rewrite isolate manager

mobile/lib/domain/services/sync_stream.service.dart

@@ -5,6 +5,7 @@ import 'dart:async';
 import 'package:collection/collection.dart';
 import 'package:immich_mobile/domain/interfaces/sync_api.interface.dart';
 import 'package:immich_mobile/domain/interfaces/sync_stream.interface.dart';
+import 'package:immich_mobile/domain/utils/cancel.exception.dart';
 import 'package:logging/logging.dart';
 import 'package:openapi/api.dart';
 
@@ -13,12 +14,15 @@ class SyncStreamService {
 
   final ISyncApiRepository _syncApiRepository;
   final ISyncStreamRepository _syncStreamRepository;
+  final Completer<bool>? _cancelCompleter;
 
   SyncStreamService({
     required ISyncApiRepository syncApiRepository,
     required ISyncStreamRepository syncStreamRepository,
+    Completer<bool>? cancelCompleter,
   })  : _syncApiRepository = syncApiRepository,
-        _syncStreamRepository = syncStreamRepository;
+        _syncStreamRepository = syncStreamRepository,
+        _cancelCompleter = cancelCompleter;
 
   Future<bool> _handleSyncData(
     SyncEntityType type,
@@ -65,7 +69,8 @@ class SyncStreamService {
     // the following flag ensures that the onDone callback is not called
     // before the events are processed and also that events are processed sequentially
     Completer? mutex;
-    final subscription = _syncApiRepository.getSyncEvents(types).listen(
+    StreamSubscription? subscription;
+    subscription = _syncApiRepository.getSyncEvents(types).listen(
       (events) async {
         if (events.isEmpty) {
           _logger.warning("Received empty sync events");
@@ -77,6 +82,18 @@ class SyncStreamService {
           await mutex!.future;
         }
 
+        if (_cancelCompleter?.isCompleted ?? false) {
+          _logger.info("Sync cancelled, stopping stream");
+          subscription?.cancel();
+          if (!streamCompleter.isCompleted) {
+            streamCompleter.completeError(
+              const CancelException(),
+              StackTrace.current,
+            );
+          }
+          return;
+        }
+
         // Take control of the mutex and process the events
         mutex = Completer();
 
@@ -85,6 +102,20 @@ class SyncStreamService {
           final Map<SyncEntityType, String> acks = {};
 
           for (final entry in eventsMap.entries) {
+            if (_cancelCompleter?.isCompleted ?? false) {
+              _logger.info("Sync cancelled, stopping stream");
+              mutex?.complete();
+              mutex = null;
+              if (!streamCompleter.isCompleted) {
+                streamCompleter.completeError(
+                  const CancelException(),
+                  StackTrace.current,
+                );
+              }
+
+              return;
+            }
+
             final type = entry.key;
             final data = entry.value;
 
@@ -133,7 +164,10 @@ class SyncStreamService {
         }
       },
     );
-    return await streamCompleter.future.whenComplete(subscription.cancel);
+    return await streamCompleter.future.whenComplete(() {
+      _logger.info("Sync stream completed");
+      return subscription?.cancel();
+    });
   }
 
   Future<void> syncUsers() =>

mobile/lib/domain/utils/background_sync.dart

@@ -0,0 +1,42 @@
+// ignore_for_file: avoid-passing-async-when-sync-expected
+
+import 'dart:async';
+
+import 'package:async/async.dart';
+import 'package:immich_mobile/providers/infrastructure/cancel.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/sync_stream.provider.dart';
+import 'package:immich_mobile/utils/isolate.dart';
+
+class BackgroundSyncManager {
+  CancelableOperation<void>? _userSyncFuture;
+
+  BackgroundSyncManager();
+
+  Future<void> cancel() async {
+    await _userSyncFuture?.cancel();
+    _userSyncFuture = null;
+  }
+
+  Future<void> syncUsers() async {
+    if (_userSyncFuture != null) {
+      return _userSyncFuture!.valueOrCancellation();
+    }
+
+    if (_userSyncFuture == null) {
+      final isolate = await IsolateManager.spawn(
+        computation: (ref) => ref.read(syncStreamServiceProvider).syncUsers(),
+        onCancel: (ref) => ref.read(cancellationProvider).complete(true),
+      );
+      _userSyncFuture = CancelableOperation.fromFuture(
+        isolate.run(),
+        onCancel: () {
+          isolate.cancel();
+          _userSyncFuture = null;
+        },
+      );
+      return _userSyncFuture!
+          .valueOrCancellation()
+          .then((_) => _userSyncFuture = null);
+    }
+  }
+}

