Share thread calendar cache with sticky date index

Signed-off-by: Tom Brow <tomb@block.xyz>

mobile/lib/features/channels/thread_detail_page.dart

@@ -313,7 +313,9 @@ class ThreadDetailPage extends HookConsumerWidget {
     const headIndex = 0;
     int indexForReply(int chronologicalIndex) => chronologicalIndex + 1;
     final tailAnchorIndex = replies.length + 1;
+    final calendarDays = ref.watch(timelineCalendarDaysFactoryProvider)();
     final stickyDateIndex = _ThreadStickyDateIndex(
+      calendarDays: calendarDays,
       head: liveHead,
       replies: replies,
     );
@@ -923,6 +925,7 @@ class ThreadDetailPage extends HookConsumerWidget {
             children: [
               Expanded(
                 child: _ThreadMessageList(
+                  calendarDays: calendarDays,
                   headHeight: headHeight.value ?? 0,
                   onHeadHeightChanged: (height) {
                     if (context.mounted) headHeight.value = height;

mobile/lib/features/channels/thread_detail_page/message_list.dart

@@ -1,6 +1,7 @@
 part of '../thread_detail_page.dart';
 
-class _ThreadMessageList extends HookConsumerWidget {
+class _ThreadMessageList extends HookWidget {
+  final TimelineCalendarDays calendarDays;
   final double headHeight;
   final ValueChanged<double> onHeadHeightChanged;
   final LaidOutViewport viewport;
@@ -30,6 +31,7 @@ class _ThreadMessageList extends HookConsumerWidget {
   final Map<String, List<TimelineMessage>> childrenByParent;
 
   const _ThreadMessageList({
+    required this.calendarDays,
     required this.headHeight,
     required this.onHeadHeightChanged,
     required this.viewport,
@@ -144,8 +146,7 @@ class _ThreadMessageList extends HookConsumerWidget {
   }
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
-    final calendarDays = ref.watch(timelineCalendarDaysFactoryProvider)();
+  Widget build(BuildContext context) {
     final headLink = useMemoized(LayerLink.new);
     final loadingHeadLink = useMemoized(LayerLink.new);
     final headScrollPosition = useRef<ScrollPosition?>(null);

mobile/lib/features/channels/thread_detail_page/sticky_date.dart

@@ -22,6 +22,7 @@ class _ThreadStickyDateIndex {
   final int messageCount;
 
   _ThreadStickyDateIndex({
+    required TimelineCalendarDays calendarDays,
     required TimelineMessage head,
     required List<TimelineMessage> replies,
   }) : messageCount = replies.length + 1 {
@@ -32,7 +33,10 @@ class _ThreadStickyDateIndex {
       final message = messages[index];
       final startsDay =
           index == 0 ||
-          !isSameDay(messages[index - 1].createdAt, message.createdAt);
+          !calendarDays.isSameDay(
+            messages[index - 1].createdAt,
+            message.createdAt,
+          );
       if (startsDay) {
         activeDayTimestamp = message.createdAt;
         activeDayStartIndex = index;

mobile/test/features/channels/timeline_calendar_builder_cases.dart

@@ -100,6 +100,75 @@ void timelineCalendarBuilderTests() {
     }
   });
 
+  testWidgets('thread sticky index and visible rows share all conversions', (
+    tester,
+  ) async {
+    final conversions = <Map<int, int>>[];
+    final root = _textMsg(
+      id: threadIdThreadDashRoot,
+      pubkey: 'alice',
+      content: 'Root',
+      createdAt: 1000,
+    );
+    final replies = [
+      for (var i = 1; i <= 60; i++)
+        _textMsg(
+          id: 'calendar-long-$i',
+          pubkey: 'bob',
+          content: 'Reply $i',
+          createdAt: 1000 + i * 60,
+          extraTags: const [
+            ['e', threadIdThreadDashRoot, '', 'reply'],
+          ],
+        ),
+    ];
+    await tester.pumpWidget(
+      _buildTestable(
+        messages: [root],
+        threadReplies: {threadIdThreadDashRoot: replies},
+        calendarDaysFactory: () {
+          final counts = <int, int>{};
+          conversions.add(counts);
+          return TimelineCalendarDays.withConverter((timestamp) {
+            counts.update(timestamp, (count) => count + 1, ifAbsent: () => 1);
+            return DateTime.fromMillisecondsSinceEpoch(timestamp * 1000);
+          });
+        },
+      ),
+    );
+    await tester.pumpAndSettle();
+    // Discard channel caches before mounting the thread.
+    conversions.clear();
+    final head = formatTimeline([root]).single;
+    Navigator.of(tester.element(find.byType(ChannelDetailPage))).push(
+      MaterialPageRoute<void>(
+        builder: (_) => ThreadDetailPage(
+          threadHead: head,
+          allMessages: [head],
+          channelId: _channelId,
+          currentPubkey: 'self',
+          isMember: true,
+          isArchived: false,
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+    final threadCaches = conversions
+        .where((counts) => counts.containsKey(replies.last.createdAt))
+        .toList();
+    expect(threadCaches, isNotEmpty);
+    for (final counts in threadCaches) {
+      expect(
+        counts.keys,
+        containsAll([
+          root.createdAt,
+          ...replies.map((reply) => reply.createdAt),
+        ]),
+      );
+      expect(counts.values, everyElement(1));
+    }
+  });
+
   testWidgets('thread shows day dividers when replies cross days', (
     tester,
   ) async {