diff --git a/mobile/lib/mixins/stream_notifier.mixin.dart b/mobile/lib/mixins/stream_notifier.mixin.dart
new file mode 100644
index 0000000000..a068c46346
--- /dev/null
+++ b/mobile/lib/mixins/stream_notifier.mixin.dart
@@ -0,0 +1,37 @@
+import 'dart:async';
+
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+
+/// Converts a [Stream] into an [AsyncNotifier]
+///
+/// The [build] method MUST call [buildFromStream] in order to properly subscribe
+mixin StreamNotifierMixin<T> {
+  set state(AsyncValue<T> value);
+
+  /// Forwards data into the notifier from [stream]. Future will stay open until [stream] completes
+  ///
+  /// Must be called in [build]
+  Future<T> buildFromStream(
+    Ref<AsyncValue<T>> ref,
+    Stream<T> stream, {
+    required T Function(Object error, StackTrace stack) onError,
+  }) {
+    final completer = Completer<T>();
+
+    void apply(T value) {
+      if (completer.isCompleted) {
+        state = AsyncData(value);
+      } else {
+        completer.complete(value);
+      }
+    }
+
+    final subscription = stream.listen(
+      apply,
+      onError: (Object error, StackTrace stack) => apply(onError(error, stack)),
+    );
+    ref.onDispose(subscription.cancel);
+
+    return completer.future;
+  }
+}
diff --git a/mobile/lib/presentation/pages/drift_activities.page.dart b/mobile/lib/presentation/pages/drift_activities.page.dart
index ebf7c2efa7..effed4c3ef 100644
--- a/mobile/lib/presentation/pages/drift_activities.page.dart
+++ b/mobile/lib/presentation/pages/drift_activities.page.dart
@@ -9,8 +9,8 @@ import 'package:immich_mobile/extensions/asyncvalue_extensions.dart';
 import 'package:immich_mobile/extensions/build_context_extensions.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/like_activity_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/album/drift_activity_text_field.dart';
-import 'package:immich_mobile/providers/activity.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/current_album.provider.dart';
+import 'package:immich_mobile/store/activity.dart';
 import 'package:immich_mobile/widgets/activities/comment_bubble.dart';
 
 @RoutePage()
diff --git a/mobile/lib/presentation/widgets/action_buttons/like_activity_action_button.widget.dart b/mobile/lib/presentation/widgets/action_buttons/like_activity_action_button.widget.dart
index 46a5c2c41e..63c1181854 100644
--- a/mobile/lib/presentation/widgets/action_buttons/like_activity_action_button.widget.dart
+++ b/mobile/lib/presentation/widgets/action_buttons/like_activity_action_button.widget.dart
@@ -2,14 +2,14 @@ import 'package:collection/collection.dart';
 import 'package:easy_localization/easy_localization.dart';
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_data/model/activity.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
 import 'package:immich_mobile/extensions/translate_extensions.dart';
-import 'package:immich_mobile/models/activities/activity.model.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/base_action_button.widget.dart';
-import 'package:immich_mobile/providers/activity.provider.dart';
 import 'package:immich_mobile/providers/asset_viewer/asset_viewer.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/current_album.provider.dart';
 import 'package:immich_mobile/providers/user.provider.dart';
+import 'package:immich_mobile/store/activity.dart';
 
 class LikeActivityActionButton extends ConsumerWidget {
   const LikeActivityActionButton({super.key, this.iconOnly = false, this.menuItem = false});
@@ -35,8 +35,6 @@ class LikeActivityActionButton extends ConsumerWidget {
       } else {
         await ref.read(albumActivityProvider((album?.id ?? "", asset?.id)).notifier).addLike();
       }
-
-      ref.invalidate(albumActivityProvider((album?.id ?? "", asset?.id)));
     }
 
     return activities.when(
diff --git a/mobile/lib/presentation/widgets/asset_viewer/viewer_top_app_bar.widget.dart b/mobile/lib/presentation/widgets/asset_viewer/viewer_top_app_bar.widget.dart
index deae9cbd07..b85b415521 100644
--- a/mobile/lib/presentation/widgets/asset_viewer/viewer_top_app_bar.widget.dart
+++ b/mobile/lib/presentation/widgets/asset_viewer/viewer_top_app_bar.widget.dart
@@ -10,13 +10,13 @@ import 'package:immich_mobile/presentation/actions/action.widget.dart';
 import 'package:immich_mobile/presentation/actions/favorite.action.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/motion_photo_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/asset_viewer/viewer_kebab_menu.widget.dart';
-import 'package:immich_mobile/providers/activity.provider.dart';
 import 'package:immich_mobile/providers/asset_viewer/asset_viewer.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/asset_viewer/asset.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/current_album.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/readonly_mode.provider.dart';
 import 'package:immich_mobile/providers/routes.provider.dart';
 import 'package:immich_mobile/routing/router.dart';
+import 'package:immich_mobile/store/activity.dart';
 import 'package:immich_mobile/utils/timezone.dart';
 import 'package:immich_ui/immich_ui.dart';
 
