added product import and billing integration

lib/data/local/catalogue_dao.dart

@@ -239,6 +239,24 @@ class CatalogueDao {
     });
   }
 
+  /// Drops every product and forgets when the catalogue was last imported.
+  ///
+  /// Used at sign-out. Leaves customers, staff, orders and every other table
+  /// untouched — this is about the shelf, not the terminal's history — so the
+  /// next session starts with nothing to sell until it pulls a fresh copy from
+  /// the back office rather than carrying over whatever this session ended
+  /// with.
+  Future<void> clearCatalogue() async {
+    await _db.transaction((txn) async {
+      await txn.delete(Tables.products);
+      await txn.delete(
+        Tables.meta,
+        where: 'key IN (?, ?)',
+        whereArgs: [MetaKeys.lastImportAt, MetaKeys.catalogueRevision],
+      );
+    });
+  }
+
   /// Applies stock movement after a sale, clamped at zero.
   Future<void> decrementStock(Map<String, double> quantities) async {
     if (quantities.isEmpty) return;

lib/data/local/order_dao.dart

@@ -85,6 +85,46 @@ class OrderDao {
     });
   }
 
+  /// Reverses [commitSale]: deletes the order and its lines, adds the stock
+  /// back, and restores an attached customer's row exactly as passed in
+  /// (the caller supplies the pre-sale row — reconstructing it from deltas
+  /// here would get `last_visit_at` wrong).
+  Future<void> voidSale({
+    required String orderId,
+    required Map<String, double> stockMovements,
+    Map<String, Object?>? customerRow,
+  }) async {
+    await _db.transaction((txn) async {
+      await txn
+          .delete(Tables.orderItems, where: 'order_id = ?', whereArgs: [orderId]);
+      await txn.delete(Tables.orders, where: 'id = ?', whereArgs: [orderId]);
+
+      final batch = txn.batch();
+      final now = DateTime.now().millisecondsSinceEpoch;
+      stockMovements.forEach((id, qty) {
+        batch.rawUpdate(
+          'UPDATE ${Tables.products} SET stock = stock + ?, updated_at = ? '
+          'WHERE id = ?',
+          [qty, now, id],
+        );
+      });
+      if (customerRow != null) {
+        batch.update(
+          Tables.customers,
+          {
+            'loyalty_points': customerRow['loyalty_points'],
+            'lifetime_spend': customerRow['lifetime_spend'],
+            'visit_count': customerRow['visit_count'],
+            'last_visit_at': customerRow['last_visit_at'],
+          },
+          where: 'id = ?',
+          whereArgs: [customerRow['id']],
+        );
+      }
+      await batch.commit(noResult: true);
+    });
+  }
+
   Future<void> _insertOrder(DatabaseExecutor txn, SaleTransaction t) async {
     final cart = t.cart;
 

lib/data/local/terminal_identity.dart

@@ -53,7 +53,13 @@ class TerminalIdentityStore {
   ///
   /// The mint is idempotent: an existing device id is never replaced, so a
   /// terminal cannot silently change identity and orphan its own history.
-  Future<TerminalIdentity> load({String defaultStoreId = 'store-01'}) async {
+  ///
+  /// [defaultStoreId] matches the store this build's default HTTP endpoint
+  /// serves — see `syncConfigProvider` — so a fresh terminal's first import
+  /// pulls that store's real catalogue without anyone visiting Settings
+  /// first. Settings → Connectivity & sync → Configure changes it per
+  /// terminal from there.
+  Future<TerminalIdentity> load({String defaultStoreId = '1135'}) async {
     var deviceId = await _catalogue.meta(MetaKeys.deviceId);
     var code = await _catalogue.meta(MetaKeys.terminalCode);