mobile/lib/domain/utils/cancel.exception.dart

@@ -0,0 +1,8 @@
+class CancelException implements Exception {
+  final String message;
+
+  const CancelException([this.message = "Operation was cancelled."]);
+
+  @override
+  String toString() => "CancelException: $message";
+}

mobile/lib/providers/background_sync.provider.dart

@@ -1,6 +1,10 @@
-import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'dart:async';
-import 'package:immich_mobile/utils/background_sync.dart';
 
-final backgroundSyncProvider = Provider<BackgroundSyncManager>(
+import 'package:hooks_riverpod/hooks_riverpod.dart';
-  (ref) => BackgroundSyncManager(),
+import 'package:immich_mobile/domain/utils/background_sync.dart';
-);
+
+final backgroundSyncProvider = Provider<BackgroundSyncManager>((ref) {
+  final manager = BackgroundSyncManager();
+  ref.onDispose(() => unawaited(manager.cancel()));
+  return manager;
+});

mobile/lib/providers/infrastructure/cancel.provider.dart

@@ -0,0 +1,14 @@
+import 'dart:async';
+
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+
+/// Provider holding a boolean notifier that becomes true when cancellation is requested.
+/// A computation running in the isolate use the completer to implement cooperative cancellation.
+final cancellationProvider = Provider<Completer<bool>>(
+  // This will be overridden in the isolate's container.
+  // Throwing ensures it's not used without an override.
+  (ref) => throw UnimplementedError(
+    "cancellationProvider must be overridden in the isolate's ProviderContainer and not to be used in the root isolate",
+  ),
+  name: 'cancellationProvider',
+);

mobile/lib/providers/infrastructure/sync_stream.provider.dart

@@ -3,12 +3,14 @@ import 'package:immich_mobile/domain/services/sync_stream.service.dart';
 import 'package:immich_mobile/infrastructure/repositories/sync_api.repository.dart';
 import 'package:immich_mobile/infrastructure/repositories/sync_stream.repository.dart';
 import 'package:immich_mobile/providers/api.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/cancel.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/db.provider.dart';
 
 final syncStreamServiceProvider = Provider(
   (ref) => SyncStreamService(
     syncApiRepository: ref.watch(syncApiRepositoryProvider),
     syncStreamRepository: ref.watch(syncStreamRepositoryProvider),
+    cancelCompleter: ref.watch(cancellationProvider),
   ),
 );
 

mobile/lib/services/auth.service.dart

@@ -3,12 +3,14 @@ import 'dart:io';
 
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/models/store.model.dart';
+import 'package:immich_mobile/domain/utils/background_sync.dart';
 import 'package:immich_mobile/entities/store.entity.dart';
 import 'package:immich_mobile/interfaces/auth.interface.dart';
 import 'package:immich_mobile/interfaces/auth_api.interface.dart';
 import 'package:immich_mobile/models/auth/auxilary_endpoint.model.dart';
 import 'package:immich_mobile/models/auth/login_response.model.dart';
 import 'package:immich_mobile/providers/api.provider.dart';
+import 'package:immich_mobile/providers/background_sync.provider.dart';
 import 'package:immich_mobile/repositories/auth.repository.dart';
 import 'package:immich_mobile/repositories/auth_api.repository.dart';
 import 'package:immich_mobile/services/api.service.dart';
@@ -22,6 +24,7 @@ final authServiceProvider = Provider(
     ref.watch(authRepositoryProvider),
     ref.watch(apiServiceProvider),
     ref.watch(networkServiceProvider),
+    ref.watch(backgroundSyncProvider),
   ),
 );
 
@@ -30,6 +33,7 @@ class AuthService {
   final IAuthRepository _authRepository;
   final ApiService _apiService;
   final NetworkService _networkService;
+  final BackgroundSyncManager _backgroundSyncManager;
 
   final _log = Logger("AuthService");
 
@@ -38,6 +42,7 @@ class AuthService {
     this._authRepository,
     this._apiService,
     this._networkService,
+    this._backgroundSyncManager,
   );
 
