feat: content repository merges cached seasons with bundled fallback

Extends ContentRepository with optional cacheDir: cached packs in
<cacheDir>/seasons/*/pack.json merge with bundled ones (cached wins
for same id), corrupt/future-schema packs silently ignored, refresh()
fires ContentDownloader.sync() once per session. main() wires the real
cache+downloader instance; default constructor stays bundled-only for tests.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/data/content_repository.dart

@@ -1,21 +1,74 @@
 import 'dart:convert';
+import 'dart:io';
 
 import 'package:flutter/services.dart';
 
 import '../game/models/season.dart';
+import 'remote/content_downloader.dart';
 
-/// Resolves season content. Phase 3: bundled assets only; remote download
-/// and caching land in Phase 4.
+/// Resolves season content: bundled season 1 is always available offline;
+/// remotely synced packs in [cacheDir] extend or override it. Load errors on
+/// any single pack never break the list — worst case the player sees the
+/// bundled content.
 class ContentRepository {
+  ContentRepository({this.cacheDir, ContentDownloader? downloader})
+      : _downloader = downloader;
+
   static const bundledSeasonIds = ['season_001'];
 
+  final Directory? cacheDir;
+  final ContentDownloader? _downloader;
+  bool _syncedThisSession = false;
+
   Future<SeasonPack> loadBundledSeason(String seasonId) async {
     final raw =
         await rootBundle.loadString('assets/seasons/$seasonId/pack.json');
     return SeasonPack.fromJson(jsonDecode(raw) as Map<String, dynamic>);
   }
 
-  Future<List<SeasonPack>> availableSeasons() async => [
-        for (final id in bundledSeasonIds) await loadBundledSeason(id),
-      ];
+  SeasonPack? _loadCachedSeason(Directory dir) {
+    try {
+      final file = File('${dir.path}/pack.json');
+      if (!file.existsSync()) return null;
+      return SeasonPack.fromJson(
+          jsonDecode(file.readAsStringSync()) as Map<String, dynamic>);
+    } catch (_) {
+      return null; // Corrupt or future-schema pack: ignore.
+    }
+  }
+
+  /// All playable seasons, sorted by seasonId. Cached packs win over the
+  /// bundled copy of the same season (they may carry balance fixes).
+  Future<List<SeasonPack>> availableSeasons() async {
+    final byId = <String, SeasonPack>{};
+    for (final id in bundledSeasonIds) {
+      try {
+        byId[id] = await loadBundledSeason(id);
+      } catch (_) {
+        // Bundled pack should never fail; if it does, skip rather than crash.
+      }
+    }
+
+    final seasonsDir =
+        cacheDir == null ? null : Directory('${cacheDir!.path}/seasons');
+    if (seasonsDir != null && seasonsDir.existsSync()) {
+      for (final entry in seasonsDir.listSync().whereType<Directory>()) {
+        final pack = _loadCachedSeason(entry);
+        if (pack != null) byId[pack.seasonId] = pack;
+      }
+    }
+
+    final list = byId.values.toList()
+      ..sort((a, b) => a.seasonId.compareTo(b.seasonId));
+    return list;
+  }
+
+  /// Fire-once-per-session remote sync. Returns true when new content
+  /// arrived (callers then re-read [availableSeasons]).
+  Future<bool> refresh() async {
+    final downloader = _downloader;
+    if (downloader == null || _syncedThisSession) return false;
+    _syncedThisSession = true;
+    return downloader.sync();
+  }
 }

lib/main.dart

@@ -1,17 +1,48 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:path_provider/path_provider.dart';
 
 import 'app.dart';
+import 'data/content_repository.dart';
+import 'data/remote/content_downloader.dart';
 import 'data/save_repository.dart';
 import 'state/providers.dart';
 
