completed!');
               }),
         );
+      }),
+    );
   }
 
   @override
@@ -191,13 +209,27 @@ abstract class LoadableHydratedBloc<
 
   @override
   Map<String, dynamic>? toJson(LoadableState<TState> state) {
+    final stateData = state.data;
+    final key = stateData is TState ? persistenceKey(stateData) : null;
+    if (key != null &&
+        // Identity for plain data: a freezed `==` would deep-compare it.
+        (identical(key, _lastPersistedKey) ||
+            (key is Record && key == _lastPersistedKey)) &&
+        state.lastFetch == _lastPersistedFetch) {
+      return null;
+    }
+    _lastPersistedKey = key;
+    _lastPersistedFetch = state.lastFetch;
+
     Map<String, dynamic>? data;
     try {
-      final stateData = state.data;
       data = stateData is TState ? toStorage(stateData) : null;
     } catch (e) {
       log('Failed to save state ${TState.toString()}: ${e.toString()}');
     }
+    // Blocs that keep nothing on disk return null from toStorage; writing an
+    // empty wrapper per emit would be pure overhead.
+    if (stateData != null && data == null) return null;
 
     return LoadableSaveContext.wrap(
       data,
@@ -205,6 +237,13 @@ abstract class LoadableHydratedBloc<
     );
   }
 
+  /// What has to change for the state to be written to disk again. Defaults
+  /// to the data instance; blocs whose state also carries transient UI flags
+  /// can return a record of just the persisted parts (records compare with
+  /// `==`, so use fields that compare cheaply, e.g. by identity).
+  Object? persistenceKey(TState data) => data;
+
+
   Future<void> gatherData();
   TRepository repository();
 

lib/state/app/modules/chat/bloc/chat_bloc.dart

@@ -59,6 +59,12 @@ class ChatBloc
   @override
   ChatState fromStorage(Map<String, dynamic> json) => ChatState.fromJson(json);
 
+  // Loading-older and reply-reference flips must not re-persist up to 500
+  // messages; GetChatResponse has no `==`, so it compares by identity here.
+  @override
+  Object? persistenceKey(ChatState data) =>
+      (data.currentToken, data.chatResponse, data.hasMoreOld);
+
   @override
   Map<String, dynamic>? toStorage(ChatState state) {
     final response = state.chatResponse;

lib/state/app/modules/chat_list/bloc/chat_list_bloc.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:convert';
 import 'dart:developer';
 
 import 'package:flutter_app_badge/flutter_app_badge.dart';
@@ -6,6 +7,7 @@ import 'package:flutter_app_badge/flutter_app_badge.dart';
 import '../../../../../api/marianumcloud/talk/actions/talk_actions.dart';
 import '../../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
 import '../../../../../api/marianumcloud/talk/room/get_room_response.dart';
+import '../../../../../utils/session_single_flight.dart';
 import '../../../infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart';
 import '../../../infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc_event.dart';
 import '../repository/chat_list_repository.dart';
@@ -74,13 +76,32 @@ class ChatListBloc
       renew: renew,
       onError: (e) => capturedError = e,
     );
+    _lastRoomsJson = null;
     add(DataGathered((s) => s.copyWith(rooms: rooms)));
     _updateAppBadge(rooms);
 
     if (capturedError != null) throw capturedError!;
   }
 
-  Future<void> refresh({bool renew = true, bool silent = false}) async {
+  final SessionSingleFlight _refreshFlight = SessionSingleFlight();
+
+  /// Concurrent callers (tab switch, poll, push, resume) join the running
+  /// refresh instead of each fetching and re-emitting the full room list.
+  Future<void> refresh({bool renew = true, bool silent = false}) =>
+      _refreshFlight.run(() => _refresh(renew: renew, silent: silent));
+
+  /// Skips the refresh when the list was fetched within [maxAge].
+  Future<void> refreshIfOlderThan(Duration maxAge) {
+    final lastFetch = state.lastFetch;
+    if (lastFetch != null &&
+        DateTime.now().millisecondsSinceEpoch - lastFetch <
+            maxAge.inMilliseconds) {
+      return Future.value();
+    }
+    return refresh();
+  }
+
+  Future<void> _refresh({required bool renew, required bool silent}) async {
     if (!silent) add(RefetchStarted<ChatListState>());
     Object? capturedError;
     try {
@@ -88,6 +109,11 @@ class ChatListBloc
         renew: renew,
         onError: (e) => capturedError = e,
       );
+      if (silent) {
+        if (_isUnchanged(rooms)) return;
+      } else {
+        _lastRoomsJson = null;
+      }
       add(DataGathered((s) => s.copyWith(rooms: rooms)));
       _updateAppBadge(rooms);
     } catch (e) {
@@ -96,6 +122,23 @@ class ChatListBloc
     if (capturedError != null) addLoadingError(capturedError!);
   }
 
+  // Encoded room data of the last applied poll result; response headers are
+  // left out because they differ on every request.
+  String? _lastRoomsJson;
+
+  /// A background poll that returns the same rooms would otherwise rebuild the
+  /// list and re-persist the whole state every 15 s.
+  bool _isUnchanged(GetRoomResponse rooms) {
+    final encoded = jsonEncode(rooms.data);
+    final unchanged =
+        encoded == _lastRoomsJson &&
+        innerState?.rooms != null &&
+        state.error == null &&
+        !state.isLoading;
+    _lastRoomsJson = encoded;
+    return unchanged;
+  }
+
   /// Creates (or resolves) a 1:1 chat and returns its room token, or null in
   /// demo mode. Refreshes the list so the room shows up.
   Future<String?> createDirectChat(String invite) async {
@@ -171,6 +214,7 @@ class ChatListBloc
     }).toSet();
     if (!changed) return;
     final newRooms = GetRoomResponse(updated)..headers = rooms.headers;
+    _lastRoomsJson = null;
     add(Emit((s) => s.copyWith(rooms: newRooms)));
     _updateAppBadge(newRooms);
   }

lib/state/app/modules/foreign_timetable/bloc/foreign_timetable_bloc.dart

@@ -142,12 +142,11 @@ class ForeignTimetableBloc
 
       add(
         Emit(
-          (s) => s.copyWith(
+          (s) => s.withReferenceData(
             rooms: rooms,
             subjects: subjects,
             schoolHolidays: schoolHolidays,
             schoolyear: schoolyear,
-            dataVersion: s.dataVersion + 1,
           ),
         ),
       );
@@ -157,11 +156,7 @@ class ForeignTimetableBloc
 
     try {
       final timegrid = await repo.data.getTimegrid();
-      add(
-        Emit(
-          (s) => s.copyWith(timegrid: timegrid, dataVersion: s.dataVersion + 1),
-        ),
-      );
+      add(Emit((s) => s.withReferenceData(timegrid: timegrid)));
     } catch (_) {
       // Timegrid load failure falls back to a hardcoded schedule in the UI.
     }

lib/state/app/modules/marianum_dates/data_provider/marianum_dates_get_events.dart

@@ -1,5 +1,6 @@
 import 'package:dio/dio.dart';
 import 'package:enough_icalendar/enough_icalendar.dart';
+import 'package:flutter/foundation.dart';
 
 import '../bloc/marianum_dates_state.dart';
 
@@ -19,6 +20,12 @@ class MarianumDatesGetEvents {
     final body = response.data;
     if (body == null || body.isEmpty) return [];
 
+    // The public feed holds hundreds of events back to 1981; parsing it on
+    // the UI isolate froze the page for a noticeable moment on every open.
+    return compute(parseEvents, body);
+  }
+
+  static List<MarianumDate> parseEvents(String body) {
     final root = VComponent.parse(body);
     final calendar = root is VCalendar ? root : null;
     final source = calendar?.children ?? root.children;

lib/state/app/modules/settings/bloc/settings_cubit.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 import 'dart:developer';
 
+import 'package:collection/collection.dart';
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 
 import '../../../../../storage/settings.dart';
@@ -10,6 +11,8 @@ import '../../../../../view/pages/settings/data/default_settings.dart';
 class SettingsCubit extends HydratedCubit<Settings> {
   static const _debounceTag = 'settings_persist';
   bool _emitScheduled = false;
+  Map<String, dynamic>? _lastEmittedJson;
+  Timer? _silentSave;
 
   SettingsCubit() : super(DefaultSettings.get());
 
@@ -34,21 +37,53 @@ class SettingsCubit extends HydratedCubit<Settings> {
     return state;
   }
 
+  /// Persists in-place mutations without notifying listeners. For high-frequency
+  /// writes nobody renders live (chat drafts per keystroke): a regular write
+  /// would rebuild the app root and every settings watcher on each change.
+  void saveSilently() {
+    _silentSave?.cancel();
+    _silentSave = Timer(const Duration(milliseconds: 800), flushSilentSave);
+  }
+
+  /// Writes a pending [saveSilently] right away (e.g. when the app pauses).
+  void flushSilentSave() {
+    if (_silentSave == null) return;
+    _silentSave!.cancel();
+    _silentSave = null;
+    HydratedBloc.storage.write(storageToken, state.toJson());
+  }
+
   void _emitFreshInstance() {
     try {
-      emit(Settings.fromJson(state.toJson()));
+      final json = state.toJson();
+      // The debounced emit usually follows the microtask emit with identical
+      // content; skip it instead of rebuilding every listener a second time.
+      if (const DeepCollectionEquality().equals(json, _lastEmittedJson)) {
+        return;
+      }
+      _lastEmittedJson = json;
+      emit(Settings.fromJson(json));
     } catch (e) {
       log('Failed to refresh settings state: $e');
     }
   }
 
   Future<void> reset() async {
+    _silentSave?.cancel();
+    _silentSave = null;
+    _lastEmittedJson = null;
     emit(DefaultSettings.get());
   }
 
   // Modules missing from a stale persisted moduleOrder are handled at read
   // time by AppModule.effectiveModuleOrder (inserted at their default
   // position) — no healing on hydration needed.
+  @override
+  Future<void> close() {
+    flushSilentSave();
+    return super.close();
+  }
+
   @override
   Settings fromJson(Map<String, dynamic> json) {
     try {

lib/state/app/modules/ticker/bloc/ticker_page_bloc.dart

@@ -1,3 +1,8 @@
+import 'dart:async';
+
+import 'package:hydrated_bloc/hydrated_bloc.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
 import '../../../../../api/errors/ticker_content_unavailable_exception.dart';
 import '../../../../../api/marianumconnect/queries/get_ticker_page/get_ticker_page_response.dart';
 import '../../../infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart';
@@ -17,7 +22,35 @@ class TickerPageBloc
         > {
   final String slug;
 
-  TickerPageBloc(this.slug);
+  TickerPageBloc(this.slug) {
+    unawaited(_rememberSlug());
+  }
+
+  static const _recentSlugsKey = 'tickerPageRecentSlugs';
+  static const _keepPages = 50;
+
+  /// Every page ever opened used to stay in the hydrated box forever — and
+  /// the whole box is decoded before the first frame on each cold start.
+  /// The most recently opened pages (far more than a normal reader revisits)
+  /// keep their offline copy; only long-forgotten ones are dropped.
+  Future<void> _rememberSlug() async {
+    try {
+      final prefs = await SharedPreferences.getInstance();
+      final recent = prefs.getStringList(_recentSlugsKey) ?? <String>[];
+      recent
+        ..remove(slug)
+        ..insert(0, slug);
+      for (final evicted in recent.skip(_keepPages)) {
+        await HydratedBloc.storage.delete('$storagePrefix$evicted');
+      }
+      await prefs.setStringList(
+        _recentSlugsKey,
+        recent.take(_keepPages).toList(),
+      );
+    } on Object {
+      // Best effort: a failed cleanup only leaves an extra offline copy.
+    }
+  }
 
   @override
   String get id => slug;

lib/state/app/modules/timetable/bloc/timetable_bloc.dart

@@ -133,11 +133,7 @@ class TimetableBloc
 
   Future<void> _refreshSubjects() async {
     final subjects = await repo.data.getSubjects(renew: true);
-    add(
-      DataGathered(
-        (s) => s.copyWith(subjects: subjects, dataVersion: s.dataVersion + 1),
-      ),
-    );
+    add(DataGathered((s) => s.withReferenceData(subjects: subjects)));
   }
 
