fixed possible lockups on app start

lib/main.dart

@@ -43,14 +43,15 @@ import 'state/app/modules/chat_list/bloc/chat_list_bloc.dart';
 import 'state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart';
 import 'state/app/modules/settings/bloc/settings_cubit.dart';
 import 'state/app/modules/timetable/bloc/timetable_bloc.dart';
+import 'storage/hydrated_storage_bootstrap.dart';
 import 'storage/settings.dart';
 import 'theming/dark_app_theme.dart';
 import 'theming/light_app_theme.dart';
 import 'utils/app_paths.dart';
 import 'utils/downloads/download_manager.dart';
+import 'view/login/account_loading_screen.dart';
 import 'view/login/login.dart';
 import 'view/login/post_login_splash.dart';
-import 'widget/app_progress_indicator.dart';
 import 'widget/avatar_disk_cache.dart';
 import 'widget/breaker/breaker.dart';
 import 'widget/debug/cache_view.dart';
@@ -58,40 +59,107 @@ import 'widget/downloads/download_tray.dart';
 import 'widget/emergency/emergency_notice_gate.dart';
 import 'widget_data/widget_sync.dart';
 
+/// Runs one startup step with a time limit. Anything that throws or hangs
+/// before `runApp` would otherwise leave the native launch screen up for
+/// good, so failures are logged and reported and the app starts degraded.
+Future<void> _startupStep(
+  String name,
+  Future<void> Function() step, {
+  Duration? timeout = const Duration(seconds: 10),
+  bool report = true,
+}) async {
+  try {
+    final future = step();
+    await (timeout == null ? future : future.timeout(timeout));
+  } catch (e, s) {
+    log('Startup step "$name" failed: $e', stackTrace: s);
+    if (report) {
+      ClientErrorReporter.reportPlatformError('Startup step "$name": $e', s);
+    }
+  }
+}
+
+void _installErrorHandlers() {
+  if (kReleaseMode) {
+    ErrorWidget.builder = (error) => Material(
+      color: Colors.white,
+      child: Center(
+        child: Padding(
+          padding: const EdgeInsets.all(24),
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              const Icon(Icons.phonelink_erase_rounded, size: 40),
+              const SizedBox(height: 12),
+              Text(error.toStringShort(), textAlign: TextAlign.center),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  FlutterError.onError = (details) {
+    log(
+      'Uncaught Flutter error: ${details.exception}',
+      stackTrace: details.stack,
+    );
+    ClientErrorReporter.reportFlutterError(details);
+    FlutterError.presentError(details);
+  };
+  PlatformDispatcher.instance.onError = (error, stack) {
+    log('Uncaught platform error: $error', stackTrace: stack);
+    ClientErrorReporter.reportPlatformError(error, stack);
+    return true;
+  };
+}
+
 Future<void> main() async {
   log('MarianumMobile started');
   WidgetsFlutterBinding.ensureInitialized();
+  // Before any initialisation so startup failures reach the backend too.
+  _installErrorHandlers();
 
-  void addCertificateAsTrusted(ByteData certificate) => SecurityContext
+  Future<void> trustCertificate(String asset) => PlatformAssetBundle()
-      .defaultContext
+      .load(asset)
-      .setTrustedCertificatesBytes(certificate.buffer.asUint8List());
+      .then(
+        (certificate) => SecurityContext.defaultContext
+            .setTrustedCertificatesBytes(certificate.buffer.asUint8List()),
+      );
 