diff --git a/mobile/lib/providers/activity.provider.dart b/mobile/lib/providers/activity.provider.dart
deleted file mode 100644
index b2cdbcf18c..0000000000
--- a/mobile/lib/providers/activity.provider.dart
+++ /dev/null
@@ -1,81 +0,0 @@
-import 'package:collection/collection.dart';
-import 'package:hooks_riverpod/hooks_riverpod.dart';
-import 'package:immich_mobile/models/activities/activity.model.dart';
-import 'package:immich_mobile/providers/activity_service.provider.dart';
-
-// ignore: unintended_html_in_doc_comment
-/// Maintains the current list of all activities for <share-album-id, asset>
-
-final albumActivityProvider = AsyncNotifierProvider.autoDispose
-    .family<AlbumActivity, List<Activity>, (String albumId, String? assetId)>(AlbumActivity.new);
-
-class AlbumActivity extends AutoDisposeFamilyAsyncNotifier<List<Activity>, (String albumId, String? assetId)> {
-  late String albumId;
-  late String? assetId;
-
-  @override
-  Future<List<Activity>> build((String albumId, String? assetId) args) async {
-    albumId = args.$1;
-    assetId = args.$2;
-    return ref.watch(activityServiceProvider).getAllActivities(albumId, assetId: assetId);
-  }
-
-  Future<void> removeActivity(String id) async {
-    if (await ref.watch(activityServiceProvider).removeActivity(id)) {
-      final removedActivity = _removeFromState(id);
-      if (removedActivity == null) {
-        return;
-      }
-
-      if (assetId != null) {
-        ref.read(albumActivityProvider((albumId, assetId)).notifier)._removeFromState(id);
-      }
-    }
-  }
-
-  Future<void> addLike() async {
-    final activity = await ref.watch(activityServiceProvider).addActivity(albumId, ActivityType.like, assetId: assetId);
-    if (activity.hasValue) {
-      _addToState(activity.requireValue);
-      if (assetId != null) {
-        ref.read(albumActivityProvider((albumId, assetId)).notifier)._addToState(activity.requireValue);
-      }
-    }
-  }
-
-  Future<void> addComment(String comment) async {
-    final activity = await ref
-        .watch(activityServiceProvider)
-        .addActivity(albumId, ActivityType.comment, assetId: assetId, comment: comment);
-
-    if (activity.hasValue) {
-      _addToState(activity.requireValue);
-      if (assetId != null) {
-        ref.read(albumActivityProvider((albumId, assetId)).notifier)._addToState(activity.requireValue);
-      }
-    }
-  }
-
-  void _addToState(Activity activity) {
-    final activities = state.valueOrNull ?? [];
-    if (activities.any((a) => a.id == activity.id)) {
-      return;
-    }
-    state = AsyncData([...activities, activity]);
-  }
-
-  Activity? _removeFromState(String id) {
-    final activities = state.valueOrNull;
-    if (activities == null) {
-      return null;
-    }
-    final activity = activities.firstWhereOrNull((a) => a.id == id);
-    if (activity == null) {
-      return null;
-    }
-
-    final updated = [...activities]..remove(activity);
-    state = AsyncData(updated);
-    return activity;
-  }
-}
diff --git a/mobile/lib/providers/activity_service.provider.dart b/mobile/lib/providers/activity_service.provider.dart
deleted file mode 100644
index 3be6c6b234..0000000000
--- a/mobile/lib/providers/activity_service.provider.dart
+++ /dev/null
@@ -1,13 +0,0 @@
-import 'package:hooks_riverpod/hooks_riverpod.dart';
-import 'package:immich_mobile/providers/infrastructure/asset.provider.dart';
-import 'package:immich_mobile/providers/infrastructure/timeline.provider.dart';
-import 'package:immich_mobile/repositories/activity_api.repository.dart';
-import 'package:immich_mobile/services/activity.service.dart';
-
-final activityServiceProvider = Provider.autoDispose<ActivityService>((ref) {
-  return ActivityService(
-    ref.watch(activityApiRepositoryProvider),
-    ref.watch(timelineFactoryProvider),
-    ref.watch(assetServiceProvider),
-  );
-});
diff --git a/mobile/lib/providers/infrastructure/data_store.dart b/mobile/lib/providers/infrastructure/data_store.dart
index 835f7eac2f..05d2190ee6 100644
--- a/mobile/lib/providers/infrastructure/data_store.dart
+++ b/mobile/lib/providers/infrastructure/data_store.dart
@@ -11,6 +11,8 @@ abstract final class Store {
 
   static final people = _store((c) => c.people);
 
