fix(mobile): update timeline args on layout constraint changes

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

@@ -86,13 +86,14 @@ class TimelineStateNotifier extends Notifier<TimelineState> {
 // This provider watches the buckets from the timeline service & args and serves the segments.
 // It should be used only after the timeline service and timeline args provider is overridden
 final timelineSegmentProvider = StreamProvider.autoDispose<List<Segment>>((ref) async* {
-  final args = ref.watch(timelineArgsProvider);
-  final columnCount = args.columnCount;
-  final spacing = args.spacing;
-  final availableTileWidth = args.maxWidth - (spacing * (columnCount - 1));
+  // maxHeight is left out on purpose, a height-only change must not restart the bucket stream
+  final (maxWidth, columnCount, spacing, groupByArg) = ref.watch(
+    timelineArgsProvider.select((args) => (args.maxWidth, args.columnCount, args.spacing, args.groupBy)),
+  );
+  final availableTileWidth = maxWidth - (spacing * (columnCount - 1));
   final tileExtent = math.max(0, availableTileWidth) / columnCount;
 
-  final groupBy = args.groupBy ?? ref.watch(appConfigProvider.select((config) => config.timeline.groupAssetsBy));
+  final groupBy = groupByArg ?? ref.watch(appConfigProvider.select((config) => config.timeline.groupAssetsBy));
 
   final timelineService = ref.watch(timelineServiceProvider);
   yield* timelineService.watchBuckets().map((buckets) {

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

@@ -29,7 +29,7 @@ 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';
 
-class Timeline extends StatelessWidget {
+class Timeline extends ConsumerWidget {
   const Timeline({
     super.key,
     this.topSliverWidget,
@@ -62,15 +62,18 @@ class Timeline extends StatelessWidget {
   final Widget? loadingWidget;
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
+    final columnCount = ref.watch(appConfigProvider.select((config) => config.timeline.tilesPerRow));
     return LayoutBuilder(
       builder: (_, constraints) => ProviderScope(
         overrides: [
-          timelineArgsProvider.overrideWith(
-            (ref) => TimelineArgs(
+          // overrideWithValue keeps the scoped args in sync with the latest constraints on rebuilds,
+          // a function override would stay locked to the first frame's constraints for the whole session
+          timelineArgsProvider.overrideWithValue(
+            TimelineArgs(
               maxWidth: constraints.maxWidth,
               maxHeight: constraints.maxHeight,
-              columnCount: ref.watch(appConfigProvider.select((config) => config.timeline.tilesPerRow)),
+              columnCount: columnCount,
               showStorageIndicator: showStorageIndicator,
               withStack: withStack,
               groupBy: groupBy,
@@ -168,13 +171,11 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
   void didUpdateWidget(covariant _SliverTimeline oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.maxWidth != oldWidget.maxWidth) {
-      final asyncSegments = ref.read(timelineSegmentProvider);
-      asyncSegments.whenData((segments) {
-        final index = _getCurrentAssetIndex(segments);
-        // Refresh to wait for new segments to be generated with the updated width before restoring the scroll position
-        final _ = ref.refresh(timelineArgsProvider);
-        _restoreAssetIndex = index;
-      });
+      // The updated args already regenerate the segments, only remember the scroll position to restore it afterwards
+      final segments = ref.read(timelineSegmentProvider).valueOrNull;
+      if (segments != null && _scrollController.hasClients) {
+        _restoreAssetIndex = _getCurrentAssetIndex(segments);
+      }
     }
   }
 

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

@@ -1,3 +1,4 @@
+import 'package:collection/collection.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/services/timeline.service.dart';
 import 'package:immich_mobile/infrastructure/repositories/timeline.repository.dart';
@@ -39,5 +40,10 @@ final timelineUsersProvider = StreamProvider<List<String>>((ref) {
     return Stream.value([]);
   }
 