   final initialisationTasks = [
-    Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform)
+    _startupStep(
-        .then<void>((_) {})
+      'firebase',
-        .onError((error, _) => log('Error initializing Firebase: $error')),
+      () => Firebase.initializeApp(
-    PlatformAssetBundle()
+        options: DefaultFirebaseOptions.currentPlatform,
-        .load('assets/ca/lets-encrypt-r3.pem')
-        .then(addCertificateAsTrusted),
-    PlatformAssetBundle()
-        .load('assets/ca/lets-encrypt-r10.pem')
-        .then(addCertificateAsTrusted),
-    PlatformAssetBundle()
-        .load('assets/ca/lets-encrypt-r13.pem')
-        .then(addCertificateAsTrusted),
-    Future(() async {
-      final storage = await HydratedStorage.build(
-        storageDirectory: HydratedStorageDirectory(
-          (await getTemporaryDirectory()).path,
       ),
-      );
+    ),
-      HydratedBloc.storage = storage;
+    _startupStep(
-    }),
+      'ca certificates',
-    Future(() async {
+      () => Future.wait([
+        trustCertificate('assets/ca/lets-encrypt-r3.pem'),
+        trustCertificate('assets/ca/lets-encrypt-r10.pem'),
+        trustCertificate('assets/ca/lets-encrypt-r13.pem'),
+      ]),
+    ),
+    _startupStep('hydrated storage', () async {
+      final path = (await getTemporaryDirectory()).path;
+      HydratedBloc.storage = await buildHydratedStorageWithFallback(path);
+    }, timeout: null),
+    _startupStep('documents dir', () async {
       AppPaths.documentsDir = (await getApplicationDocumentsDirectory()).path;
     }),
-    AccountData().waitForPopulation(),
+    // The keychain may still be locked right after device unlock; AccountData
-    ShareIntentListener.instance.initialize(),
+    // keeps retrying, so on timeout the app starts on the loading screen and
+    // flips to the real state once the session is readable (see _MainState).
+    _startupStep(
+      'account data',
+      AccountData().waitForPopulation,
+      timeout: const Duration(seconds: 5),
+      // Expected on every background wake of a locked device; not an error.
+      report: false,
+    ),
+    _startupStep('share intent', ShareIntentListener.instance.initialize),
   ];
 
   log('starting app initialisation...');
@@ -101,8 +169,11 @@ Future<void> main() async {
   // 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.
-  await NotificationService().initializeNotifications();
+  await _startupStep(
-  await PushRenderer.ensureChannels();
+    'notifications',
+    NotificationService().initializeNotifications,
+  );
+  await _startupStep('notification channels', PushRenderer.ensureChannels);
   FirebaseMessaging.onBackgroundMessage(pushOnBackgroundMessage);
 
   // Wire up the native background downloader (progress notifications + tap
@@ -116,7 +187,7 @@ 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 WidgetSync.ensureInitialized();
+  await _startupStep('widget sync', WidgetSync.ensureInitialized);
   unawaited(
     WidgetBackgroundTask.initialize().onError(
       (e, _) => log('Workmanager init failed: $e'),
@@ -157,50 +228,13 @@ Future<void> main() async {
   // placeholder flash.
   AvatarDiskCache.instance.warmUp();
 
-  if (kReleaseMode) {
-    ErrorWidget.builder = (error) => Material(
-      color: Colors.white,
-      child: Center(
-        child: Padding(
-          padding: const EdgeInsets.all(24),
-          child: Column(
-            mainAxisSize: MainAxisSize.min,
-            children: [
-              const Icon(Icons.phonelink_erase_rounded, size: 40),
-              const SizedBox(height: 12),
-              Text(error.toStringShort(), textAlign: TextAlign.center),
-            ],
-          ),
-        ),
-      ),
-    );
-  }
-
-  FlutterError.onError = (details) {
-    log(
-      'Uncaught Flutter error: ${details.exception}',
-      stackTrace: details.stack,
-    );
-    ClientErrorReporter.reportFlutterError(details);
-    FlutterError.presentError(details);
-  };
-  PlatformDispatcher.instance.onError = (error, stack) {
-    log('Uncaught platform error: $error', stackTrace: stack);
-    ClientErrorReporter.reportPlatformError(error, stack);
-    return true;
-  };
-
   log('running app...');
   runApp(
     MultiBlocProvider(
       providers: [
         BlocProvider<SettingsCubit>(create: (_) => SettingsCubit()),
         BlocProvider<AccountBloc>(
-          create: (_) => AccountBloc(
+          create: (_) => AccountBloc(initialStatus: _initialAccountStatus()),
-            initialStatus: AccountData().isPopulated()
-                ? AccountStatus.loggedIn
-                : AccountStatus.loggedOut,
-          ),
         ),
         BlocProvider<BreakerBloc>(create: (_) => BreakerBloc()),
         BlocProvider<CapabilitiesCubit>(create: (_) => CapabilitiesCubit()),
@@ -218,6 +252,12 @@ Future<void> main() async {
   );
 }
 