+  static final activities = _store((c) => c.activities);
+
   /// Direct database access for the repositories that have not yet moved into `immich_data`
   // TODO(rewrite): Remove this provider once all repositories have migrated to `immich_data`
   static final db = _store((c) => c.db);
diff --git a/mobile/lib/services/activity.service.dart b/mobile/lib/services/activity.service.dart
deleted file mode 100644
index 0d4709d0d5..0000000000
--- a/mobile/lib/services/activity.service.dart
+++ /dev/null
@@ -1,66 +0,0 @@
-import 'package:hooks_riverpod/hooks_riverpod.dart';
-import 'package:immich_mobile/constants/errors.dart';
-import 'package:immich_mobile/domain/services/asset.service.dart';
-import 'package:immich_mobile/domain/services/timeline.service.dart';
-import 'package:immich_mobile/mixins/error_logger.mixin.dart';
-import 'package:immich_mobile/models/activities/activity.model.dart';
-import 'package:immich_mobile/presentation/widgets/asset_viewer/asset_viewer.page.dart';
-import 'package:immich_mobile/providers/infrastructure/current_album.provider.dart';
-import 'package:immich_mobile/repositories/activity_api.repository.dart';
-import 'package:immich_mobile/routing/router.dart';
-import 'package:logging/logging.dart';
-
-class ActivityService with ErrorLoggerMixin {
-  final ActivityApiRepository _activityApiRepository;
-  final TimelineFactory _timelineFactory;
-  final AssetService _assetService;
-
-  @override
-  final Logger logger = Logger("ActivityService");
-
-  ActivityService(this._activityApiRepository, this._timelineFactory, this._assetService);
-
-  Future<List<Activity>> getAllActivities(String albumId, {String? assetId}) async {
-    return logError(
-      () => _activityApiRepository.getAll(albumId, assetId: assetId),
-      defaultValue: [],
-      errorMessage: "Failed to get all activities for album $albumId",
-    );
-  }
-
-  Future<bool> removeActivity(String id) async {
-    return logError(
-      () async {
-        try {
-          await _activityApiRepository.delete(id);
-        } on NoResponseDtoError {
-          return true;
-        }
-        return true;
-      },
-      defaultValue: false,
-      errorMessage: "Failed to delete activity",
-    );
-  }
-
-  AsyncFuture<Activity> addActivity(String albumId, ActivityType type, {String? assetId, String? comment}) async {
-    return guardError(
-      () => _activityApiRepository.create(albumId, type, assetId: assetId, comment: comment),
-      errorMessage: "Failed to create $type for album $albumId",
-    );
-  }
-
-  Future<AssetViewerRoute?> buildAssetViewerRoute(String assetId, WidgetRef ref) async {
-    final asset = await _assetService.getRemoteAsset(assetId);
-    if (asset == null) {
-      return null;
-    }
-
-    AssetViewer.setAsset(ref, asset);
-    return AssetViewerRoute(
-      initialIndex: 0,
-      timelineService: _timelineFactory.fromAssets([asset], TimelineOrigin.albumActivities),
-      currentAlbum: ref.read(currentRemoteAlbumProvider),
-    );
-  }
-}
diff --git a/mobile/lib/store/activity.dart b/mobile/lib/store/activity.dart
new file mode 100644
index 0000000000..5c2fe21229
--- /dev/null
+++ b/mobile/lib/store/activity.dart
@@ -0,0 +1,61 @@
+import 'dart:async';
+
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_data/model/activity.dart';
+import 'package:immich_mobile/mixins/error_logger.mixin.dart';
+import 'package:immich_mobile/mixins/stream_notifier.mixin.dart';
+import 'package:immich_mobile/providers/infrastructure/data_store.dart';
+import 'package:logging/logging.dart';
+
+/// Activities associated with a `albumId`, `assetId` pair
+final albumActivityProvider = AsyncNotifierProvider.autoDispose
+    .family<_AlbumActivity, List<Activity>, (String albumId, String? assetId)>(_AlbumActivity.new);
+
+class _AlbumActivity extends AutoDisposeFamilyAsyncNotifier<List<Activity>, (String albumId, String? assetId)>
+    with ErrorLoggerMixin, StreamNotifierMixin<List<Activity>> {
+  @override
+  final Logger logger = Logger("ActivityService");
+
+  late String albumId;
+  late String? assetId;
+
+  @override
+  Future<List<Activity>> build((String albumId, String? assetId) args) {
+    albumId = args.$1;
+    assetId = args.$2;
+
+    return buildFromStream(
+      ref,
+      // TODO(rewrite): `force: true` matches the previous behavior of a HTTP request on mount
+      ref.watch(Store.activities).getAll(albumId, assetId: assetId, force: true),
+      onError: (error, stack) {
+        logger.severe("Failed to get all activities for album $albumId", error, stack);
+        return const [];
+      },
+    );
+  }
+
+  Future<void> removeActivity(String id) async {
+    await logError(
+      () async {
+        await ref.read(Store.activities).remove(albumId, id);
+      },
+      defaultValue: null,
+      errorMessage: "Failed to delete activity",
+    );
+  }
+
+  Future<void> addLike() async {
+    await guardError(
+      () => ref.read(Store.activities).addLike(albumId, assetId: assetId),
+      errorMessage: "Failed to create like for album $albumId",
+    );
+  }
+
+  Future<void> addComment(String comment) async {
+    await guardError(
+      () => ref.read(Store.activities).addComment(albumId, comment, assetId: assetId),
+      errorMessage: "Failed to create comment for album $albumId",
+    );
+  }
+}
diff --git a/mobile/lib/utils/provider_utils.dart b/mobile/lib/utils/provider_utils.dart
index 05bb729c50..6f944a4440 100644
--- a/mobile/lib/utils/provider_utils.dart
+++ b/mobile/lib/utils/provider_utils.dart
@@ -1,14 +1,12 @@
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/providers/infrastructure/search.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/user.provider.dart';
-import 'package:immich_mobile/repositories/activity_api.repository.dart';
 import 'package:immich_mobile/repositories/asset_api.repository.dart';
 import 'package:immich_mobile/repositories/drift_album_api_repository.dart';
 import 'package:immich_mobile/repositories/partner_api.repository.dart';
 
 void invalidateAllApiRepositoryProviders(WidgetRef ref) {
   ref.invalidate(userApiRepositoryProvider);
-  ref.invalidate(activityApiRepositoryProvider);
   ref.invalidate(partnerApiRepositoryProvider);
   ref.invalidate(assetApiRepositoryProvider);
   ref.invalidate(searchApiRepositoryProvider);
diff --git a/mobile/lib/widgets/activities/comment_bubble.dart b/mobile/lib/widgets/activities/comment_bubble.dart
index fcaff8bfc3..94ecaa729c 100644
--- a/mobile/lib/widgets/activities/comment_bubble.dart
+++ b/mobile/lib/widgets/activities/comment_bubble.dart
@@ -1,14 +1,18 @@
 import 'package:auto_route/auto_route.dart';
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_data/model/activity.dart';
+import 'package:immich_mobile/domain/services/timeline.service.dart';
 import 'package:immich_mobile/extensions/build_context_extensions.dart';
 import 'package:immich_mobile/extensions/datetime_extensions.dart';
-import 'package:immich_mobile/models/activities/activity.model.dart';
+import 'package:immich_mobile/presentation/widgets/asset_viewer/asset_viewer.page.dart';
 import 'package:immich_mobile/presentation/widgets/images/remote_image_provider.dart';
-import 'package:immich_mobile/providers/activity.provider.dart';
-import 'package:immich_mobile/providers/activity_service.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/asset.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/current_album.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/timeline.provider.dart';
 import 'package:immich_mobile/providers/user.provider.dart';
+import 'package:immich_mobile/routing/router.dart';
+import 'package:immich_mobile/store/activity.dart';
 import 'package:immich_mobile/widgets/activities/dismissible_activity.dart';
 import 'package:immich_mobile/widgets/common/user_circle_avatar.dart';
 
