fix(mobile): keep drag select going while the grid auto scrolls

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

@@ -1,6 +1,5 @@
 import 'package:immich_mobile/domain/models/album/local_album.model.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
-import 'package:immich_mobile/domain/models/asset_edit.model.dart';
 import 'package:immich_mobile/domain/models/exif.model.dart';
 import 'package:immich_mobile/infrastructure/repositories/local_asset.repository.dart';
 import 'package:immich_mobile/infrastructure/repositories/remote_asset.repository.dart';
@@ -78,12 +77,4 @@ class AssetService {
     await _apiRepository.updateFavorite(remoteIds, isFavorite);
     await _remoteRepository.updateFavorite(remoteIds, isFavorite);
   }
-
-  Future<void> applyEdits(String remoteId, List<AssetEdit> edits) async {
-    if (edits.isEmpty) {
-      await _apiRepository.removeEdits(remoteId);
-    } else {
-      await _apiRepository.editAsset(remoteId, edits);
-    }
-  }
 }

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

@@ -182,6 +182,18 @@ class TimelineService {
     return _buffer.slice(start, start + count);
   }
 
+  /// Reads a range without disturbing the buffer; queries the source if it isn't resident.
+  Future<List<BaseAsset>> getAssetsRange(int index, int count) async {
+    if (index < 0 || count <= 0 || index >= _totalAssets) {
+      return const [];
+    }
+    final clamped = math.min(count, _totalAssets - index);
+    if (hasRange(index, clamped)) {
+      return getAssets(index, clamped);
+    }
+    return _assetSource(index, clamped);
+  }
+
   // Preload assets around the given index for asset viewer
   Future<void> preloadAssets(int index) => _mutex.run(() => _loadAssets(index, math.min(5, _totalAssets - index)));
 

mobile/lib/presentation/actions/edit.action.dart

@@ -1,70 +0,0 @@
-import 'dart:async';
-
-import 'package:auto_route/auto_route.dart';
-import 'package:flutter/material.dart';
-import 'package:hooks_riverpod/hooks_riverpod.dart';
-import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
-import 'package:immich_mobile/domain/models/asset_edit.model.dart';
-import 'package:immich_mobile/generated/translations.g.dart';
-import 'package:immich_mobile/presentation/actions/action.dart';
-import 'package:immich_mobile/presentation/pages/edit/editor.provider.dart';
-import 'package:immich_mobile/presentation/widgets/images/image_provider.dart';
-import 'package:immich_mobile/providers/infrastructure/asset.provider.dart';
-import 'package:immich_mobile/providers/server_info.provider.dart';
-import 'package:immich_mobile/providers/websocket.provider.dart';
-import 'package:immich_mobile/routing/router.dart';
-import 'package:immich_mobile/utils/semver.dart';
-
-class EditAssetAction extends AssetAction<RemoteAsset> {
-  const EditAssetAction({required super.assets});
-
-  @override
-  IconData get icon => Icons.tune;
-
-  @override
-  String label(ActionScope scope) => scope.context.t.edit;
-
-  @override
-  Iterable<RemoteAsset> filter(ActionScope scope) =>
-      assets.where((asset) => asset is RemoteAsset && asset.ownerId == scope.authUser.id && asset.isEditable).cast();
-
-  @override
-  bool isVisible(ActionScope scope) =>
-      filter(scope).length == 1 &&
-      scope.ref.watch(serverInfoProvider).serverVersion >= const SemVer(major: 2, minor: 6, patch: 0);
-
-  @override
-  Future<void> onAction(ActionScope scope) async {
-    final ActionScope(:context, :ref) = scope;
-
-    final asset = filter(scope).first;
-    final remoteId = asset.id;
-    final repository = ref.read(remoteAssetRepositoryProvider);
-    final (edits, exif) = await (repository.getAssetEdits(remoteId), repository.getExif(remoteId)).wait;
-    if (exif == null || !context.mounted) {
-      return;
-    }
-
-    ref.read(editorStateProvider.notifier).init(edits, exif);
-    unawaited(
-      context.pushRoute(
-        DriftEditImageRoute(
-          image: Image(image: getFullImageProvider(asset, edited: false)),
-          applyEdits: (newEdits) => applyEdits(ref, remoteId, newEdits),
-        ),
-      ),
-    );
-  }
-}
-
-@visibleForTesting
-Future<void> applyEdits(WidgetRef ref, String remoteId, List<AssetEdit> edits) async {
-  final websocket = ref.read(websocketProvider.notifier);
-
-  bool isCurrentId(dynamic data) => data is Map && (data['asset'] as Map?)?['id'] == remoteId;
-  await ref.read(assetServiceProvider).applyEdits(remoteId, edits);
-  await Future.any([
-    websocket.waitForEvent('AssetEditReadyV1', isCurrentId, const Duration(seconds: 10)),
-    websocket.waitForEvent('AssetEditReadyV2', isCurrentId, const Duration(seconds: 10)),
-  ]).catchError((_) {});
-}

mobile/lib/presentation/actions/favorite.action.dart

@@ -21,7 +21,7 @@ class FavoriteAction extends AssetAction<RemoteAsset> {
       .where(
         (asset) => asset is RemoteAsset && asset.ownerId == scope.authUser.id && asset.isFavorite == !shouldFavorite,
       )
-      .cast();
+      .cast<RemoteAsset>();
 
   @override
   bool isVisible(ActionScope scope) => filter(scope).isNotEmpty;

mobile/lib/presentation/widgets/action_buttons/edit_image_action_button.widget.dart

@@ -0,0 +1,59 @@
+import 'dart:async';
+
+import 'package:auto_route/auto_route.dart';
+import 'package:flutter/material.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_mobile/constants/enums.dart';
+import 'package:immich_mobile/domain/models/asset_edit.model.dart';
+import 'package:immich_mobile/extensions/translate_extensions.dart';
+import 'package:immich_mobile/presentation/pages/edit/editor.provider.dart';
+import 'package:immich_mobile/presentation/widgets/action_buttons/base_action_button.widget.dart';
+import 'package:immich_mobile/presentation/widgets/images/image_provider.dart';
+import 'package:immich_mobile/providers/asset_viewer/asset_viewer.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/action.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/asset.provider.dart';
+import 'package:immich_mobile/routing/router.dart';
+
+class EditImageActionButton extends ConsumerWidget {
+  const EditImageActionButton({super.key});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final currentAsset = ref.watch(assetViewerProvider.select((s) => s.currentAsset));
+
+    Future<void> editImage(List<AssetEdit> edits) async {
+      if (currentAsset == null || currentAsset.remoteId == null) {
+        return;
+      }
+
+      await ref.read(actionProvider.notifier).applyEdits(ActionSource.viewer, edits);
+    }
+
+    Future<void> onPress() async {
+      if (currentAsset == null || currentAsset.remoteId == null) {
+        return;
+      }
+
+      final imageProvider = getFullImageProvider(currentAsset, edited: false);
+
+      final image = Image(image: imageProvider);
+      final (edits, exifInfo) = await (
+        ref.read(remoteAssetRepositoryProvider).getAssetEdits(currentAsset.remoteId!),
+        ref.read(remoteAssetRepositoryProvider).getExif(currentAsset.remoteId!),
+      ).wait;
+
+      if (exifInfo == null) {
+        return;
+      }
+
+      ref.read(editorStateProvider.notifier).init(edits, exifInfo);
+      await context.pushRoute(DriftEditImageRoute(image: image, applyEdits: editImage));
+    }
+
+    return BaseActionButton(
+      iconData: Icons.tune,
+      label: "edit".t(context: context),
+      onPressed: onPress,
+    );
+  }
+}

mobile/lib/presentation/widgets/asset_viewer/bottom_bar.widget.dart

@@ -4,12 +4,11 @@ import 'package:immich_mobile/constants/enums.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
 import 'package:immich_mobile/domain/services/timeline.service.dart';
 import 'package:immich_mobile/extensions/build_context_extensions.dart';
-import 'package:immich_mobile/presentation/actions/action.widget.dart';
-import 'package:immich_mobile/presentation/actions/edit.action.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/add_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/delete_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/delete_local_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/delete_permanent_action_button.widget.dart';
+import 'package:immich_mobile/presentation/widgets/action_buttons/edit_image_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/restore_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/share_action_button.widget.dart';
 import 'package:immich_mobile/presentation/widgets/action_buttons/upload_action_button.widget.dart';
@@ -18,9 +17,10 @@ import 'package:immich_mobile/providers/asset_viewer/asset_viewer.provider.dart'
 import 'package:immich_mobile/providers/infrastructure/readonly_mode.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/timeline.provider.dart';
 import 'package:immich_mobile/providers/routes.provider.dart';
+import 'package:immich_mobile/providers/server_info.provider.dart';
 import 'package:immich_mobile/providers/user.provider.dart';
+import 'package:immich_mobile/utils/semver.dart';
 import 'package:immich_mobile/widgets/asset_viewer/video_controls.dart';
-import 'package:immich_ui/immich_ui.dart';
 
 class ViewerBottomBar extends ConsumerWidget {
   const ViewerBottomBar({super.key});
@@ -37,10 +37,10 @@ class ViewerBottomBar extends ConsumerWidget {
     final isOwner = asset is RemoteAsset && asset.ownerId == user?.id;
     final showingDetails = ref.watch(assetViewerProvider.select((s) => s.showingDetails));
     final isInLockedView = ref.watch(inLockedViewProvider);
+    final serverInfo = ref.watch(serverInfoProvider);
     final isInTrash = ref.read(timelineServiceProvider).origin == TimelineOrigin.trash;
 
     final originalTheme = context.themeData;
-    final actionAsset = [asset];
 
     final actions = <Widget>[
       if (isInTrash && isOwner && asset.hasRemote)
@@ -51,7 +51,9 @@ class ViewerBottomBar extends ConsumerWidget {
       if (!isInLockedView) ...[
         if (!isInTrash) ...[
           if (asset.isLocalOnly) const UploadActionButton(source: ActionSource.viewer),
-          ActionColumnButtonWidget(action: EditAssetAction(assets: actionAsset)),
+          // edit sync was added in 2.6.0
+          if (asset.isEditable && serverInfo.serverVersion >= const SemVer(major: 2, minor: 6, patch: 0))
+            const EditImageActionButton(),
           if (asset.hasRemote) AddActionButton(originalTheme: originalTheme),
         ],
         if (isOwner) ...[
@@ -102,10 +104,7 @@ class ViewerBottomBar extends ConsumerWidget {
                           OcrToggleButton(asset: asset),
                           if (asset.isVideo) VideoControls(videoPlayerName: asset.heroTag),
                           if (!isReadonlyModeEnabled)
-                            ImmichColorOverride(
-                              color: Colors.white,
-                              child: Row(mainAxisAlignment: MainAxisAlignment.spaceEvenly, children: actions),
-                            ),
+                            Row(mainAxisAlignment: MainAxisAlignment.spaceEvenly, children: actions),
                         ],
                       ),
                     ),

