feat(iap): remove_ads purchase/restore service + adsRemoved notifier

lib/services/iap_service.dart

@@ -0,0 +1,73 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:in_app_purchase/in_app_purchase.dart';
+
+import 'ad_config.dart';
+
+/// Wraps the non-consumable `remove_ads` purchase. On any verified purchase
+/// or restore of the product it invokes [onEntitlementGranted]; the caller
+/// flips the AdsRemovedNotifier. All failures are swallowed.
+class IapService {
+  IapService({required this.onEntitlementGranted});
+
+  final Future<void> Function() onEntitlementGranted;
+  final InAppPurchase _iap = InAppPurchase.instance;
+  StreamSubscription<List<PurchaseDetails>>? _sub;
+  ProductDetails? _product;
+
+  bool get available => _available;
+  bool _available = false;
+
+  ProductDetails? get product => _product;
+
+  Future<void> initialize() async {
+    try {
+      _available = await _iap.isAvailable();
+      if (!_available) return;
+      _sub = _iap.purchaseStream.listen(_onPurchases,
+          onError: (_) {}, cancelOnError: false);
+      final response =
+          await _iap.queryProductDetails({AdConfig.removeAdsProductId});
+      if (response.productDetails.isNotEmpty) {
+        _product = response.productDetails.first;
+      }
+    } catch (e) {
+      debugPrint('IAP init failed: $e');
+    }
+  }
+
+  Future<void> buyRemoveAds() async {
+    final product = _product;
+    if (product == null) return;
+    try {
+      await _iap.buyNonConsumable(
+          purchaseParam: PurchaseParam(productDetails: product));
+    } catch (e) {
+      debugPrint('IAP buy failed: $e');
+    }
+  }
+
+  Future<void> restorePurchases() async {
+    try {
+      await _iap.restorePurchases();
+    } catch (e) {
+      debugPrint('IAP restore failed: $e');
+    }
+  }
+
+  Future<void> _onPurchases(List<PurchaseDetails> purchases) async {
+    for (final p in purchases) {
+      if (p.productID != AdConfig.removeAdsProductId) continue;
+      if (p.status == PurchaseStatus.purchased ||
+          p.status == PurchaseStatus.restored) {
+        await onEntitlementGranted();
+      }
+      if (p.pendingCompletePurchase) {
+        await _iap.completePurchase(p);
+      }
+    }
+  }
+
+  void dispose() => _sub?.cancel();
+}

lib/state/ads_notifier.dart

@@ -0,0 +1,17 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'providers.dart';
+
+/// Whether the player owns the remove-ads entitlement. Seeded from the save
+/// repository; [grant] flips it on (after a successful purchase/restore) and
+/// persists.
+class AdsRemovedNotifier extends Notifier<bool> {
+  @override
+  bool build() => ref.read(saveRepositoryProvider).adsRemoved;
+
+  Future<void> grant() async {
+    if (state) return;
+    await ref.read(saveRepositoryProvider).setAdsRemoved(true);
+    state = true;
+  }
+}

lib/state/providers.dart

@@ -6,6 +6,7 @@ import '../data/streak.dart';
 import '../game/models/season.dart';
 import '../services/analytics_service.dart';
 import '../services/audio_service.dart';
+import 'ads_notifier.dart';
 import 'endless_best_notifier.dart';
 import 'game_session_notifier.dart';
 import 'progress_notifier.dart';
@@ -71,6 +72,9 @@ final endlessBestProvider = NotifierProvider<EndlessBestNotifier, int>(
   EndlessBestNotifier.new,
 );
 
+final adsRemovedProvider =
+    NotifierProvider<AdsRemovedNotifier, bool>(AdsRemovedNotifier.new);
+
 final analyticsProvider = Provider<AnalyticsService>(
   (ref) => AnalyticsService(DebugAnalyticsBackend()),
 );

test/state/ads_notifier_test.dart

@@ -0,0 +1,22 @@
+import 'package:block_seasons/data/save_repository.dart';
+import 'package:block_seasons/state/ads_notifier.dart';
+import 'package:block_seasons/state/providers.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+void main() {
+  test('reads persisted ownership and updates on grant', () async {
+    SharedPreferences.setMockInitialValues({});
+    final repo = await SaveRepository.open();
+    final container = ProviderContainer(
+      overrides: [saveRepositoryProvider.overrideWithValue(repo)],
+    );
+    addTearDown(container.dispose);
+
+    expect(container.read(adsRemovedProvider), isFalse);
+    await container.read(adsRemovedProvider.notifier).grant();
+    expect(container.read(adsRemovedProvider), isTrue);
+    expect(repo.adsRemoved, isTrue);
+  });
+}