improved performance and battery usage on older devices

lib/view/pages/talk/chat_list.dart

@@ -75,6 +75,17 @@ class _ChatListViewState extends State<_ChatListView> {
   @override
   Widget build(BuildContext context) {
     final bloc = context.read<ChatListBloc>();
+    // Selected here, not in the LoadableStateConsumer child: that closure runs
+    // during the consumer's build, where this context may not subscribe.
+    // Draft keys are part of the selection so the draft marker follows; the
+    // draft text itself is saved without notifying.
+    final (favoritesToTop, unreadToTop, _) = context.select(
+      (SettingsCubit c) => (
+        c.state.talkSettings.sortFavoritesToTop,
+        c.state.talkSettings.sortUnreadToTop,
+        c.state.talkSettings.drafts.keys.join('|'),
+      ),
+    );
     return SplitView.material(
       placeholder: const SplitViewPlaceholder(),
       breakpoint: 1000,
@@ -129,13 +140,9 @@ class _ChatListViewState extends State<_ChatListView> {
               final rooms = state.rooms;
               if (rooms == null) return const SizedBox.shrink();
 
-              final talkSettings = context
-                  .watch<SettingsCubit>()
-                  .val()
-                  .talkSettings;
               final sorted = rooms.sortBy(
-                favoritesToTop: talkSettings.sortFavoritesToTop,
-                unreadToTop: talkSettings.sortUnreadToTop,
+                favoritesToTop: favoritesToTop,
+                unreadToTop: unreadToTop,
               );
 
               if (sorted.isEmpty) {
@@ -145,23 +152,25 @@ class _ChatListViewState extends State<_ChatListView> {
                 );
               }
 
-              return ListView(
+              final drafts = _settings.val().talkSettings.drafts;
+              final indexByToken = {
+                for (var i = 0; i < sorted.length; i++) sorted[i].token: i,
+              };
+              return ListView.builder(
                 padding: EdgeInsets.zero,
-                children: sorted.map((room) {
-                  final hasDraft = _settings
-                      .val()
-                      .talkSettings
-                      .drafts
-                      .containsKey(room.token);
-                  // Stable key keeps element identity across re-sorts so the
-                  // inner UserAvatar reuses its cached bytes instead of
-                  // flashing on every list update.
+                itemCount: sorted.length,
+                // Keeps each tile's state (cached avatar bytes) with its room
+                // when a re-sort moves it to another index.
+                findChildIndexCallback: (key) =>
+                    indexByToken[(key as ValueKey<String>).value],
+                itemBuilder: (context, index) {
+                  final room = sorted[index];
                   return ChatTile(
                     key: ValueKey(room.token),
                     data: room,
-                    hasDraft: hasDraft,
+                    hasDraft: drafts.containsKey(room.token),
                   );
-                }).toList(),
+                },
               );
             },
           ),