mobile/lib/presentation/widgets/timeline/drag_selection_controller.dart

@@ -0,0 +1,175 @@
+import 'dart:collection';
+
+import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+
+// Tracks the [anchor..current] range selected by a drag. The in-buffer part of
+// each tick is selected synchronously so it follows the finger without racing;
+// the rare beyond-buffer part is read async (applied only if still in range) and
+// [end] reads whatever is still missing so the final range always lands.
+class DragSelectionController {
+  DragSelectionController({required this.getAssetSafe, required this.getAssetsRange, required this.onChange});
+
+  final BaseAsset? Function(int index) getAssetSafe;
+  final Future<List<BaseAsset>> Function(int index, int count) getAssetsRange;
+  final void Function(Set<BaseAsset> select, Set<BaseAsset> deselect) onChange;
+
+  final HashMap<int, BaseAsset> _selected = HashMap();
+  // Indices the buffer didn't hold yet (the edge outran the async buffer-load on a
+  // fast scroll); read in by _extendPending and guaranteed by end().
+  final Set<int> _pending = {};
+  int? _anchor;
+  int? _lo;
+  int? _hi;
+  bool _disposed = false;
+
+  // Call before starting a new drag so a previous drag's in-flight read can't
+  // leak into the new selection.
+  void dispose() => _disposed = true;
+
+  void _emit(Set<BaseAsset> select, Set<BaseAsset> deselect) {
+    if (_disposed) {
+      return;
+    }
+    onChange(select, deselect);
+  }
+
+  void start(int anchor) {
+    _selected.clear();
+    _pending.clear();
+    _anchor = anchor;
+    _lo = anchor;
+    _hi = anchor;
+    _select(anchor);
+    _extendPending();
+  }
+
+  void enter(int current) {
+    final anchor = _anchor;
+    if (anchor == null || _lo == null || _hi == null) {
+      return;
+    }
+    final ns = current < anchor ? current : anchor;
+    final ne = current < anchor ? anchor : current;
+    final ps = _lo!;
+    final pe = _hi!;
+    if (ns == ps && ne == pe) {
+      return;
+    }
+
+    final toSelect = <BaseAsset>{};
+    final toDeselect = <BaseAsset>{};
+
+    _forEach(ps, ns - 1, (k) => _removeIndex(k, toDeselect));
+    _forEach(ne + 1, pe, (k) => _removeIndex(k, toDeselect));
+    _forEach(ns, ps - 1, (k) => _addIndex(k, toSelect));
+    _forEach(pe + 1, ne, (k) => _addIndex(k, toSelect));
+
+    _lo = ns;
+    _hi = ne;
+
+    if (toSelect.isNotEmpty || toDeselect.isNotEmpty) {
+      _emit(toSelect, toDeselect);
+    }
+    _extendPending();
+  }
+
+  Future<void> end() async {
+    final lo = _lo;
+    final hi = _hi;
+    if (lo == null || hi == null) {
+      return;
+    }
+    final missing = <int>[];
+    for (var k = lo; k <= hi; k++) {
+      if (!_selected.containsKey(k)) {
+        missing.add(k);
+      }
+    }
+    if (missing.isEmpty) {
+      return;
+    }
+    final from = missing.first;
+    final assets = await getAssetsRange(from, missing.last - from + 1);
+    final missingSet = missing.toSet();
+    final toSelect = <BaseAsset>{};
+    for (var i = 0; i < assets.length; i++) {
+      final idx = from + i;
+      if (missingSet.contains(idx) && !_selected.containsKey(idx)) {
+        _selected[idx] = assets[i];
+        _pending.remove(idx);
+        toSelect.add(assets[i]);
+      }
+    }
+    if (toSelect.isNotEmpty) {
+      _emit(toSelect, const {});
+    }
+  }
+
+  void _select(int index) {
+    final asset = getAssetSafe(index);
+    if (asset != null) {
+      _selected[index] = asset;
+      _pending.remove(index);
+      _emit({asset}, const {});
+    } else {
+      _pending.add(index);
+    }
+  }
+
+  void _addIndex(int index, Set<BaseAsset> toSelect) {
+    if (_selected.containsKey(index)) {
+      return;
+    }
+    final asset = getAssetSafe(index);
+    if (asset != null) {
+      _selected[index] = asset;
+      _pending.remove(index);
+      toSelect.add(asset);
+    } else {
+      _pending.add(index);
+    }
+  }
+
+  void _removeIndex(int index, Set<BaseAsset> toDeselect) {
+    _pending.remove(index);
+    final asset = _selected.remove(index);
+    if (asset != null) {
+      toDeselect.add(asset);
+    }
+  }
+
+  Future<void> _extendPending() async {
+    if (_pending.isEmpty) {
+      return;
+    }
+    var from = _pending.first;
+    var to = _pending.first;
+    for (final k in _pending) {
+      if (k < from) {
+        from = k;
+      }
+      if (k > to) {
+        to = k;
+      }
+    }
+    final assets = await getAssetsRange(from, to - from + 1);
+    final toSelect = <BaseAsset>{};
+    for (var i = 0; i < assets.length; i++) {
+      final idx = from + i;
+      if (_pending.contains(idx) && _lo != null && idx >= _lo! && idx <= _hi!) {
+        _selected[idx] = assets[i];
+        toSelect.add(assets[i]);
+      }
+    }
+    _pending.removeWhere((idx) => _selected.containsKey(idx));
+    if (toSelect.isNotEmpty) {
+      _emit(toSelect, const {});
+    }
+  }
+
+  void _forEach(int lo, int hi, void Function(int) fn) {
+    for (var k = lo; k <= hi; k++) {
+      fn(k);
+    }
+  }
+}

mobile/lib/presentation/widgets/timeline/timeline.widget.dart

@@ -1,5 +1,4 @@
 import 'dart:async';
-import 'dart:collection';
 import 'dart:math' as math;
 
 import 'package:collection/collection.dart';
@@ -8,7 +7,6 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
-import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
 import 'package:immich_mobile/domain/models/events.model.dart';
 import 'package:immich_mobile/domain/models/timeline.model.dart';
 import 'package:immich_mobile/domain/utils/event_stream.dart';
@@ -20,6 +18,7 @@ import 'package:immich_mobile/presentation/widgets/timeline/constants.dart';
 import 'package:immich_mobile/presentation/widgets/timeline/scrubber.widget.dart';
 import 'package:immich_mobile/presentation/widgets/timeline/segment.model.dart';
 import 'package:immich_mobile/presentation/widgets/timeline/timeline.state.dart';
+import 'package:immich_mobile/presentation/widgets/timeline/drag_selection_controller.dart';
 import 'package:immich_mobile/presentation/widgets/timeline/timeline_drag_region.dart';
 import 'package:immich_mobile/providers/infrastructure/readonly_mode.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/settings.provider.dart';
@@ -29,6 +28,27 @@ import 'package:immich_mobile/widgets/common/immich_sliver_app_bar.dart';
 import 'package:immich_mobile/widgets/common/mesmerizing_sliver_app_bar.dart';
 import 'package:immich_mobile/widgets/common/selection_sliver_app_bar.dart';
 
+// First asset index of the row shown at [offset]. Pure for testing.
+@visibleForTesting
+int? assetIndexAtOffset(
+  List<Segment> segments,
+  double offset, {
+  required int columnCount,
+  required double maxScrollExtent,
+}) {
+  final clamped = offset.clamp(0.0, maxScrollExtent);
+  final segment = segments.findByOffset(clamped) ?? segments.lastOrNull;
+  if (segment == null) {
+    return null;
+  }
+  final rowIndex = segment.getMinChildIndexForScrollOffset(clamped);
+  if (rowIndex > segment.firstIndex) {
+    final rowIndexInSegment = rowIndex - (segment.firstIndex + 1);
+    return segment.firstAssetIndex + rowIndexInSegment * columnCount;
+  }
+  return segment.firstAssetIndex;
+}
+
 class Timeline extends StatelessWidget {
   const Timeline({
     super.key,
@@ -140,9 +160,10 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
   StreamSubscription? _eventSubscription;
 
   // Drag selection state
+  static const _autoScrollStep = 175.0;
+  static const _autoScrollDuration = Duration(milliseconds: 125);
   bool _dragging = false;
-  TimelineAssetIndex? _dragAnchorIndex;
-  final Set<BaseAsset> _draggedAssets = HashSet();
+  DragSelectionController? _dragController;
   ScrollPhysics? _scrollPhysics;
 
   int _perRow = 4;
@@ -226,26 +247,18 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
     EventStream.shared.emit(MultiSelectToggleEvent(isEnabled));
   }
 
-  int? _getCurrentAssetIndex(List<Segment> segments) {
-    final currentOffset = _scrollController.offset.clamp(0.0, _scrollController.position.maxScrollExtent);
-    final segment = segments.findByOffset(currentOffset) ?? segments.lastOrNull;
-    int? targetAssetIndex;
-    if (segment != null) {
-      final rowIndex = segment.getMinChildIndexForScrollOffset(currentOffset);
-      if (rowIndex > segment.firstIndex) {
-        final rowIndexInSegment = rowIndex - (segment.firstIndex + 1);
-        final assetsPerRow = ref.read(timelineArgsProvider).columnCount;
-        final assetIndexInSegment = rowIndexInSegment * assetsPerRow;
-        targetAssetIndex = segment.firstAssetIndex + assetIndexInSegment;
-      } else {
-        targetAssetIndex = segment.firstAssetIndex;
-      }
-    }
-    return targetAssetIndex;
-  }
+  int? _getCurrentAssetIndex(List<Segment> segments) => _assetIndexAtOffset(segments, _scrollController.offset);
+
+  int? _assetIndexAtOffset(List<Segment> segments, double offset) => assetIndexAtOffset(
+    segments,
+    offset,
+    columnCount: ref.read(timelineArgsProvider).columnCount,
+    maxScrollExtent: _scrollController.position.maxScrollExtent,
+  );
 
   @override
   void dispose() {
+    _dragController?.dispose();
     _scrollController.dispose();
     _eventSubscription?.cancel();
     super.dispose();
@@ -295,9 +308,21 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
 
