second commit

lib/domain/repositories/customer_repository.dart

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+import '../entities/customer.dart';
+
+abstract class CustomerRepository {
+  /// Primary lookup on the Existing Customer screen.
+  Future<Customer?> findByMobile(String mobile);
+
+  Future<Customer?> findById(String id);
+
+  Future<Customer> create(Customer customer);
+
+  Future<Customer> update(Customer customer);
+
+  /// Applies loyalty and lifetime-spend changes once a sale completes.
+  Future<Customer> recordSale({
+    required String customerId,
+    required double amount,
+    required int pointsEarned,
+    required int pointsRedeemed,
+  });
+
+  Future<List<Customer>> search(String query);
+
+  Future<List<Customer>> recent({int limit = 20});
+}

lib/domain/repositories/product_repository.dart

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+import '../entities/product.dart';
+
+/// Contract for catalogue access. Implemented in the data layer so the
+/// presentation layer never depends on Hive, HTTP or any other detail.
+abstract class ProductRepository {
+  Future<List<Product>> getAll();
+
+  Future<List<Product>> getByCategory(ProductCategory category);
+
+  /// Exact barcode lookup — the hot path for scanner billing.
+  Future<Product?> findByBarcode(String barcode);
+
+  Future<Product?> findById(String id);
+
+  /// Fuzzy search across name, barcode, SKU, brand and category.
+  Future<List<Product>> search(String query);
+
+  /// Decrements stock after a completed sale.
+  Future<void> decrementStock(Map<String, double> quantitiesByProductId);
+
+  Future<void> upsert(Product product);
+}

lib/domain/repositories/sync_repository.dart

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+import '../entities/shift_report.dart';
+import '../entities/sync_event.dart';
+
+/// The terminal's two network touchpoints, plus the durable event log.
+abstract class SyncRepository {
+  /// True once products have been pulled onto this terminal.
+  bool get hasCatalogue;
+
+  DateTime? get lastImportAt;
+  String? get catalogueRevision;
+
+  /// Pulls the catalogue and writes it locally.
+  ///
+  /// Records a [SyncEventType.catalogueImport] event whether or not it
+  /// succeeds, so the log reflects every attempt.
+  Future<SyncEvent> importCatalogue({
+    void Function(double progress, String stage)? onProgress,
+  });
+
+  /// Builds the day's report from locally stored sales.
+  ShiftReport buildShiftReport({
+    required DateTime businessDate,
+    required String terminalId,
+    required String cashierName,
+  });
+
+  /// Queues the report and attempts to push it.
+  ///
+  /// On failure the event is kept in [SyncStatus.failed] so nothing is lost.
+  Future<SyncEvent> pushShiftReport(ShiftReport report);
+
+  /// Retries a previously failed or pending push.
+  Future<SyncEvent> retry(String eventId);
+
+  List<SyncEvent> get events;
+
+  bool get hasUnsyncedEvents;
+}

lib/domain/repositories/transaction_repository.dart

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+import '../entities/transaction.dart';
+
+abstract class TransactionRepository {
+  Future<SaleTransaction> save(SaleTransaction transaction);
+
+  Future<List<SaleTransaction>> history({int limit = 50});
+
+  Future<SaleTransaction?> findByInvoice(String invoiceNumber);
+
+  /// Next invoice sequence for the current month.
+  Future<int> nextInvoiceSequence();
+
+  Future<void> park(ParkedBill bill);
+
+  Future<List<ParkedBill>> parkedBills();
+
+  Future<void> removeParked(String id);
+
+  Future<double> salesTotalForDay(DateTime day);
+}