improved performance and battery usage on older devices

lib/state/app/modules/ticker/bloc/ticker_page_bloc.dart

@@ -1,3 +1,8 @@
+import 'dart:async';
+
+import 'package:hydrated_bloc/hydrated_bloc.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
 import '../../../../../api/errors/ticker_content_unavailable_exception.dart';
 import '../../../../../api/marianumconnect/queries/get_ticker_page/get_ticker_page_response.dart';
 import '../../../infrastructure/utility_widgets/loadable_hydrated_bloc/loadable_hydrated_bloc.dart';
@@ -17,7 +22,35 @@ class TickerPageBloc
         > {
   final String slug;
 
-  TickerPageBloc(this.slug);
+  TickerPageBloc(this.slug) {
+    unawaited(_rememberSlug());
+  }
+
+  static const _recentSlugsKey = 'tickerPageRecentSlugs';
+  static const _keepPages = 50;
+
+  /// Every page ever opened used to stay in the hydrated box forever — and
+  /// the whole box is decoded before the first frame on each cold start.
+  /// The most recently opened pages (far more than a normal reader revisits)
+  /// keep their offline copy; only long-forgotten ones are dropped.
+  Future<void> _rememberSlug() async {
+    try {
+      final prefs = await SharedPreferences.getInstance();
+      final recent = prefs.getStringList(_recentSlugsKey) ?? <String>[];
+      recent
+        ..remove(slug)
+        ..insert(0, slug);
+      for (final evicted in recent.skip(_keepPages)) {
+        await HydratedBloc.storage.delete('$storagePrefix$evicted');
+      }
+      await prefs.setStringList(
+        _recentSlugsKey,
+        recent.take(_keepPages).toList(),
+      );
+    } on Object {
+      // Best effort: a failed cleanup only leaves an extra offline copy.
+    }
+  }
 
   @override
   String get id => slug;