   Future<void> _loadCurrentWeek(
@@ -177,12 +173,11 @@ class TimetableBloc
 
       add(
         Emit(
-          (s) => s.copyWith(
+          (s) => s.withReferenceData(
             rooms: rooms,
             subjects: subjects,
             schoolHolidays: schoolHolidays,
             schoolyear: schoolyear,
-            dataVersion: s.dataVersion + 1,
           ),
         ),
       );
@@ -192,11 +187,7 @@ class TimetableBloc
 
     try {
       final timegrid = await repo.data.getTimegrid(renew: renew);
-      add(
-        Emit(
-          (s) => s.copyWith(timegrid: timegrid, dataVersion: s.dataVersion + 1),
-        ),
-      );
+      add(Emit((s) => s.withReferenceData(timegrid: timegrid)));
     } catch (_) {
       // Timegrid load failure falls back to a hardcoded schedule in the UI layer.
     }
@@ -212,12 +203,7 @@ class TimetableBloc
         renew: renew,
         onError: onError,
       );
-      add(
-        Emit(
-          (s) =>
-              s.copyWith(customEvents: events, dataVersion: s.dataVersion + 1),
-        ),
-      );
+      add(Emit((s) => s.withReferenceData(customEvents: events)));
     } catch (e) {
       onError?.call(e);
     }
@@ -225,11 +211,7 @@ class TimetableBloc
 
   Future<void> _refreshCustomEvents() async {
     final events = await repo.data.getCustomEvents(renew: true);
-    add(
-      DataGathered(
-        (s) => s.copyWith(customEvents: events, dataVersion: s.dataVersion + 1),
-      ),
-    );
+    add(DataGathered((s) => s.withReferenceData(customEvents: events)));
   }
 
   void _prefetchAdjacentWeeks(DateTime start, DateTime end) {

lib/state/app/modules/timetable/bloc/timetable_state.dart

@@ -7,6 +7,7 @@ import '../../../../../api/marianumconnect/queries/timetable_get_subjects/timeta
 import '../../../../../api/marianumconnect/queries/timetable_get_timegrid/timetable_get_timegrid_response.dart';
 import '../../../../../api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
 import '../../../../../api/mhsl/custom_timetable_event/get/get_custom_timetable_event_response.dart';
+import '../../../../../utils/json_equality.dart';
 import 'week_cache.dart';
 
 part 'timetable_state.freezed.dart';
@@ -58,6 +59,45 @@ abstract class TimetableState with _$TimetableState {
     return copyWith(weekCache: updated, dataVersion: dataVersion + 1);
   }
 
+  /// Applies freshly loaded reference data. Values whose content equals the
+  /// current one keep the old instance, and when nothing changed at all this
+  /// returns `this` — every `dataVersion` bump and new identity makes the
+  /// calendar rebuild all appointments and break regions.
+  TimetableState withReferenceData({
+    TimetableGetRoomsResponse? rooms,
+    TimetableGetSubjectsResponse? subjects,
+    TimetableGetHolidaysResponse? schoolHolidays,
+    TimetableGetSchoolyearResponse? schoolyear,
+    TimetableGetTimegridResponse? timegrid,
+    GetCustomTimetableEventResponse? customEvents,
+  }) {
+    T? changed<T>(T? next, T? current) =>
+        next == null || sameJson(next, current) ? null : next;
+    final newRooms = changed(rooms, this.rooms);
+    final newSubjects = changed(subjects, this.subjects);
+    final newHolidays = changed(schoolHolidays, this.schoolHolidays);
+    final newSchoolyear = changed(schoolyear, this.schoolyear);
+    final newTimegrid = changed(timegrid, this.timegrid);
+    final newCustomEvents = changed(customEvents, this.customEvents);
+    if (newRooms == null &&
+        newSubjects == null &&
+        newHolidays == null &&
+        newSchoolyear == null &&
+        newTimegrid == null &&
+        newCustomEvents == null) {
+      return this;
+    }
+    return copyWith(
+      rooms: newRooms ?? this.rooms,
+      subjects: newSubjects ?? this.subjects,
+      schoolHolidays: newHolidays ?? this.schoolHolidays,
+      schoolyear: newSchoolyear ?? this.schoolyear,
+      timegrid: newTimegrid ?? this.timegrid,
+      customEvents: newCustomEvents ?? this.customEvents,
+      dataVersion: dataVersion + 1,
+    );
+  }
+
   bool get hasReferenceData =>
       rooms != null &&
       subjects != null &&

lib/state/app/modules/timetable/bloc/week_cache.dart

@@ -1,13 +1,12 @@
-import 'package:collection/collection.dart';
-
 import '../../../../../api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
 import '../../../../../extensions/date_time.dart';
+import '../../../../../utils/json_equality.dart';
 
 /// Weeks kept around the viewed week and around today's week. Everything
 /// further away is dropped: every state emit re-serializes the whole cache for
 /// HydratedBloc and the calendar rebuilds its appointments from all of it, so
 /// an unbounded cache makes week swipes slower the longer the app is used.
-const int kWeekCacheRadius = 4;
+const int kWeekCacheRadius = 8;
 
 /// Returns the cache with [week] stored under [weekStart], pruned to the
 /// weeks near [viewedWeekStart] or [now]. Returns null when the stored week
@@ -21,10 +20,7 @@ Map<String, TimetableGetWeekResponse>? mergeWeekIntoCache(
 }) {
   final key = weekStart.weekKey();
   final existing = cache[key];
-  if (existing != null &&
-      const DeepCollectionEquality().equals(existing.toJson(), week.toJson())) {
-    return null;
-  }
+  if (sameJson(existing, week)) return null;
 
   final viewedMonday = viewedWeekStart.mondayOfWeek;
   final todayMonday = now.mondayOfWeek;

lib/utils/json_equality.dart

@@ -0,0 +1,7 @@
+import 'dart:convert';
+
+/// Content equality for API models that define no `==` but serialise to JSON.
+/// Comparing the encoded strings is cheaper than a deep map walk and treats
+/// both sides identically (same `toJson`, same field order).
+bool sameJson(Object? a, Object? b) =>
+    a != null && b != null && jsonEncode(a) == jsonEncode(b);

lib/utils/recurrence_occurrences.dart

@@ -0,0 +1,75 @@
+import 'package:rrule/rrule.dart';
+
+/// Memoised RRULE expansion.
+///
+/// `RecurrenceRule.getInstances` always starts at the series anchor, so asking
+/// for one week of a daily event created two years ago walks ~750 occurrences
+/// (tens of ms each time on older phones) — and the calendar asks once per
+/// week and event, the home widget twice per publish. Here each series keeps
+/// its parsed rule, the occurrences found so far and the live iterator, so
+/// later queries only extend the expansion instead of restarting it.
+class RecurrenceOccurrences {
+  RecurrenceOccurrences._();
+
+  static const int _maxSeries = 64;
+  static final Map<(String, DateTime), _Series> _cache = {};
+
+  /// UTC occurrences of [rule] anchored at [anchorUtc] in
+  /// `[fromUtc, toUtc)`, in ascending order. Throws like
+  /// [RecurrenceRule.fromString] for an invalid rule.
+  static List<DateTime> between(
+    String rule,
+    DateTime anchorUtc,
+    DateTime fromUtc,
+    DateTime toUtc,
+  ) {
+    final key = (rule, anchorUtc);
+    var series = _cache.remove(key);
+    series ??= _Series(RecurrenceRule.fromString(rule), anchorUtc);
+    // Re-insert to keep the map in least-recently-used order.
+    _cache[key] = series;
+    if (_cache.length > _maxSeries) _cache.remove(_cache.keys.first);
+    return series.between(fromUtc, toUtc);
+  }
+
+  /// Drops all memoised series (tests).
+  static void clear() => _cache.clear();
+}
+
+class _Series {
+  final Iterator<DateTime> _iterator;
+  final List<DateTime> _found = [];
+  bool _exhausted = false;
+
+  _Series(RecurrenceRule rule, DateTime anchorUtc)
+    : _iterator = rule.getInstances(start: anchorUtc).iterator;
+
+  List<DateTime> between(DateTime fromUtc, DateTime toUtc) {
+    while (!_exhausted && (_found.isEmpty || _found.last.isBefore(toUtc))) {
+      if (_iterator.moveNext()) {
+        _found.add(_iterator.current);
+      } else {
+        _exhausted = true;
+      }
+    }
+    final start = _lowerBound(fromUtc);
+    return [
+      for (var i = start; i < _found.length && _found[i].isBefore(toUtc); i++)
+        _found[i],
+    ];
+  }
+
+  int _lowerBound(DateTime value) {
+    var low = 0;
+    var high = _found.length;
+    while (low < high) {
+      final mid = (low + high) >> 1;
+      if (_found[mid].isBefore(value)) {
+        low = mid + 1;
+      } else {
+        high = mid;
+      }
+    }
+    return low;
+  }
+}

lib/utils/screen_bound_image.dart

@@ -0,0 +1,25 @@
+import 'package:flutter/widgets.dart';
+
+/// Wraps [provider] so it decodes at most [scale] × the screen's longest
+/// physical side (capped at [maxPx]). Camera-sized photos otherwise decode at
+/// full resolution — 50–200 MB each — which gets the app killed on
+/// low-memory devices.
+ImageProvider screenBoundImage(
+  BuildContext context,
+  ImageProvider provider, {
+  double scale = 1,
+  int maxPx = 4096,
+}) {
+  final bound =
+      (MediaQuery.sizeOf(context).longestSide *
+              MediaQuery.devicePixelRatioOf(context) *
+              scale)
+          .round()
+          .clamp(1, maxPx);
+  return ResizeImage(
+    provider,
+    width: bound,
+    height: bound,
+    policy: ResizeImagePolicy.fit,
+  );
+}

lib/utils/session_single_flight.dart

@@ -0,0 +1,21 @@
+import '../model/account_data.dart';
+
+/// Joins concurrent calls into the one already running for the same account
+/// session. A run left over from a signed-out session never blocks the next
+/// account's first call.
+class SessionSingleFlight {
+  Future<void>? _running;
+  int? _epoch;
+
+  Future<void> run(Future<void> Function() action) {
+    final epoch = AccountData().sessionEpoch;
+    final running = _running;
+    if (running != null && _epoch == epoch) return running;
+    _epoch = epoch;
+    late final Future<void> current;
+    current = action().whenComplete(() {
+      if (identical(_running, current)) _running = null;
+    });
+    return _running = current;
+  }
+}

lib/view/pages/files/data/sort_options.dart

@@ -21,7 +21,7 @@ class SortOptions {
     SortOption.name: BetterSortOption(
       displayName: 'Name',
       icon: Icons.sort_by_alpha_outlined,
-      compare: (a, b) => a.name.toLowerCase().compareTo(b.name.toLowerCase()),
+      compare: (a, b) => a.lowerName.compareTo(b.lowerName),
     ),
     SortOption.date: BetterSortOption(
       displayName: 'Datum',

lib/view/pages/files/files.dart

@@ -4,6 +4,8 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:persistent_bottom_nav_bar_v2/persistent_bottom_nav_bar_v2.dart';
 
+import '../../../api/marianumcloud/webdav/queries/list_files/cacheable_file.dart';
+import '../../../api/marianumcloud/webdav/queries/list_files/list_files_response.dart';
 import '../../../state/app/infrastructure/loadable_state/loadable_state.dart';
 import '../../../state/app/infrastructure/loadable_state/view/loadable_state_consumer.dart';
 import '../../../state/app/infrastructure/utility_widgets/bloc_module.dart';
@@ -47,6 +49,22 @@ class _FilesViewState extends State<_FilesView> {
   late bool currentSortDirection;
   late final StreamSubscription<String> _invalidationSub;
 