   /// Validates the provided server URL by resolving and setting the endpoint.
@@ -117,6 +122,7 @@ class AuthService {
   /// All deletions are executed in parallel using [Future.wait].
   Future<void> clearLocalData() {
     return Future.wait([
+      _backgroundSyncManager.cancel(),
       _authRepository.clearLocalData(),
       Store.delete(StoreKey.currentUser),
       Store.delete(StoreKey.accessToken),

mobile/lib/utils/background_sync.dart

@@ -1,20 +0,0 @@
-// ignore_for_file: avoid-passing-async-when-sync-expected
-
-import 'dart:async';
-
-import 'package:async/async.dart';
-import 'package:immich_mobile/providers/infrastructure/sync_stream.provider.dart';
-import 'package:immich_mobile/utils/isolate.dart';
-
-class BackgroundSyncManager {
-  // This prevents multiple syncs from running at the same time
-  final _userSyncCache = AsyncCache.ephemeral();
-
-  BackgroundSyncManager();
-
-  Future<void> syncUsers() => _userSyncCache.fetch(
-        () => runInIsolate(
-          (ref) => ref.read(syncStreamServiceProvider).syncUsers(),
-        ),
-      );
-}

mobile/lib/utils/bootstrap.dart

@@ -48,11 +48,15 @@ abstract final class Bootstrap {
     );
   }
 
-  static Future<void> initDomain(Isar db) async {
+  static Future<void> initDomain(
+    Isar db, {
+    bool shouldBufferLogs = true,
+  }) async {
     await StoreService.init(storeRepository: IsarStoreRepository(db));
     await LogService.init(
       logRepository: IsarLogRepository(db),
       storeRepository: IsarStoreRepository(db),
+      shouldBuffer: shouldBufferLogs,
     );
   }
 }

mobile/lib/utils/isolate.dart

@@ -1,66 +1,401 @@
+// ignore_for_file: avoid-missing-completer-stack-trace
+
 import 'dart:async';
 import 'dart:isolate';
 import 'dart:ui';
 
-import 'package:flutter/material.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/providers/db.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/cancel.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/db.provider.dart';
 import 'package:immich_mobile/utils/bootstrap.dart';
 import 'package:logging/logging.dart';
 
+/// Exception thrown when IsolateManager is used incorrectly from a non-root isolate.
 class InvalidIsolateUsageException implements Exception {
   const InvalidIsolateUsageException();
 
   @override
   String toString() =>
-      "IsolateHelper should only be used from the root isolate";
+      "IsolateManager should only be used from the root isolate";
 }
 
