debug: throttle timeline watch

# Conflicts:
#	mobile/lib/presentation/widgets/timeline/fixed/segment.model.dart
#	mobile/lib/presentation/widgets/timeline/timeline.widget.dart

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

@@ -138,7 +138,9 @@ class LocalSyncService {
       final Stopwatch stopwatch = Stopwatch()..start();
 
       final deviceAlbums = await _nativeSyncApi.getAlbums();
+      final getAlbumsTime = stopwatch.elapsedMilliseconds;
       final dbAlbums = await _localAlbumRepository.getAll(sortBy: {SortLocalAlbumsBy.id});
+      final getAllTime = stopwatch.elapsedMilliseconds;
 
       await diffSortedLists(
         dbAlbums,
@@ -148,10 +150,15 @@ class LocalSyncService {
         onlyFirst: removeAlbum,
         onlySecond: addAlbum,
       );
+      final diffTime = stopwatch.elapsedMilliseconds;
 
       await _nativeSyncApi.checkpointSync();
       stopwatch.stop();
-      _log.info("Full device sync took - ${stopwatch.elapsedMilliseconds}ms");
+      _log.info(
+        "Full device sync took - ${stopwatch.elapsedMilliseconds}ms "
+        "(getAlbums=${getAlbumsTime}ms, getAll=${getAllTime - getAlbumsTime}ms, "
+        "diff=${diffTime - getAllTime}ms, checkpoint=${stopwatch.elapsedMilliseconds - diffTime}ms)",
+      );
     } on PlatformException catch (e, s) {
       if (e.code == _kSyncCancelledCode) {
         _log.warning("Full device sync cancelled");

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

@@ -10,6 +10,8 @@ import 'package:immich_mobile/domain/utils/event_stream.dart';
 import 'package:immich_mobile/infrastructure/repositories/settings.repository.dart';
 import 'package:immich_mobile/infrastructure/repositories/timeline.repository.dart';
 import 'package:immich_mobile/utils/async_mutex.dart';
+import 'package:logging/logging.dart';
+import 'package:stream_transform/stream_transform.dart';
 
 typedef TimelineAssetSource = Future<List<BaseAsset>> Function(int index, int count);
 
@@ -90,6 +92,7 @@ class TimelineFactory {
 }
 
 class TimelineService {
+  static final Logger _log = Logger('TimelineService');
   final TimelineAssetSource _assetSource;
   final TimelineBucketSource _bucketSource;
   final TimelineOrigin origin;
@@ -105,37 +108,53 @@ class TimelineService {
     : this._(assetSource: query.assetSource, bucketSource: query.bucketSource, origin: query.origin);
 
   TimelineService._({required this._assetSource, required this._bucketSource, required this.origin}) {
-    _bucketSubscription = _bucketSource().listen((buckets) {
+    _bucketSubscription = watchBuckets().listen(
-      _mutex.run(() async {
+      (buckets) {
-        final totalAssets = buckets.fold<int>(0, (acc, bucket) => acc + bucket.assetCount);
+        _mutex.run(() async {
+          try {
+            final totalAssets = buckets.fold<int>(0, (acc, bucket) => acc + bucket.assetCount);
 
-        if (totalAssets == 0) {
+            _log.info(
-          _bufferOffset = 0;
+              '[$origin] bucket emission: ${buckets.length} buckets / $totalAssets assets '
-          _buffer = [];
+              '(current _totalAssets=$_totalAssets, _bufferOffset=$_bufferOffset, _buffer=${_buffer.length})',
-        } else {
+            );
-          final int offset;
+
-          final int count;
+            if (totalAssets == 0) {
-          // When the buffer is empty or the old bufferOffset is greater than the new total assets,
+              _bufferOffset = 0;
-          // we need to reset the buffer and load the first batch of assets.
+              _buffer = [];
-          if (_bufferOffset >= totalAssets || _buffer.isEmpty) {
+            } else {
-            offset = 0;
+              final int offset;
-            count = kTimelineAssetLoadBatchSize;
+              final int count;
-          } else {
+              // When the buffer is empty or the old bufferOffset is greater than the new total assets,
-            offset = _bufferOffset;
+              // we need to reset the buffer and load the first batch of assets.
-            count = math.min(_buffer.length, totalAssets - _bufferOffset);
+              if (_bufferOffset >= totalAssets || _buffer.isEmpty) {
+                offset = 0;
+                count = kTimelineAssetLoadBatchSize;
+              } else {
+                offset = _bufferOffset;
+                count = math.min(_buffer.length, totalAssets - _bufferOffset);
+              }
+              _buffer = await _assetSource(offset, count);
+              _bufferOffset = offset;
+              _log.info('[$origin] buffer reloaded: offset=$offset requested=$count got=${_buffer.length}');
+            }
+
+            _totalAssets = totalAssets;
+            EventStream.shared.emit(const TimelineReloadEvent());
+          } catch (error, stack) {
+            _log.severe('[$origin] bucket reload FAILED — _totalAssets stuck at $_totalAssets', error, stack);
+            rethrow;
           }
-          _buffer = await _assetSource(offset, count);
+        });
-          _bufferOffset = offset;
+      },
-        }
+      onError: (Object error, StackTrace stack) {
-
+        _log.severe('[$origin] bucket stream errored', error, stack);
-        // change the state's total assets count only after the buffer is reloaded
+      },
-        _totalAssets = totalAssets;
+    );
-        EventStream.shared.emit(const TimelineReloadEvent());
-      });
-    });
   }
 