+  // The list builder also runs for loading flips and parent rebuilds; only a
+  // new listing or a changed sort needs another sort pass.
+  Object? _sortedKey;
+  List<CacheableFile> _sortedFiles = const [];
+
+  List<CacheableFile> _sorted(ListFilesResponse listing, bool foldersToTop) {
+    final key = (listing, currentSort, currentSortDirection, foldersToTop);
+    if (key == _sortedKey) return _sortedFiles;
+    _sortedKey = key;
+    return _sortedFiles = listing.sortBy(
+      sortOption: currentSort,
+      foldersToTop: foldersToTop,
+      reversed: currentSortDirection,
+    );
+  }
+
   // Cache key in FilesBloc's pathString format: '/' for root, otherwise
   // segments joined without leading/trailing slash.
   String get _myPathString => widget.path.isEmpty ? '/' : widget.path.join('/');
@@ -98,6 +116,11 @@ class _FilesViewState extends State<_FilesView> {
   @override
   Widget build(BuildContext context) {
     final bloc = context.read<FilesBloc>();
+    // Selected here, not in the LoadableStateConsumer child: that closure runs
+    // during the consumer's build, where this context may not subscribe.
+    final foldersToTop = context.select(
+      (SettingsCubit c) => c.state.fileSettings.sortFoldersToTop,
+    );
     return Scaffold(
       appBar: AppBar(
         title: Text(widget.path.isNotEmpty ? widget.path.last : 'Dateien'),
@@ -153,15 +176,7 @@ class _FilesViewState extends State<_FilesView> {
                     text: 'Der Ordner ist leer',
                   );
                 }
-                final files = listing.sortBy(
-                  sortOption: currentSort,
-                  foldersToTop: context
-                      .watch<SettingsCubit>()
-                      .val()
-                      .fileSettings
-                      .sortFoldersToTop,
-                  reversed: currentSortDirection,
-                );
+                final files = _sorted(listing, foldersToTop);
                 return ListView.builder(
                   padding: EdgeInsets.zero,
                   itemCount: files.length,

lib/view/pages/files/files_upload_dialog.dart

@@ -191,18 +191,23 @@ class _FilesUploadDialogState extends State<FilesUploadDialog> {
       }
 
       final HttpClientResponse uploadTask;
+      final fileIndex = _uploadableFiles.indexOf(file);
+      var lastPercent = -1;
       try {
         uploadTask = await webdavClient.putFile(
           File(filePath),
           fileStat,
           PathUri.parse(fullRemotePath),
           onProgress: (progress) {
+            // Called per 64 KB chunk — thousands of times for a video. Only
+            // rebuild when the visible percentage actually moves.
+            final percent = (progress * 100).floor();
+            if (!mounted || percent == lastPercent) return;
+            lastPercent = percent;
             setState(() {
               file._uploadProgress = progress;
               _overallProgressValue =
-                  ((progress + _uploadableFiles.indexOf(file)) /
-                          _uploadableFiles.length)
-                      .toDouble();
+                  ((progress + fileIndex) / _uploadableFiles.length).toDouble();
             });
           },
         );
@@ -246,7 +251,12 @@ class _FilesUploadDialogState extends State<FilesUploadDialog> {
               itemCount: _uploadableFiles.length,
               itemBuilder: (context, index) {
                 final currentFile = _uploadableFiles[index];
+                // Only sync when it differs: assigning text resets selection
+                // and notifies the field on every (progress) rebuild.
+                if (currentFile.fileNameController.text !=
+                    currentFile.fileName) {
                   currentFile.fileNameController.text = currentFile.fileName;
+                }
                 return ListTile(
                   title: TextField(
                     readOnly: _isUploading,

lib/view/pages/files/search/files_search_controller.dart

@@ -26,6 +26,14 @@ class FilesSearchController extends ChangeNotifier {
   Object? _serverError;
   int _serverEpoch = 0;
   bool _disposed = false;
+  Future<List<CacheableFile>>? _localIndex;
+
+  Future<List<CacheableFile>> _searchLocal(List<String> pathScope) async =>
+      searchLocalCacheIndex(
+        await (_localIndex ??= loadLocalCacheIndex()),
+        _query,
+        pathScope: pathScope,
+      );
 
   /// Guards against the race where the search delegate is closed (and the
   /// controller disposed) while a debounced cache scan or server call is
@@ -80,7 +88,7 @@ class FilesSearchController extends ChangeNotifier {
     _serverError = null;
     _safeNotify();
 
-    final cacheHits = await searchLocalCaches(_query, pathScope: _pathScope);
+    final cacheHits = await _searchLocal(_pathScope);
     if (epoch != _serverEpoch) return;
     _cacheResults = cacheHits;
     _safeNotify();
@@ -101,7 +109,7 @@ class FilesSearchController extends ChangeNotifier {
     _serverError = null;
     _safeNotify();
 
-    final cacheHits = await searchLocalCaches(_query);
+    final cacheHits = await _searchLocal(const []);
     if (epoch != _serverEpoch) return;
     _cacheResults = cacheHits;
     _safeNotify();

lib/view/pages/files/search/files_search_results.dart

@@ -104,31 +104,42 @@ class FilesSearchResults extends StatelessWidget {
   Widget _resultList(BuildContext context, List<CacheableFile> combined) {
     final groups = _groupByParent(combined);
     final orderedKeys = groups.keys.toList()..sort();
-    final items = <Widget>[];
-    for (final folder in orderedKeys) {
+    // Flat (folder header | file) rows built lazily: results can run into
+    // the hundreds and arrive in several batches per query.
+    final rows = <(String, CacheableFile?)>[
+      for (final folder in orderedKeys) ...[
+        (folder, null),
+        for (final file in groups[folder]!) (folder, file),
+      ],
+    ];
+    return ListView.builder(
+      padding: EdgeInsets.zero,
+      itemCount: rows.length,
+      itemBuilder: (context, index) {
+        final (folder, file) = rows[index];
         final segments = _segmentsOf(folder);
-      items.add(
-        _FolderHeader(
+        if (file == null) {
+          return _FolderHeader(
+            key: ValueKey('folder:$folder'),
             folder: folder,
             onOpen: () {
               onResultTap?.call();
               AppRoutes.openFolder(context, segments);
             },
-        ),
           );
-      for (final file in groups[folder]!) {
-        items.add(
-          FileElement(
+        }
+        return FileElement(
           file,
           segments,
           controller.retry,
+          key: ValueKey('file:${file.path}'),
           highlight: controller.query,
-          ),
+        );
+      },
     );
   }
-    }
-    return ListView(padding: EdgeInsets.zero, children: items);
-  }
+
+  static final RegExp _edgeSlashes = RegExp(r'^/+|/+$');
 
   Map<String, List<CacheableFile>> _groupByParent(List<CacheableFile> files) {
     final map = <String, List<CacheableFile>>{};
@@ -139,7 +150,7 @@ class FilesSearchResults extends StatelessWidget {
   }
 
   String _parentOf(CacheableFile file) {
-    final stripped = file.path.replaceAll(RegExp(r'^/+|/+$'), '');
+    final stripped = file.path.replaceAll(_edgeSlashes, '');
     final segments = stripped.split('/');
     if (segments.length <= 1) return '/';
     segments.removeLast();
@@ -147,7 +158,7 @@ class FilesSearchResults extends StatelessWidget {
   }
 
   List<String> _segmentsOf(String folder) {
-    final stripped = folder.replaceAll(RegExp(r'^/+|/+$'), '');
+    final stripped = folder.replaceAll(_edgeSlashes, '');
     if (stripped.isEmpty) return const [];
     return stripped.split('/');
   }
@@ -156,7 +167,11 @@ class FilesSearchResults extends StatelessWidget {
 class _FolderHeader extends StatelessWidget {
   final String folder;
   final VoidCallback onOpen;
-  const _FolderHeader({required this.folder, required this.onOpen});
+  const _FolderHeader({
+    required this.folder,
+    required this.onOpen,
+    super.key,
+  });
 
   @override
   Widget build(BuildContext context) {

lib/view/pages/files/search/local_cache_search.dart

@@ -1,49 +1,29 @@
 import 'dart:convert';
 
-import 'package:localstore/localstore.dart';
+import 'package:flutter/foundation.dart';
 
+import '../../../../api/cache_store.dart';
 import '../../../../api/marianumcloud/webdav/queries/list_files/cacheable_file.dart';
 import '../../../../api/marianumcloud/webdav/queries/list_files/list_files_response.dart';
-import '../../../../api/request_cache.dart';
 
 /// Document key prefix used by `ListFilesCache._documentId`.
 const String _folderCachePrefix = 'wd-folder-';
 
-/// Scans every cached folder listing in Localstore and returns files/folders
-/// whose name contains [query] (case-insensitive).
-///
-/// [pathScope] restricts results to entries whose WebDAV path starts with
-/// the given folder. Pass an empty list (or null) to search globally.
-///
-/// [docs] is an injection seam for tests — production callers leave it null
-/// so the helper reads from the real Localstore.
-Future<List<CacheableFile>> searchLocalCaches(
-  String query, {
-  List<String>? pathScope,
-  Map<String, dynamic>? docs,
-}) async {
-  final trimmed = query.trim();
-  if (trimmed.isEmpty) return const [];
-  final needle = trimmed.toLowerCase();
-  final scopePrefix = pathScope == null || pathScope.isEmpty
-      ? ''
-      : '${pathScope.join('/')}/';
-
-  final raw =
-      docs ??
-      await Localstore.instance.collection(RequestCache.collection).get();
-  if (raw == null || raw.isEmpty) return const [];
-
-  final results = <String, CacheableFile>{};
-  for (final entry in raw.entries) {
-    final docKey = entry.key.split('/').last;
-    if (!docKey.startsWith(_folderCachePrefix)) continue;
-
-    final value = entry.value;
-    if (value is! Map) continue;
-    final json = value['json'];
-    if (json is! String) continue;
+/// Every file and folder from the cached folder listings, deduplicated by
+/// path. Built once per search session: reading and parsing all listings on
+/// each keystroke used to stall typing.
+Future<List<CacheableFile>> loadLocalCacheIndex() async {
+  final entries = await CacheStore.instance.readAll(prefix: _folderCachePrefix);
+  if (entries.isEmpty) return const [];
+  final payloads = [for (final entry in entries.values) entry.json];
+  return compute(buildLocalCacheIndex, payloads);
+}
 
+/// Parses cached `ListFilesResponse` payloads into a deduplicated file list.
+/// Unparsable payloads are skipped.
+List<CacheableFile> buildLocalCacheIndex(List<String> payloads) {
+  final byPath = <String, CacheableFile>{};
+  for (final json in payloads) {
     final ListFilesResponse listing;
     try {
       listing = ListFilesResponse.fromJson(
@@ -52,14 +32,32 @@ Future<List<CacheableFile>> searchLocalCaches(
     } on Object {
       continue;
     }
-
     for (final file in listing.files) {
-      if (!file.name.toLowerCase().contains(needle)) continue;
-      if (scopePrefix.isNotEmpty && !file.path.startsWith(scopePrefix)) {
-        continue;
-      }
-      results[file.path] ??= file;
+      byPath[file.path] ??= file;
     }
   }
-  return results.values.toList();
+  return byPath.values.toList();
+}
+
+/// Files in [index] whose name contains [query] (case-insensitive).
+///
+/// [pathScope] restricts results to entries whose WebDAV path starts with
+/// the given folder. Pass an empty list (or null) to search globally.
+List<CacheableFile> searchLocalCacheIndex(
+  List<CacheableFile> index,
+  String query, {
+  List<String>? pathScope,
+}) {
+  final trimmed = query.trim();
+  if (trimmed.isEmpty) return const [];
+  final needle = trimmed.toLowerCase();
+  final scopePrefix = pathScope == null || pathScope.isEmpty
+      ? ''
+      : '${pathScope.join('/')}/';
+  return [
+    for (final file in index)
+      if (file.lowerName.contains(needle) &&
+          (scopePrefix.isEmpty || file.path.startsWith(scopePrefix)))
+        file,
+  ];
 }

lib/view/pages/foreign_timetable/element_picker_page.dart

@@ -7,6 +7,7 @@ import '../../../api/marianumconnect/queries/timetable_get_element_week/timetabl
 import '../../../api/marianumconnect/queries/timetable_get_rooms/timetable_get_rooms.dart';
 import '../../../api/marianumconnect/queries/timetable_get_students/timetable_get_students.dart';
 import '../../../api/marianumconnect/queries/timetable_get_teachers/timetable_get_teachers.dart';
+import '../../../model/account_data.dart';
 import '../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../storage/timetable_favorites_settings.dart';
 import '../../../utils/haptics.dart';
@@ -31,7 +32,14 @@ class _ElementPickerPageState extends State<ElementPickerPage> {
 