-// !! Should be used only from the root isolate
+/// Exception thrown when an isolate computation is cancelled via [IsolateManager.cancel].
-Future<T?> runInIsolate<T>(
+class IsolateCancelledException implements Exception {
-  FutureOr<T> Function(ProviderContainer ref) computation, {
+  final String? debugLabel;
+  const IsolateCancelledException([this.debugLabel]);
+
+  @override
+  String toString() =>
+      "Isolate computation${debugLabel == null ? '' : ' ($debugLabel)'} was cancelled.";
+}
+
+/// Signature for the computation function to be executed in the isolate.
+/// It receives a Riverpod [ProviderContainer] for dependency injection.
+typedef Computation<T> = FutureOr<T> Function(ProviderContainer ref);
+
+enum _IsolateCommand {
+  cancel,
+  start,
+}
+
+/// Manages running a [Computation] in a separate isolate with Riverpod support
+/// and optional cancellation.
+///
+/// Similar to [compute] or [Isolate.run], but provides:
+/// - A pre-configured Riverpod [ProviderContainer] to the computation.
+/// - An optional `onCancel` computation for cleanup.
+/// - A `cancel()` method to attempt cancellation.
+class IsolateManager<T> {
+  final SendPort _sendPort;
+  final ReceivePort _receivePort;
+  final Completer<T?> _completer = Completer<T?>();
+  final String? _debugLabel;
+  StreamSubscription? _subscription;
+  bool _isClosed = false;
+  bool _isRunning = false;
+
+  IsolateManager._(this._sendPort, this._receivePort, this._debugLabel) {
+    _subscription = _receivePort.listen(
+      _handleResponseFromIsolate,
+      onDone: () {
+        // If the port closes before the completer finishes, signal an error.
+        if (_completer.isCompleted) {
+          return;
+        }
+
+        _completer.completeError(
+          RemoteError(
+            "Isolate terminated unexpectedly${_debugLabel == null ? '' : ' ($_debugLabel)'}",
+            "",
+          ),
+          StackTrace.empty,
+        );
+        _isClosed = true;
+      },
+    );
+  }
+
+  /// Spawns a new isolate and prepares it to run the [computation].
+  ///
+  /// - [computation]: The function to run in the isolate.
+  /// - [onCancel]: An optional function to run if `cancel()` is called before the computation completes.
+  /// - [debugLabel]: An optional label for debugging.
+  ///
+  /// Must be called from the root isolate.
+  static Future<IsolateManager<T>> spawn<T>({
+    required Computation<T> computation,
+    Computation<T>? onCancel,
     String? debugLabel,
   }) async {
+    final Logger logger = Logger("IsolateManager");
+    // Port for receiving the [SendPort] from the new isolate.
+    final initPort = RawReceivePort();
+    // Completer to synchronize the establishment of the main communication channel.
+    final connection = Completer<(ReceivePort, SendPort)>.sync();
+
+    initPort.handler = (initialMessage) {
+      if (initialMessage == null) {
+        // onExit handler message, isolate terminated without sending a SendPort.
+        initPort.close();
+        connection.completeError(
+          RemoteError(
+            "Isolate exited unexpectedly during initialization${debugLabel == null ? '' : ' ($debugLabel)'}",
+            "",
+          ),
+          StackTrace.empty,
+        );
+        return;
+      }
+      // The first message should be the SendPort for commands.
+      final commandPort = initialMessage as SendPort;
+      connection.complete(
+        (ReceivePort.fromRawReceivePort(initPort), commandPort),
+      );
+    };
+
     final token = RootIsolateToken.instance;
     if (token == null) {
+      initPort.close(); // Clean up before throwing
       throw const InvalidIsolateUsageException();
     }
 
-  return await Isolate.run(() async {
+    try {
-    BackgroundIsolateBinaryMessenger.ensureInitialized(token);
+      await Isolate.spawn(
-    DartPluginRegistrant.ensureInitialized();
+        _IsolateRunner._execute,
-
+        _IsolateRunner(
-    final db = await Bootstrap.initIsar();
+          computation: computation,
-    await Bootstrap.initDomain(db);
+          sendPort: initPort.sendPort,
-    final ref = ProviderContainer(
+          token: token,
-      overrides: [
+          onCancel: onCancel,
-        // TODO: Remove once isar is removed
+          debugLabel: debugLabel,
-        dbProvider.overrideWithValue(db),
+        ),
-        isarProvider.overrideWithValue(db),
+        errorsAreFatal: true,
-      ],
+        onExit: initPort.sendPort, // Send null on exit
+        onError: initPort.sendPort, // Errors during spawn sent here
+        debugName: debugLabel,
       );
-
+    } catch (e, s) {
-    Logger log = Logger("IsolateLogger");
+      logger.warning(
+        "Failed to spawn isolate${debugLabel == null ? '' : ' - $debugLabel'}",
+        e,
+        s,
+      );
+      initPort.close();
+      rethrow;
+    }
 