@@ -33,15 +37,19 @@ class CommentBubble extends ConsumerWidget {
     );
 
     Future<void> openAssetViewer() async {
-      final activityService = ref.read(activityServiceProvider);
-      final route = await activityService.buildAssetViewerRoute(activity.assetId!, ref);
-      if (!context.mounted) {
+      final asset = await ref.read(assetServiceProvider).getRemoteAsset(activity.assetId!);
+      if (asset == null || !context.mounted) {
         return;
       }
 
-      if (route != null) {
-        await context.pushRoute(route);
-      }
+      AssetViewer.setAsset(ref, asset);
+      await context.pushRoute(
+        AssetViewerRoute(
+          initialIndex: 0,
+          timelineService: ref.read(timelineFactoryProvider).fromAssets([asset], TimelineOrigin.albumActivities),
+          currentAlbum: ref.read(currentRemoteAlbumProvider),
+        ),
+      );
     }
 
     // avatar (hidden for own messages)
diff --git a/mobile/packages/data/lib/data_controller.dart b/mobile/packages/data/lib/data_controller.dart
index be364be160..461eab254f 100644
--- a/mobile/packages/data/lib/data_controller.dart
+++ b/mobile/packages/data/lib/data_controller.dart
@@ -2,7 +2,9 @@ import 'package:flutter/foundation.dart';
 import 'package:immich_data/db/database.dart';
 import 'package:immich_data/db/logger.dart';
 import 'package:immich_data/db/person.dart';
+import 'package:immich_data/server/activity.dart';
 import 'package:immich_data/server/person.dart';
+import 'package:immich_data/store/activity.dart';
 import 'package:immich_data/store/person.dart';
 import 'package:openapi/api.dart';
 import 'package:sqlite3/common.dart';
@@ -62,6 +64,10 @@ class DataController {
     PersonApiRepository(PeopleApi(_apiClient)),
   );
 
+  // This is optional and not lazy so we only call `dispose` if necessary
+  ActivityService? _activities;
+  ActivityService get activities => _activities ??= ActivityService(ActivityApiRepository(ActivitiesApi(_apiClient)));
+
   /// Direct database access for the logic that has not yet moved into this package
   // TODO(rewrite): Remove once all repositories have migrated into this package
   Drift get db => _db;
@@ -71,6 +77,9 @@ class DataController {
   DriftLogger get logDb => _logDb;
 
   Future<void> close() async {
+    await _activities?.dispose();
+    _activities = null;
+
     await _db.close();
 
     // Close after the primary DB to ensure all logs are captured
diff --git a/mobile/lib/models/activities/activity.model.dart b/mobile/packages/data/lib/model/activity.dart
similarity index 89%
rename from mobile/lib/models/activities/activity.model.dart
rename to mobile/packages/data/lib/model/activity.dart
index d3f99aea64..946c74d4e5 100644
--- a/mobile/lib/models/activities/activity.model.dart
+++ b/mobile/packages/data/lib/model/activity.dart
@@ -1,4 +1,4 @@
-import 'package:immich_mobile/domain/models/user.model.dart';
+import 'package:immich_data/model/user/user.dart';
 
 enum ActivityType { comment, like }
 
@@ -61,9 +61,3 @@ class Activity {
     return id.hashCode ^ assetId.hashCode ^ comment.hashCode ^ createdAt.hashCode ^ type.hashCode ^ user.hashCode;
   }
 }
-
-class ActivityStats {
-  final int comments;
-
-  const ActivityStats({required this.comments});
-}
diff --git a/mobile/lib/repositories/activity_api.repository.dart b/mobile/packages/data/lib/server/activity.dart
similarity index 61%
rename from mobile/lib/repositories/activity_api.repository.dart
rename to mobile/packages/data/lib/server/activity.dart
index 9ae83b0e7b..6e999a3b96 100644
--- a/mobile/lib/repositories/activity_api.repository.dart
+++ b/mobile/packages/data/lib/server/activity.dart
@@ -1,18 +1,15 @@
-import 'package:hooks_riverpod/hooks_riverpod.dart';
-import 'package:immich_mobile/infrastructure/utils/user.converter.dart';
-import 'package:immich_mobile/models/activities/activity.model.dart';
-import 'package:immich_mobile/providers/api.provider.dart';
-import 'package:immich_mobile/repositories/api.repository.dart';
+import 'package:immich_data/model/activity.dart';
+import 'package:immich_data/server/api_repository.dart';
+import 'package:immich_data/server/util/convert.dart';
+import 'package:meta/meta.dart';
 import 'package:openapi/api.dart';
 
-final activityApiRepositoryProvider = Provider(
-  (ref) => ActivityApiRepository(ref.watch(apiServiceProvider).activitiesApi),
-);
-
+/// Immich HTTP API for album activity (comments and likes)
 class ActivityApiRepository extends ApiRepository {
   final ActivitiesApi _api;
 
-  ActivityApiRepository(this._api);
+  @internal
+  const ActivityApiRepository(this._api);
 
   Future<List<Activity>> getAll(String albumId, {String? assetId}) async {
     final response = await checkNull(_api.getActivities(albumId, assetId: assetId));
@@ -31,19 +28,15 @@ class ActivityApiRepository extends ApiRepository {
   }
 
   Future<void> delete(String id) {
+    // TODO(agg23): I think this is a bug; `checkNull` will always throw here
     return checkNull(_api.deleteActivity(id));
   }
 