   // Drag selection methods
   void _setDragStartIndex(TimelineAssetIndex index) {
+    // Stop the old drag's controller so its in-flight read can't leak into this one.
+    _dragController?.dispose();
+    final timelineService = ref.read(timelineServiceProvider);
+    _dragController = DragSelectionController(
+      getAssetSafe: timelineService.getAssetSafe,
+      getAssetsRange: timelineService.getAssetsRange,
+      onChange: (select, deselect) {
+        if (!mounted) {
+          return;
+        }
+        ref.read(multiSelectProvider.notifier).selectRange(select, deselect);
+      },
+    )..start(index.assetIndex);
     setState(() {
       _scrollPhysics = const ClampingScrollPhysics();
-      _dragAnchorIndex = index;
       _dragging = true;
     });
   }
@@ -313,8 +338,12 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
     });
     setState(() {
       _dragging = false;
-      _draggedAssets.clear();
     });
+    // Apply the full final range even if a read is still in flight on lift.
+    final finishing = _dragController?.end();
+    if (finishing != null) {
+      unawaited(finishing);
+    }
     final timelineState = ref.read(timelineStateProvider.notifier);
     Future.delayed(const Duration(milliseconds: 300), () {
       timelineState.setScrolling(false);
@@ -322,42 +351,33 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
   }
 
   void _dragScroll(ScrollDirection direction) {
-    _scrollController.animateTo(
-      _scrollController.offset + (direction == ScrollDirection.forward ? 175 : -175),
-      duration: const Duration(milliseconds: 125),
-      curve: Curves.easeOut,
-    );
+    final position = _scrollController.position;
+    final step = direction == ScrollDirection.forward ? _autoScrollStep : -_autoScrollStep;
+    final target = (_scrollController.offset + step).clamp(0.0, position.maxScrollExtent);
+    _scrollController.animateTo(target, duration: _autoScrollDuration, curve: Curves.easeOut);
+
+    // A held finger emits no move events, so extend the selection to the asset
+    // at the leading edge of the scroll instead.
+    final controller = _dragController;
+    if (controller == null) {
+      return;
+    }
+    final segments = ref.read(timelineSegmentProvider).valueOrNull;
+    if (segments == null) {
+      return;
+    }
+    final edgeOffset = direction == ScrollDirection.forward ? target + position.viewportDimension : target;
+    final edgeIndex = _assetIndexAtOffset(segments, edgeOffset);
+    if (edgeIndex != null) {
+      controller.enter(edgeIndex);
+    }
   }
 
   void _handleDragAssetEnter(TimelineAssetIndex index) {
-    if (_dragAnchorIndex == null || !_dragging) {
+    if (!_dragging) {
       return;
     }
-
-    final timelineService = ref.read(timelineServiceProvider);
-    final dragAnchorIndex = _dragAnchorIndex!;
-
-    // Calculate the range of assets to select
-    final startIndex = math.min(dragAnchorIndex.assetIndex, index.assetIndex);
-    final endIndex = math.max(dragAnchorIndex.assetIndex, index.assetIndex);
-    final count = endIndex - startIndex + 1;
-
-    // Load the assets in the range
-    if (timelineService.hasRange(startIndex, count)) {
-      final selectedAssets = timelineService.getAssets(startIndex, count);
-
-      // Clear previous drag selection and add new range
-      final multiSelectNotifier = ref.read(multiSelectProvider.notifier);
-      for (final asset in _draggedAssets) {
-        multiSelectNotifier.deselectAsset(asset);
-      }
-      _draggedAssets.clear();
-
-      for (final asset in selectedAssets) {
-        multiSelectNotifier.selectAsset(asset);
-        _draggedAssets.add(asset);
-      }
-    }
+    _dragController?.enter(index.assetIndex);
   }
 
   @override

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

@@ -1,11 +1,13 @@
 import 'dart:async';
 
+import 'package:auto_route/auto_route.dart';
 import 'package:background_downloader/background_downloader.dart';
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/constants/enums.dart';
 import 'package:immich_mobile/domain/models/album/album.model.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+import 'package:immich_mobile/domain/models/asset_edit.model.dart';
 import 'package:immich_mobile/domain/services/asset.service.dart';
 import 'package:immich_mobile/domain/services/remote_album.service.dart';
 import 'package:immich_mobile/models/download/livephotos_medatada.model.dart';
@@ -15,13 +17,18 @@ import 'package:immich_mobile/providers/infrastructure/album.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/asset.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/asset_viewer/asset.provider.dart' show assetExifProvider;
 import 'package:immich_mobile/providers/infrastructure/tag.provider.dart';
+import 'package:immich_mobile/providers/server_info.provider.dart';
 import 'package:immich_mobile/providers/timeline/multiselect.provider.dart';
 import 'package:immich_mobile/providers/user.provider.dart';
+import 'package:immich_mobile/providers/websocket.provider.dart';
+import 'package:immich_mobile/routing/router.dart';
 import 'package:immich_mobile/services/action.service.dart';
 import 'package:immich_mobile/services/download.service.dart';
 import 'package:immich_mobile/services/foreground_upload.service.dart';
+import 'package:immich_mobile/utils/semver.dart';
 import 'package:immich_mobile/widgets/asset_grid/delete_dialog.dart';
 import 'package:logging/logging.dart';
+import 'package:openapi/api.dart';
 
 final actionProvider = NotifierProvider<ActionNotifier, void>(ActionNotifier.new, dependencies: [multiSelectProvider]);
 
@@ -128,6 +135,16 @@ class ActionNotifier extends Notifier<void> {
     };
   }
 
+  Future<ActionResult> troubleshoot(ActionSource source, BuildContext context) async {
+    final assets = _getAssets(source);
+    if (assets.length > 1) {
+      return ActionResult(count: assets.length, success: false, error: 'Cannot troubleshoot multiple assets');
+    }
+    unawaited(context.pushRoute(AssetTroubleshootRoute(asset: assets.first)));
+
+    return ActionResult(count: assets.length, success: true);
+  }
+
   Future<ActionResult> shareLink(ActionSource source, BuildContext context) async {
     final ids = _getRemoteIdsForSource(source);
     try {
@@ -614,6 +631,37 @@ class ActionNotifier extends Notifier<void> {
       });
     }
   }
+
+  Future<ActionResult> applyEdits(ActionSource source, List<AssetEdit> edits) async {
+    final ids = _getOwnedRemoteIdsForSource(source);
+
+    if (ids.length != 1) {
+      _logger.warning('applyEdits called with multiple assets, expected single asset');
+      return ActionResult(count: ids.length, success: false, error: 'Expected single asset for applying edits');
+    }
+
+    Future<void> editReady;
+    if (ref.read(serverInfoProvider).serverVersion >= const SemVer(major: 3, minor: 0, patch: 0)) {
+      editReady = ref.read(websocketProvider.notifier).waitForEvent("AssetEditReadyV2", (dynamic data) {
+        final eventAsset = SyncAssetV2.fromJson(data["asset"]);
+        return eventAsset?.id == ids.first;
+      }, const Duration(seconds: 10));
+    } else {
+      editReady = ref.read(websocketProvider.notifier).waitForEvent("AssetEditReadyV1", (dynamic data) {
+        final eventAsset = SyncAssetV1.fromJson(data["asset"]);
+        return eventAsset?.id == ids.first;
+      }, const Duration(seconds: 10));
+    }
+
+    try {
+      await _service.applyEdits(ids.first, edits);
+      await editReady;
+      return const ActionResult(count: 1, success: true);
+    } catch (error, stack) {
+      _logger.severe('Failed to apply edits to assets', error, stack);
+      return ActionResult(count: ids.length, success: false, error: error.toString());
+    }
+  }
 }
 
 extension on Iterable<RemoteAsset> {

mobile/lib/providers/timeline/multiselect.provider.dart

@@ -97,6 +97,15 @@ class MultiSelectNotifier extends Notifier<MultiSelectState> {
     }
   }
 
+  // Drops the previous drag range and adds the new one in a single update. The
+  // full-set copy per drag tick is the accepted cost of immutable state.
+  void selectRange(Set<BaseAsset> toSelect, Set<BaseAsset> toDeselect) {
+    final selectedAssets = state.selectedAssets.toSet()
+      ..removeAll(toDeselect)
+      ..addAll(toSelect);
+    state = state.copyWith(selectedAssets: selectedAssets);
+  }
+
   void reset() {
     state = const MultiSelectState(selectedAssets: {}, lockedSelectionAssets: {}, forceEnable: false);
   }

mobile/lib/services/action.service.dart

@@ -5,6 +5,7 @@ import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/constants/enums.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+import 'package:immich_mobile/domain/models/asset_edit.model.dart';
 import 'package:immich_mobile/domain/models/store.model.dart';
 import 'package:immich_mobile/domain/services/tag.service.dart';
 import 'package:immich_mobile/entities/store.entity.dart';
@@ -304,6 +305,14 @@ class ActionService {
     return true;
   }
 
+  Future<void> applyEdits(String remoteId, List<AssetEdit> edits) async {
+    if (edits.isEmpty) {
+      await _assetApiRepository.removeEdits(remoteId);
+    } else {
+      await _assetApiRepository.editAsset(remoteId, edits);
+    }
+  }
+
   Future<int> _deleteLocalAssets(List<String> localIds) async {
     final deletedIds = await _assetMediaRepository.deleteAll(localIds);
     if (deletedIds.isEmpty) {

mobile/test/domain/service.mock.dart

@@ -5,7 +5,6 @@ import 'package:immich_mobile/domain/services/user.service.dart';
 import 'package:immich_mobile/domain/utils/background_sync.dart';
 import 'package:immich_mobile/platform/native_sync_api.g.dart';
 import 'package:immich_mobile/services/app_settings.service.dart';
-import 'package:immich_mobile/services/server_info.service.dart';
 import 'package:mocktail/mocktail.dart';
 
 class MockStoreService extends Mock implements StoreService {}
@@ -21,5 +20,3 @@ class MockPartnerService extends Mock implements PartnerService {}
 class MockAssetService extends Mock implements AssetService {}
 
 class MockUserService extends Mock implements UserService {}
-
-class MockServerInfoService extends Mock implements ServerInfoService {}

mobile/test/unit/factories/remote_asset_factory.dart

@@ -5,13 +5,7 @@ import '../../utils.dart';
 class RemoteAssetFactory {
   const RemoteAssetFactory();
 