     try {
-      final result = await computation(ref);
+      final (ReceivePort receivePort, SendPort sendPort) =
-      // Wait for isolate to end; i.e, logs to be flushed
+          await connection.future;
-      await Future.delayed(Durations.short2);
+      return IsolateManager._(sendPort, receivePort, debugLabel);
-      return result;
+    } catch (e) {
+      // If connection.future completed with an error (e.g., isolate exited early)
+      logger.warning(
+        "Isolate connection failed${debugLabel == null ? '' : ' - $debugLabel'}",
+        e,
+      );
+      // initPort is closed by the handler in case of error/null message
+      rethrow;
+    }
+  }
+
+  /// Starts the computation in the isolate.
+  ///
+  /// Returns a future that completes with the result of the computation,
+  /// or an error if the computation fails or is cancelled.
+  Future<T?> run() {
+    if (_isClosed) {
+      return Future.error(StateError("IsolateManager is already closed"));
+    }
+    if (_isRunning) {
+      return Future.error(
+        StateError("Isolate computation is already running"),
+      );
+    }
+    _isRunning = true;
+    _sendPort.send(_IsolateCommand.start);
+    return _completer.future;
+  }
+
+  /// Attempts to cancel the computation.
+  ///
+  /// If the computation has not yet completed, this will cause the future
+  /// returned by [run] to complete with an [IsolateCancelledException].
+  /// An optional `onCancel` computation might be executed in the isolate.
+  ///
+  /// Does nothing if the computation has already completed or the manager is closed.
+  void cancel() {
+    if (_isClosed || _completer.isCompleted) {
+      return;
+    }
+    if (!_isRunning) {
+      _close(IsolateCancelledException(_debugLabel));
+      return;
+    }
+
+    // If running, send cancel command. The isolate will handle sending back the error.
+    _sendPort.send(_IsolateCommand.cancel);
+  }
+
+  /// Closes communication channels and completes the future with the given error.
+  void _close([Object? error, StackTrace? stackTrace]) {
+    if (_isClosed) return;
+    _isClosed = true;
+    unawaited(_subscription?.cancel());
+    _receivePort.close();
+    if (!_completer.isCompleted) {
+      if (error == null) {
+        _completer.completeError(
+          StateError("IsolateManager closed without result or error."),
+          StackTrace.empty,
+        );
+      } else {
+        _completer.completeError(error, stackTrace);
+      }
+    }
+  }
+
+  /// Handles messages received from the isolate.
+  void _handleResponseFromIsolate(Object? response) {
+    if (_isClosed) return;
+
+    // Expect list: [result] or [error, stackTrace] or [IsolateCancelledException]
+    final list = response as List<Object?>;
+    Object? error;
+    StackTrace? stackTrace;
+
+    if (list.length == 2) {
+      error = list.firstOrNull;
+      final remoteStack = list.elementAtOrNull(1);
+      if (remoteStack is StackTrace) {
+        stackTrace = remoteStack;
+      } else if (error is String && remoteStack is String?) {
+        // Reconstruct RemoteError if possible
+        error = RemoteError(error, remoteStack ?? "");
+        stackTrace = (error as RemoteError).stackTrace;
+      }
+    } else if (list.length == 1) {
+      final result = list.firstOrNull;
+      if (result is IsolateCancelledException) {
+        error = result;
+      } else {
+        // Success case
+        if (!_completer.isCompleted) {
+          _completer.complete(result as T?);
+        }
+        _close();
+        return;
+      }
+    } else {
+      error = RemoteError(
+        "Invalid message format from isolate",
+        response.toString(),
+      );
+    }
+
+    // If we reached here, it's an error or cancellation
+    _close(error, stackTrace);
+  }
+}
+
+/// Internal helper class that runs within the isolate.
+class _IsolateRunner<T> {
+  final Computation<T> _computation;
+  final Computation<T>? _onCancel;
+  final String? _debugLabel;
+
+  final RootIsolateToken _token;
+  final SendPort _sendPort; // Port to send results/errors back to main
+  ReceivePort? _receivePort; // Port to receive commands from main
+  bool _cancelled = false;
+  bool _computationStarted = false;
+  ProviderContainer? _ref; // Hold ref for cleanup
+
+  _IsolateRunner({
+    required Computation<T> computation,
+    required SendPort sendPort,
+    required RootIsolateToken token,
+    Computation<T>? onCancel,
+    String? debugLabel,
+  })  : _computation = computation,
+        _sendPort = sendPort,
+        _token = token,
+        _onCancel = onCancel,
+        _debugLabel = debugLabel;
+
+  /// Entry point for the isolate.
+  static void _execute(_IsolateRunner<Object?> runner) {
+    runner._start();
+  }
+
+  /// Initializes the isolate environment and listens for commands.
+  void _start() {
+    BackgroundIsolateBinaryMessenger.ensureInitialized(_token);
+    DartPluginRegistrant.ensureInitialized();
+
+    _receivePort = ReceivePort();
+    _sendPort.send(_receivePort!.sendPort);
+
+    // Listen for commands from the main isolate.
+    // ignore: avoid-passing-async-when-sync-expected
+    final _ = _receivePort!.listen((message) async {
+      if (_cancelled) return;
+
+      switch (message) {
+        case _IsolateCommand.cancel:
+          _cancelled = true;
+          // Run onCancel if computation hasn't started or finished
+          if (_onCancel == null) {
+            // Close the receive port and exit when no cleanup is needed
+            _sendPort.send([IsolateCancelledException(_debugLabel)]);
+            _cleanupAndExit();
+          } else {
+            await _runCleanup(_onCancel);
+          }
+          break;
+        case _IsolateCommand.start:
+          if (_computationStarted) return; // Ignore duplicate start
+          _computationStarted = true;
+          await _exec();
+          _cleanupAndExit();
+          break;
+      }
+    });
+  }
+
+  /// Executes the main computation.
+  Future<void> _exec() async {
+    Logger log = Logger("IsolateRunner");
+    try {
+      _ref = await _bootstrap();
+      if (_cancelled) return;
+
+      final potentiallyAsyncResult = _computation(_ref!);
+      final T result;
+      if (potentiallyAsyncResult is Future<T>) {
+        result = await potentiallyAsyncResult;
+      } else {
+        result = potentiallyAsyncResult;
+      }
+
+      if (_cancelled) return;
+
+      _sendPort.send([result]);
     } catch (error, stack) {
+      if (_cancelled) return;
       log.severe(
-        "Error in runInIsolate${debugLabel == null ? '' : ' for $debugLabel'}",
+        "Error in computation${_debugLabel == null ? '' : ' ($_debugLabel)'}",
         error,
         stack,
       );
+      _sendPort.send([error, stack]);
+    }
+    // Cleanup happens in _cleanupAndExit called by the listener
+  }
+
+  /// Executes the onCancel computation.
+  Future<void> _runCleanup(Computation<T> cleanupFunc) async {
+    Logger log = Logger("IsolateRunner");
+    try {
+      if (_ref == null) {
+        log.warning("IsolateRunner cleanup called without ref");
+        return;
+      }
+      await cleanupFunc(_ref!);
+    } catch (e, s) {
+      log.warning("Error during isolate onCancel cleanup", e, s);
+      // Don't send this error back, primary goal is cancellation signal
+    }
+  }
+
+  Future<ProviderContainer> _bootstrap() async {
+    final db = await Bootstrap.initIsar();
+    await Bootstrap.initDomain(db, shouldBufferLogs: false);
+    return ProviderContainer(
+      overrides: [
+        dbProvider.overrideWithValue(db),
+        isarProvider.overrideWithValue(db),
+        cancellationProvider.overrideWithValue(Completer()),
+      ],
+    );
+  }
+
+  /// Closes resources and the receive port.
+  Future<void> _cleanupAndExit() async {
+    // Always close the db connections and dispose ref if created
+    try {
+      await _ref?.read(driftProvider).close();
+      await _ref?.read(isarProvider).close();
+      _ref?.dispose();
+    } catch (e) {
+      if (kDebugMode) {
+        print("Error during resource cleanup: $e");
+      }
     } finally {
-      // Always close the new db connection on Isolate end
+      _receivePort?.close();
-      ref.read(driftProvider).close();
+    }
-      ref.read(dbProvider).close();
-      ref.read(isarProvider).close();
   }
-    return null;
-  });
 }