   // One in-flight/resolved future per type so switching tabs (or rebuilds)
   // never re-fetches a list that's already loaded.
-  final Map<TimetableElementType, Future<List<_PickerItem>>> _futures = {};
+  // Session-wide (per account): the student list alone has 1000+ entries and
+  // used to be downloaded again every time the picker opened.
+  static final Map<
+    TimetableElementType,
+    ({int epoch, DateTime at, Future<List<_PickerItem>> items})
+  >
+  _futures = {};
+  static const Duration _listMaxAge = Duration(minutes: 15);
   // Memoised combined future for the "Alle" tab; rebuilt on retry.
   Future<List<_PickerItem>>? _allFuture;
 
@@ -47,8 +55,25 @@ class _ElementPickerPageState extends State<ElementPickerPage> {
     return _allFuture ??= _loadAll();
   }
 
-  Future<List<_PickerItem>> _loadFor(TimetableElementType type) =>
-      _futures.putIfAbsent(type, () => _fetch(type));
+  Future<List<_PickerItem>> _loadFor(TimetableElementType type) {
+    final epoch = AccountData().sessionEpoch;
+    final cached = _futures[type];
+    if (cached != null &&
+        cached.epoch == epoch &&
+        DateTime.now().difference(cached.at) < _listMaxAge) {
+      return cached.items;
+    }
+    final items = _fetch(type);
+    _futures[type] = (epoch: epoch, at: DateTime.now(), items: items);
+    // A failed load must not stick for the rest of the session.
+    items.then(
+      (_) {},
+      onError: (Object _) {
+        if (identical(_futures[type]?.items, items)) _futures.remove(type);
+      },
+    );
+    return items;
+  }
 
   Future<List<_PickerItem>> _loadAll() async {
     final lists = await Future.wait(TimetableElementType.values.map(_loadFor));
@@ -117,20 +142,16 @@ class _ElementPickerPageState extends State<ElementPickerPage> {
     Haptics.selection();
     // Hand the selection back to the timetable view, which renders the foreign
     // plan inline. We do not navigate to a new page.
-    Navigator.of(context).pop((
-      type: item.type,
-      id: item.id,
-      label: item.primary,
-    ));
+    Navigator.of(
+      context,
+    ).pop((type: item.type, id: item.id, label: item.primary));
   }
 
   void _openFavorite(FavoriteTimetableElement favorite) {
     Haptics.selection();
-    Navigator.of(context).pop((
-      type: favorite.type,
-      id: favorite.id,
-      label: favorite.label,
-    ));
+    Navigator.of(
+      context,
+    ).pop((type: favorite.type, id: favorite.id, label: favorite.label));
   }
 
   void _toggleFavorite(TimetableElementType type, int id, String label) {
@@ -325,9 +346,7 @@ class _ElementPickerPageState extends State<ElementPickerPage> {
     return ListTile(
       leading: Icon(_iconFor(item.type)),
       title: Text(item.primary),
-      subtitle: subtitleParts.isEmpty
-          ? null
-          : Text(subtitleParts.join(' · ')),
+      subtitle: subtitleParts.isEmpty ? null : Text(subtitleParts.join(' · ')),
       trailing: IconButton(
         icon: Icon(isFavorite ? Icons.star : Icons.star_border),
         tooltip: isFavorite ? 'Favorit entfernen' : 'Als Favorit markieren',

lib/view/pages/settings/chat_background_settings_page.dart

@@ -214,8 +214,11 @@ class ChatBackgroundSettingsPage extends StatelessWidget {
       final file = File(AppPaths.chatBackgroundImage);
       await file.writeAsBytes(bytes);
       // Same filename across replacements → the decoded image is cached under
-      // an identical key. Evict so the new bytes actually show.
-      await FileImage(file).evict();
+      // an identical key (for "cover" also wrapped in a viewport-sized
+      // ResizeImage). Clearing the cache is fine for this rare action.
+      PaintingBinding.instance.imageCache
+        ..clear()
+        ..clearLiveImages();
       final cs = settings.val(write: true).chatBackgroundSettings;
       cs.imageVersion++;
       cs.type = ChatBackgroundType.image;

lib/view/pages/settings/sections/dev_tools_section.dart

@@ -3,13 +3,13 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 
+import '../../../../api/cache_store.dart';
 import '../../../../routing/app_routes.dart';
 import '../../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../../storage/dev_tools_settings.dart';
 import '../../../../storage/settings.dart' as model;
 import '../../../../widget/centered_leading.dart';
 import '../../../../widget/confirm_dialog.dart';
-import '../../../../widget/debug/cache_view.dart';
 import '../../../../widget/debug/json_viewer.dart';
 import '../../../../widget/details_bottom_sheet.dart';
 import '../widgets/endpoint_picker.dart';
@@ -24,6 +24,9 @@ class DevToolsSection extends StatefulWidget {
 }
 
 class _DevToolsSectionState extends State<DevToolsSection> {
+  // Kept across rebuilds: the size walk lists the whole cache directory.
+  Future<int>? _cacheSize;
+
   @override
   Widget build(BuildContext context) => Column(
     children: [
@@ -153,7 +156,7 @@ class _DevToolsSectionState extends State<DevToolsSection> {
         leading: const CenteredLeading(Icon(Icons.data_object)),
         title: const Text('Cache-storage JSON dump'),
         subtitle: FutureBuilder(
-          future: const CacheView().totalSize(),
+          future: _cacheSize ??= CacheStore.instance.totalSize(),
           builder: (context, snapshot) => Text(
             "etwa ${snapshot.hasError
                 ? "?"
@@ -169,8 +172,9 @@ class _DevToolsSectionState extends State<DevToolsSection> {
             content:
                 'Alle cache Einträge werden gelöscht. Der Cache wird bei Nutzung der App automatisch erneut aufgebaut',
             confirmButton: 'Unwiederruflich löschen',
-            onConfirm: () =>
-                const CacheView().clear().then((value) => setState(() {})),
+            onConfirm: () => CacheStore.instance.clear().then(
+              (value) => setState(() => _cacheSize = null),
+            ),
           ).asDialog(context);
         },
         trailing: const Icon(Icons.arrow_right),

lib/view/pages/talk/chat_list.dart

@@ -75,6 +75,17 @@ class _ChatListViewState extends State<_ChatListView> {
   @override
   Widget build(BuildContext context) {
     final bloc = context.read<ChatListBloc>();
+    // Selected here, not in the LoadableStateConsumer child: that closure runs
+    // during the consumer's build, where this context may not subscribe.
+    // Draft keys are part of the selection so the draft marker follows; the
+    // draft text itself is saved without notifying.
+    final (favoritesToTop, unreadToTop, _) = context.select(
+      (SettingsCubit c) => (
+        c.state.talkSettings.sortFavoritesToTop,
+        c.state.talkSettings.sortUnreadToTop,
+        c.state.talkSettings.drafts.keys.join('|'),
+      ),
+    );
     return SplitView.material(
       placeholder: const SplitViewPlaceholder(),
       breakpoint: 1000,
@@ -129,13 +140,9 @@ class _ChatListViewState extends State<_ChatListView> {
               final rooms = state.rooms;
               if (rooms == null) return const SizedBox.shrink();
 
-              final talkSettings = context
-                  .watch<SettingsCubit>()
-                  .val()
-                  .talkSettings;
               final sorted = rooms.sortBy(
-                favoritesToTop: talkSettings.sortFavoritesToTop,
-                unreadToTop: talkSettings.sortUnreadToTop,
+                favoritesToTop: favoritesToTop,
+                unreadToTop: unreadToTop,
               );
 
               if (sorted.isEmpty) {
@@ -145,23 +152,25 @@ class _ChatListViewState extends State<_ChatListView> {
                 );
               }
 
-              return ListView(
+              final drafts = _settings.val().talkSettings.drafts;
+              final indexByToken = {
+                for (var i = 0; i < sorted.length; i++) sorted[i].token: i,
+              };
+              return ListView.builder(
                 padding: EdgeInsets.zero,
-                children: sorted.map((room) {
-                  final hasDraft = _settings
-                      .val()
-                      .talkSettings
-                      .drafts
-                      .containsKey(room.token);
-                  // Stable key keeps element identity across re-sorts so the
-                  // inner UserAvatar reuses its cached bytes instead of
-                  // flashing on every list update.
+                itemCount: sorted.length,
+                // Keeps each tile's state (cached avatar bytes) with its room
+                // when a re-sort moves it to another index.
+                findChildIndexCallback: (key) =>
+                    indexByToken[(key as ValueKey<String>).value],
+                itemBuilder: (context, index) {
+                  final room = sorted[index];
                   return ChatTile(
                     key: ValueKey(room.token),
                     data: room,
-                    hasDraft: hasDraft,
+                    hasDraft: drafts.containsKey(room.token),
                   );
-                }).toList(),
+                },
               );
             },
           ),

lib/view/pages/talk/chat_view.dart

@@ -14,6 +14,7 @@ import '../../../state/app/infrastructure/loadable_state/view/loadable_state_con
 import '../../../state/app/modules/chat/bloc/chat_bloc.dart';
 import '../../../state/app/modules/chat/bloc/chat_state.dart';
 import '../../../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
+import '../../../utils/debouncer.dart';
 import '../../../widget/chat_background.dart';
 import '../../../widget/clickable_app_bar.dart';
 import '../../../widget/user_avatar.dart';
@@ -118,6 +119,7 @@ class _ChatViewState extends State<ChatView> with RouteAware {
     _markAsReadFinal();
     _chatBlocRef?.leaveChat(widget.room.token);
     _searchTextController.dispose();
+    Debouncer.cancel(_searchDebounceTag);
     super.dispose();
   }
 
@@ -150,6 +152,45 @@ class _ChatViewState extends State<ChatView> with RouteAware {
     context.read<ChatBloc>().setToken(widget.room.token);
   }
 
+  void _refetch({bool renew = false}) => _refresh();
+
+  // The built rows only depend on the chat data and the search state; the list
+  // itself rebuilds far more often (loading flips, keyboard, parent rebuilds),
+  // and re-sorting plus re-creating every bubble each time is wasted work.
+  Object? _itemsKey;
+  List<Widget> _items = const [];
+
+  List<Widget> _itemsFor(ChatState state) {
+    final key = (
+      state.chatResponse,
+      state.isLoadingOlder,
+      state.hasMoreOld,
+      _searchActive,
+      _searchQuery,
+      _activeMatchIndex,
+      widget.room,
+    );
+    if (key == _itemsKey) return _items;
+    _itemsKey = key;
+    final items = _buildMessages(state.chatResponse!).reversed.toList();
+    // reverse:true renders index 0 at the bottom, so the top marker
+    // (spinner / start-of-chat) goes at the end.
+    if (state.isLoadingOlder) {
+      items.add(const _LoadingOlderIndicator());
+    } else if (!state.hasMoreOld) {
+      items.add(
+        ChatBubble(
+          key: const ValueKey('chat-start'),
+          isSender: false,
+          bubbleData: GetChatResponseObject.getTextDummy('Anfang des Chats'),
+          chatData: widget.room,
+          refetch: _refetch,
+        ),
+      );
+    }
+    return _items = items;
+  }
+
   void _enterSearchMode() {
     setState(() {
       _searchActive = true;
@@ -163,6 +204,7 @@ class _ChatViewState extends State<ChatView> with RouteAware {
   }
 
   void _exitSearchMode() {
+    Debouncer.cancel(_searchDebounceTag);
     setState(() {
       _searchActive = false;
       _searchQuery = '';
@@ -175,7 +217,22 @@ class _ChatViewState extends State<ChatView> with RouteAware {
     });
   }
 