-  static RemoteAsset create({
-    String? id,
-    String? name,
-    String? ownerId,
-    bool isFavorite = false,
-    AssetType type = .image,
-  }) {
+  static RemoteAsset create({String? id, String? name, String? ownerId, bool isFavorite = false}) {
     id = TestUtils.uuid(id);
 
     return RemoteAsset(
@@ -19,7 +13,7 @@ class RemoteAssetFactory {
       name: name ?? 'remote_$id.jpg',
       ownerId: TestUtils.uuid(ownerId),
       checksum: 'checksum-$id',
-      type: type,
+      type: .image,
       createdAt: TestUtils.yesterday(),
       updatedAt: TestUtils.now(),
       isFavorite: isFavorite,

mobile/test/unit/mocks.dart

@@ -1,12 +1,7 @@
 import 'dart:typed_data';
 
 import 'package:immich_mobile/constants/enums.dart';
-import 'package:immich_mobile/domain/models/album/local_album.model.dart';
-import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
-import 'package:immich_mobile/domain/models/asset_edit.model.dart';
-import 'package:immich_mobile/domain/models/exif.model.dart';
 import 'package:immich_mobile/domain/models/user.model.dart';
-import 'package:immich_mobile/platform/native_sync_api.g.dart';
 import 'package:mocktail/mocktail.dart' as mock;
 import 'package:mocktail/mocktail.dart';
 
@@ -17,12 +12,11 @@ import 'factories/local_asset_factory.dart';
 import 'factories/user_factory.dart';
 
 class RepositoryMocks {
-  final localAlbum = LocalAlbumRepositoryStub(MockLocalAlbumRepository());
-  final localAsset = LocalAssetRepositoryStub(MockDriftLocalAssetRepository());
+  final localAlbum = MockLocalAlbumRepository();
+  final localAsset = MockDriftLocalAssetRepository();
   final trashedAsset = MockTrashedLocalAssetRepository();
-  final remoteAsset = RemoteAssetRepositoryStub(MockRemoteAssetRepository());
 
-  final nativeApi = NativeSyncApiStub(MockNativeSyncApi());
+  final nativeApi = MockNativeSyncApi();
 
   RepositoryMocks() {
     resetAll();
@@ -30,41 +24,17 @@ class RepositoryMocks {
 
   void resetAll() {
     _registerFallbacks();
-    localAlbum.reset();
-    localAsset.reset();
+    reset(localAlbum);
+    reset(localAsset);
     reset(trashedAsset);
-    remoteAsset.reset();
-    nativeApi.reset();
-    _stubLocalAlbumRepository();
-    _stubLocalAssetRepository();
-    _stubNativeSyncApi();
-    _stubRemoteAssetRepository();
-  }
-
-  void _stubLocalAlbumRepository() {
-    when(localAlbum.getBackupAlbums).thenAnswer((_) async => []);
-    when(localAlbum.getAssetsToHash).thenAnswer((_) async => []);
-  }
-
-  void _stubLocalAssetRepository() {
-    when(localAsset.reconcileHashesFromCloudId).thenAnswer((_) async => {});
-    when(localAsset.updateHashes).thenAnswer((_) async => {});
-  }
-
-  void _stubNativeSyncApi() {
-    when(nativeApi.hashAssets).thenAnswer((_) async => []);
-  }
-
-  void _stubRemoteAssetRepository() {
-    when(remoteAsset.getAssetEdits).thenAnswer((_) async => []);
-    when(remoteAsset.getExif).thenAnswer((_) async => null);
+    reset(nativeApi);
   }
 }
 
 class ServiceMocks {
-  final partner = PartnerServiceStub(MockPartnerService());
-  final user = UserServiceStub(MockUserService());
-  final asset = AssetServiceStub(MockAssetService());
+  final PartnerStub partner = PartnerStub(MockPartnerService());
+  final UserStub user = UserStub(MockUserService());
+  final asset = AssetStub(MockAssetService());
 
   ServiceMocks() {
     resetAll();
@@ -99,7 +69,6 @@ class ServiceMocks {
 
   void _stubAssetService() {
     when(asset.updateFavorite).thenAnswer((_) async {});
-    when(asset.applyEdits).thenAnswer((_) async {});
   }
 }
 
@@ -107,40 +76,13 @@ void _registerFallbacks() {
   registerFallbackValue(LocalAlbumFactory.create());
   registerFallbackValue(LocalAssetFactory.create());
   registerFallbackValue(Uint8List(0));
-  registerFallbackValue(<AssetEdit>[]);
 }
 
-extension type const Stub<T extends Mock>(T mockedClass) {
-  void reset() => mock.reset(mockedClass);
+extension type const Stub<T extends Mock>(T mockedService) {
+  void reset() => mock.reset(mockedService);
 }
 
-extension type const LocalAlbumRepositoryStub(MockLocalAlbumRepository repo) implements Stub<MockLocalAlbumRepository> {
-  Future<List<LocalAlbum>> Function() get getBackupAlbums =>
-      () => repo.getBackupAlbums();
-
-  Future<List<LocalAsset>> Function() get getAssetsToHash =>
-      () => repo.getAssetsToHash(any());
-}
-
-extension type const LocalAssetRepositoryStub(MockDriftLocalAssetRepository repo)
-    implements Stub<MockDriftLocalAssetRepository> {
-  Future<void> Function() get reconcileHashesFromCloudId =>
-      () => repo.reconcileHashesFromCloudId();
-
-  Future<void> Function() get updateHashes =>
-      () => repo.updateHashes(any());
-}
-
-extension type const RemoteAssetRepositoryStub(MockRemoteAssetRepository repo)
-    implements Stub<MockRemoteAssetRepository> {
-  Future<List<AssetEdit>> Function() get getAssetEdits =>
-      () => repo.getAssetEdits(any());
-
-  Future<ExifInfo?> Function() get getExif =>
-      () => repo.getExif(any());
-}
-
-extension type const PartnerServiceStub(MockPartnerService service) implements Stub<MockPartnerService> {
+extension type const PartnerStub(MockPartnerService service) implements Stub<MockPartnerService> {
   Stream<Iterable<User>> Function() get getCandidates =>
       () => service.getCandidates(any());
 
@@ -168,7 +110,7 @@ extension type const PartnerServiceStub(MockPartnerService service) implements S
       );
 }
 
-extension type const UserServiceStub(MockUserService service) implements Stub<MockUserService> {
+extension type const UserStub(MockUserService service) implements Stub<MockUserService> {
   UserDto Function() get getMyUser =>
       () => service.getMyUser();
 
@@ -185,15 +127,7 @@ extension type const UserServiceStub(MockUserService service) implements Stub<Mo
       () => service.createProfileImage(any(), any());
 }
 
-extension type const AssetServiceStub(MockAssetService service) implements Stub<MockAssetService> {
+extension type const AssetStub(MockAssetService service) implements Stub<MockAssetService> {
   Future<void> Function() get updateFavorite =>
       () => service.updateFavorite(any(), any());
-
-  Future<void> Function() get applyEdits =>
-      () => service.applyEdits(any(), any());
-}
-
-extension type const NativeSyncApiStub(MockNativeSyncApi api) implements Stub<MockNativeSyncApi> {
-  Future<List<HashResult>> Function() get hashAssets =>
-      () => api.hashAssets(any(), allowNetworkAccess: any(named: 'allowNetworkAccess'));
 }

mobile/test/unit/presentation/actions/asset_debug_action_test.dart

@@ -6,7 +6,7 @@ import 'package:immich_mobile/presentation/actions/asset_debug.action.dart';
 import 'package:immich_ui/immich_ui.dart';
 
 import '../../factories/remote_asset_factory.dart';
-import '../presentation_context.dart';
+import '../../presentation_context.dart';
 
 void main() {
   late PresentationContext context;
@@ -23,8 +23,8 @@ void main() {
   group('AssetDebugAction', () {
     testWidgets('visible for a single asset when advanced troubleshooting is on', (tester) async {
       await tester.pumpTestWidget(
-        context,
         ActionIconButtonWidget(action: AssetDebugAction(assets: [RemoteAssetFactory.create()])),
+        overrides: context.overrides,
       );
 
       expect(find.byType(ImmichIconButton), findsOneWidget);
@@ -32,10 +32,10 @@ void main() {
 
     testWidgets('hidden for multiple assets', (tester) async {
       await tester.pumpTestWidget(
-        context,
         ActionIconButtonWidget(
           action: AssetDebugAction(assets: [RemoteAssetFactory.create(), RemoteAssetFactory.create()]),
         ),
+        overrides: context.overrides,
       );
 
       expect(find.byType(ImmichIconButton), findsNothing);
@@ -44,8 +44,8 @@ void main() {
     testWidgets('hidden when advanced troubleshooting is off', (tester) async {
       await StoreService.I.put(StoreKey.advancedTroubleshooting, false);
       await tester.pumpTestWidget(
-        context,
         ActionIconButtonWidget(action: AssetDebugAction(assets: [RemoteAssetFactory.create()])),
+        overrides: context.overrides,
       );
 
       expect(find.byType(ImmichIconButton), findsNothing);