mobile/test/domain/service.mock.dart

@@ -1,7 +1,10 @@
 import 'package:immich_mobile/domain/services/store.service.dart';
 import 'package:immich_mobile/domain/services/user.service.dart';
+import 'package:immich_mobile/domain/utils/background_sync.dart';
 import 'package:mocktail/mocktail.dart';
 
 class MockStoreService extends Mock implements StoreService {}
 
 class MockUserService extends Mock implements UserService {}
+
+class MockBackgroundSyncManager extends Mock implements BackgroundSyncManager {}

mobile/test/domain/services/sync_stream_service_test.dart

@@ -7,6 +7,7 @@ import 'package:immich_mobile/domain/interfaces/sync_api.interface.dart';
 import 'package:immich_mobile/domain/interfaces/sync_stream.interface.dart';
 import 'package:immich_mobile/domain/models/sync_event.model.dart';
 import 'package:immich_mobile/domain/services/sync_stream.service.dart';
+import 'package:immich_mobile/domain/utils/cancel.exception.dart';
 import 'package:mocktail/mocktail.dart';
 import 'package:openapi/api.dart';
 
@@ -57,7 +58,9 @@ void main() {
   });
 
   tearDown(() async {
+    if (!streamController.isClosed) {
       await streamController.close();
+    }
   });
 
