fix(mobile): stop sync albums crashing on the main isolate (#29133)

the album sync provider read cancellationProvider, which only exists in the background isolate and throws on the main one. moved the cancel signal onto the isolate call path.

fixes #29125
fixes #29119

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

@@ -7,7 +7,6 @@ import 'package:immich_mobile/domain/services/store.service.dart';
 import 'package:immich_mobile/infrastructure/repositories/local_album.repository.dart';
 import 'package:immich_mobile/infrastructure/repositories/remote_album.repository.dart';
 import 'package:immich_mobile/providers/infrastructure/album.provider.dart';
-import 'package:immich_mobile/providers/infrastructure/cancel.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/store.provider.dart';
 import 'package:immich_mobile/repositories/drift_album_api_repository.dart';
 import 'package:immich_mobile/utils/debug_print.dart';
@@ -19,7 +18,6 @@ final syncLinkedAlbumServiceProvider = Provider(
     ref.watch(remoteAlbumRepository),
     ref.watch(driftAlbumApiRepositoryProvider),
     ref.watch(storeServiceProvider),
-    cancellation: ref.watch(cancellationProvider),
   ),
 );
 
@@ -28,19 +26,17 @@ class SyncLinkedAlbumService {
   final DriftRemoteAlbumRepository _remoteAlbumRepository;
   final DriftAlbumApiRepository _albumApiRepository;
   final StoreService _storeService;
-  final Completer<void>? _cancellation;
 
   SyncLinkedAlbumService(
     this._localAlbumRepository,
     this._remoteAlbumRepository,
     this._albumApiRepository,
-    this._storeService, {
-    this._cancellation,
-  });
+    this._storeService,
+  );
 
   final _log = Logger("SyncLinkedAlbumService");
 
-  Future<void> syncLinkedAlbums(String userId) async {
+  Future<void> syncLinkedAlbums(String userId, {Completer<void>? cancellation}) async {
     final selectedAlbums = await _localAlbumRepository.getBackupAlbums();
 
     await Future.wait(
@@ -64,7 +60,7 @@ class SyncLinkedAlbumService {
           final album = await _albumApiRepository.addAssets(
             remoteAlbum.id,
             assetIds,
-            abortTrigger: _cancellation?.future,
+            abortTrigger: cancellation?.future,
           );
           await _remoteAlbumRepository.addAssets(remoteAlbum.id, album.added);
         }

mobile/lib/domain/utils/sync_linked_album.dart

@@ -2,6 +2,7 @@ import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/models/store.model.dart';
 import 'package:immich_mobile/domain/services/sync_linked_album.service.dart';
 import 'package:immich_mobile/entities/store.entity.dart';
+import 'package:immich_mobile/providers/infrastructure/cancel.provider.dart';
 import 'package:logging/logging.dart';
 
 Future<void> syncLinkedAlbumsIsolated(ProviderContainer ref) {
@@ -10,5 +11,7 @@ Future<void> syncLinkedAlbumsIsolated(ProviderContainer ref) {
     Logger("SyncLinkedAlbum").warning("No user logged in, skipping linked album sync");
     return Future.value();
   }
-  return ref.read(syncLinkedAlbumServiceProvider).syncLinkedAlbums(user.id);
+  return ref
+      .read(syncLinkedAlbumServiceProvider)
+      .syncLinkedAlbums(user.id, cancellation: ref.read(cancellationProvider));
 }

mobile/test/domain/services/sync_linked_album_service_test.dart

@@ -0,0 +1,44 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_mobile/domain/services/sync_linked_album.service.dart';
+import 'package:immich_mobile/providers/infrastructure/album.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/store.provider.dart';
+import 'package:immich_mobile/repositories/drift_album_api_repository.dart';
+
+import '../../infrastructure/repository.mock.dart';
+import '../service.mock.dart';
+
+void main() {
+  // A container with the service's deps overridden but cancellationProvider left
+  // alone, i.e. the root (main) isolate, where cancellationProvider has no
+  // override and throws if read. The UI reads this provider here.
+  ProviderContainer rootContainer() {
+    final container = ProviderContainer(
+      overrides: [
+        localAlbumRepository.overrideWithValue(MockLocalAlbumRepository()),
+        remoteAlbumRepository.overrideWithValue(MockRemoteAlbumRepository()),
+        driftAlbumApiRepositoryProvider.overrideWithValue(MockDriftAlbumApiRepository()),
+        storeServiceProvider.overrideWithValue(MockStoreService()),
+      ],
+    );
+    addTearDown(container.dispose);
+    return container;
+  }
+
+  // Regression for #29125 (Sync Albums toggle) and #29119 (can't leave the album
+  // selection screen): #28694 made the provider watch cancellationProvider, so
+  // reading it off the isolate threw. The cancellation now lives on the isolate
+  // call path, not the provider, so the UI can build it.
+  test('builds on the root isolate without a cancellationProvider override', () {
+    final container = rootContainer();
+
+    expect(() => container.read(syncLinkedAlbumServiceProvider), returnsNormally);
+    expect(container.read(syncLinkedAlbumServiceProvider), isA<SyncLinkedAlbumService>());
+  });
+
+  test('manageLinkedAlbums runs from the UI without a cancellation signal', () {
+    final service = rootContainer().read(syncLinkedAlbumServiceProvider);
+
+    expect(service.manageLinkedAlbums(const [], 'user-1'), completes);
+  });
+}