mobile/test/unit/presentation/actions/edit_action_test.dart

@@ -1,112 +0,0 @@
-import 'package:flutter/material.dart';
-import 'package:flutter_test/flutter_test.dart';
-import 'package:hooks_riverpod/hooks_riverpod.dart';
-import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
-import 'package:immich_mobile/domain/models/asset_edit.model.dart';
-import 'package:immich_mobile/models/server_info/server_version.model.dart';
-import 'package:immich_mobile/presentation/actions/action.widget.dart';
-import 'package:immich_mobile/presentation/actions/edit.action.dart';
-import 'package:immich_mobile/providers/server_info.provider.dart';
-import 'package:immich_mobile/providers/websocket.provider.dart';
-import 'package:immich_ui/immich_ui.dart';
-import 'package:mocktail/mocktail.dart';
-
-import '../../../domain/service.mock.dart';
-import '../../../infrastructure/repository.mock.dart';
-import '../../factories/remote_asset_factory.dart';
-import '../../riverpod_mocks.dart';
-import '../presentation_context.dart';
-
-void main() {
-  late PresentationContext context;
-  late MockRemoteAssetRepository remoteAssetRepo;
-  late MockAssetService assetService;
-
-  const supportedVersion = ServerVersion(major: 2, minor: 6, patch: 0);
-  const unsupportedVersion = ServerVersion(major: 2, minor: 5, patch: 9);
-
-  setUp(() async {
-    context = await PresentationContext.create();
-    remoteAssetRepo = context.repository.remoteAsset.repo;
-    assetService = context.service.asset.service;
-  });
-
-  tearDown(() {
-    context.dispose();
-  });
-
-  List<Override> overrides(ServerVersion version) => [
-    serverInfoProvider.overrideWith((ref) => FakeServerInfoNotifier(version)),
-  ];
-
-  RemoteAsset owned({AssetType type = AssetType.image}) =>
-      RemoteAssetFactory.create(ownerId: context.currentUser.id, type: type);
-
-  Future<void> pumpAction(WidgetTester tester, EditAssetAction action, {ServerVersion version = supportedVersion}) =>
-      tester.pumpTestWidget(context, ActionIconButtonWidget(action: action), overrides: overrides(version));
-
-  group('EditAssetAction', () {
-    testWidgets('visible for a single owned editable asset on a supported server', (tester) async {
-      await pumpAction(tester, EditAssetAction(assets: [owned()]));
-
-      expect(find.byType(ImmichIconButton), findsOneWidget);
-    });
-
-    testWidgets('hidden when the server is older than 2.6.0', (tester) async {
-      await pumpAction(tester, EditAssetAction(assets: [owned()]), version: unsupportedVersion);
-
-      expect(find.byType(ImmichIconButton), findsNothing);
-    });
-
-    testWidgets('hidden for more than one asset', (tester) async {
-      await pumpAction(tester, EditAssetAction(assets: [owned(), owned()]));
-
-      expect(find.byType(ImmichIconButton), findsNothing);
-    });
-
-    testWidgets('hidden for an asset owned by someone else', (tester) async {
-      await pumpAction(tester, EditAssetAction(assets: [RemoteAssetFactory.create()]));
-
-      expect(find.byType(ImmichIconButton), findsNothing);
-    });
-
-    testWidgets('hidden for a non-editable asset', (tester) async {
-      await pumpAction(tester, EditAssetAction(assets: [owned(type: AssetType.video)]));
-
-      expect(find.byType(ImmichIconButton), findsNothing);
-    });
-  });
-
-  group('EditAssetAction onAction', () {
-    testWidgets('reads the edits and exif for the asset from the repository', (tester) async {
-      final asset = owned();
-      await tester.pumpTestAction(context, EditAssetAction(assets: [asset]), overrides: overrides(supportedVersion));
-      await tester.pumpAndSettle();
-
-      verify(() => remoteAssetRepo.getAssetEdits(asset.id)).called(1);
-      verify(() => remoteAssetRepo.getExif(asset.id)).called(1);
-    });
-
-    testWidgets('applyEdits forwards the edits to the service and waits for both ready events', (tester) async {
-      late FakeWebsocketNotifier websocket;
-      const edits = <AssetEdit>[];
-
-      late WidgetRef capturedRef;
-      await tester.pumpTestWidget(
-        context,
-        Consumer(
-          builder: (_, ref, _) {
-            capturedRef = ref;
-            return const SizedBox.shrink();
-          },
-        ),
-        overrides: [websocketProvider.overrideWith((ref) => websocket = FakeWebsocketNotifier(ref))],
-      );
-
-      await applyEdits(capturedRef, 'asset-1', edits);
-
-      verify(() => assetService.applyEdits('asset-1', edits)).called(1);
-      expect(websocket.waitedEvents, containsAll(['AssetEditReadyV1', 'AssetEditReadyV2']));
-    });
-  });
-}

mobile/test/unit/presentation/actions/favorite_action_test.dart

@@ -1,26 +1,30 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
 import 'package:immich_mobile/presentation/actions/favorite.action.dart';
+import 'package:immich_mobile/providers/infrastructure/asset.provider.dart';
 import 'package:mocktail/mocktail.dart';
 
-import '../../../domain/service.mock.dart';
 import '../../factories/remote_asset_factory.dart';
-import '../presentation_context.dart';
+import '../../presentation_context.dart';
 
 void main() {
   late PresentationContext context;
-  late MockAssetService assetService;
 
   setUp(() async {
     context = await PresentationContext.create();
-    assetService = context.service.asset.service;
   });
 
   tearDown(() {
     context.dispose();
   });
 
+  List<Override> overrides() => [
+    ...context.overrides,
+    assetServiceProvider.overrideWithValue(context.mocks.asset.service),
+  ];
+
   RemoteAsset owned({bool isFavorite = false}) =>
       RemoteAssetFactory.create(ownerId: context.currentUser.id, isFavorite: isFavorite);
 
@@ -28,48 +32,48 @@ void main() {
     testWidgets('favorites the eligible owned assets', (tester) async {
       final asset = owned();
 
-      await tester.pumpTestAction(context, FavoriteAction(assets: [asset]));
+      await tester.pumpTestAction(FavoriteAction(assets: [asset]), overrides: overrides());
 
-      verify(() => assetService.updateFavorite([asset.id], true)).called(1);
+      verify(() => context.mocks.asset.service.updateFavorite([asset.id], true)).called(1);
     });
 
     testWidgets('unfavorite the eligible owned assets', (tester) async {
       final asset = owned(isFavorite: true);
 
-      await tester.pumpTestAction(context, FavoriteAction(assets: [asset]));
+      await tester.pumpTestAction(FavoriteAction(assets: [asset]), overrides: overrides());
 
-      verify(() => assetService.updateFavorite([asset.id], false)).called(1);
+      verify(() => context.mocks.asset.service.updateFavorite([asset.id], false)).called(1);
     });
 
     testWidgets('ignores assets owned by someone else', (tester) async {
       final mine = owned();
       final theirs = RemoteAssetFactory.create();
 
-      await tester.pumpTestAction(context, FavoriteAction(assets: [mine, theirs]));
+      await tester.pumpTestAction(FavoriteAction(assets: [mine, theirs]), overrides: overrides());
 
-      verify(() => assetService.updateFavorite([mine.id], true)).called(1);
+      verify(() => context.mocks.asset.service.updateFavorite([mine.id], true)).called(1);
     });
 
     testWidgets('batches every eligible owned asset into a single call', (tester) async {
       final first = owned();
       final second = owned();
 
-      await tester.pumpTestAction(context, FavoriteAction(assets: [first, second]));
+      await tester.pumpTestAction(FavoriteAction(assets: [first, second]), overrides: overrides());
 
-      verify(() => assetService.updateFavorite([first.id, second.id], true)).called(1);
+      verify(() => context.mocks.asset.service.updateFavorite([first.id, second.id], true)).called(1);
     });
 
     testWidgets('skips owned assets already in the target state', (tester) async {
       final stale = owned();
       final alreadyFavorite = owned(isFavorite: true);
 
-      await tester.pumpTestAction(context, FavoriteAction(assets: [stale, alreadyFavorite]));
+      await tester.pumpTestAction(FavoriteAction(assets: [stale, alreadyFavorite]), overrides: overrides());
 
-      verify(() => assetService.updateFavorite([stale.id], true)).called(1);
+      verify(() => context.mocks.asset.service.updateFavorite([stale.id], true)).called(1);
     });
 
     testWidgets('shows a confirmation snackbar on success', (tester) async {
-      await tester.pumpTestAction(context, FavoriteAction(assets: [owned()]));
+      await tester.pumpTestAction(FavoriteAction(assets: [owned()]), overrides: overrides());
       await tester.pumpUntilFound(find.byType(SnackBar));
 
       expect(find.byType(SnackBar), findsOneWidget);

mobile/test/unit/presentation/actions/partner_action_test.dart

@@ -4,19 +4,17 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/models/user.model.dart';
 import 'package:immich_mobile/presentation/actions/partner.action.dart';
+import 'package:immich_mobile/providers/infrastructure/user.provider.dart';
 import 'package:mocktail/mocktail.dart';
 
-import '../../../domain/service.mock.dart';
 import '../../factories/user_factory.dart';
-import '../presentation_context.dart';
+import '../../presentation_context.dart';
 
 void main() {
   late PresentationContext context;
-  late MockPartnerService partnerService;
 
   setUp(() async {
     context = await PresentationContext.create();
-    partnerService = context.service.partner.service;
   });
 
   tearDown(() {
@@ -24,6 +22,8 @@ void main() {
   });
 
   List<Override> overrides({List<User> candidates = const []}) => [
+    ...context.overrides,
+    partnerServiceProvider.overrideWithValue(context.mocks.partner.service),
     candidatesStateProvider.overrideWith((ref) => Stream<Iterable<User>>.value(candidates)),
   ];
 
@@ -31,24 +31,22 @@ void main() {
     testWidgets('creates a partner for the selected candidate', (tester) async {
       final candidate = UserFactory.create();
 
-      await tester.pumpTestAction(context, const PartnerAddAction(), overrides: overrides(candidates: [candidate]));
+      await tester.pumpTestAction(const PartnerAddAction(), overrides: overrides(candidates: [candidate]));
       await tester.pumpUntilFound(find.text(candidate.name));
       await tester.tap(find.text(candidate.name));
       await tester.pumpAndSettle();
 
-      verify(() => partnerService.create(sharedById: context.currentUser.id, sharedWithId: candidate.id)).called(1);
+      verify(
+        () => context.mocks.partner.service.create(sharedById: context.currentUser.id, sharedWithId: candidate.id),
+      ).called(1);
     });
 
     testWidgets('creates nothing when the selection dialog is dismissed', (tester) async {
-      await tester.pumpTestAction(
-        context,
-        const PartnerAddAction(),
-        overrides: overrides(candidates: [UserFactory.create()]),
-      );
+      await tester.pumpTestAction(const PartnerAddAction(), overrides: overrides(candidates: [UserFactory.create()]));
       await tester.sendKeyEvent(LogicalKeyboardKey.escape); // dismiss without selecting
       await tester.pumpAndSettle();
 
-      verifyNever(context.service.partner.create);
+      verifyNever(context.mocks.partner.create);
     });
   });
 
@@ -56,27 +54,27 @@ void main() {
     testWidgets('deletes the partner after confirmation', (tester) async {
       final partner = UserFactory.create();
       await tester.pumpTestAction(
-        context,
         PartnerRemoveAction(sharedWithId: partner.id, partnerName: partner.name),
         overrides: overrides(),
       );
       await tester.tap(find.byType(TextButton).last); // confirm
       await tester.pumpAndSettle();
 
-      verify(() => partnerService.delete(sharedById: context.currentUser.id, sharedWithId: partner.id)).called(1);
+      verify(
+        () => context.mocks.partner.service.delete(sharedById: context.currentUser.id, sharedWithId: partner.id),
+      ).called(1);
     });
 
     testWidgets('deletes nothing when the confirmation is cancelled', (tester) async {
       final partner = UserFactory.create();
       await tester.pumpTestAction(
-        context,
         PartnerRemoveAction(sharedWithId: partner.id, partnerName: partner.name),
         overrides: overrides(),
       );
       await tester.tap(find.byType(TextButton).first); // cancel
       await tester.pumpAndSettle();
 
-      verifyNever(context.service.partner.delete);
+      verifyNever(context.mocks.partner.delete);
     });
   });
 }

mobile/test/unit/presentation/actions/timeline_action_test.dart

@@ -7,7 +7,7 @@ import 'package:immich_mobile/presentation/actions/timeline.action.dart';
 import 'package:immich_mobile/providers/timeline/multiselect.provider.dart';
 
 import '../../factories/remote_asset_factory.dart';
-import '../presentation_context.dart';
+import '../../presentation_context.dart';
 
 class _FakeAction extends BaseAction {
   _FakeAction({this.visible = true, this.error});
@@ -48,7 +48,8 @@ void main() {
     context.dispose();
   });
 