-  Stream<List<Bucket>> Function() get watchBuckets => _bucketSource;
+  Stream<List<Bucket>> Function() get watchBuckets =>
+      () => _bucketSource().throttle(const Duration(milliseconds: 500), trailing: true);
 
   Future<List<BaseAsset>> loadAssets(int index, int count) => _mutex.run(() => _loadAssets(index, count));
 
@@ -164,6 +183,13 @@ class TimelineService {
     _buffer = await _assetSource(start, len);
     _bufferOffset = start;
 
+    if (!hasRange(index, count)) {
+      _log.warning(
+        '[$origin] _loadAssets($index, $count): buffer loaded (offset=$start, got=${_buffer.length}) but still '
+        'out of range — _totalAssets=$_totalAssets. getAssets is about to throw RangeError.',
+      );
+    }
+
     return getAssets(index, count);
   }
 

mobile/lib/presentation/widgets/timeline/fixed/segment.model.dart

@@ -23,6 +23,7 @@ import 'package:immich_mobile/providers/infrastructure/readonly_mode.provider.da
 import 'package:immich_mobile/providers/infrastructure/timeline.provider.dart';
 import 'package:immich_mobile/providers/timeline/multiselect.provider.dart';
 import 'package:immich_mobile/routing/router.dart';
+import 'package:logging/logging.dart';
 
 class FixedSegment extends Segment {
   final double tileHeight;
@@ -90,6 +91,7 @@ class FixedSegment extends Segment {
 }
 
 class _FixedSegmentRow extends ConsumerWidget {
+  static final Logger _log = Logger('TimelineRow');
   final int assetIndex;
   final int assetCount;
   final double tileHeight;
@@ -109,8 +111,20 @@ class _FixedSegmentRow extends ConsumerWidget {
     final isScrubbing = ref.watch(timelineStateProvider.select((s) => s.isScrubbing));
     final timelineService = ref.read(timelineServiceProvider);
     final isDynamicLayout = columnCount <= (context.isMobile ? 2 : 3);
+    final inRange = timelineService.hasRange(assetIndex, assetCount);
 
-    if (timelineService.hasRange(assetIndex, assetCount)) {
+    if (assetIndex == 0) {
+      _log.info(
+        'row[0] inRange=$inRange isScrubbing=$isScrubbing totalAssets=${timelineService.totalAssets} '
+        'branch=${inRange
+            ? "assets"
+            : isScrubbing
+            ? "placeholder(scrubbing)"
+            : "future(load)"}',
+      );
+    }
+
+    if (inRange) {
       return _buildAssetRow(
         context,
         timelineService.getAssets(assetIndex, assetCount),
@@ -129,6 +143,13 @@ class _FixedSegmentRow extends ConsumerWidget {
         if (snapshot.connectionState != ConnectionState.done) {
           return _buildPlaceholder(context);
         }
+        if (snapshot.hasError) {
+          _log.warning(
+            'render row loadAssets($assetIndex, $assetCount) failed (totalAssets=${timelineService.totalAssets})',
+            snapshot.error,
+            snapshot.stackTrace,
+          );
+        }
         return _buildAssetRow(context, snapshot.requireData, timelineService, isDynamicLayout);
       },
     );

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

@@ -13,6 +13,7 @@ import 'package:immich_mobile/presentation/widgets/timeline/timeline.state.dart'
 import 'package:immich_mobile/providers/haptic_feedback.provider.dart';
 import 'package:immich_mobile/utils/debounce.dart';
 import 'package:intl/intl.dart' hide TextDirection;
+import 'package:logging/logging.dart';
 