+/// Remote content origin. Swap per environment with
+/// --dart-define=CONTENT_BASE_URL=...; the default points at the production
+/// Firebase Hosting site (owner setup pending).
+const contentBaseUrl = String.fromEnvironment(
+  'CONTENT_BASE_URL',
+  defaultValue: 'https://block-seasons.web.app/content',
+);
+
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
   final saveRepository = await SaveRepository.open();
-  runApp(
-    ProviderScope(
-      overrides: [saveRepositoryProvider.overrideWithValue(saveRepository)],
-      child: const BlockSeasonsApp(),
-    ),
-  );
+
+  ContentRepository contentRepository;
+  try {
+    final support = await getApplicationSupportDirectory();
+    final cacheDir = Directory('${support.path}/content');
+    contentRepository = ContentRepository(
+      cacheDir: cacheDir,
+      downloader: ContentDownloader(
+        baseUrl: contentBaseUrl,
+        cacheDir: cacheDir,
+      ),
+    );
+  } catch (e) {
+    debugPrint('content cache unavailable, bundled only: $e');
+    contentRepository = ContentRepository();
+  }
+
+  runApp(ProviderScope(
+    overrides: [
+      saveRepositoryProvider.overrideWithValue(saveRepository),
+      contentRepositoryProvider.overrideWithValue(contentRepository),
+    ],
+    child: const BlockSeasonsApp(),
+  ));
 }

test/data/content_repository_test.dart

@@ -1,4 +1,8 @@
+import 'dart:convert';
+import 'dart:io';
+
 import 'package:block_seasons/data/content_repository.dart';
+import 'package:block_seasons/game/models/season.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
@@ -25,4 +29,75 @@ void main() {
     final seasons = await repo.availableSeasons();
     expect(seasons.map((s) => s.seasonId), contains('season_001'));
   });
+
+  group('cache merge and fallback', () {
+    late Directory tmp;
+
+    setUp(() async {
+      tmp = await Directory.systemTemp.createTemp('bs_repo_');
+    });
+
+    tearDown(() async {
+      if (await tmp.exists()) await tmp.delete(recursive: true);
+    });
+
+    Map<String, dynamic> packJson(String id) => {
+          'schemaVersion': 1,
+          'seasonId': id,
+          'version': 1,
+          'title': {'en': id},
+          'theme': const SeasonTheme().toJson(),
+          'stages': [
+            {
+              'id': '${id}_001',
+              'seed': 1,
+              'moveLimit': 10,
+              'preset': [],
+              'objectives': [
+                {'type': 'reachScore', 'target': 100}
+              ],
+              'stars': {
+                'two': {'movesLeft': 2},
+                'three': {'movesLeft': 4}
+              },
+              'generatorProfile': 'mid',
+            }
+          ],
+        };
+
+    Future<void> putCachedSeason(String id) async {
+      final dir = Directory('${tmp.path}/seasons/$id');
+      await dir.create(recursive: true);
+      await File('${dir.path}/pack.json')
+          .writeAsString(jsonEncode(packJson(id)));
+    }
+
+    test('merges cached seasons after bundled ones, sorted by id', () async {
+      TestWidgetsFlutterBinding.ensureInitialized();
+      await putCachedSeason('season_002');
+      final repo = ContentRepository(cacheDir: tmp);
+      final seasons = await repo.availableSeasons();
+      expect(seasons.map((s) => s.seasonId).toList(),
+          ['season_001', 'season_002']);
+    });
+
+    test('cached copy of a bundled season wins over the bundle', () async {
+      TestWidgetsFlutterBinding.ensureInitialized();
+      await putCachedSeason('season_001');
+      final repo = ContentRepository(cacheDir: tmp);
+      final seasons = await repo.availableSeasons();
+      // Cached fake has exactly 1 stage; the bundled real one has 60.
+      expect(seasons.single.stages, hasLength(1));
+    });
+
+    test('corrupt cached pack falls back to bundle silently', () async {
+      TestWidgetsFlutterBinding.ensureInitialized();
+      final dir = Directory('${tmp.path}/seasons/season_001');
+      await dir.create(recursive: true);
+      await File('${dir.path}/pack.json').writeAsString('{not json');
+      final repo = ContentRepository(cacheDir: tmp);
+      final seasons = await repo.availableSeasons();
+      expect(seasons.single.stages, hasLength(60));
+    });
+  });
 }