+AccountStatus _initialAccountStatus() {
+  final account = AccountData();
+  if (account.isPopulated()) return AccountStatus.loggedIn;
+  return account.isLoaded ? AccountStatus.loggedOut : AccountStatus.undefined;
+}
+
 class Main extends StatefulWidget {
   const Main({super.key});
 
@@ -374,7 +414,8 @@ class _MainState extends State<Main> {
                     // away instead of deferring it to the next app start.
                     if (accountState.status == AccountStatus.loggedIn) {
                       final settingsCubit = context.read<SettingsCubit>();
-                    final capabilitiesCubit = context.read<CapabilitiesCubit>();
+                      final capabilitiesCubit = context
+                          .read<CapabilitiesCubit>();
                       unawaited(
                         capabilitiesCubit.load().then((_) {
                           if (!mounted) return;
@@ -428,7 +469,8 @@ class _MainState extends State<Main> {
                           chatBloc: chatBloc,
                           breakerBloc: breakerBloc,
                           capabilitiesCubit: capabilitiesCubit,
-                        nextcloudCapabilitiesCubit: nextcloudCapabilitiesCubit,
+                          nextcloudCapabilitiesCubit:
+                              nextcloudCapabilitiesCubit,
                         ),
                       );
                     });
@@ -444,30 +486,16 @@ class _MainState extends State<Main> {
                             if (_showPostLoginSplash)
                               PostLoginSplash(
                                 key: const ValueKey('post-login-splash'),
-                              onComplete: () =>
+                                onComplete: () => setState(
-                                  setState(() => _showPostLoginSplash = false),
+                                  () => _showPostLoginSplash = false,
+                                ),
                               ),
                           ],
                         );
                       case AccountStatus.loggedOut:
                         return const Login();
                       case AccountStatus.undefined:
-                      return Scaffold(
+                        return const AccountLoadingScreen();
-                        backgroundColor: LightAppTheme.marianumRed,
-                        body: const Center(
-                          child: Column(
-                            mainAxisAlignment: MainAxisAlignment.center,
-                            children: [
-                              AppProgressIndicator.large(color: Colors.white),
-                              SizedBox(height: 16),
-                              Text(
-                                'Konto wird geladen…',
-                                style: TextStyle(color: Colors.white),
-                              ),
-                            ],
-                          ),
-                        ),
-                      );
                     }
                   },
                 ),

lib/model/account_data.dart

@@ -1,11 +1,14 @@
 import 'dart:async';
 import 'dart:convert';
+import 'dart:developer';
+import 'dart:io';
 
 import 'package:crypto/crypto.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 import '../push/push_secure_storage.dart';
+import '../utils/exponential_backoff.dart';
 
 class AccountData {
   static const _usernameField = 'username';
@@ -26,7 +29,22 @@ class AccountData {
   // Keeps isPopulated()/getPassword() valid; demo mode never uses a real one.
   static const _demoPasswordPlaceholder = 'demo';
 
-  static const FlutterSecureStorage _secureStorage = FlutterSecureStorage();
+  // `first_unlock` so a background launch on a locked device (silent push,
+  // BGAppRefresh) can still read the session. Items written by older versions
+  // carry the plugin default `unlocked` and are invisible to this instance
+  // until _migrateKeychainAccessibility moved them over.
+  static const FlutterSecureStorage _secureStorage = FlutterSecureStorage(
+    iOptions: IOSOptions(accessibility: KeychainAccessibility.first_unlock),
+  );
+  static const FlutterSecureStorage _legacySecureStorage = FlutterSecureStorage(
+    iOptions: IOSOptions(accessibility: KeychainAccessibility.unlocked),
+  );
+  static const List<String> _sessionFields = [
+    _usernameField,
+    _passwordField,
+    _demoField,
+    _loginFlowField,
+  ];
 
   static final AccountData _instance = AccountData._construct();
   Completer<void> _populated = Completer();
@@ -34,7 +52,7 @@ class AccountData {
   factory AccountData() => _instance;
 
   AccountData._construct() {
-    _migrateAndLoad();
+    unawaited(_loadWithRetry());
   }
 