 /// A widget that will display a BoxScrollView with a ScrollThumb that can be dragged
 /// for quick navigation of the BoxScrollView.
@@ -84,6 +85,7 @@ List<_Segment> _buildSegments({required List<Segment> layoutSegments, required d
 }
 
 class ScrubberState extends ConsumerState<Scrubber> with TickerProviderStateMixin {
+  static final Logger _log = Logger('Scrubber');
   String? _lastLabel;
   double _thumbTopOffset = 0.0;
   bool _isDragging = false;
@@ -114,6 +116,7 @@ class ScrubberState extends ConsumerState<Scrubber> with TickerProviderStateMixi
   @override
   void initState() {
     super.initState();
+    _log.info('Scrubber initState');
     _isDragging = false;
     _segments = _buildSegments(layoutSegments: widget.layoutSegments, timelineHeight: _scrubberHeight);
     _thumbAnimationController = AnimationController(vsync: this, duration: kTimelineScrubberFadeInDuration);
@@ -134,7 +137,10 @@ class ScrubberState extends ConsumerState<Scrubber> with TickerProviderStateMixi
   void didUpdateWidget(covariant Scrubber oldWidget) {
     super.didUpdateWidget(oldWidget);
 
-    if (oldWidget.layoutSegments.lastOrNull?.endOffset != widget.layoutSegments.lastOrNull?.endOffset) {
+    final oldEnd = oldWidget.layoutSegments.lastOrNull?.endOffset;
+    final newEnd = widget.layoutSegments.lastOrNull?.endOffset;
+    if (oldEnd != newEnd) {
+      _log.info('Scrubber layoutSegments endOffset $oldEnd -> $newEnd (isDragging=$_isDragging)');
       _segments = _buildSegments(layoutSegments: widget.layoutSegments, timelineHeight: _scrubberHeight);
       _monthCount = getMonthCount();
     }
@@ -142,6 +148,15 @@ class ScrubberState extends ConsumerState<Scrubber> with TickerProviderStateMixi
 
   @override
   void dispose() {
+    if (_isDragging || _currentScrubberDate != null || _scrubberDebouncer != null) {
+      _log.warning(
+        'Scrubber dispose mid-scrub '
+        '(isDragging=$_isDragging, pendingDate=$_currentScrubberDate, '
+        'debouncerPending=${_scrubberDebouncer != null}) — scrubbing reset may be orphaned',
+      );
+    } else {
+      _log.info('Scrubber dispose');
+    }
     _thumbAnimationController.dispose();
     _labelAnimationController.dispose();
     _fadeOutTimer?.cancel();
@@ -208,6 +223,7 @@ class ScrubberState extends ConsumerState<Scrubber> with TickerProviderStateMixi
   }
 
   void _onDragStart(DragStartDetails _) {
+    _log.info('scrub dragStart');
     setState(() {
       _isDragging = true;
       _labelAnimationController.forward();
@@ -222,9 +238,15 @@ class ScrubberState extends ConsumerState<Scrubber> with TickerProviderStateMixi
     }
 
     if (_scrubberHeight <= 0) {
+      _log.warning('drag ignored: scrubberHeight=$_scrubberHeight <= 0');
       return;
     }
 
+    final maxScrollExtent = _scrollController.hasClients ? _scrollController.position.maxScrollExtent : -1;
+    if (maxScrollExtent <= 0) {
+      _log.warning('drag ineffective: hasClients=${_scrollController.hasClients} maxScrollExtent=$maxScrollExtent');
+    }
+
     if (_thumbAnimationController.status != AnimationStatus.forward) {
       _thumbAnimationController.forward();
     }
@@ -344,6 +366,7 @@ class ScrubberState extends ConsumerState<Scrubber> with TickerProviderStateMixi
   }
 
   void _onDragEnd(DragEndDetails _) {
+    _log.info('scrub dragEnd -> setScrubbing(false)');
     _labelAnimationController.reverse();
     setState(() {
       _isDragging = false;

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

@@ -7,6 +7,7 @@ import 'package:immich_mobile/presentation/widgets/timeline/fixed/segment_builde
 import 'package:immich_mobile/presentation/widgets/timeline/segment.model.dart';
 import 'package:immich_mobile/providers/infrastructure/settings.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/timeline.provider.dart';
+import 'package:logging/logging.dart';
 
 class TimelineArgs {
   final double maxWidth;
@@ -71,14 +72,27 @@ class TimelineState {
 }
 
 class TimelineStateNotifier extends Notifier<TimelineState> {
+  static final Logger _log = Logger('TimelineState');
+
   void setScrubbing(bool isScrubbing) {
+    if (state.isScrubbing != isScrubbing) {
+      _log.info('isScrubbing ${state.isScrubbing} -> $isScrubbing  (from ${_callSite()})');
+    }
     state = state.copyWith(isScrubbing: isScrubbing);
   }
 
   void setScrolling(bool isScrolling) {
+    if (state.isScrolling != isScrolling) {
+      _log.info('isScrolling ${state.isScrolling} -> $isScrolling  (from ${_callSite()})');
+    }
     state = state.copyWith(isScrolling: isScrolling);
   }
 