-  return ref.watch(timelineRepositoryProvider).watchTimelineUserIds(currentUserId);
+  // Drift re-emits a fresh but content-identical list on unrelated table updates,
+  // which would dispose and rebuild the timeline service mid-load
+  return ref
+      .watch(timelineRepositoryProvider)
+      .watchTimelineUserIds(currentUserId)
+      .distinct(const ListEquality<String>().equals);
 });

mobile/test/presentation/widgets/timeline/timeline_args_test.dart

@@ -0,0 +1,119 @@
+import 'dart:async';
+
+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/config/app_config.dart';
+import 'package:immich_mobile/domain/models/timeline.model.dart';
+import 'package:immich_mobile/domain/services/timeline.service.dart';
+import 'package:immich_mobile/presentation/widgets/timeline/timeline.state.dart';
+import 'package:immich_mobile/presentation/widgets/timeline/timeline.widget.dart';
+import 'package:immich_mobile/providers/infrastructure/settings.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/timeline.provider.dart';
+
+// A first fetch that never delivers - the state a suspended or storm-starved
+// bucket watch is stuck in when the timeline mounts on a zero-sized first frame
+class _FrozenBucketService implements TimelineService {
+  final _ctrl = StreamController<List<Bucket>>.broadcast();
+
+  @override
+  Stream<List<Bucket>> Function() get watchBuckets =>
+      () => _ctrl.stream;
+
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}
+
+class _EmptyBucketService implements TimelineService {
+  @override
+  Stream<List<Bucket>> Function() get watchBuckets =>
+      () => Stream.value(const []);
+
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}
+
+void main() {
+  testWidgets('timeline args follow constraints after a zero-sized first frame while buckets are still loading', (
+    tester,
+  ) async {
+    tester.view.physicalSize = Size.zero;
+    tester.view.devicePixelRatio = 3.0;
+    addTearDown(tester.view.reset);
+
+    TimelineArgs? probed;
+    final probe = Consumer(
+      builder: (_, ref, __) {
+        probed = ref.watch(timelineArgsProvider);
+        return const SizedBox.shrink();
+      },
+    );
+
+    await tester.pumpWidget(
+      ProviderScope(
+        overrides: [
+          timelineServiceProvider.overrideWithValue(_FrozenBucketService()),
+          appConfigProvider.overrideWithValue(const AppConfig()),
+        ],
+        child: MaterialApp(home: Timeline(withScrubber: false, readOnly: true, loadingWidget: probe)),
+      ),
+    );
+    await tester.pump();
+
+    expect(probed, isNotNull);
+    expect(probed!.maxWidth, 0.0);
+
+    tester.view.physicalSize = const Size(1206, 2622);
+    await tester.pump();
+    await tester.pump();
+
+    expect(
+      probed!.maxWidth,
+      402.0,
+      reason: 'args locked to the zero-sized first frame leave the timeline blank for the whole session',
+    );
+  });
+
+  testWidgets('timeline args follow constraints after a zero-sized first frame once buckets resolve', (tester) async {
+    tester.view.physicalSize = Size.zero;
+    tester.view.devicePixelRatio = 3.0;
+    addTearDown(tester.view.reset);
+
+    TimelineArgs? probed;
+    final probe = SliverToBoxAdapter(
+      child: Consumer(
+        builder: (_, ref, __) {
+          probed = ref.watch(timelineArgsProvider);
+          return const SizedBox.shrink();
+        },
+      ),
+    );
+
+    await tester.pumpWidget(
+      ProviderScope(
+        overrides: [
+          timelineServiceProvider.overrideWithValue(_EmptyBucketService()),
+          appConfigProvider.overrideWithValue(const AppConfig()),
+        ],
+        child: MaterialApp(
+          home: Timeline(
+            withScrubber: false,
+            readOnly: true,
+            appBar: const SliverToBoxAdapter(child: SizedBox.shrink()),
+            topSliverWidget: probe,
+          ),
+        ),
+      ),
+    );
+    await tester.pump();
+    await tester.pump();
+
+    tester.view.physicalSize = const Size(1206, 2622);
+    await tester.pump();
+    await tester.pump();
+    await tester.pump();
+
+    expect(probed, isNotNull);
+    expect(probed!.maxWidth, 402.0);
+  });
+}