+  late final String _searchDebounceTag =
+      'chat-search-${identityHashCode(this)}';
+
+  /// Matching re-scans the whole history and rebuilds every row, so it runs
+  /// once typing pauses instead of per keystroke.
   void _onSearchChanged(String q) {
+    Debouncer.debounce(
+      _searchDebounceTag,
+      const Duration(milliseconds: 200),
+      () {
+        if (mounted) _applySearch(q);
+      },
+    );
+  }
+
+  void _applySearch(String q) {
     final chatResponse = context.read<ChatBloc>().state.data?.chatResponse;
     setState(() {
       _searchQuery = q;
@@ -268,9 +325,13 @@ class _ChatViewState extends State<ChatView> with RouteAware {
         messages.add(
           ChatBubble(
             isSender: false,
+            key: ValueKey(
+              'day-${elementDate.year}-${elementDate.month}-'
+              '${elementDate.day}',
+            ),
             bubbleData: GetChatResponseObject.getDateDummy(element.timestamp),
             chatData: widget.room,
-            refetch: ({bool renew = false}) => _refresh(),
+            refetch: _refetch,
           ),
         );
       }
@@ -286,6 +347,7 @@ class _ChatViewState extends State<ChatView> with RouteAware {
 
       messages.add(
         ChatBubble(
+          key: ValueKey(element.id),
           isSender:
               element.actorId == widget.selfId &&
               (element.messageType ==
@@ -294,7 +356,7 @@ class _ChatViewState extends State<ChatView> with RouteAware {
                       GetRoomResponseObjectMessageType.deletedComment),
           bubbleData: element,
           chatData: widget.room,
-          refetch: ({bool renew = false}) => _refresh(),
+          refetch: _refetch,
           isRead: element.id <= commonRead,
           selfId: widget.selfId,
           highlightQuery: highlightQuery,
@@ -317,17 +379,7 @@ class _ChatViewState extends State<ChatView> with RouteAware {
 
   @override
   Widget build(BuildContext context) {
-    // Swallow the first back gesture while the keyboard is visible so it
-    // dismisses the IME instead of popping the chat — matches platform UX
-    // expectations (e.g. WhatsApp/Telegram) and prevents accidental exits
-    // mid-typing.
-    final keyboardOpen = MediaQuery.viewInsetsOf(context).bottom > 0;
-    return PopScope(
-      canPop: !keyboardOpen,
-      onPopInvokedWithResult: (didPop, _) {
-        if (didPop) return;
-        FocusManager.instance.primaryFocus?.unfocus();
-      },
+    return _KeyboardDismissPopScope(
       child: Scaffold(
         backgroundColor: const Color(0xffefeae2),
         appBar: _searchActive
@@ -376,25 +428,7 @@ class _ChatViewState extends State<ChatView> with RouteAware {
                       state.currentToken == widget.room.token,
                   enablePullToRefresh: false,
                   child: (state, _) {
-                    final items = _buildMessages(
-                      state.chatResponse!,
-                    ).reversed.toList();
-                    // reverse:true renders index 0 at the bottom, so the top
-                    // marker (spinner / start-of-chat) goes at the end.
-                    if (state.isLoadingOlder) {
-                      items.add(const _LoadingOlderIndicator());
-                    } else if (!state.hasMoreOld) {
-                      items.add(
-                        ChatBubble(
-                          isSender: false,
-                          bubbleData: GetChatResponseObject.getTextDummy(
-                            'Anfang des Chats',
-                          ),
-                          chatData: widget.room,
-                          refetch: ({bool renew = false}) => _refresh(),
-                        ),
-                      );
-                    }
+                    final items = _itemsFor(state);
                     _itemCount = items.length;
                     return ScrollablePositionedList.builder(
                       reverse: true,
@@ -448,3 +482,27 @@ class _LoadingOlderIndicator extends StatelessWidget {
     ),
   );
 }
+
+/// Swallows the first back gesture while the keyboard is visible so it
+/// dismisses the IME instead of popping the chat — matches platform UX
+/// expectations (e.g. WhatsApp/Telegram) and prevents accidental exits
+/// mid-typing. A separate widget so the per-frame inset changes during the
+/// keyboard animation only rebuild this scope, not the whole chat.
+class _KeyboardDismissPopScope extends StatelessWidget {
+  final Widget child;
+
+  const _KeyboardDismissPopScope({required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    final keyboardOpen = MediaQuery.viewInsetsOf(context).bottom > 0;
+    return PopScope(
+      canPop: !keyboardOpen,
+      onPopInvokedWithResult: (didPop, _) {
+        if (didPop) return;
+        FocusManager.instance.primaryFocus?.unfocus();
+      },
+      child: child,
+    );
+  }
+}

lib/view/pages/talk/widgets/chat_bubble.dart

@@ -59,6 +59,13 @@ class _ChatBubbleState extends State<ChatBubble>
     with SingleTickerProviderStateMixin, DownloadTrigger<ChatBubble> {
   late ChatMessage message;
 
+  // The parsed message and its widget are only rebuilt when their inputs
+  // change. The bubble itself rebuilds on every chat emit, swipe frame and
+  // keyboard frame; re-running rich-object parsing, linkify/Markdown and emoji
+  // detection each time is what makes long chats stutter.
+  Object? _messageKey;
+  late Widget _messageWidget;
+
   Offset _position = Offset.zero;
   Offset _dragStartPosition = Offset.zero;
   bool _swipeActionArmed = false;
@@ -185,12 +192,34 @@ class _ChatBubbleState extends State<ChatBubble>
     }
   }
 
-  @override
-  Widget build(BuildContext context) {
+  void _updateMessage(BuildContext context) {
+    final style = _messageTextStyle(context);
+    final renderMarkdown =
+        widget.bubbleData.markdown &&
+        widget.bubbleData.messageType ==
+            GetRoomResponseObjectMessageType.comment;
+    final key = (
+      widget.bubbleData,
+      widget.highlightQuery,
+      style,
+      renderMarkdown,
+    );
+    if (key == _messageKey) return;
+    _messageKey = key;
     message = ChatMessage(
       originalMessage: widget.bubbleData.message,
       originalData: widget.bubbleData.messageParameters,
     );
+    _messageWidget = message.getWidget(
+      highlightQuery: widget.highlightQuery,
+      style: style,
+      renderMarkdown: renderMarkdown,
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    _updateMessage(context);
     final showActorDisplayName =
         _rendersAsCommentBubble &&
         widget.chatData.type != GetRoomResponseObjectConversationType.oneToOne;
@@ -277,14 +306,7 @@ class _ChatBubbleState extends State<ChatBubble>
                 actorText: actorText,
                 actorWidget: actorWidget,
                 timeText: timeText,
-                messageWidget: message.getWidget(
-                  highlightQuery: widget.highlightQuery,
-                  style: _messageTextStyle(context),
-                  renderMarkdown:
-                      widget.bubbleData.markdown &&
-                      widget.bubbleData.messageType ==
-                          GetRoomResponseObjectMessageType.comment,
-                ),
+                messageWidget: _messageWidget,
                 parent: parent,
                 bubbleData: widget.bubbleData,
                 isSender: widget.isSender,
@@ -350,10 +372,12 @@ class _BubbleContent extends StatelessWidget {
   Widget build(BuildContext context) => MergeSemantics(
     child: Container(
       constraints: BoxConstraints(
-        maxWidth: MediaQuery.of(context).size.width * 0.9,
+        maxWidth: MediaQuery.sizeOf(context).width * 0.9,
         minWidth: showActorDisplayName
-            ? actorText.size.width
-            : timeText.size.width + (isSender ? spacing + timeIconSize : 0) + 3,
+            ? actorText.measuredWidth(context)
+            : timeText.measuredWidth(context) +
+                  (isSender ? spacing + timeIconSize : 0) +
+                  3,
       ),
       child: Stack(
         children: [

lib/view/pages/talk/widgets/chat_bubble_reactions.dart

@@ -34,7 +34,7 @@ class ChatBubbleReactions extends StatelessWidget {
     return Transform.translate(
       offset: const Offset(0, -10),
       child: Container(
-        width: MediaQuery.of(context).size.width,
+        width: MediaQuery.sizeOf(context).width,
         margin: const EdgeInsets.only(left: 15, right: 15),
         child: Wrap(
           alignment: isSender ? WrapAlignment.end : WrapAlignment.start,

lib/view/pages/talk/widgets/chat_textfield.dart

@@ -83,12 +83,20 @@ class _ChatTextfieldState extends State<ChatTextfield> {
     );
   }
 
+  /// Called per keystroke, so the text itself is saved silently; only a draft
+  /// appearing or disappearing notifies listeners (the chat list's marker).
   void _setDraft(String text) {
-    final talkSettings = settings.val(write: true).talkSettings;
+    final drafts = settings.val().talkSettings.drafts;
+    final hadDraft = drafts.containsKey(widget.sendToToken);
     if (text.isNotEmpty) {
-      talkSettings.drafts[widget.sendToToken] = text;
+      drafts[widget.sendToToken] = text;
     } else {
-      talkSettings.drafts.removeWhere((key, _) => key == widget.sendToToken);
+      drafts.remove(widget.sendToToken);
+    }
+    if (hadDraft != text.isNotEmpty) {
+      settings.val(write: true);
+    } else {
+      settings.saveSilently();
     }
   }
 
@@ -276,17 +284,22 @@ class _ChatTextfieldState extends State<ChatTextfield> {
 
   @override
   Widget build(BuildContext context) {
-    final chatBloc = context.watch<ChatBloc>();
-    final chatState = chatBloc.state.data;
+    final chatBloc = context.read<ChatBloc>();
+    // Only the reply reference is rendered from the chat state; loading flags
+    // and paging emits don't need to rebuild the input.
+    final (referenceMessageId, chatResponse) = context.select(
+      (ChatBloc b) => (
+        b.state.data?.referenceMessageId,
+        b.state.data?.chatResponse,
+      ),
+    );
 
     Widget replyBanner = const SizedBox.shrink();
-    if (chatState != null &&
-        chatState.referenceMessageId != null &&
-        chatState.chatResponse != null) {
+    if (referenceMessageId != null && chatResponse != null) {
       try {
-        final referenceMessage = chatState.chatResponse!
-            .sortByTimestamp()
-            .firstWhere((e) => e.id == chatState.referenceMessageId);
+        final referenceMessage = chatResponse.data.firstWhere(
+          (e) => e.id == referenceMessageId,
+        );
         replyBanner = Row(
           children: [
             Expanded(

lib/view/pages/talk/widgets/chat_tile.dart

@@ -68,15 +68,25 @@ class _ChatTileState extends State<ChatTile> {
   /// One-line preview of the last message: rich-object placeholders resolved,
   /// newlines flattened and — for Markdown messages — formatting stripped so
   /// the list shows readable text rather than raw markers.
+  ///
+  /// Memoised per last message: the tile rebuilds on every chat-list emit and
+  /// the Markdown strip is a full parse. Keyed by content, since every refresh
+  /// delivers new message objects.
   String _lastMessagePreview() {
     final last = widget.data.lastMessage;
+    final key = (last.id, last.message, last.markdown);
+    if (key == _previewFor) return _preview;
     final text = RichObjectStringProcessor.parseToString(
       last.message.replaceAll('\n', ' '),
       last.messageParameters,
     );
-    return last.markdown ? markdownToPlainText(text) : text;
+    _previewFor = key;
+    return _preview = last.markdown ? markdownToPlainText(text) : text;
   }
 
+  Object? _previewFor;
+  String _preview = '';
+
   Future<void> _setCurrentAsRead() async {
     final token = widget.data.token;
     final lastId = widget.data.lastMessage.id;
@@ -89,7 +99,11 @@ class _ChatTileState extends State<ChatTile> {
 
