feat: add historical data

test/remote_sync_service_test.dart

@@ -443,4 +443,152 @@ void main() {
       },
     );
   });
+
+  group('tab events', () {
+    Future<void> queueEvent(String id, DateTime createdAt) async {
+      await database
+          .into(database.tabEvents)
+          .insert(
+            TabEventsCompanion.insert(
+              id: id,
+              payload: jsonEncode({'id': id, 'type': 'line_added'}),
+              createdAt: createdAt,
+            ),
+          );
+    }
+
+    Future<List<String>> outboxIds() async {
+      final rows = await database.select(database.tabEvents).get();
+      return [for (final row in rows) row.id];
+    }
+
+    List<String> sentIds([int request = 0]) => [
+      for (final event in server.syncRequests[request]['events'] as List)
+        event['id'] as String,
+    ];
+
+    test('sends at most 500 events, oldest first', () async {
+      final start = DateTime(2026, 10, 24, 20);
+      // Inserted newest first, so only the timestamps give the order
+      for (var i = 501; i >= 1; i--) {
+        await queueEvent('e$i', start.add(Duration(minutes: i)));
+      }
+
+      await service.sync();
+
+      expect(sentIds(), [for (var i = 1; i <= 500; i++) 'e$i']);
+      expect(server.syncRequests.single['events'].first, {
+        'id': 'e1',
+        'type': 'line_added',
+      });
+    });
+
+    test('deletes exactly the acknowledged and rejected events', () async {
+      final now = DateTime.now();
+      for (final id in ['e1', 'e2', 'e3']) {
+        await queueEvent(id, now);
+      }
+      server.respondWith({
+        'acknowledgedEventIds': ['e1'],
+        'rejectedEvents': [
+          {'id': 'e2', 'reason': 'unknown type'},
+          {'reason': 'not an object'},
+        ],
+      });
+
+      await service.sync();
+
+      expect(await outboxIds(), ['e3']);
+    });
+
+    test('a failed sync deletes nothing', () async {
+      await queueEvent('e1', DateTime.now());
+      server.syncResponse = http.Response(
+        jsonEncode({
+          'acknowledgedEventIds': ['e1'],
+        }),
+        500,
+      );
+
+      await service.sync();
+
+      expect(await outboxIds(), ['e1']);
+    });
+
+    test('an older server without event fields keeps the events', () async {
+      await queueEvent('e1', DateTime.now());
+
+      await service.sync();
+
+      expect(await outboxIds(), ['e1']);
+    });
+
+    test('events created during the sync wait for the next one', () async {
+      final tab = await barTabService.createTab(customerName: 'Alice');
+      await barTabService.addProductToTab(tabId: tab.id, product: _beer);
+      server.holdSync = Completer<void>();
+
+      final running = service.sync();
+      await pumpEventQueue();
+      await barTabService.addProductToTab(tabId: tab.id, product: _beer);
+      server.respondWith({'acknowledgedEventIds': sentIds()});
+      server.holdSync!.complete();
+      server.holdSync = null;
+      await running;
+
+      expect(sentIds(), hasLength(1));
+      final remaining = await outboxIds();
+      expect(remaining, hasLength(1));
+      expect(remaining, isNot(contains(sentIds().single)));
+    });
+
+    test('a close_tab command writes one settled event', () async {
+      final tab = await barTabService.createTab(customerName: 'Alice');
+      await barTabService.addProductToTab(tabId: tab.id, product: _beer);
+      await barTabService.addProductToTab(tabId: tab.id, product: _beer);
+      final current = (await barTabService.getTabById(tab.id))!;
+      server.respondWith({
+        'commands': [
+          _closeCommand(
+            id: 'cmd-1',
+            tabId: tab.id,
+            expectedVersion: current.version,
+          ),
+        ],
+      });
+
+      // The second sync receives the same command again
+      await service.sync();
+      await service.sync();
+
+      final settled = [
+        for (final event in server.syncRequests.last['events'] as List)
+          if (event['type'] == 'settled') event,
+      ];
+      expect(settled, hasLength(1));
+      expect(settled.single['commandId'], 'cmd-1');
+      expect(settled.single['paymentMethod'], 'payconiq');
+      expect(settled.single['amountInCents'], 800);
+      expect(settled.single['customerName'], 'Alice');
+    });
+
+    test('a conflicting close_tab command writes no settled event', () async {
+      final tab = await barTabService.createTab(customerName: 'Alice');
+      await barTabService.addProductToTab(tabId: tab.id, product: _beer);
+      server.respondWith({
+        'commands': [
+          _closeCommand(id: 'cmd-1', tabId: tab.id, expectedVersion: 1),
+        ],
+      });
+
+      await service.sync();
+      await service.sync();
+
+      final types = [
+        for (final event in server.syncRequests.last['events'] as List)
+          event['type'],
+      ];
+      expect(types, ['line_added']);
+    });
+  });
 }