-  Future<ActivityStats> getStats(String albumId, {String? assetId}) async {
-    final response = await checkNull(_api.getActivityStatistics(albumId, assetId: assetId));
-    return ActivityStats(comments: response.comments);
-  }
-
   static Activity _toActivity(ActivityResponseDto dto) => Activity(
     id: dto.id,
     createdAt: dto.createdAt,
     type: dto.type == ReactionType.comment ? ActivityType.comment : ActivityType.like,
-    user: UserConverter.fromSimpleUserDto(dto.user),
+    user: DtoConverter.toUser(dto.user),
     assetId: dto.assetId,
     comment: dto.comment.orElse(null),
   );
diff --git a/mobile/packages/data/lib/server/util/convert.dart b/mobile/packages/data/lib/server/util/convert.dart
new file mode 100644
index 0000000000..49e0d7225d
--- /dev/null
+++ b/mobile/packages/data/lib/server/util/convert.dart
@@ -0,0 +1,29 @@
+import 'package:immich_data/model/user/user.dart';
+import 'package:openapi/api.dart';
+
+abstract final class DtoConverter {
+  // TODO(rewrite): This is duplicated from lib/infrastructure/utils/user.converter.dart
+  static UserDto toUser(UserResponseDto dto) => UserDto(
+    id: dto.id,
+    email: dto.email,
+    name: dto.name,
+    isAdmin: false,
+    updatedAt: DateTime.now(),
+    hasProfileImage: dto.profileImagePath.isNotEmpty,
+    profileChangedAt: dto.profileChangedAt,
+    avatarColor: _toAvatarColor(dto.avatarColor),
+  );
+}
+
+AvatarColor _toAvatarColor(UserAvatarColor color) => switch (color) {
+  UserAvatarColor.red => AvatarColor.red,
+  UserAvatarColor.green => AvatarColor.green,
+  UserAvatarColor.blue => AvatarColor.blue,
+  UserAvatarColor.purple => AvatarColor.purple,
+  UserAvatarColor.orange => AvatarColor.orange,
+  UserAvatarColor.pink => AvatarColor.pink,
+  UserAvatarColor.amber => AvatarColor.amber,
+  UserAvatarColor.yellow => AvatarColor.yellow,
+  UserAvatarColor.gray => AvatarColor.gray,
+  UserAvatarColor.primary || _ => AvatarColor.primary,
+};
diff --git a/mobile/packages/data/lib/store/activity.dart b/mobile/packages/data/lib/store/activity.dart
new file mode 100644
index 0000000000..71a0573cfd
--- /dev/null
+++ b/mobile/packages/data/lib/store/activity.dart
@@ -0,0 +1,87 @@
+import 'package:immich_data/model/activity.dart';
+import 'package:immich_data/server/activity.dart';
+import 'package:immich_data/server/errors.dart';
+import 'package:immich_data/store/util/stream_cache.dart';
+import 'package:meta/meta.dart';
+
+/// Activities (comments and likes) on shared albums and their assets
+///
+/// State is fetched over HTTP and mutated and cached in memory
+// TODO(agg23): This should not be called simply "Activity"
+class ActivityService {
+  final ActivityApiRepository _api;
+
+  late final StreamCache<(String albumId, String? assetId), List<Activity>> _cache = StreamCache(
+    fetch: (scope) => _api.getAll(scope.$1, assetId: scope.$2),
+  );
+
+  @internal
+  ActivityService(this._api);
+
+  /// All activities for an album specified by [albumId], or all activities for a specific asset within that album.
+  /// Providing [force] will make a new HTTP request on stream open (legacy behavior)
+  ///
+  /// **NOTE:** This is currently reactive only to in memory mutation, not live HTTP changes
+  Stream<List<Activity>> getAll(String albumId, {String? assetId, bool force = false}) {
+    return _cache.get((albumId, assetId), force: force);
+  }
+
+  /// Add a comment to an album or asset. Providing [assetId] will add to the corresponding asset, otherwise the comment will be added to the album
+  Future<Activity> addComment(String albumId, String comment, {String? assetId}) async {
+    final activity = await _api.create(albumId, ActivityType.comment, assetId: assetId, comment: comment);
+    _upsert(albumId, activity);
+    return activity;
+  }
+
+  /// Add a like to an album or asset Providing [assetId] will add to the corresponding asset, otherwise the like will be added to the album
+  Future<Activity> addLike(String albumId, {String? assetId}) async {
+    final activity = await _api.create(albumId, ActivityType.like, assetId: assetId);
+    _upsert(albumId, activity);
+    return activity;
+  }
+
+  /// Remove an activity by its [activityId]
+  Future<void> remove(String albumId, String activityId) async {
+    try {
+      await _api.delete(activityId);
+    } on NoResponseDtoError {
+      // TODO(agg23): This error should not be thrown at all
+    }
+
+    // Only drop on "success" (including the broken NoResponseDtoError above)
+    _drop(albumId, activityId);
+  }
+
+  /// Terminate all streams and dispose of the cache
+  Future<void> dispose() {
+    return _cache.dispose();
+  }
+
+  /// Apply an activity upsert to the in memory cache
+  void _upsert(String albumId, Activity activity) {
+    _cache.update(
+      // If there is a list for our album, we update it no matter what
+      // If there is a list for our specific asset, we also update that
+      (scope) => scope.$1 == albumId && (scope.$2 == null || scope.$2 == activity.assetId),
+      (activities) {
+        final index = activities.indexWhere((a) => a.id == activity.id);
+
+        if (index == -1) {
+          // Insert new item
+          return [...activities, activity];
+        } else if (activities[index] == activity) {
+          // No change
+          return activities;
+        } else {
+          // Update existing
+          return [...activities]..[index] = activity;
+        }
+      },
+    );
+  }
+
+  /// Drop an activity from any cache entry that may contain it
+  void _drop(String albumId, String activityId) {
+    _cache.update((scope) => scope.$1 == albumId, (activities) => activities.where((a) => a.id != activityId).toList());
+  }
+}
diff --git a/mobile/packages/data/lib/store/person.dart b/mobile/packages/data/lib/store/person.dart
index 59cef4d234..7ec5dfe31a 100644
--- a/mobile/packages/data/lib/store/person.dart
+++ b/mobile/packages/data/lib/store/person.dart
@@ -3,11 +3,11 @@ import 'package:immich_data/model/person.dart';
 import 'package:immich_data/server/person.dart';
 import 'package:meta/meta.dart';
 
