added local db

lib/domain/repositories/sync_repository.dart

@@ -1,38 +1,79 @@
 import '../entities/shift_report.dart';
 import '../entities/sync_event.dart';
+import '../entities/transaction.dart';
 
-/// The terminal's two network touchpoints, plus the durable event log.
+/// Result of one end-of-day upload.
+class SyncOutcome {
+  const SyncOutcome({
+    required this.attempted,
+    required this.uploaded,
+    this.error,
+  });
+
+  final int attempted;
+  final int uploaded;
+  final String? error;
+
+  bool get isSuccess => error == null;
+  bool get hadNothingToDo => attempted == 0;
+  int get remaining => attempted - uploaded;
+}
+
+/// One row of the order sync log.
+class OrderSyncRow {
+  const OrderSyncRow({
+    required this.orderId,
+    required this.invoiceNumber,
+    required this.total,
+    required this.createdAt,
+    required this.isSynced,
+    this.syncedAt,
+    this.attempts = 0,
+    this.error,
+  });
+
+  final String orderId;
+  final String invoiceNumber;
+  final double total;
+  final DateTime createdAt;
+  final bool isSynced;
+  final DateTime? syncedAt;
+  final int attempts;
+  final String? error;
+}
+
+/// The terminal's two network touchpoints.
+///
+/// Morning: pull the catalogue. End of day: upload every order still at
+/// `sync_status = 0`. Nothing else leaves the device.
 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.
+  /// Morning step — downloads products and writes them to SQLite.
   Future<SyncEvent> importCatalogue({
     void Function(double progress, String stage)? onProgress,
   });
 
-  /// Builds the day's report from locally stored sales.
-  ShiftReport buildShiftReport({
-    required DateTime businessDate,
+  /// How many bills are still held locally.
+  Future<int> unsyncedCount();
+
+  Future<List<SaleTransaction>> unsyncedOrders();
+
+  /// Today's trading totals, read back from SQLite.
+  Future<ShiftReport> todayReport({
     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);
+  /// End-of-day step — uploads pending orders and flips the accepted ones to
+  /// `sync_status = 1`. Failures leave every row untouched at 0.
+  Future<SyncOutcome> syncOrders({
+    void Function(double progress, String stage)? onProgress,
+  });
 
-  /// Retries a previously failed or pending push.
-  Future<SyncEvent> retry(String eventId);
+  Future<List<OrderSyncRow>> orderSyncRows({int limit = 200});
 
   List<SyncEvent> get events;
-
-  bool get hasUnsyncedEvents;
 }