perf(tabs): release stale image and tab state

apps/weblibre/lib/features/geckoview/domain/providers/tab_state.dart

@@ -36,6 +36,7 @@ import 'package:weblibre/features/geckoview/domain/entities/states/translation.d
 import 'package:weblibre/features/geckoview/domain/providers.dart';
 import 'package:weblibre/features/geckoview/domain/providers/selected_tab.dart';
 import 'package:weblibre/features/geckoview/domain/providers/tab_detail_state.dart';
+import 'package:weblibre/features/geckoview/domain/providers/tab_list.dart';
 import 'package:weblibre/features/geckoview/features/find_in_page/domain/repositories/find_in_page.dart';
 import 'package:weblibre/features/geckoview/features/tabs/data/entities/isolation_context.dart';
 import 'package:weblibre/features/geckoview/features/tabs/data/entities/tab_mode.dart';
@@ -75,6 +76,14 @@ class TabStates extends _$TabStates {
     state = {...state}..[tabId] = next;
   }
 
+  void _removeAll(Set<String> tabIds) {
+    if (!state.keys.any(tabIds.contains)) {
+      return;
+    }
+
+    state = {...state}..removeWhere((tabId, _) => tabIds.contains(tabId));
+  }
+
   Future<void> _onTabContentStateChange(TabContentState contentState) async {
     final current = await patchedState(contentState.id);
 
@@ -187,6 +196,9 @@ class TabStates extends _$TabStates {
         bytes,
         targetWidth: thumbnailDecodeWidth,
         allowUpscaling: false,
+        // Periodic screenshots are almost always unique. Caching each decode
+        // retained up to 100 obsolete GPU images in the global icon LRU.
+        cacheResult: false,
       ),
     );
 
@@ -415,6 +427,29 @@ class TabStates extends _$TabStates {
       },
     );
 
+    ref.listen(tabListProvider, (previous, next) {
+      if (previous == null) {
+        // The first list can be a partial restore snapshot. There is no reliable
+        // removal signal until Gecko has emitted at least two snapshots.
+        return;
+      }
+
+      final activeTabIds = next.value.toSet();
+      final removedTabIds = previous.value
+          .where((tabId) => !activeTabIds.contains(tabId))
+          .toSet();
+      if (removedTabIds.isEmpty) {
+        return;
+      }
+
+      _removeAll(removedTabIds);
+      ref.read(tabProgressStatesProvider.notifier).removeAll(removedTabIds);
+      ref.read(tabThumbnailsProvider.notifier).removeAll(removedTabIds);
+      ref.read(tabHistoryStatesProvider.notifier).removeAll(removedTabIds);
+      ref.read(tabFindResultStatesProvider.notifier).removeAll(removedTabIds);
+      ref.read(tabTranslationStatesProvider.notifier).removeAll(removedTabIds);
+    });
+
     ref.onDispose(() async {
       for (final sub in subscriptions) {
         await sub.cancel();