   String? _username;
@@ -175,12 +193,36 @@ class AccountData {
     }
   }
 
+  /// iOS keychain reads fail while protected data is unavailable (app launch
+  /// racing the unlock, background wake on a locked device). Without a retry
+  /// the completer never resolved and the app stayed on the launch screen.
+  Future<void> _loadWithRetry() async {
+    for (var attempt = 1; !_populated.isCompleted; attempt++) {
+      try {
+        await _migrateAndLoad();
+        return;
+      } catch (e, s) {
+        log('AccountData load failed (attempt $attempt): $e', stackTrace: s);
+        await Future<void>.delayed(exponentialBackoff(attempt));
+      }
+    }
+  }
+
+  /// Stops waiting for the stored session; the app then behaves as logged
+  /// out. The keychain entries stay untouched so a later start can still
+  /// restore the session.
+  void abandonLoad() {
+    if (!_populated.isCompleted) _populated.complete();
+  }
+
   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';
+    _usesLoginFlow =
+        (await _secureStorage.read(key: _loginFlowField)) == 'true';
     try {
       _appPassword = await pushSecureStorage.read(key: _appPasswordField);
       _appPasswordTalk = await pushSecureStorage.read(
@@ -210,11 +252,25 @@ class AccountData {
     await prefs.remove(_passwordField);
   }
 
+  Future<void> _migrateKeychainAccessibility() async {
+    if (!Platform.isIOS) return;
+    for (final field in _sessionFields) {
+      final value = await _legacySecureStorage.read(key: field);
+      if (value == null) continue;
+      // Same account+service: the legacy item has to go before the re-add.
+      await _legacySecureStorage.delete(key: field);
+      await _secureStorage.write(key: field, value: value);
+    }
+  }
+
   Future<bool> waitForPopulation() async {
     await _populated.future;
     return isPopulated();
   }
 
+  /// True once the stored session has been read (or given up on).
+  bool get isLoaded => _populated.isCompleted;
+
   bool isPopulated() => _username != null && _password != null;
 
   /// Returns the value for an HTTP `Authorization` header using HTTP Basic.

lib/storage/hydrated_storage_bootstrap.dart

@@ -0,0 +1,54 @@
+import 'dart:developer';
+import 'dart:io';
+
+import 'package:hydrated_bloc/hydrated_bloc.dart';
+
+/// Opens the HydratedBloc box; a corrupt box is dropped and rebuilt, and if
+/// even that fails the app runs on [InMemoryStorage] instead of never
+/// reaching `runApp`.
+Future<Storage> buildHydratedStorageWithFallback(String directoryPath) async {
+  final directory = HydratedStorageDirectory(directoryPath);
+  try {
+    return await HydratedStorage.build(storageDirectory: directory);
+  } catch (e, s) {
+    log('HydratedStorage open failed, rebuilding: $e', stackTrace: s);
+  }
+  try {
+    await _deleteHydratedBox(directoryPath);
+    return await HydratedStorage.build(storageDirectory: directory);
+  } catch (e, s) {
+    log('HydratedStorage rebuild failed, using memory: $e', stackTrace: s);
+    return InMemoryStorage();
+  }
+}
+
+Future<void> _deleteHydratedBox(String directoryPath) async {
+  final directory = Directory(directoryPath);
+  if (!directory.existsSync()) return;
+  await for (final entity in directory.list()) {
+    final name = entity.uri.pathSegments.lastWhere((s) => s.isNotEmpty);
+    if (entity is File && name.startsWith('hydrated_box')) {
+      await entity.delete();
+    }
+  }
+}
+
+/// Non-persistent [Storage]; state lives for the session only.
+class InMemoryStorage implements Storage {
+  final Map<String, dynamic> _values = {};
+
+  @override
+  dynamic read(String key) => _values[key];
+
+  @override
+  Future<void> write(String key, dynamic value) async => _values[key] = value;
+
+  @override
+  Future<void> delete(String key) async => _values.remove(key);
+
+  @override
+  Future<void> clear() async => _values.clear();
+
+  @override
+  Future<void> close() async {}
+}

lib/utils/exponential_backoff.dart

@@ -0,0 +1,11 @@
+/// Delay before retry number [attempt] (1-based): [base] doubled per attempt,
+/// capped at [max].
+Duration exponentialBackoff(
+  int attempt, {
+  Duration base = const Duration(milliseconds: 500),
+  Duration max = const Duration(seconds: 5),
+}) {
+  final exponent = (attempt - 1).clamp(0, 30);
+  final millis = base.inMilliseconds * (1 << exponent);
+  return millis >= max.inMilliseconds ? max : Duration(milliseconds: millis);
+}