+// TODO(rewrite): This needs to be made reactive
 class PersonService {
   final PersonDatabaseRepository _db;
   final PersonApiRepository _api;
 
-  /// Constructed by [ImmichData]; the app obtains instances from there.
   @internal
   const PersonService(this._db, this._api);
 
diff --git a/mobile/packages/data/lib/store/util/stream_cache.dart b/mobile/packages/data/lib/store/util/stream_cache.dart
new file mode 100644
index 0000000000..f3064ccb67
--- /dev/null
+++ b/mobile/packages/data/lib/store/util/stream_cache.dart
@@ -0,0 +1,144 @@
+import 'dart:async';
+
+/// A in memory cache for streams that are backed by emphemeral data (typically HTTP servers).
+/// Values are fetched on demand and disposed of when the last subscriber disconnects
+class StreamCache<K, V extends Object> {
+  final Future<V> Function(K key) _fetch;
+
+  final Map<K, _CacheEntry<V>> _entries = {};
+  final Map<K, Future<void>> _inflightFetches = {};
+
+  StreamCache({required this._fetch});
+
+  /// A live view of the value corresponding to [key]. [force] skips the cached emission and always fetches
+  // TODO(rewrite): Remove force; it exists only for old Flutter views that expect 0 data on first subscribe
+  Stream<V> get(K key, {bool force = false}) {
+    // Reprents this call's subscription
+    late final StreamController<V> localStreamController;
+    // Reprents the source of all updates for this key, shared between individual `get` callers
+    StreamSubscription<V>? cacheStreamController;
+
+    localStreamController = StreamController(
+      onListen: () {
+        final entry = _entries.putIfAbsent(key, _CacheEntry.new).ref();
+
+        // Push stream updates from the upstream to the local controller
+        cacheStreamController = entry.updateStreamController.stream.listen(
+          localStreamController.add,
+          onDone: () => unawaited(localStreamController.close()),
+        );
+
+        final currentData = entry.value;
+        if (currentData != null && !force) {
+          // If we have a cached value at call time, and we're not using legacy `force` behavior, immediately emit that value
+          localStreamController.add(currentData);
+        }
+
+        if (currentData == null || force) {
+          // No data/force request, request new data from upstream
+          unawaited(
+            _fetchDeduped(
+              key,
+            ).catchError((Object error, StackTrace stack) => localStreamController.addError(error, stack)),
+          );
+        }
+      },
+      onCancel: () async {
+        await cacheStreamController?.cancel();
+
+        final entry = _entries[key];
+        if (entry == null) {
+          return;
+        }
+
+        if (entry.deref().refCount <= 0) {
+          _entries.remove(key);
+        }
+      },
+    );
+
+    return localStreamController.stream;
+  }
+
+  /// Apply [transform] to all values corresponding to keys matching [predicate]
+  ///
+  /// Returning the same value (identity) from [transform] will not emit a new value
+  void update(bool Function(K key) predicate, V Function(V value) transform) {
+    for (final MapEntry(:key, value: entry) in _entries.entries) {
+      if (!predicate(key)) {
+        continue;
+      }
+
+      final currentValue = entry.value;
+      if (currentValue == null) {
+        continue;
+      }
+
+      final newValue = transform(currentValue);
+      if (!identical(newValue, currentValue)) {
+        entry.value = newValue;
+      }
+    }
+  }
+
+  /// Close all streams and delete caches
+  Future<void> dispose() async {
+    _inflightFetches.clear();
+
+    final oldEntries = [..._entries.values];
+    _entries.clear();
+
+    await Future.wait(oldEntries.map((entry) => entry.updateStreamController.close()));
+  }
+
+  /// Fetch a single value matching the provided [key]. If a matching fetch is already in progress, await that fetch
+  Future<void> _fetchDeduped(K key) {
+    return _inflightFetches.putIfAbsent(key, () async {
+      try {
+        final data = await _fetch(key);
+        final entry = _entries[key];
+
+        if (entry != null) {
+          entry.value = data;
+        }
+      } finally {
+        unawaited(_inflightFetches.remove(key));
+      }
+    });
+  }
+}
+
+/// A streaming in memory cache entry
+class _CacheEntry<V> {
+  V? _value;
+  int refCount = 0;
+
+  final StreamController<V> updateStreamController = StreamController.broadcast();
+
+  /// The current value in the cache
+  V? get value => _value;
+
+  /// Set the current cache value, sending it to all subscribers
+  set value(V newValue) {
+    _value = newValue;
+    updateStreamController.add(newValue);
+  }
+
+  /// Increments the reference count of the entry
+  _CacheEntry<V> ref() {
+    refCount += 1;
+    return this;
+  }
+
+  /// Decrements the reference count of the entry. If there are no active references, closes the update stream
+  _CacheEntry<V> deref() {
+    if (refCount == 0) {
+      unawaited(updateStreamController.close());
+
+      return this;
+    }
+
+    refCount -= 1;
+    return this;
+  }
+}
diff --git a/mobile/packages/data/pubspec.yaml b/mobile/packages/data/pubspec.yaml
index 55f3958078..ceb9e608bf 100644
--- a/mobile/packages/data/pubspec.yaml
+++ b/mobile/packages/data/pubspec.yaml
@@ -27,6 +27,7 @@ dev_dependencies:
   flutter_lints: ^5.0.0
   flutter_test:
     sdk: flutter
+  mocktail: ^1.0.5
 