   @override
   Widget build(BuildContext context) {
-    final chatBloc = context.watch<ChatBloc>();
+    // Only the open token matters here (split-view highlight); watching the
+    // whole bloc rebuilt every tile on each message of the open chat.
+    final currentToken = context.select(
+      (ChatBloc b) => b.state.data?.currentToken,
+    );
     final isGroup =
         widget.data.type != GetRoomResponseObjectConversationType.oneToOne;
     final circleAvatar = UserAvatar(
@@ -100,7 +114,7 @@ class _ChatTileState extends State<ChatTile> {
     return ListTile(
       style: ListTileStyle.list,
       tileColor:
-          chatBloc.state.data?.currentToken == widget.data.token &&
+          currentToken == widget.data.token &&
               TalkNavigator.isSecondaryVisible(context)
           ? Theme.of(context).primaryColor.withAlpha(100)
           : null,

lib/view/pages/timetable/data/calendar_logic.dart

@@ -1,7 +1,7 @@
-import 'package:rrule/rrule.dart';
 import 'package:syncfusion_flutter_calendar/calendar.dart';
 
 import '../../../../extensions/date_time.dart';
+import '../../../../utils/recurrence_occurrences.dart';
 import 'arbitrary_appointment.dart';
 import 'calendar_layout.dart';
 import 'lesson_period_schedule.dart';
@@ -103,7 +103,6 @@ partitionAppointmentsForWeek(
       continue;
     }
     try {
-      final parsed = RecurrenceRule.fromString(rule);
       final anchorUtc = a.startTime.toUtc();
       final duration = a.endTime.difference(a.startTime);
       // Day-keyed set of exception dates so occurrences scheduled for one
@@ -112,9 +111,12 @@ partitionAppointmentsForWeek(
       final exceptionDayKeys = (a.recurrenceExceptionDates ?? const <DateTime>[])
           .map((d) => '${d.year}-${d.month}-${d.day}')
           .toSet();
-      for (final occUtc in parsed.getInstances(start: anchorUtc)) {
-        if (!occUtc.isBefore(weekEndUtc)) break;
-        if (occUtc.isBefore(weekStartUtc)) continue;
+      for (final occUtc in RecurrenceOccurrences.between(
+        rule,
+        anchorUtc,
+        weekStartUtc,
+        weekEndUtc,
+      )) {
         final occLocal = occUtc.toLocal();
         if (exceptionDayKeys.contains(
           '${occLocal.year}-${occLocal.month}-${occLocal.day}',

lib/view/pages/timetable/timetable.dart

@@ -266,11 +266,12 @@ class _ViewingBanner extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
-    final isFavorite = context
-        .watch<SettingsCubit>()
-        .val()
-        .timetableFavoritesSettings
-        .isFavorite(element.type, element.id);
+    final isFavorite = context.select(
+      (SettingsCubit c) => c.state.timetableFavoritesSettings.isFavorite(
+        element.type,
+        element.id,
+      ),
+    );
 
     final onColor = theme.colorScheme.onSecondaryContainer;
     // Compact icon button: ~32px square, no extra padding, so the banner stays

lib/view/pages/timetable/widgets/timetable_calendar_view.dart

@@ -7,10 +7,10 @@ import '../../../../extensions/date_time.dart';
 import '../../../../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
 import '../../../../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../../../../state/app/modules/timetable/bloc/timetable_state.dart';
-import '../../../../storage/timetable_settings.dart';
 import '../data/arbitrary_appointment.dart';
 import '../data/lesson_period_schedule.dart';
 import '../data/timetable_appointment_factory.dart';
+import '../data/timetable_name_mode.dart';
 import 'custom_workweek_calendar.dart';
 import 'special_regions_builder.dart';
 
@@ -51,9 +51,10 @@ class TimetableCalendarViewState extends State<TimetableCalendarView> {
       GlobalKey<CustomWorkWeekCalendarState>();
 
   List<Appointment>? _cachedAppointments;
-  // TimetableSettings and List define no `==`, so record equality degrades to
-  // the same identity checks the cache always used.
-  (int, TimetableSettings, List<CustomTimetableEvent>, bool)? _cacheKey;
+  // Settings are keyed by the values the factory reads: the settings object is
+  // re-created on every settings write, so its identity would miss the cache
+  // for unrelated changes. The event list has no `==` and compares by identity.
+  (int, bool, TimetableNameMode, List<CustomTimetableEvent>, bool)? _cacheKey;
 
   // Stable identities let the calendar reuse its per-week pages across
   // rebuilds; rebuilding these every frame would invalidate that cache.
@@ -71,13 +72,16 @@ class TimetableCalendarViewState extends State<TimetableCalendarView> {
   }
 
   List<Appointment> _appointments(TimetableState state) {
-    final timetableSettings = context
-        .watch<SettingsCubit>()
-        .val()
-        .timetableSettings;
+    final (connectDoubleLessons, nameMode) = context.select(
+      (SettingsCubit c) => (
+        c.state.timetableSettings.connectDoubleLessons,
+        c.state.timetableSettings.timetableNameMode,
+      ),
+    );
     final key = (
       state.dataVersion,
-      timetableSettings,
+      connectDoubleLessons,
+      nameMode,
       widget.customEvents,
       widget.showClassInsteadOfTeacher,
     );
@@ -91,7 +95,7 @@ class TimetableCalendarViewState extends State<TimetableCalendarView> {
       customEvents: widget.customEvents,
       subjects: state.subjects?.result ?? const [],
       holidays: state.schoolHolidays?.result ?? const [],
-      settings: timetableSettings,
+      settings: context.read<SettingsCubit>().val().timetableSettings,
       now: DateTime.now(),
       showClassInsteadOfTeacher: widget.showClassInsteadOfTeacher,
     ).build();

lib/widget/chat_background.dart

@@ -8,6 +8,7 @@ import '../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../storage/chat_background_settings.dart';
 import '../theming/app_theme.dart';
 import '../utils/app_paths.dart';
+import '../utils/screen_bound_image.dart';
 
 /// Renders the configurable chat background behind [child].
 ///
@@ -24,7 +25,13 @@ class ChatBackground extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final s = context.watch<SettingsCubit>().val().chatBackgroundSettings;
+    // Value snapshot: the settings object is mutated in place, so only copied
+    // values can tell whether the background actually changed.
+    context.select((SettingsCubit c) {
+      final s = c.state.chatBackgroundSettings;
+      return (s.type, s.fit, s.colorValue, s.imageVersion, s.dim, s.blur);
+    });
+    final s = context.read<SettingsCubit>().val().chatBackgroundSettings;
     final dark = AppTheme.isDarkMode(context);
 
     final Widget background;
@@ -32,7 +39,9 @@ class ChatBackground extends StatelessWidget {
       case ChatBackgroundType.none:
         background = ColoredBox(color: Theme.of(context).colorScheme.surface);
       case ChatBackgroundType.color:
-        background = ColoredBox(color: Color(s.colorValue ?? _fallbackColor.toARGB32()));
+        background = ColoredBox(
+          color: Color(s.colorValue ?? _fallbackColor.toARGB32()),
+        );
       case ChatBackgroundType.pattern:
         background = _imageLayer(
           const AssetImage('assets/background/chat.png'),
@@ -41,12 +50,17 @@ class ChatBackground extends StatelessWidget {
           isPattern: true,
         );
       case ChatBackgroundType.image:
+        final image = FileImage(File(AppPaths.chatBackgroundImage));
         background = KeyedSubtree(
           // imageVersion changes on every replacement, forcing a fresh subtree
           // alongside the explicit ImageCache evict in the settings handler.
           key: ValueKey(s.imageVersion),
+          // Only "cover" scales the photo to the screen; tile/center render
+          // it unscaled, so those keep the natural size.
           child: _imageLayer(
-            FileImage(File(AppPaths.chatBackgroundImage)),
+            s.fit == ChatBackgroundFit.cover
+                ? screenBoundImage(context, image)
+                : image,
             s,
             dark,
             isPattern: false,
@@ -57,7 +71,9 @@ class ChatBackground extends StatelessWidget {
     return Stack(
       fit: StackFit.expand,
       children: [
-        Positioned.fill(child: background),
+        // Own layer: without it every scroll frame of the message list above
+        // repaints the (possibly tiled or blurred) background as well.
+        Positioned.fill(child: RepaintBoundary(child: background)),
         if (s.dim > 0)
           Positioned.fill(
             child: ColoredBox(color: Colors.black.withValues(alpha: s.dim)),

lib/widget/debug/cache_view.dart

@@ -2,10 +2,9 @@ import 'dart:convert';
 import 'package:filesize/filesize.dart';
 import 'package:flutter/material.dart';
 import 'package:jiffy/jiffy.dart';
-import 'package:localstore/localstore.dart';
 
 import '../../../widget/placeholder_view.dart';
-import '../../api/request_cache.dart';
+import '../../api/cache_store.dart';
 import '../app_progress_indicator.dart';
 import 'json_viewer.dart';
 
@@ -15,31 +14,11 @@ class CacheView extends StatefulWidget {
   @override
   State<CacheView> createState() => _CacheViewState();
 
-  Future<void> clear() async {
-    await Localstore.instance.collection(RequestCache.collection).delete();
-  }
-
-  Future<int> totalSize() async {
-    final data = await Localstore.instance
-        .collection(RequestCache.collection)
-        .get();
-    if (data == null || data.isEmpty) return 0;
-    return data.values.fold<int>(
-          0,
-          (sum, value) => sum + jsonEncode(value).length,
-        ) *
-        8;
-  }
 }
 
 class _CacheViewState extends State<CacheView> {
-  late Future<Map<String, dynamic>?> files;
-
-  @override
-  void initState() {
-    files = Localstore.instance.collection(RequestCache.collection).get();
-    super.initState();
-  }
+  late final Future<Map<String, CacheEntry>> files = CacheStore.instance
+      .readAll();
 
   @override
   Widget build(BuildContext context) => Scaffold(
@@ -47,24 +26,23 @@ class _CacheViewState extends State<CacheView> {
     body: FutureBuilder(
       future: files,
       builder: (context, snapshot) {
-        if (snapshot.hasData) {
+        if (snapshot.hasData && snapshot.data!.isNotEmpty) {
           return ListView.builder(
             itemCount: snapshot.data!.length,
             itemBuilder: (context, index) {
               final key = snapshot.data!.keys.elementAt(index);
-              final element = snapshot.data![key] as Map<String, dynamic>;
-              final filename = key.split('/').last;
+              final element = snapshot.data![key]!;
 
               return ListTile(
                 leading: const Icon(Icons.text_snippet_outlined),
-                title: Text(filename),
+                title: Text(key),
                 subtitle: Text(
-                  '${filesize(jsonEncode(element).length * 8)}, ${Jiffy.parseFromMillisecondsSinceEpoch(element['lastupdate'] as int).fromNow()}',
+                  '${filesize(utf8.encode(element.json).length)}, ${Jiffy.parseFromMillisecondsSinceEpoch(element.lastUpdate).fromNow()}',
                 ),
                 trailing: const Icon(Icons.arrow_right),
                 onTap: () => JsonViewer.asDialog(
                   context,
-                  jsonDecode(element['json'] as String) as Map<String, dynamic>,
+                  jsonDecode(element.json) as Map<String, dynamic>,
                 ),
               );
             },

lib/widget/file_viewer.dart

@@ -4,6 +4,7 @@ import 'dart:io';
 import 'dart:math';
 
 import 'package:file_picker/file_picker.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:flutter_svg/flutter_svg.dart';
@@ -15,6 +16,7 @@ import '../routing/app_routes.dart';
 import '../share_intent/remote_file_ref.dart';
 import '../state/app/modules/settings/bloc/settings_cubit.dart';
 import '../utils/downloads/download_manager.dart';
+import '../utils/screen_bound_image.dart';
 import 'app_progress_indicator.dart';
 import 'async_action_button.dart';
 import 'centered_leading.dart';
@@ -49,6 +51,7 @@ class FileViewer extends StatefulWidget {
 enum FileViewingActions { openExternal, share, save, sendToChat, saveToCloud }
 
 class _FileViewerState extends State<FileViewer> {
+  Future<_TextPayload>? _textPayload;
   final PhotoViewController photoViewController = PhotoViewController();
 