   // Helper to trigger sync and add events to the stream
@@ -83,8 +86,8 @@ void main() {
         await expectLater(future, completes);
         // Verify ack includes last ack from each successfully handled type
         verify(
-          () => mockSyncApiRepo
+          () =>
-              .ack(any(that: containsAllInOrder(["5", "2", "4", "3"]))),
+              mockSyncApiRepo.ack(any(that: containsAll(["5", "2", "4", "3"]))),
         ).called(1);
       },
     );
@@ -159,9 +162,8 @@ void main() {
       await triggerSyncAndEmit(events);
 
       // Expect ack only for userDeleteV1 (ack: "2") and partnerDeleteV1 (ack: "4")
-      verify(
+      verify(() => mockSyncApiRepo.ack(any(that: containsAll(["2", "4"]))))
-        () => mockSyncApiRepo.ack(any(that: containsAllInOrder(["2", "4"]))),
+          .called(1);
-      ).called(1);
     });
 
     test("does not process or ack when stream emits an empty list", () async {
@@ -183,15 +185,19 @@ void main() {
       int callOrder = 0;
       int handler1StartOrder = -1;
       int handler2StartOrder = -1;
+      int handler1Calls = 0;
+      int handler2Calls = 0;
 
       when(() => mockSyncStreamRepo.updateUsersV1(any())).thenAnswer((_) async {
-        handler1StartOrder = ++callOrder; // Record when handler 1 starts
+        handler1Calls++;
-        await completer1.future; // Wait for external signal
+        handler1StartOrder = ++callOrder;
+        await completer1.future;
         return true;
       });
       when(() => mockSyncStreamRepo.updatePartnerV1(any()))
           .thenAnswer((_) async {
-        handler2StartOrder = ++callOrder; // Record when handler 2 starts
+        handler2Calls++;
+        handler2StartOrder = ++callOrder;
         await completer2.future;
         return true;
       });
@@ -200,44 +206,98 @@ void main() {
       final batch2 = SyncStreamStub.partnerEvents;
 
       final syncFuture = sut.syncUsers();
-      streamController.add(batch1); // Emit first batch
+      await pumpEventQueue();
+
+      streamController.add(batch1);
+      await pumpEventQueue();
+      // Small delay to ensure the first handler starts
+      await Future.delayed(const Duration(milliseconds: 20));
 
-      // Ensure first batch processing starts
-      await Future.delayed(const Duration(milliseconds: 10));
       expect(handler1StartOrder, 1, reason: "Handler 1 should start first");
+      expect(handler1Calls, 1);
 
-      streamController.add(batch2); // Emit second batch while first is waiting
+      streamController.add(batch2);
+      await pumpEventQueue();
+      // Small delay
+      await Future.delayed(const Duration(milliseconds: 20));
 
-      await Future.delayed(const Duration(milliseconds: 10));
+      expect(handler2StartOrder, -1, reason: "Handler 2 should wait");
-      // Handler 2 should NOT have started yet because mutex is held by handler 1
+      expect(handler2Calls, 0);
-      expect(
-        handler2StartOrder,
-        -1,
-        reason: "Handler 2 should wait for Handler 1",
-      );
 
-      completer1.complete(); // Allow first handler to finish
+      completer1.complete();
-      // Allow second batch to start processing
+      await pumpEventQueue(times: 40);
-      await Future.delayed(const Duration(milliseconds: 10));
+      // Small delay to ensure the second handler starts
+      await Future.delayed(const Duration(milliseconds: 20));
 
-      // Now handler 2 should start
+      expect(handler2StartOrder, 2, reason: "Handler 2 should start after H1");
-      expect(
+      expect(handler2Calls, 1);
-        handler2StartOrder,
-        2,
-        reason: "Handler 2 should start after Handler 1 finishes",
-      );
 
-      completer2.complete(); // Allow second handler to finish
+      completer2.complete();
-      await streamController.close(); // Close stream
+      await pumpEventQueue(times: 40);
-      await syncFuture; // Wait for overall completion
+      // Small delay before closing the stream
+      await Future.delayed(const Duration(milliseconds: 20));
+
+      if (!streamController.isClosed) {
+        await streamController.close();
+      }
+      await pumpEventQueue(times: 40);
+      // Small delay to ensure the sync completes
+      await Future.delayed(const Duration(milliseconds: 20));
+
+      await syncFuture;
 