-  List<Override> overrides() => [
+  List<Override> seededOverrides() => [
+    ...context.overrides,
     multiSelectProvider.overrideWith(
       () => MultiSelectNotifier(
         MultiSelectState(selectedAssets: {RemoteAssetFactory.create()}, lockedSelectionAssets: const {}),
@@ -60,7 +61,6 @@ void main() {
     late ActionScope scope;
     late ProviderContainer container;
     await tester.pumpTestWidget(
-      context,
       Consumer(
         builder: (innerContext, ref, _) {
           scope = ActionScope(context: innerContext, ref: ref, authUser: context.currentUser);
@@ -68,7 +68,7 @@ void main() {
           return const SizedBox.shrink();
         },
       ),
-      overrides: overrides(),
+      overrides: seededOverrides(),
     );
     return (scope, container);
   }
@@ -97,8 +97,8 @@ void main() {
 
     testWidgets('delegates visibility to the wrapped action', (tester) async {
       await tester.pumpTestWidget(
-        context,
         ActionIconButtonWidget(action: TimelineAction(action: _FakeAction(visible: false))),
+        overrides: context.overrides,
       );
 
       expect(find.byType(ActionIconButtonWidget), findsOneWidget);

mobile/test/unit/presentation/partner_page_test.dart

@@ -7,7 +7,7 @@ import 'package:immich_mobile/presentation/actions/partner.action.dart';
 
 import '../factories/partner_user_factory.dart';
 import '../factories/user_factory.dart';
-import 'presentation_context.dart';
+import '../presentation_context.dart';
 
 void main() {
   late PresentationContext context;
@@ -19,7 +19,7 @@ void main() {
     testWidgets('shows the empty-state add button when there are no partners', (tester) async {
       final action = const PartnerAddAction();
 
-      await tester.pumpTestWidget(context, const PartnerSharedByList(partners: []));
+      await tester.pumpTestWidget(const PartnerSharedByList(partners: []), overrides: context.overrides);
 
       expect(find.byType(ListView), findsNothing);
       expect(find.widgetWithIcon(TextButton, action.icon), findsOneWidget);
@@ -28,7 +28,8 @@ void main() {
     testWidgets('renders a tile per partner with name and email', (tester) async {
       final partner1 = PartnerFactory.create();
       final partner2 = PartnerFactory.create();
-      await tester.pumpTestWidget(context, PartnerSharedByList(partners: [partner1, partner2]));
+      await tester.pumpTestWidget(PartnerSharedByList(partners: [partner1, partner2]), overrides: context.overrides);
+
       expect(find.byType(ListTile), findsNWidgets(2));
       expect(find.text(partner1.name), findsOneWidget);
       expect(find.text(partner1.email), findsOneWidget);
@@ -40,7 +41,7 @@ void main() {
       final partner1 = PartnerFactory.create(inTimeline: true);
       final partner2 = PartnerFactory.create();
       final action = const PartnerRemoveAction(sharedWithId: '', partnerName: '');
-      await tester.pumpTestWidget(context, PartnerSharedByList(partners: [partner1, partner2]));
+      await tester.pumpTestWidget(PartnerSharedByList(partners: [partner1, partner2]), overrides: context.overrides);
       expect(find.byIcon(action.icon), findsNWidgets(2));
     });
   });
@@ -61,12 +62,13 @@ void main() {
     }
 
     List<Override> withCandidates(List<User> candidates) => [
+      ...context.overrides,
       candidatesStateProvider.overrideWith((ref) => Stream<Iterable<User>>.value(candidates)),
     ];
 
     testWidgets('renders an option per candidate fetched from the provider', (tester) async {
       final user = UserFactory.create();
-      await tester.pumpTestWidget(context, dialogWidget(), overrides: withCandidates([user]));
+      await tester.pumpTestWidget(dialogWidget(), overrides: withCandidates([user]));
 
       await tester.tap(find.byKey(dialogButtonKey));
       await tester.pumpAndSettle();
@@ -76,7 +78,7 @@ void main() {
     });
 
     testWidgets('shows no options when the provider returns no candidates', (tester) async {
-      await tester.pumpTestWidget(context, dialogWidget(), overrides: withCandidates(const []));
+      await tester.pumpTestWidget(dialogWidget(), overrides: withCandidates(const []));
 
       await tester.tap(find.byKey(dialogButtonKey));
       await tester.pumpAndSettle();
@@ -87,11 +89,7 @@ void main() {
     testWidgets('pops the selected candidate when an option is tapped', (tester) async {
       final user = UserFactory.create();
       User? selected;
-      await tester.pumpTestWidget(
-        context,
-        dialogWidget(onClosed: (user) => selected = user),
-        overrides: withCandidates([user]),
-      );
+      await tester.pumpTestWidget(dialogWidget(onClosed: (user) => selected = user), overrides: withCandidates([user]));
 
       await tester.tap(find.byKey(dialogButtonKey));
       await tester.pumpAndSettle();

mobile/test/unit/presentation/widgets/timeline/asset_index_at_offset_test.dart

@@ -0,0 +1,60 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:immich_mobile/domain/models/timeline.model.dart';
+import 'package:immich_mobile/presentation/widgets/timeline/fixed/segment.model.dart';
+import 'package:immich_mobile/presentation/widgets/timeline/segment.model.dart';
+import 'package:immich_mobile/presentation/widgets/timeline/timeline.widget.dart';
+
+void main() {
+  // Two day-segments, 4 columns, 8 assets each (2 rows). header 50, tile 100, no spacing.
+  //   A: header@[0,50)  rows@50,150   assets 0..7    offset [0,250]
+  //   B: header@[250,300) rows@300,400 assets 8..15  offset [250,500]
+  const columnCount = 4;
+  const maxScrollExtent = 500.0;
+  final segments = <Segment>[
+    const FixedSegment(
+      firstIndex: 0,
+      lastIndex: 2,
+      startOffset: 0,
+      endOffset: 250,
+      firstAssetIndex: 0,
+      bucket: Bucket(assetCount: 8),
+      tileHeight: 100,
+      columnCount: columnCount,
+      headerExtent: 50,
+      spacing: 0,
+      header: HeaderType.day,
+    ),
+    const FixedSegment(
+      firstIndex: 3,
+      lastIndex: 5,
+      startOffset: 250,
+      endOffset: 500,
+      firstAssetIndex: 8,
+      bucket: Bucket(assetCount: 8),
+      tileHeight: 100,
+      columnCount: columnCount,
+      headerExtent: 50,
+      spacing: 0,
+      header: HeaderType.day,
+    ),
+  ];
+
+  int? at(double offset) =>
+      assetIndexAtOffset(segments, offset, columnCount: columnCount, maxScrollExtent: maxScrollExtent);
+
+  test('maps an offset to the first asset of the row shown there', () {
+    expect(at(0), 0); // top of segment A
+    expect(at(150), 4); // second row of A
+    expect(at(350), 8); // first row of B
+    expect(at(450), 12); // second row of B
+  });
+
+  test('clamps offsets outside the scroll range', () {
+    expect(at(-100), 0); // below the top -> first asset
+    expect(at(9999), at(maxScrollExtent)); // past the end -> same as the max offset
+  });
+
+  test('returns null for empty segments', () {
+    expect(assetIndexAtOffset(const [], 100, columnCount: columnCount, maxScrollExtent: maxScrollExtent), isNull);
+  });
+}

mobile/test/unit/presentation/widgets/timeline/drag_selection_controller_test.dart

@@ -0,0 +1,157 @@
+import 'dart:async';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+import 'package:immich_mobile/presentation/widgets/timeline/drag_selection_controller.dart';
+
+import '../../../factories/remote_asset_factory.dart';
+
+void main() {
+  const total = 50;
+  late List<BaseAsset> all;
+  late Set<int> inBuffer; // indices getAssetSafe resolves synchronously
+  late List<Completer<List<BaseAsset>>> reads; // pending async reads, completed manually
+  late List<({int from, int count})> readArgs;
+  late Set<BaseAsset> selected;
+  late DragSelectionController sut;
+
+  Set<BaseAsset> range(int lo, int hi) => {for (var i = lo; i <= hi; i++) all[i]};
+
+  void completeRead(int i) {
+    final a = readArgs[i];
+    reads[i].complete([for (var k = a.from; k < a.from + a.count && k < total; k++) all[k]]);
+  }
+
+  Future<void> settle() => Future(() {});
+
+  setUp(() {
+    all = List.generate(total, (i) => RemoteAssetFactory.create(id: 'a${i.toString().padLeft(3, '0')}'));
+    inBuffer = {for (var i = 0; i < total; i++) i}; // default: everything buffered (sync)
+    reads = [];
+    readArgs = [];
+    selected = {};
+    sut = DragSelectionController(
+      getAssetSafe: (i) => inBuffer.contains(i) ? all[i] : null,
+      getAssetsRange: (from, count) {
+        final c = Completer<List<BaseAsset>>();
+        reads.add(c);
+        readArgs.add((from: from, count: count));
+        return c.future;
+      },
+      onChange: (select, deselect) {
+        selected
+          ..addAll(select)
+          ..removeAll(deselect);
+      },
+    );
+  });
+
+  group('live selection (all in buffer, synchronous)', () {
+    test('dragging down selects the whole range as it grows', () {
+      sut.start(2);
+      sut.enter(6);
+      sut.enter(12);
+      expect(selected, range(2, 12));
+      expect(reads, isEmpty, reason: 'everything buffered -> no async read');
+    });
+
+    test('dragging back up toward the anchor deselects the shrunk tail', () {
+      sut.start(2);
+      sut.enter(12);
+      expect(selected, range(2, 12));
+      sut.enter(6); // reverse
+      expect(selected, range(2, 6));
+      sut.enter(3); // reverse more
+      expect(selected, range(2, 3));
+    });
+
+    test('dragging past the anchor flips the range', () {
+      sut.start(10);
+      sut.enter(14);
+      expect(selected, range(10, 14));
+      sut.enter(7); // crosses the anchor
+      expect(selected, range(7, 10));
+    });
+  });
+
+  group('beyond-buffer (async)', () {
+    setUp(() => inBuffer = {}); // nothing buffered -> every tile needs an async read
+
+    test('drag-end fills the full range even if every live read is still in flight', () async {
+      sut.start(0);
+      sut.enter(20);
+      // simulate the real-rate race: none of the in-drag reads have completed
+      expect(selected, isEmpty);
+
+      final ending = sut.end();
+      // end() issues its own read for the missing range; complete it
+      completeRead(reads.length - 1);
+      await ending;
+
+      expect(selected, range(0, 20), reason: 'final range must always apply on drag-end');
+    });
+
+    test('out-of-order live read completions never corrupt the selection', () async {
+      sut.start(0); // issues read for [0,1]
+      sut.enter(10); // issues read for [0,11]
+      sut.enter(20); // issues read for [0,21]
+      expect(reads.length, 3);
+
+      // complete newest first, then older ones (out of order)
+      completeRead(2);
+      await settle();
+      completeRead(1);
+      await settle();
+      completeRead(0);
+      await settle();
+
+      expect(selected, range(0, 20));
+
+      final ending = sut.end();
+      await ending; // nothing missing -> no extra read
+      expect(selected, range(0, 20));
+    });
+
+    test('a disposed controller never emits when its in-flight read resolves', () async {
+      sut.start(0); // read [0,1] (pending, in flight)
+      sut.enter(20); // read [0,21] (pending, in flight)
+      expect(selected, isEmpty);
+
+      // a new drag starts -> the old controller is disposed
+      final ending = sut.end(); // issues end()'s fill read
+      sut.dispose();
+
+      // every in-flight read for the old controller now resolves
+      for (var i = 0; i < reads.length; i++) {
+        if (!reads[i].isCompleted) {
+          completeRead(i);
+        }
+      }
+      await ending;
+      await settle();
+
+      expect(selected, isEmpty, reason: 'a disposed controller must not leak into the new selection');
+    });
+
+    test('a late read for tiles dragged back out of range is ignored', () async {
+      sut.start(0); // read [0,1]
+      sut.enter(20); // read [0,21]
+      sut.enter(5); // shrink back; read [0,6]
+      // complete the stale wide read AFTER the shrink
+      completeRead(1); // [0,21]
+      await settle();
+      // indices 6..20 left the range -> must not be selected
+      expect(selected.intersection(range(6, 20)), isEmpty);
+
+      final ending = sut.end();
+      // complete any read end() issued for the (now smaller) missing range
+      for (var i = 0; i < reads.length; i++) {
+        if (!reads[i].isCompleted) {
+          completeRead(i);
+        }
+      }
+      await ending;
+      expect(selected, range(0, 5));
+    });
+  });
+}