   late SettingsCubit settings = context.read<SettingsCubit>();
@@ -302,7 +305,13 @@ class _FileViewerState extends State<FileViewer> {
       controller: photoViewController,
       maxScale: 3.0,
       minScale: 0.1,
-      imageProvider: Image.file(File(widget.path)).image,
+      // 2× the screen stays sharp while zooming in; the 4096 px cap only
+      // bites on camera-sized photos.
+      imageProvider: screenBoundImage(
+        context,
+        FileImage(File(widget.path)),
+        scale: 2,
+      ),
       backgroundDecoration: BoxDecoration(
         color: Theme.of(context).colorScheme.surface,
       ),
@@ -348,13 +357,17 @@ class _FileViewerState extends State<FileViewer> {
   Widget _buildTextView() => Scaffold(
     appBar: _appbar(),
     body: FutureBuilder<_TextPayload>(
-      future: _readTextPayload(),
+      // Cached: a future created in build re-read the file on every rebuild.
+      future: _textPayload ??= compute(
+        _loadTextPayload,
+        (widget.path, _textViewMaxBytes),
+      ),
       builder: (context, snapshot) {
         if (!snapshot.hasData) {
           return const Center(child: AppProgressIndicator.large());
         }
         final payload = snapshot.data!;
-        final lines = const LineSplitter().convert(payload.content);
+        final lines = payload.lines;
         // Stable gutter width — sized by the highest line number's digit count.
         final gutterWidth = (lines.length.toString().length * 9.0) + 16;
         return SelectionArea(
@@ -443,38 +456,6 @@ class _FileViewerState extends State<FileViewer> {
   }
 
   static const int _textViewMaxBytes = 5 * 1024 * 1024;
-
-  Future<_TextPayload> _readTextPayload() async {
-    final file = File(widget.path);
-    final size = await file.length();
-    final ext = widget.path.split('.').last.toLowerCase();
-    if (size <= _textViewMaxBytes) {
-      final raw = await file.readAsString();
-      return _TextPayload(content: _maybePrettify(raw, ext), truncated: false);
-    }
-    final raf = await file.open();
-    try {
-      final bytes = await raf.read(_textViewMaxBytes);
-      // Truncated payloads stay raw — a parser would choke on the dangling tail.
-      return _TextPayload(
-        content: utf8.decode(bytes, allowMalformed: true),
-        truncated: true,
-      );
-    } finally {
-      await raf.close();
-    }
-  }
-
-  /// Falls through to the original text on parse errors.
-  String _maybePrettify(String content, String ext) {
-    if (ext != 'json') return content;
-    try {
-      final parsed = jsonDecode(content);
-      return const JsonEncoder.withIndent('  ').convert(parsed);
-    } on Object {
-      return content;
-    }
-  }
 }
 
 class _ActionDescriptor {
@@ -489,7 +470,47 @@ class _ActionDescriptor {
 }
 
 class _TextPayload {
-  final String content;
+  final List<String> lines;
   final bool truncated;
-  const _TextPayload({required this.content, required this.truncated});
+  const _TextPayload({required this.lines, required this.truncated});
+}
+
+/// Reads, prettifies (JSON) and splits a text file on a background isolate:
+/// up to 5 MB of decoding and line splitting would otherwise freeze the UI.
+Future<_TextPayload> _loadTextPayload((String, int) args) async {
+  final (path, maxBytes) = args;
+  final file = File(path);
+  final size = await file.length();
+  final ext = path.split('.').last.toLowerCase();
+  if (size <= maxBytes) {
+    final raw = await file.readAsString();
+    return _TextPayload(
+      lines: const LineSplitter().convert(_maybePrettify(raw, ext)),
+      truncated: false,
+    );
+  }
+  final raf = await file.open();
+  try {
+    final bytes = await raf.read(maxBytes);
+    // Truncated payloads stay raw — a parser would choke on the dangling tail.
+    return _TextPayload(
+      lines: const LineSplitter().convert(
+        utf8.decode(bytes, allowMalformed: true),
+      ),
+      truncated: true,
+    );
+  } finally {
+    await raf.close();
+  }
+}
+
+/// Falls through to the original text on parse errors.
+String _maybePrettify(String content, String ext) {
+  if (ext != 'json') return content;
+  try {
+    final parsed = jsonDecode(content);
+    return const JsonEncoder.withIndent('  ').convert(parsed);
+  } on Object {
+    return content;
+  }
 }

lib/widget/prosemirror/pm_image_view.dart

@@ -10,9 +10,33 @@ class PmImageView extends StatelessWidget {
 
   const PmImageView({required this.node, super.key});
 
+  /// Full-resolution source, used for the zoomable fullscreen view.
+  static ImageProvider? sourceProvider(PmImage node) {
+    final bytes = node.bytes;
+    if (bytes != null) return MemoryImage(bytes);
+    if (node.src.startsWith('http')) {
+      return CachedNetworkImageProvider(node.src);
+    }
+    return null;
+  }
+
+  /// Inline images never render wider than the screen, so they are decoded at
+  /// most at its physical width instead of the (often camera-sized) original.
+  /// [PmJsonView] precaches through this too, so both hit the same cache key.
+  static ImageProvider? inlineProvider(BuildContext context, PmImage node) {
+    final source = sourceProvider(node);
+    if (source == null) return null;
+    final width =
+        (MediaQuery.sizeOf(context).width *
+                MediaQuery.devicePixelRatioOf(context))
+            .round();
+    return ResizeImage(source, width: width);
+  }
+
   @override
   Widget build(BuildContext context) {
-    final provider = _imageProvider();
+    final provider = sourceProvider(node);
+    final inline = inlineProvider(context, node);
     return LayoutBuilder(
       builder: (context, constraints) {
         final available = constraints.maxWidth.isFinite
@@ -22,7 +46,13 @@ class PmImageView extends StatelessWidget {
 
         Widget image = ConstrainedBox(
           constraints: BoxConstraints(maxWidth: targetWidth ?? available),
-          child: _imageWidget(context, provider),
+          child: inline == null
+              ? _brokenImage(context)
+              : Image(
+                  image: inline,
+                  errorBuilder: (context, error, stack) =>
+                      _brokenImage(context),
+                ),
         );
 
         final href = node.href;
@@ -43,30 +73,6 @@ class PmImageView extends StatelessWidget {
     );
   }
 
-  ImageProvider? _imageProvider() {
-    if (node.bytes != null) return MemoryImage(node.bytes!);
-    if (node.src.startsWith('http')) {
-      return CachedNetworkImageProvider(node.src);
-    }
-    return null;
-  }
-
-  Widget _imageWidget(BuildContext context, ImageProvider? provider) {
-    if (node.bytes != null) {
-      return Image.memory(
-        node.bytes!,
-        errorBuilder: (context, error, stack) => _brokenImage(context),
-      );
-    }
-    if (node.src.startsWith('http')) {
-      return CachedNetworkImage(
-        imageUrl: node.src,
-        errorWidget: (context, url, error) => _brokenImage(context),
-      );
-    }
-    return _brokenImage(context);
-  }
-
   Widget _brokenImage(BuildContext context) {
     final theme = Theme.of(context);
     return DecoratedBox(

lib/widget/prosemirror/pm_json_view.dart

@@ -1,9 +1,9 @@
-import 'package:cached_network_image/cached_network_image.dart';
 import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
 
 import '../app_progress_indicator.dart';
 import 'pm_document_view.dart';
+import 'pm_image_view.dart';
 import 'pm_node.dart';
 
 /// Renders raw ProseMirror JSON and memoises the parsed tree across rebuilds.
@@ -31,7 +31,7 @@ class PmJsonView extends StatefulWidget {
 class _PmJsonViewState extends State<PmJsonView> {
   PmNode? _shown;
   PmNode? _pending;
-  List<ImageProvider> _pendingProviders = const [];
+  List<PmImage> _pendingImages = const [];
   bool _precacheStarted = false;
   int _generation = 0;
 
@@ -62,17 +62,17 @@ class _PmJsonViewState extends State<PmJsonView> {
 
   void _parse() {
     final doc = PmNode.fromJson(widget.json);
-    final providers = <ImageProvider>[];
-    _collectProviders(doc, providers);
+    final images = <PmImage>[];
+    _collectImages(doc, images);
     _generation++;
     _precacheStarted = false;
-    if (providers.isEmpty) {
+    if (images.isEmpty) {
       _shown = doc;
       _pending = null;
-      _pendingProviders = const [];
+      _pendingImages = const [];
     } else {
       _pending = doc;
-      _pendingProviders = providers;
+      _pendingImages = images;
     }
   }
 
@@ -82,7 +82,8 @@ class _PmJsonViewState extends State<PmJsonView> {
     _precacheStarted = true;
     final generation = _generation;
     Future.wait([
-          for (final provider in _pendingProviders)
+          for (final image in _pendingImages)
+            if (PmImageView.inlineProvider(context, image) case final provider?)
               precacheImage(provider, context, onError: (_, _) {}),
         ])
         .timeout(PmJsonView.precacheTimeout, onTimeout: () => const [])
@@ -91,23 +92,16 @@ class _PmJsonViewState extends State<PmJsonView> {
             setState(() {
               _shown = pending;
               _pending = null;
-              _pendingProviders = const [];
+              _pendingImages = const [];
             });
           }
         });
   }
 
-  void _collectProviders(PmNode node, List<ImageProvider> out) {
-    if (node is PmImage) {
-      final bytes = node.bytes;
-      if (bytes != null) {
-        out.add(MemoryImage(bytes));
-      } else if (node.src.startsWith('http')) {
-        out.add(CachedNetworkImageProvider(node.src));
-      }
-    }
+  void _collectImages(PmNode node, List<PmImage> out) {
+    if (node is PmImage) out.add(node);
     for (final child in node.children) {
-      _collectProviders(child, out);
+      _collectImages(child, out);
     }
   }
 

lib/widget/share_position_origin.dart

@@ -4,7 +4,7 @@ class SharePositionOrigin {
   static Rect get(BuildContext context) => Rect.fromLTWH(
     0,
     0,
-    MediaQuery.of(context).size.width,
-    MediaQuery.of(context).size.height / 2,
+    MediaQuery.sizeOf(context).width,
+    MediaQuery.sizeOf(context).height / 2,
   );
 }

lib/widget/user_avatar.dart

@@ -389,6 +389,10 @@ class _UserAvatarState extends State<UserAvatar> {
           payload.bytes,
           width: radius * 2,
           height: radius * 2,
+          // Group avatars arrive at a fixed large server size; decoding them
+          // at display size keeps a chat list from filling the image cache.
+          cacheWidth: (radius * 2 * MediaQuery.devicePixelRatioOf(context))
+              .round(),
           fit: BoxFit.cover,
           gaplessPlayback: true,
         );

lib/widget_data/widget_data_mapper.dart

@@ -1,7 +1,5 @@
 import 'dart:developer';
 
-import 'package:rrule/rrule.dart';
-
 import '../api/marianumconnect/queries/timetable_get_holidays/timetable_get_holidays_response.dart';
 import '../api/marianumconnect/queries/timetable_get_rooms/timetable_get_rooms_response.dart';
 import '../api/marianumconnect/queries/timetable_get_subjects/timetable_get_subjects_response.dart';
@@ -10,6 +8,7 @@ import '../api/marianumconnect/queries/timetable_get_week/timetable_get_week_res
 import '../api/mhsl/custom_timetable_event/custom_timetable_event.dart';
 import '../api/mhsl/custom_timetable_event/get/get_custom_timetable_event_response.dart';
 import '../extensions/date_time.dart';
+import '../utils/recurrence_occurrences.dart';
 import '../view/pages/timetable/data/lesson_labels.dart';
 import '../view/pages/timetable/data/lesson_merger.dart';
 import '../view/pages/timetable/data/lesson_period_schedule.dart';
@@ -443,11 +442,13 @@ class WidgetDataMapper {
     }
 
     try {
-      final parsed = RecurrenceRule.fromString(rule);
       final anchorUtc = event.startDate.toUtc();
-      for (final occUtc in parsed.getInstances(start: anchorUtc)) {
-        if (!occUtc.isBefore(rangeEndUtc)) break;
-        if (occUtc.isBefore(rangeStartUtc)) continue;
+      for (final occUtc in RecurrenceOccurrences.between(
+        rule,
+        anchorUtc,
+        rangeStartUtc,
+        rangeEndUtc,
+      )) {
         final occLocal = occUtc.toLocal();
         final occStart = DateTime(
           occLocal.year,

lib/widget_data/widget_publisher.dart

@@ -1,3 +1,4 @@
+import 'dart:convert';
 import 'dart:developer';
 
 import 'package:flutter/foundation.dart';
@@ -20,22 +21,65 @@ class WidgetPublisher {
   static DateTime widgetNow() =>
       kDebugMode ? DateTime.now().add(debugTimeShift) : DateTime.now();
 
