refactor(puzzle): address review on offline puzzle setting

- Remove now-unused kPuzzleLocalQueueLength constant and its stale comment
- Clamp nbOfflinePuzzles on load in PuzzlePreferences.build() so corrupted
  or manually edited prefs cannot bypass the 50-500 bounds
- Add a widget test covering the offline puzzles settings tile and picker

Author: wernerhp

lib/src/model/puzzle/puzzle_preferences.dart

@@ -26,7 +26,12 @@ class PuzzlePreferences extends Notifier<PuzzlePrefs> with SessionPreferencesSto
 
   @override
   PuzzlePrefs build() {
-    return fetch();
+    final prefs = fetch();
+    // Clamp the offline queue length loaded from storage: corrupted or
+    // manually edited prefs could otherwise bypass the bounds enforced by
+    // [setNbOfflinePuzzles] and trigger very large downloads.
+    final clamped = prefs.nbOfflinePuzzles.clamp(kMinOfflinePuzzles, kMaxOfflinePuzzles);
+    return clamped == prefs.nbOfflinePuzzles ? prefs : prefs.copyWith(nbOfflinePuzzles: clamped);
   }
 
   Future<void> setDifficulty(PuzzleDifficulty difficulty) async {

lib/src/model/puzzle/puzzle_service.dart

@@ -18,10 +18,6 @@ import 'package:result_extensions/result_extensions.dart';
 
 part 'puzzle_service.freezed.dart';
 
-/// Default size of puzzle local cache. Used as a fallback; the effective
-/// queue length is user-configurable via [PuzzlePrefs.nbOfflinePuzzles].
-const kPuzzleLocalQueueLength = 50;
-
 /// A provider for [PuzzleService].
 final puzzleServiceProvider = FutureProvider<PuzzleService>((Ref ref) {
   final nbOfflinePuzzles = ref.watch(

test/view/puzzle/puzzle_screen_test.dart

@@ -123,6 +123,53 @@ void main() {
       expect(find.text('Your turn'), findsOneWidget);
     });
 
+    testWidgets(
+      'Changing the offline puzzles setting updates the displayed value',
+      variant: kPlatformVariant,
+      (tester) async {
+        final app = await makeTestProviderScopeApp(
+          tester,
+          home: PuzzleScreen(
+            angle: const PuzzleTheme(PuzzleThemeKey.mix),
+            puzzleId: puzzle.puzzle.id,
+          ),
+          overrides: {
+            puzzleBatchStorageProvider: puzzleBatchStorageProvider.overrideWith(
+              (ref) => mockBatchStorage,
+            ),
+            puzzleStorageProvider: puzzleStorageProvider.overrideWith((ref) => mockHistoryStorage),
+          },
+        );
+
+        when(
+          () => mockHistoryStorage.fetch(puzzleId: puzzle.puzzle.id),
+        ).thenAnswer((_) async => puzzle);
+
+        await tester.pumpWidget(app);
+
+        // wait for the puzzle to load
+        await tester.pump(const Duration(milliseconds: 200));
+
+        // open settings
+        await tester.tap(find.byIcon(Icons.settings));
+        await tester.pumpAndSettle();
+
+        // the offline puzzles tile shows the default value
+        final tileFinder = find.widgetWithText(SettingsListTile, 'Offline puzzles');
+        expect(tileFinder, findsOneWidget);
+        expect(tester.widget<SettingsListTile>(tileFinder).settingsValue, '50');
+
+        // open the choice picker and select a larger value
+        await tester.tap(tileFinder);
+        await tester.pumpAndSettle();
+        await tester.tap(find.text('200').last);
+        await tester.pumpAndSettle();
+
+        // the tile reflects the new value
+        expect(tester.widget<SettingsListTile>(tileFinder).settingsValue, '200');
+      },
+    );
+
     testWidgets('Loads next puzzle when no puzzleId is passed', (tester) async {
       final app = await makeTestProviderScopeApp(
         tester,