mobile/test/unit/presentation_context.dart

@@ -13,21 +13,16 @@ import 'package:immich_mobile/infrastructure/repositories/db.repository.dart';
 import 'package:immich_mobile/infrastructure/repositories/store.repository.dart';
 import 'package:immich_mobile/presentation/actions/action.dart';
 import 'package:immich_mobile/presentation/actions/action.widget.dart';
-import 'package:immich_mobile/providers/infrastructure/asset.provider.dart';
-import 'package:immich_mobile/providers/infrastructure/user.provider.dart';
 import 'package:immich_mobile/providers/user.provider.dart';
 import 'package:immich_ui/immich_ui.dart';
 import 'package:mocktail/mocktail.dart';
 
-import '../../test_utils.dart';
-import '../factories/user_factory.dart';
-import '../mocks.dart';
+import '../test_utils.dart';
+import 'factories/user_factory.dart';
+import 'mocks.dart';
 
 class PresentationContext {
-  PresentationContext._({required UserDto user})
-    : currentUser = user,
-      service = ServiceMocks(),
-      repository = RepositoryMocks() {
+  PresentationContext._({required UserDto user}) : currentUser = user, mocks = ServiceMocks() {
     setup();
   }
 
@@ -36,15 +31,9 @@ class PresentationContext {
   static Drift? _db;
 
   final UserDto currentUser;
-  final ServiceMocks service;
-  final RepositoryMocks repository;
+  final ServiceMocks mocks;
 
-  List<Override> get overrides => [
-    currentUserProvider.overrideWith((ref) => CurrentUserProvider(service.user.service)),
-    assetServiceProvider.overrideWithValue(service.asset.service),
-    partnerServiceProvider.overrideWithValue(service.partner.service),
-    remoteAssetRepositoryProvider.overrideWithValue(repository.remoteAsset.repo),
-  ];
+  List<Override> get overrides => [currentUserProvider.overrideWith((ref) => CurrentUserProvider(mocks.user.service))];
 
   static Future<PresentationContext> create() async {
     TestUtils.init();
@@ -58,18 +47,18 @@ class PresentationContext {
   }
 
   void setup() {
-    when(service.user.tryGetMyUser).thenReturn(currentUser);
+    when(mocks.user.tryGetMyUser).thenReturn(currentUser);
   }
 
   void dispose() {
     addTearDown(() {
-      service.resetAll();
+      mocks.resetAll();
     });
   }
 }
 
 extension PumpPresentationWidget on WidgetTester {
-  Future<void> pumpTestWidget(PresentationContext context, Widget widget, {List<Override> overrides = const []}) async {
+  Future<void> pumpTestWidget(Widget widget, {List<Override> overrides = const []}) async {
     await pumpWidget(
       EasyLocalization(
         supportedLocales: locales.values.toList(),
@@ -80,7 +69,7 @@ extension PumpPresentationWidget on WidgetTester {
         useFallbackTranslations: true,
         assetLoader: const CodegenLoader(),
         child: ProviderScope(
-          overrides: [...context.overrides, ...overrides],
+          overrides: overrides,
           child: Builder(
             builder: (context) => MaterialApp(
               debugShowCheckedModeBanner: false,
@@ -97,12 +86,8 @@ extension PumpPresentationWidget on WidgetTester {
     await pumpAndSettle();
   }
 
-  Future<void> pumpTestAction(
-    PresentationContext context,
-    BaseAction action, {
-    List<Override> overrides = const [],
-  }) async {
-    await pumpTestWidget(context, ActionIconButtonWidget(action: action), overrides: overrides);
+  Future<void> pumpTestAction(BaseAction action, {List<Override> overrides = const []}) async {
+    await pumpTestWidget(ActionIconButtonWidget(action: action), overrides: overrides);
     await tap(find.byType(ImmichIconButton));
     await pump();
   }

mobile/test/unit/riverpod_mocks.dart

@@ -1,24 +0,0 @@
-import 'package:immich_mobile/models/server_info/server_version.model.dart';
-import 'package:immich_mobile/providers/server_info.provider.dart';
-import 'package:immich_mobile/providers/websocket.provider.dart';
-
-import '../domain/service.mock.dart';
-
-class FakeServerInfoNotifier extends ServerInfoNotifier {
-  FakeServerInfoNotifier([ServerVersion version = const ServerVersion(major: 2, minor: 6, patch: 0)])
-    : super(MockServerInfoService()) {
-    state = state.copyWith(serverVersion: version);
-  }
-}
-
-class FakeWebsocketNotifier extends WebsocketNotifier {
-  FakeWebsocketNotifier(super.ref);
-
-  final List<String> waitedEvents = [];
-
-  @override
-  Future<void> waitForEvent(String event, bool Function(dynamic)? predicate, Duration timeout) {
-    waitedEvents.add(event);
-    return Future.value();
-  }
-}

mobile/test/unit/services/hash_service_test.dart

@@ -14,11 +14,14 @@ void main() {
 
   setUp(() {
     sut = HashService(
-      localAlbumRepository: mocks.localAlbum.repo,
-      localAssetRepository: mocks.localAsset.repo,
-      nativeSyncApi: mocks.nativeApi.api,
+      localAlbumRepository: mocks.localAlbum,
+      localAssetRepository: mocks.localAsset,
+      nativeSyncApi: mocks.nativeApi,
       trashedLocalAssetRepository: mocks.trashedAsset,
     );
+
+    when(() => mocks.localAsset.reconcileHashesFromCloudId()).thenAnswer((_) async => {});
+    when(() => mocks.localAsset.updateHashes(any())).thenAnswer((_) async => {});
   });
 
   tearDown(() {
@@ -29,20 +32,22 @@ void main() {
     group('hashAssets', () {
       test('skips albums with no assets to hash', () async {
         final album = LocalAlbumFactory.create(assetCount: 0);
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getAssetsToHash(album.id)).thenAnswer((_) async => []);
 
         await sut.hashAssets();
 
-        verifyNever(mocks.nativeApi.hashAssets);
+        verifyNever(() => mocks.nativeApi.hashAssets(any(), allowNetworkAccess: any(named: 'allowNetworkAccess')));
       });
 
       test('skips empty batches', () async {
         final album = LocalAlbumFactory.create();
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getAssetsToHash(album.id)).thenAnswer((_) async => []);
 
         await sut.hashAssets();
 
-        verifyNever(mocks.nativeApi.hashAssets);
+        verifyNever(() => mocks.nativeApi.hashAssets(any(), allowNetworkAccess: any(named: 'allowNetworkAccess')));
       });
 
       test('processes assets when available', () async {
@@ -50,17 +55,15 @@ void main() {
         final asset = LocalAssetFactory.create();
         final result = HashResult(assetId: asset.id, hash: 'test-hash');
 
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [album]);
-        when(() => mocks.localAlbum.repo.getAssetsToHash(album.id)).thenAnswer((_) async => [asset]);
-        when(
-          () => mocks.nativeApi.api.hashAssets([asset.id], allowNetworkAccess: false),
-        ).thenAnswer((_) async => [result]);
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getAssetsToHash(album.id)).thenAnswer((_) async => [asset]);
+        when(() => mocks.nativeApi.hashAssets([asset.id], allowNetworkAccess: false)).thenAnswer((_) async => [result]);
 
         await sut.hashAssets();
 
-        verify(() => mocks.nativeApi.api.hashAssets([asset.id], allowNetworkAccess: false)).called(1);
+        verify(() => mocks.nativeApi.hashAssets([asset.id], allowNetworkAccess: false)).called(1);
         final captured =
-            verify(() => mocks.localAsset.repo.updateHashes(captureAny())).captured.first as Map<String, String>;
+            verify(() => mocks.localAsset.updateHashes(captureAny())).captured.first as Map<String, String>;
         expect(captured.length, 1);
         expect(captured[asset.id], result.hash);
       });
@@ -69,16 +72,16 @@ void main() {
         final album = LocalAlbumFactory.create();
         final asset = LocalAssetFactory.create();
 