+  /// Identical snapshots are still re-written after this long, so the stored
+  /// `fetchedAt` (freshness for the background refresh) doesn't go stale.
+  static const Duration _republishAfter = Duration(minutes: 10);
+
+  static Future<void> _queue = Future.value();
+  static (bool, String, bool)? _lastFlags;
+  static String? _lastSignature;
+  static DateTime? _lastPublishedAt;
+
+  /// Forgets what was written last, so the next publish writes again. Called
+  /// whenever the stored widget data is cleared (sign-out).
+  static void resetDedupe() {
+    _lastSignature = null;
+    _lastPublishedAt = null;
+  }
+
+  /// Publishes run one at a time: they are fire-and-forget from the bloc
+  /// stream, and interleaved writes could leave day and week data from
+  /// different states behind.
+  /// [epoch] is the session the [state] belongs to; defaults to the current
+  /// one. Callers that delay the publish must capture it up front.
   static Future<void> publishFromBlocState(
     TimetableState state, {
     Settings? settings,
     bool isTeacher = false,
+    int? epoch,
+  }) {
+    final sessionEpoch = epoch ?? AccountData().sessionEpoch;
+    return _queue = _queue.then(
+      (_) => _publish(
+        state,
+        settings: settings,
+        isTeacher: isTeacher,
+        epoch: sessionEpoch,
+      ),
+    );
+  }
+
+  static Future<void> _publish(
+    TimetableState state, {
+    required Settings? settings,
+    required bool isTeacher,
+    required int epoch,
   }) async {
-    final epoch = AccountData().sessionEpoch;
+    if (!AccountData().isCurrentSession(epoch)) return;
     try {
       final connectDouble =
           settings?.timetableSettings.connectDoubleLessons ?? true;
       // Mirror into widget storage so the background isolate sees the same
       // values the user just toggled — concurrently, they are independent.
+      final flags = (connectDouble, _themeName(settings?.appTheme), isTeacher);
+      if (flags != _lastFlags) {
         await Future.wait([
-        WidgetSync.setConnectDoubleLessons(connectDouble),
-        WidgetSync.setThemeMode(_themeName(settings?.appTheme)),
-        WidgetSync.setIsTeacher(isTeacher),
+          WidgetSync.setConnectDoubleLessons(flags.$1),
+          WidgetSync.setThemeMode(flags.$2),
+          WidgetSync.setIsTeacher(flags.$3),
         ]);
+        _lastFlags = flags;
+      }
       final lessons = state.getAllKnownLessons();
       final now = widgetNow();
       final dayData = WidgetDataMapper.buildDayData(
@@ -63,6 +107,20 @@ class WidgetPublisher {
       // A publish still running at sign-out would put the previous account's
       // plan back onto the just cleared widget.
       if (!AccountData().isCurrentSession(epoch)) return;
+      // Most bloc emits (week swipes, prefetches) don't touch the widget's
+      // window; skip the SharedPreferences commits and widget re-render then.
+      final signature = jsonEncode([
+        _withoutFetchedAt(dayData.toJson()),
+        _withoutFetchedAt(weekData.toJson()),
+      ]);
+      final lastAt = _lastPublishedAt;
+      if (signature == _lastSignature &&
+          lastAt != null &&
+          now.difference(lastAt) < _republishAfter) {
+        return;
+      }
+      _lastSignature = signature;
+      _lastPublishedAt = now;
       await WidgetSync.writeDayData(dayData);
       await WidgetSync.writeWeekData(weekData);
       await WidgetSync.setLoggedIn(true);
@@ -74,6 +132,9 @@ class WidgetPublisher {
     }
   }
 
+  static Map<String, Object?> _withoutFetchedAt(Map<String, Object?> json) =>
+      Map.of(json)..remove('fetchedAt');
+
   static String _themeName(ThemeMode? mode) {
     switch (mode) {
       case ThemeMode.light:

lib/widget_data/widget_sync.dart

@@ -5,6 +5,7 @@ import 'dart:developer';
 import 'package:home_widget/home_widget.dart';
 
 import 'widget_data.dart';
+import 'widget_publisher.dart';
 
 /// Bridge to the native widget host. All keys/names live here so the Kotlin
 /// and Swift sides stay in sync.
@@ -109,6 +110,7 @@ class WidgetSync {
   }
 
   static Future<void> clear() async {
+    WidgetPublisher.resetDedupe();
     await ensureInitialized();
     await HomeWidget.saveWidgetData<String>(dayDataKey, null);
     await HomeWidget.saveWidgetData<String>(weekDataKey, null);

test/api/cache_store_test.dart

@@ -0,0 +1,21 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/api/cache_store.dart';
+
+void main() {
+  group('CacheStore.parse', () {
+    test('splits the timestamp header from the payload', () {
+      final entry = CacheStore.parse('1700000000000\n{"a":"b\\nc"}');
+      expect(entry!.lastUpdate, 1700000000000);
+      expect(entry.json, '{"a":"b\\nc"}');
+    });
+
+    test('keeps newlines inside the payload', () {
+      expect(CacheStore.parse('1\nline1\nline2')!.json, 'line1\nline2');
+    });
+
+    test('rejects files without a valid header', () {
+      expect(CacheStore.parse('{"a":1}'), isNull);
+      expect(CacheStore.parse('abc\n{}'), isNull);
+    });
+  });
+}

test/state/timetable_reference_data_test.dart

@@ -0,0 +1,32 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/api/marianumconnect/queries/timetable_get_rooms/timetable_get_rooms_response.dart';
+import 'package:marianum_mobile/state/app/modules/timetable/bloc/timetable_state.dart';
+
+TimetableGetRoomsResponse _rooms(String name) => TimetableGetRoomsResponse(
+  result: [McRoom(id: 1, shortName: name, longName: name)],
+);
+
+void main() {
+  final base = TimetableState(
+    startDate: DateTime(2026, 9, 21),
+    endDate: DateTime(2026, 9, 25),
+    rooms: _rooms('A101'),
+    dataVersion: 3,
+  );
+
+  test('returns the same state when the content is unchanged', () {
+    expect(base.withReferenceData(rooms: _rooms('A101')), same(base));
+  });
+
+  test('bumps dataVersion and takes the new value when content changed', () {
+    final next = _rooms('B202');
+    final result = base.withReferenceData(rooms: next);
+    expect(result.rooms, same(next));
+    expect(result.dataVersion, 4);
+  });
+
+  test('keeps unchanged instances when only another field changed', () {
+    final result = base.withReferenceData(rooms: _rooms('A101'));
+    expect(result.rooms, same(base.rooms));
+  });
+}

test/utils/recurrence_occurrences_test.dart

@@ -0,0 +1,48 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/utils/recurrence_occurrences.dart';
+
+void main() {
+  setUp(RecurrenceOccurrences.clear);
+
+  final anchor = DateTime.utc(2024, 9, 2, 8);
+
+  test('returns only occurrences inside the half-open range', () {
+    final hits = RecurrenceOccurrences.between(
+      'RRULE:FREQ=DAILY',
+      anchor,
+      DateTime.utc(2026, 9, 21),
+      DateTime.utc(2026, 9, 24),
+    );
+    expect(hits, [
+      DateTime.utc(2026, 9, 21, 8),
+      DateTime.utc(2026, 9, 22, 8),
+      DateTime.utc(2026, 9, 23, 8),
+    ]);
+  });
+
+  test('answers earlier ranges after a later one was expanded', () {
+    RecurrenceOccurrences.between(
+      'RRULE:FREQ=WEEKLY',
+      anchor,
+      DateTime.utc(2026, 1, 1),
+      DateTime.utc(2026, 1, 31),
+    );
+    final hits = RecurrenceOccurrences.between(
+      'RRULE:FREQ=WEEKLY',
+      anchor,
+      DateTime.utc(2024, 9, 1),
+      DateTime.utc(2024, 9, 10),
+    );
+    expect(hits, [DateTime.utc(2024, 9, 2, 8), DateTime.utc(2024, 9, 9, 8)]);
+  });
+
+  test('stops at the end of a finite series', () {
+    final hits = RecurrenceOccurrences.between(
+      'RRULE:FREQ=DAILY;COUNT=2',
+      anchor,
+      DateTime.utc(2024, 1, 1),
+      DateTime.utc(2030, 1, 1),
+    );
+    expect(hits, hasLength(2));
+  });
+}

test/view/files/local_cache_search_test.dart

@@ -11,13 +11,10 @@ CacheableFile _file({
   bool isDirectory = false,
 }) => CacheableFile(path: path, isDirectory: isDirectory, name: name);
 
-Map<String, dynamic> _doc(ListFilesResponse listing) => {
-  'json': jsonEncode(listing.toJson()),
-  'lastupdate': 0,
-};
+String _payload(ListFilesResponse listing) => jsonEncode(listing.toJson());
 
 void main() {
-  group('searchLocalCaches', () {
+  group('local cache index', () {
     final root = ListFilesResponse({
       _file(path: 'Documents/', name: 'Documents', isDirectory: true),
       _file(path: 'Photos/', name: 'Photos', isDirectory: true),
@@ -27,51 +24,45 @@ void main() {
       _file(path: 'Documents/Tax-Report.pdf', name: 'Tax-Report.pdf'),
       _file(path: 'Documents/Notes.txt', name: 'Notes.txt'),
     });
-    final docs = {
-      '/MarianumMobile/wd-folder-aaa': _doc(root),
-      '/MarianumMobile/wd-folder-bbb': _doc(documents),
-      '/MarianumMobile/get-room-ccc': {'json': '{}', 'lastupdate': 0},
-    };
+    final index = buildLocalCacheIndex([
+      _payload(root),
+      _payload(documents),
+    ]);
 
-    test('matches by name case-insensitively across all caches', () async {
-      final hits = await searchLocalCaches('report', docs: docs);
+    test('matches by name case-insensitively across all caches', () {
+      final hits = searchLocalCacheIndex(index, 'report');
       final paths = hits.map((f) => f.path).toSet();
       expect(paths, {'Reports.pdf', 'Documents/Tax-Report.pdf'});
     });
 
-    test('returns empty list for empty query', () async {
-      expect(await searchLocalCaches('   ', docs: docs), isEmpty);
+    test('returns empty list for empty query', () {
+      expect(searchLocalCacheIndex(index, '   '), isEmpty);
     });
 
-    test('respects pathScope prefix', () async {
-      final hits = await searchLocalCaches(
+    test('respects pathScope prefix', () {
+      final hits = searchLocalCacheIndex(
+        index,
         'report',
         pathScope: ['Documents'],
-        docs: docs,
       );
       expect(hits.map((f) => f.path), ['Documents/Tax-Report.pdf']);
     });
 
-    test('ignores non-folder cache documents', () async {
-      final hits = await searchLocalCaches('anything', docs: docs);
-      // Only documents starting with `wd-folder-` are scanned. The unrelated
-      // `get-room-ccc` doc must not crash the helper.
-      expect(hits, isEmpty);
+    test('skips payloads that are not folder listings', () {
+      expect(buildLocalCacheIndex(['not json', '{"foo": 1}']), isEmpty);
     });
 
-    test('deduplicates entries that appear in multiple cached folders',
-        () async {
+    test('deduplicates entries that appear in multiple cached folders', () {
       final shared = _file(
         path: 'Documents/Tax-Report.pdf',
         name: 'Tax-Report.pdf',
       );
       final dedupRoot = ListFilesResponse({shared});
-      final dedupDocs = {
-        '/MarianumMobile/wd-folder-aaa': _doc(dedupRoot),
-        '/MarianumMobile/wd-folder-bbb': _doc(dedupRoot),
-      };
-      final hits = await searchLocalCaches('tax', docs: dedupDocs);
-      expect(hits, hasLength(1));
+      final dedupIndex = buildLocalCacheIndex([
+        _payload(dedupRoot),
+        _payload(dedupRoot),
+      ]);
+      expect(searchLocalCacheIndex(dedupIndex, 'tax'), hasLength(1));
     });
   });
 }