-      // Verify handlers were called and acks sent for both batches eventually
       verify(() => mockSyncStreamRepo.updateUsersV1(any())).called(1);
       verify(() => mockSyncStreamRepo.updatePartnerV1(any())).called(1);
-      // Acks might be called separately or combined depending on timing, check count
       verify(() => mockSyncApiRepo.ack(any())).called(2);
     });
 
+    test(
+      "stops processing and ack when cancel completer is completed",
+      () async {
+        final cancelCompleter = Completer<bool>();
+        sut = SyncStreamService(
+          syncApiRepository: mockSyncApiRepo,
+          syncStreamRepository: mockSyncStreamRepo,
+          cancelCompleter: cancelCompleter,
+        );
+
+        final processingCompleter = Completer<void>();
+        bool handlerStarted = false;
+
+        // Make handler wait so we can cancel it mid-flight
+        when(() => mockSyncStreamRepo.updateUsersV1(any()))
+            .thenAnswer((_) async {
+          handlerStarted = true;
+          await processingCompleter
+              .future; // Wait indefinitely until test completes it
+          return true;
+        });
+
+        final syncFuture = sut.syncUsers();
+        await pumpEventQueue(times: 30);
+
+        streamController.add(SyncStreamStub.userEvents);
+        // Ensure processing starts
+        await Future.delayed(const Duration(milliseconds: 10));
+
+        expect(handlerStarted, isTrue, reason: "Handler should have started");
+
+        cancelCompleter.complete(true); // Signal cancellation
+
+        // Allow cancellation logic to propagate
+        await Future.delayed(const Duration(milliseconds: 10));
+
+        // Complete the handler's completer after cancellation signal
+        // to ensure the cancellation logic itself isn't blocked by the handler.
+        processingCompleter.complete();
+
+        await expectLater(syncFuture, throwsA(isA<CancelException>()));
+
+        // Verify that ack was NOT called because processing was cancelled
+        verifyNever(() => mockSyncApiRepo.ack(any()));
+      },
+    );
+
     test("completes successfully when ack call throws an exception", () async {
       when(() => mockSyncApiRepo.ack(any())).thenThrow(Exception("Ack Error"));
       final events = [

mobile/test/services/auth.service_test.dart

@@ -8,6 +8,7 @@ import 'package:isar/isar.dart';
 import 'package:mocktail/mocktail.dart';
 import 'package:openapi/api.dart';
 
+import '../domain/service.mock.dart';
 import '../repository.mocks.dart';
 import '../service.mocks.dart';
 import '../test_utils.dart';
@@ -18,6 +19,7 @@ void main() {
   late MockAuthRepository authRepository;
   late MockApiService apiService;
   late MockNetworkService networkService;
+  late MockBackgroundSyncManager backgroundSyncManager;
   late Isar db;
 
   setUp(() async {
@@ -25,12 +27,14 @@ void main() {
     authRepository = MockAuthRepository();
     apiService = MockApiService();
     networkService = MockNetworkService();
+    backgroundSyncManager = MockBackgroundSyncManager();
 
     sut = AuthService(
       authApiRepository,
       authRepository,
       apiService,
       networkService,
+      backgroundSyncManager,
     );
 
     registerFallbackValue(Uri());
@@ -116,24 +120,28 @@ void main() {
   group('logout', () {
     test('Should logout user', () async {
       when(() => authApiRepository.logout()).thenAnswer((_) async => {});
+      when(() => backgroundSyncManager.cancel()).thenAnswer((_) async => {});
       when(() => authRepository.clearLocalData())
           .thenAnswer((_) => Future.value(null));
 
       await sut.logout();
 
       verify(() => authApiRepository.logout()).called(1);
+      verify(() => backgroundSyncManager.cancel()).called(1);
       verify(() => authRepository.clearLocalData()).called(1);
     });
 
     test('Should clear local data even on server error', () async {
       when(() => authApiRepository.logout())
           .thenThrow(Exception('Server error'));
+      when(() => backgroundSyncManager.cancel()).thenAnswer((_) async => {});
       when(() => authRepository.clearLocalData())
           .thenAnswer((_) => Future.value(null));
 
       await sut.logout();
 
       verify(() => authApiRepository.logout()).called(1);
+      verify(() => backgroundSyncManager.cancel()).called(1);
       verify(() => authRepository.clearLocalData()).called(1);
     });
   });