lib/view/login/account_loading_screen.dart

@@ -0,0 +1,74 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+
+import '../../model/account_data.dart';
+import '../../theming/light_app_theme.dart';
+import '../../widget/app_progress_indicator.dart';
+
+/// Shown while the stored session is still being read. Normally gone within
+/// a second; after [hintDelay] it offers a way out so a keychain that keeps
+/// failing can never trap the user on a spinner.
+class AccountLoadingScreen extends StatefulWidget {
+  const AccountLoadingScreen({super.key});
+
+  static const Duration hintDelay = Duration(seconds: 15);
+
+  @override
+  State<AccountLoadingScreen> createState() => _AccountLoadingScreenState();
+}
+
+class _AccountLoadingScreenState extends State<AccountLoadingScreen> {
+  Timer? _hintTimer;
+  bool _showHint = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _hintTimer = Timer(AccountLoadingScreen.hintDelay, () {
+      if (mounted) setState(() => _showHint = true);
+    });
+  }
+
+  @override
+  void dispose() {
+    _hintTimer?.cancel();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+    backgroundColor: LightAppTheme.marianumRed,
+    body: Center(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 32),
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            const AppProgressIndicator.large(color: Colors.white),
+            const SizedBox(height: 16),
+            const Text(
+              'Konto wird geladen…',
+              style: TextStyle(color: Colors.white),
+            ),
+            if (_showHint) ...[
+              const SizedBox(height: 32),
+              const Text(
+                'Das dauert länger als üblich. Die gespeicherte Anmeldung '
+                'konnte noch nicht gelesen werden.',
+                textAlign: TextAlign.center,
+                style: TextStyle(color: Colors.white70),
+              ),
+              const SizedBox(height: 8),
+              TextButton(
+                onPressed: AccountData().abandonLoad,
+                style: TextButton.styleFrom(foregroundColor: Colors.white),
+                child: const Text('Zur Anmeldung'),
+              ),
+            ],
+          ],
+        ),
+      ),
+    ),
+  );
+}

test/storage/in_memory_storage_test.dart

@@ -0,0 +1,21 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/storage/hydrated_storage_bootstrap.dart';
+
+void main() {
+  test('InMemoryStorage round-trips, deletes and clears', () async {
+    final storage = InMemoryStorage();
+    expect(storage.read('a'), isNull);
+
+    await storage.write('a', {'x': 1});
+    await storage.write('b', 'two');
+    expect(storage.read('a'), {'x': 1});
+    expect(storage.read('b'), 'two');
+
+    await storage.delete('a');
+    expect(storage.read('a'), isNull);
+    expect(storage.read('b'), 'two');
+
+    await storage.clear();
+    expect(storage.read('b'), isNull);
+  });
+}

test/utils/exponential_backoff_test.dart

@@ -0,0 +1,35 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:marianum_mobile/utils/exponential_backoff.dart';
+
+void main() {
+  group('exponentialBackoff', () {
+    test('doubles per attempt starting at base', () {
+      expect(exponentialBackoff(1), const Duration(milliseconds: 500));
+      expect(exponentialBackoff(2), const Duration(seconds: 1));
+      expect(exponentialBackoff(3), const Duration(seconds: 2));
+      expect(exponentialBackoff(4), const Duration(seconds: 4));
+    });
+
+    test('caps at max', () {
+      expect(exponentialBackoff(5), const Duration(seconds: 5));
+      expect(exponentialBackoff(40), const Duration(seconds: 5));
+      expect(exponentialBackoff(1000), const Duration(seconds: 5));
+    });
+
+    test('treats attempt 0 and negatives like the first attempt', () {
+      expect(exponentialBackoff(0), const Duration(milliseconds: 500));
+      expect(exponentialBackoff(-3), const Duration(milliseconds: 500));
+    });
+
+    test('honours custom base and max', () {
+      expect(
+        exponentialBackoff(
+          3,
+          base: const Duration(seconds: 1),
+          max: const Duration(seconds: 3),
+        ),
+        const Duration(seconds: 3),
+      );
+    });
+  });
+}