+  static String _callSite() {
+    final frames = StackTrace.current.toString().split('\n');
+    return frames.length > 2 ? frames[2].trim() : 'unknown';
+  }
+
   @override
   TimelineState build() => const TimelineState(isScrubbing: false, isScrolling: false);
 }
@@ -96,6 +110,11 @@ final timelineSegmentProvider = StreamProvider.autoDispose<List<Segment>>((ref)
 
   final timelineService = ref.watch(timelineServiceProvider);
   yield* timelineService.watchBuckets().map((buckets) {
+    final layoutTotal = buckets.fold<int>(0, (acc, bucket) => acc + bucket.assetCount);
+    Logger('TimelineService').info(
+      '[${timelineService.origin}] segment layout: '
+      '${buckets.length} buckets / $layoutTotal assets (service.totalAssets=${timelineService.totalAssets})',
+    );
     return FixedSegmentBuilder(
       buckets: buckets,
       tileHeight: tileExtent,

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

@@ -28,6 +28,7 @@ import 'package:immich_mobile/providers/timeline/multiselect.provider.dart';
 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';
+import 'package:logging/logging.dart';
 
 class Timeline extends StatelessWidget {
   const Timeline({
@@ -136,6 +137,7 @@ class _SliverTimeline extends ConsumerStatefulWidget {
 }
 
 class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
+  static final Logger _log = Logger('Timeline');
   late final ScrollController _scrollController;
   StreamSubscription? _eventSubscription;
 
@@ -153,6 +155,7 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
   @override
   void initState() {
     super.initState();
+    _log.info('SliverTimeline initState');
     _scrollController = ScrollController(onAttach: _restoreAssetPosition);
     _eventSubscription = EventStream.shared.listen(_onEvent);
 
@@ -179,6 +182,7 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
   }
 
   void _onEvent(Event event) {
+    _log.info('event ${event.runtimeType}');
     switch (event) {
       case ScrollToTopEvent():
         {
@@ -186,7 +190,10 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
           timelineState.setScrubbing(true);
           _scrollController
               .animateTo(0, duration: const Duration(milliseconds: 250), curve: Curves.easeInOut)
-              .whenComplete(() => timelineState.setScrubbing(false));
+              .whenComplete(() {
+                _log.info('ScrollToTop animation done -> setScrubbing(false)');
+                timelineState.setScrubbing(false);
+              });
         }
 
       case ScrollToDateEvent scrollToDateEvent:
@@ -246,6 +253,7 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
 
   @override
   void dispose() {
+    _log.info('SliverTimeline dispose');
     _scrollController.dispose();
     _eventSubscription?.cancel();
     super.dispose();
@@ -286,8 +294,12 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
               duration: const Duration(milliseconds: 500),
               curve: Curves.easeInOut,
             )
-            .whenComplete(() => timelineState.setScrubbing(false));
+            .whenComplete(() {
+              _log.info('ScrollToDate animation done -> setScrubbing(false)');
+              timelineState.setScrubbing(false);
+            });
       } else {
+        _log.info('ScrollToDate: no matching segment for $date -> setScrubbing(false)');
         timelineState.setScrubbing(false);
       }
     });

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

@@ -5,6 +5,9 @@ import 'package:immich_mobile/presentation/widgets/timeline/timeline.state.dart'
 import 'package:immich_mobile/providers/infrastructure/db.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/settings.provider.dart';
 import 'package:immich_mobile/providers/user.provider.dart';
+import 'package:logging/logging.dart';
+
+final _log = Logger('TimelineProvider');
 
 final timelineRepositoryProvider = Provider<DriftTimelineRepository>(
   (ref) => DriftTimelineRepository(ref.watch(driftProvider)),
@@ -18,7 +21,11 @@ final timelineServiceProvider = Provider<TimelineService>(
   (ref) {
     final timelineUsers = ref.watch(timelineUsersProvider).valueOrNull ?? [];
     final timelineService = ref.watch(timelineFactoryProvider).main(timelineUsers);
-    ref.onDispose(timelineService.dispose);
+    _log.info('main TimelineService built users=$timelineUsers');
+    ref.onDispose(() {
+      _log.info('main TimelineService disposed');
+      timelineService.dispose();
+    });
     return timelineService;
   },
   // Empty dependencies to inform the framework that this provider
@@ -36,8 +43,12 @@ final timelineFactoryProvider = Provider<TimelineFactory>(
 final timelineUsersProvider = StreamProvider<List<String>>((ref) {
   final currentUserId = ref.watch(currentUserProvider.select((u) => u?.id));
   if (currentUserId == null) {
+    _log.info('timelineUsers: currentUserId=null -> []');
     return Stream.value([]);
   }
 
-  return ref.watch(timelineRepositoryProvider).watchTimelineUserIds(currentUserId);
+  return ref.watch(timelineRepositoryProvider).watchTimelineUserIds(currentUserId).map((users) {
+    _log.info('timelineUsers emission: $users');
+    return users;
+  });
 });