diff --git a/test/cloud_architecture_contract_test.dart b/test/cloud_architecture_contract_test.dart
new file mode 100644
index 0000000..6aff3e1
--- /dev/null
+++ b/test/cloud_architecture_contract_test.dart
@@ -0,0 +1,64 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:motorsignal/services/cloud/cloud_models.dart';
+import 'package:motorsignal/services/entitlements/entitlement_state.dart';
+
+void main() {
+  group('Cloud architecture contracts', () {
+    test('profile DTO preserves stable identity', () {
+      final now = DateTime.utc(2026, 9, 1);
+      final profile = CloudUserProfile(
+        id: 'firebase-user-1',
+        displayName: 'Rider',
+        createdAt: now,
+        updatedAt: now,
+      );
+
+      final json = profile.toJson();
+      expect(json['id'], 'firebase-user-1');
+      expect(json['displayName'], 'Rider');
+      expect(json['createdAt'], now.toIso8601String());
+    });
+
+    test('motorcycle DTO keeps owner separate from display identity', () {
+      final now = DateTime.utc(2026, 9, 1);
+      final motorcycle = CloudMotorcycle(
+        id: '42',
+        ownerId: 'firebase-user-1',
+        year: 2001,
+        makeId: 'yamaha',
+        makeName: 'Yamaha',
+        modelId: 'yzf-r6',
+        modelName: 'YZF-R6',
+        isDefault: true,
+        createdAt: now,
+        updatedAt: now,
+      );
+
+      expect(motorcycle.toJson()['id'], '42');
+      expect(motorcycle.toJson()['ownerId'], 'firebase-user-1');
+      expect(motorcycle.toJson()['year'], 2001);
+    });
+
+    test('free entitlement exposes core capabilities but not premium capabilities', () {
+      const state = EntitlementState();
+      expect(state.canCloudBackup, isTrue);
+      expect(state.canAdvancedTelemetry, isFalse);
+      expect(state.canExportCsv, isFalse);
+      expect(state.canPlanTrips, isFalse);
+    });
+
+    test('lifetime entitlement exposes the complete Pro capability surface', () {
+      const state = EntitlementState(
+        plan: MotorSignalPlan.proLifetime,
+        status: MotorSignalEntitlementStatus.proLifetime,
+      );
+      expect(state.isPro, isTrue);
+      expect(state.canUnlimitedCloudHistory, isTrue);
+      expect(state.canAdvancedAcceleration, isTrue);
+      expect(state.canAdvancedBraking, isTrue);
+      expect(state.canAdvancedLean, isTrue);
+      expect(state.canExportPdf, isTrue);
+      expect(state.canCreateGroupRides, isTrue);
+    });
+  });
+}