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [album]);
-        when(() => mocks.localAlbum.repo.getAssetsToHash(album.id)).thenAnswer((_) async => [asset]);
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getAssetsToHash(album.id)).thenAnswer((_) async => [asset]);
         when(
-          () => mocks.nativeApi.api.hashAssets([asset.id], allowNetworkAccess: false),
+          () => mocks.nativeApi.hashAssets([asset.id], allowNetworkAccess: false),
         ).thenAnswer((_) async => [HashResult(assetId: asset.id, error: 'Failed to hash')]);
 
         await sut.hashAssets();
 
         final captured =
-            verify(() => mocks.localAsset.repo.updateHashes(captureAny())).captured.first as Map<String, String>;
+            verify(() => mocks.localAsset.updateHashes(captureAny())).captured.first as Map<String, String>;
         expect(captured.length, 0);
       });
 
@@ -86,25 +89,25 @@ void main() {
         final album = LocalAlbumFactory.create();
         final asset = LocalAssetFactory.create();
 
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [album]);
-        when(() => mocks.localAlbum.repo.getAssetsToHash(album.id)).thenAnswer((_) async => [asset]);
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getAssetsToHash(album.id)).thenAnswer((_) async => [asset]);
         when(
-          () => mocks.nativeApi.api.hashAssets([asset.id], allowNetworkAccess: false),
+          () => mocks.nativeApi.hashAssets([asset.id], allowNetworkAccess: false),
         ).thenAnswer((_) async => [HashResult(assetId: asset.id, hash: null)]);
 
         await sut.hashAssets();
 
         final captured =
-            verify(() => mocks.localAsset.repo.updateHashes(captureAny())).captured.first as Map<String, String>;
+            verify(() => mocks.localAsset.updateHashes(captureAny())).captured.first as Map<String, String>;
         expect(captured.length, 0);
       });
 
       test('batches by size limit', () async {
         const batchSize = 2;
         final sut = HashService(
-          localAlbumRepository: mocks.localAlbum.repo,
-          localAssetRepository: mocks.localAsset.repo,
-          nativeSyncApi: mocks.nativeApi.api,
+          localAlbumRepository: mocks.localAlbum,
+          localAssetRepository: mocks.localAsset,
+          nativeSyncApi: mocks.nativeApi,
           batchSize: batchSize,
           trashedLocalAssetRepository: mocks.trashedAsset,
         );
@@ -116,9 +119,12 @@ void main() {
 
         final capturedCalls = <List<String>>[];
 
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [album]);
-        when(() => mocks.localAlbum.repo.getAssetsToHash(album.id)).thenAnswer((_) async => [asset1, asset2, asset3]);
-        when(mocks.nativeApi.hashAssets).thenAnswer((invocation) async {
+        when(() => mocks.localAsset.updateHashes(any())).thenAnswer((_) async => {});
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getAssetsToHash(album.id)).thenAnswer((_) async => [asset1, asset2, asset3]);
+        when(() => mocks.nativeApi.hashAssets(any(), allowNetworkAccess: any(named: 'allowNetworkAccess'))).thenAnswer((
+          invocation,
+        ) async {
           final assetIds = invocation.positionalArguments[0] as List<String>;
           capturedCalls.add(List<String>.from(assetIds));
           return assetIds.map((id) => HashResult(assetId: id, hash: '$id-hash')).toList();
@@ -130,7 +136,7 @@ void main() {
         expect(capturedCalls[0], [asset1.id, asset2.id], reason: 'First call should batch the first two assets');
         expect(capturedCalls[1], [asset3.id], reason: 'Second call should have the remaining asset');
 
-        verify(() => mocks.localAsset.repo.updateHashes(any())).called(2);
+        verify(() => mocks.localAsset.updateHashes(any())).called(2);
       });
 
       test('handles mixed success and failure in batch', () async {
@@ -138,9 +144,9 @@ void main() {
         final asset1 = LocalAssetFactory.create();
         final asset2 = LocalAssetFactory.create();
 
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [album]);
-        when(() => mocks.localAlbum.repo.getAssetsToHash(album.id)).thenAnswer((_) async => [asset1, asset2]);
-        when(() => mocks.nativeApi.api.hashAssets([asset1.id, asset2.id], allowNetworkAccess: false)).thenAnswer(
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [album]);
+        when(() => mocks.localAlbum.getAssetsToHash(album.id)).thenAnswer((_) async => [asset1, asset2]);
+        when(() => mocks.nativeApi.hashAssets([asset1.id, asset2.id], allowNetworkAccess: false)).thenAnswer(
           (_) async => [
             HashResult(assetId: asset1.id, hash: 'asset1-hash'),
             HashResult(assetId: asset2.id, error: 'Failed to hash asset2'),
@@ -150,7 +156,7 @@ void main() {
         await sut.hashAssets();
 
         final captured =
-            verify(() => mocks.localAsset.repo.updateHashes(captureAny())).captured.first as Map<String, String>;
+            verify(() => mocks.localAsset.updateHashes(captureAny())).captured.first as Map<String, String>;
         expect(captured.length, 1);
         expect(captured[asset1.id], 'asset1-hash');
       });
@@ -161,18 +167,20 @@ void main() {
         final asset1 = LocalAssetFactory.create();
         final asset2 = LocalAssetFactory.create();
 
-        when(mocks.localAlbum.getBackupAlbums).thenAnswer((_) async => [selectedAlbum, nonSelectedAlbum]);
-        when(() => mocks.localAlbum.repo.getAssetsToHash(selectedAlbum.id)).thenAnswer((_) async => [asset1]);
-        when(() => mocks.localAlbum.repo.getAssetsToHash(nonSelectedAlbum.id)).thenAnswer((_) async => [asset2]);
-        when(mocks.nativeApi.hashAssets).thenAnswer((invocation) async {
+        when(() => mocks.localAlbum.getBackupAlbums()).thenAnswer((_) async => [selectedAlbum, nonSelectedAlbum]);
+        when(() => mocks.localAlbum.getAssetsToHash(selectedAlbum.id)).thenAnswer((_) async => [asset1]);
+        when(() => mocks.localAlbum.getAssetsToHash(nonSelectedAlbum.id)).thenAnswer((_) async => [asset2]);
+        when(() => mocks.nativeApi.hashAssets(any(), allowNetworkAccess: any(named: 'allowNetworkAccess'))).thenAnswer((
+          invocation,
+        ) async {
           final assetIds = invocation.positionalArguments[0] as List<String>;
           return assetIds.map((id) => HashResult(assetId: id, hash: '$id-hash')).toList();
         });
 
         await sut.hashAssets();
 
-        verify(() => mocks.nativeApi.api.hashAssets([asset1.id], allowNetworkAccess: true)).called(1);
-        verify(() => mocks.nativeApi.api.hashAssets([asset2.id], allowNetworkAccess: false)).called(1);
+        verify(() => mocks.nativeApi.hashAssets([asset1.id], allowNetworkAccess: true)).called(1);
+        verify(() => mocks.nativeApi.hashAssets([asset2.id], allowNetworkAccess: false)).called(1);
       });
     });
   });

mobile/test/unit/services/timeline_service_test.dart

@@ -0,0 +1,100 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:immich_mobile/constants/constants.dart';
+import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+import 'package:immich_mobile/domain/models/timeline.model.dart';
+import 'package:immich_mobile/domain/services/timeline.service.dart';
+
+import '../factories/remote_asset_factory.dart';
+
+void main() {
+  // total must exceed the sliding buffer so it cannot hold the whole library at once
+  const total = 2000;
+  late List<BaseAsset> all;
+  late TimelineService sut;
+
+  TimelineService buildService() {
+    all = List.generate(total, (i) => RemoteAssetFactory.create(id: 'a${i.toString().padLeft(5, '0')}'));
+    return TimelineService((
+      assetSource: (index, count) async {
+        final end = (index + count) > total ? total : index + count;
+        return all.sublist(index, end);
+      },
+      bucketSource: () => Stream.value([const Bucket(assetCount: total)]),
+      origin: TimelineOrigin.main,
+    ));
+  }
+
+  Future<void> settle() => Future.delayed(const Duration(milliseconds: 10));
+
+  setUp(() async {
+    sut = buildService();
+    await settle(); // let the bucket subscription load the first batch and set totalAssets
+  });
+
+  tearDown(() async {
+    await sut.dispose();
+  });
+
+  test('buffer holds the first batch but not the whole library', () {
+    expect(sut.totalAssets, total);
+    expect(sut.hasRange(0, kTimelineAssetLoadBatchSize), isTrue);
+    expect(sut.hasRange(0, total), isFalse);
+  });
+
+  // #27118 / #20855 mechanism: drag-selecting from a low anchor while the grid
+  // auto-scrolls down slides the buffer forward to follow the finger. once the
+  // buffer offset passes the anchor, hasRange(anchor, ...) is false and
+  // _handleDragAssetEnter silently stops extending the selection.
+  test('anchor drops out of the buffer after the grid scrolls down', () async {
+    const anchor = 5;
+    expect(sut.hasRange(anchor, 100), isTrue);
+
+    // the grid loads a far-down range as it auto-scrolls during the drag
+    await sut.loadAssets(1500, 1);
+
+    const current = 1500;
+    const count = current - anchor + 1;
+    expect(sut.hasRange(anchor, 1), isFalse, reason: 'anchor is now below the buffer offset');
+    expect(sut.hasRange(anchor, count), isFalse, reason: 'the full drag range is no longer resident');
+    expect(() => sut.getAssets(anchor, count), throwsRangeError);
+  });
+
+  // the fix: getAssetsRange returns the whole drag range regardless of the
+  // buffer position, so the selection keeps extending while scrolling.
+  group('getAssetsRange', () {
+    test('returns a buffered range', () async {
+      final assets = await sut.getAssetsRange(0, 50);
+      expect(assets.length, 50);
+      expect(assets.first, all[0]);
+      expect(assets.last, all[49]);
+    });
+
+    test('returns a range wider than the buffer', () async {
+      final assets = await sut.getAssetsRange(0, total);
+      expect(assets.length, total);
+      expect(assets.first, all[0]);
+      expect(assets.last, all[total - 1]);
+    });
+
+    test('returns the anchor range after the buffer scrolled past the anchor', () async {
+      const anchor = 5;
+      await sut.loadAssets(1500, 1); // buffer slides forward, dropping the anchor
+      expect(sut.hasRange(anchor, 1), isFalse);
+
+      const current = 1500;
+      const count = current - anchor + 1;
+      final assets = await sut.getAssetsRange(anchor, count);
+      expect(assets.length, count);
+      expect(assets.first, all[anchor]);
+      expect(assets.last, all[current]);
+    });
+
+    test('clamps a range that runs past the end and ignores invalid input', () async {
+      final tail = await sut.getAssetsRange(total - 10, 100);
+      expect(tail.length, 10);
+      expect(await sut.getAssetsRange(-1, 10), isEmpty);
+      expect(await sut.getAssetsRange(0, 0), isEmpty);
+      expect(await sut.getAssetsRange(total, 10), isEmpty);
+    });
+  });
+}