 # The generated openapi client depends back on immich_mobile, so resolving
 # this package pulls in the app's dependency graph. Pub only honors the root
diff --git a/mobile/packages/data/test/store/util/stream_cache_test.dart b/mobile/packages/data/test/store/util/stream_cache_test.dart
new file mode 100644
index 0000000000..7a7dac25e5
--- /dev/null
+++ b/mobile/packages/data/test/store/util/stream_cache_test.dart
@@ -0,0 +1,148 @@
+import 'dart:async';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:immich_data/store/util/stream_cache.dart';
+
+void main() {
+  late int fetches;
+  late StreamCache<String, List<String>> cache;
+
+  setUp(() {
+    fetches = 0;
+    cache = StreamCache(fetch: (key) async => ['$key-v${++fetches}']);
+    addTearDown(cache.dispose);
+  });
+
+  /// Subscribes and collects every emission
+  List<List<String>> subscribe(String key, {bool force = false}) {
+    final emissions = <List<String>>[];
+    final subscription = cache.get(key, force: force).listen(emissions.add);
+    addTearDown(subscription.cancel);
+    return emissions;
+  }
+
+  test('fetches and emits on first subscribe', () async {
+    await expectLater(cache.get('a'), emits(['a-v1']));
+  });
+
+  test('a second subscriber is served from the cache without a fetch', () async {
+    subscribe('a');
+    await pumpEventQueue();
+
+    await expectLater(cache.get('a'), emits(['a-v1']));
+
+    expect(fetches, 1);
+  });
+
+  test('force skips the cached emission and always fetches', () async {
+    subscribe('a');
+    await pumpEventQueue();
+
+    await expectLater(cache.get('a', force: true), emits(['a-v2']));
+
+    expect(fetches, 2);
+  });
+
+  test('keys are cached independently', () async {
+    await expectLater(cache.get('a'), emits(['a-v1']));
+    await expectLater(cache.get('b'), emits(['b-v2']));
+  });
+
+  test('concurrent first subscribers share a single fetch', () async {
+    final completer = Completer<List<String>>();
+    cache = StreamCache(
+      fetch: (key) {
+        fetches++;
+        return completer.future;
+      },
+    );
+    addTearDown(cache.dispose);
+    final first = subscribe('a');
+    final second = subscribe('a');
+
+    completer.complete(['shared']);
+    await pumpEventQueue();
+
+    expect(first, [
+      ['shared'],
+    ]);
+    expect(first, second);
+    expect(fetches, 1);
+  });
+
+  test('a failed fetch is a stream error and the stream survives', () async {
+    var fail = true;
+    cache = StreamCache(fetch: (key) => fail ? Future.error(StateError('down')) : Future.value(['recovered']));
+    addTearDown(cache.dispose);
+
+    final events = <Object>[];
+    final subscription = cache.get('a').listen(events.add, onError: (Object error) => events.add('error'));
+    addTearDown(subscription.cancel);
+    await pumpEventQueue();
+    expect(events, ['error']);
+
+    fail = false;
+    subscribe('a', force: true);
+    await pumpEventQueue();
+
+    expect(events, [
+      'error',
+      ['recovered'],
+    ]);
+  });
+
+  test('the cache is dropped when the last subscriber cancels', () async {
+    final subscription = cache.get('a').listen((_) {});
+    await pumpEventQueue();
+    await subscription.cancel();
+
+    await expectLater(cache.get('a'), emits(['a-v2']));
+
+    expect(fetches, 2);
+  });
+
+  group('update', () {
+    test('transforms and publishes every matching cached value', () async {
+      final a = subscribe('a');
+      final b = subscribe('b');
+      final c = subscribe('c');
+      await pumpEventQueue();
+
+      cache.update((key) => key != 'c', (value) => [...value, 'patched']);
+      await pumpEventQueue();
+
+      expect(a.last, ['a-v1', 'patched']);
+      expect(b.last, ['b-v2', 'patched']);
+      expect(c.last, ['c-v3']);
+    });
+
+    test('publishes nothing when the transform returns the identical value', () async {
+      final a = subscribe('a');
+      await pumpEventQueue();
+
+      cache.update((_) => true, (value) => value);
+      await pumpEventQueue();
+
+      expect(a, hasLength(1));
+    });
+
+    test('does not touch keys that have no cached value yet', () {
+      cache.update((_) => true, (value) => [...value, 'patched']);
+      // No cached values exist; nothing to transform and nothing thrown.
+      expect(fetches, 0);
+    });
+  });
+
+  test('dispose ends every subscriber stream', () async {
+    var done = false;
+    final subscription = cache.get('a').listen((_) {});
+    subscription.onDone(() => done = true);
+    addTearDown(subscription.cancel);
+    await pumpEventQueue();
+
+    await cache.dispose();
+    await pumpEventQueue();
+
+    expect(done, isTrue);
+  });
+}
diff --git a/mobile/test/providers/activity_provider_test.dart b/mobile/test/providers/activity_provider_test.dart
new file mode 100644
index 0000000000..c2e8c99207
--- /dev/null
+++ b/mobile/test/providers/activity_provider_test.dart
@@ -0,0 +1,144 @@
+import 'dart:async';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_data/data_controller.dart';
+import 'package:immich_data/model/activity.dart';
+import 'package:immich_data/model/user/user.dart';
+import 'package:immich_data/store/activity.dart';
+import 'package:immich_mobile/providers/infrastructure/data_store.dart';
+import 'package:immich_mobile/store/activity.dart';
+import 'package:mocktail/mocktail.dart';
+
+class MockDataController extends Mock implements DataController {}
+
+class MockActivityService extends Mock implements ActivityService {}
+
+void main() {
+  late ProviderContainer container;
+  late MockActivityService service;
+  late StreamController<List<Activity>> albumScopedStream;
+  late StreamController<List<Activity>> assetScopedStream;
+
+  const albumId = 'album-1';
+  const assetId = 'asset-1';
+  const albumScoped = (albumId, null);
+  const assetScoped = (albumId, assetId);
+
+  final user = UserDto(id: 'user-1', email: 'user@test.com', name: 'User', profileChangedAt: DateTime.utc(2025));
+
+  Activity activity(String id, {String? assetId, ActivityType type = ActivityType.comment, String? comment}) =>
+      Activity(id: id, assetId: assetId, comment: comment, createdAt: DateTime.utc(2025), type: type, user: user);
+
+  Future<void> pumpBothScopes() async {
+    container.listen(albumActivityProvider(assetScoped), (_, _) {});
+    container.listen(albumActivityProvider(albumScoped), (_, _) {});
+    albumScopedStream.add([]);
+    assetScopedStream.add([]);
+    await container.read(albumActivityProvider(assetScoped).future);
+    await container.read(albumActivityProvider(albumScoped).future);
+  }
+
+  List<String> idsIn((String, String?) scope) =>
+      container.read(albumActivityProvider(scope)).requireValue.map((a) => a.id).toList();
+
+  setUp(() {
+    service = MockActivityService();
+    albumScopedStream = StreamController<List<Activity>>.broadcast();
+    assetScopedStream = StreamController<List<Activity>>.broadcast();
+    addTearDown(albumScopedStream.close);
+    addTearDown(assetScopedStream.close);
+    when(() => service.getAll(albumId, assetId: null, force: true)).thenAnswer((_) => albumScopedStream.stream);
+    when(() => service.getAll(albumId, assetId: assetId, force: true)).thenAnswer((_) => assetScopedStream.stream);
+
+    final controller = MockDataController();
+    when(() => controller.activities).thenReturn(service);
+
+    container = ProviderContainer(overrides: [Store.overrideWithValue(controller)]);
+    addTearDown(container.dispose);
+  });
+
+  group('build', () {
+    test('album/asset scopes get their own views', () async {
+      container.listen(albumActivityProvider(assetScoped), (_, _) {});
+      container.listen(albumActivityProvider(albumScoped), (_, _) {});
+      albumScopedStream.add([activity('c1'), activity('c2', assetId: assetId)]);
+      assetScopedStream.add([activity('c2', assetId: assetId)]);
+
+      expect(await container.read(albumActivityProvider(albumScoped).future), hasLength(2));
+      expect(await container.read(albumActivityProvider(assetScoped).future), hasLength(1));
+    });
+
+    test('errors become an empty list', () async {
+      container.listen(albumActivityProvider(albumScoped), (_, _) {});
+      albumScopedStream.addError(Exception('network down'));
+
+      expect(await container.read(albumActivityProvider(albumScoped).future), isEmpty);
+    });
+  });
+
+  test('new events get pushed to Riverpod', () async {
+    await pumpBothScopes();
+
+    final like = activity('l1', assetId: assetId, type: ActivityType.like);
+    albumScopedStream.add([like]);
+    assetScopedStream.add([like]);
+    await pumpEventQueue();
+
+    expect(idsIn(albumScoped), ['l1']);
+    expect(idsIn(assetScoped), ['l1']);
+  });
+
+  group('mutations', () {
+    test('addLike calls API', () async {
+      final like = activity('l1', assetId: assetId, type: ActivityType.like);
+      when(() => service.addLike(albumId, assetId: assetId)).thenAnswer((_) async => like);
+      await pumpBothScopes();
+
+      await container.read(albumActivityProvider(assetScoped).notifier).addLike();
+
+      verify(() => service.addLike(albumId, assetId: assetId)).called(1);
+    });
+
+    test('addComment calls API', () async {
+      final comment = activity('c1', assetId: assetId, comment: 'nice');
+      when(() => service.addComment(albumId, 'nice', assetId: assetId)).thenAnswer((_) async => comment);
+      await pumpBothScopes();
+
+      await container.read(albumActivityProvider(assetScoped).notifier).addComment('nice');
+
+      verify(() => service.addComment(albumId, 'nice', assetId: assetId)).called(1);
+    });
+
+    test('removeActivity calls API', () async {
+      when(() => service.remove(albumId, 'c1')).thenAnswer((_) async {});
+      await pumpBothScopes();
+
+      await container.read(albumActivityProvider(assetScoped).notifier).removeActivity('c1');
+
+      verify(() => service.remove(albumId, 'c1')).called(1);
+    });
+  });
+
+  group('failed mutations', () {
+    test('addLike logs error', () async {
+      when(() => service.addLike(albumId, assetId: assetId)).thenAnswer((_) => Future.error(Exception('rejected')));
+      await pumpBothScopes();
+
+      await container.read(albumActivityProvider(assetScoped).notifier).addLike();
+
+      expect(idsIn(assetScoped), isEmpty);
+      expect(idsIn(albumScoped), isEmpty);
+    });
+
+    test('removeActivity logs error', () async {
+      when(() => service.remove(albumId, 'c1')).thenAnswer((_) => Future.error(Exception('rejected')));
+      await pumpBothScopes();
+
+      await container.read(albumActivityProvider(assetScoped).notifier).removeActivity('c1');
+
+      expect(idsIn(assetScoped), isEmpty);
+      expect(idsIn(albumScoped), isEmpty);
+    });
+  });
+}