fix(data-access): add guard for app actors

src/backend/src/modules/data-access/AppService.js

@@ -494,6 +494,26 @@ export default class AppService extends BaseService {
         return result.insertId;
     }
 
+    async #check_app_owner_permission (old_app, actor) {
+        // Check if app has write permission to all user's apps
+        const svc_permission = this.services.get('permission');
+        const user = actor.type.user;
+        const perm = `es:app:${user.uuid}:write`;
+        const can_write_any = await svc_permission.check(actor, perm);
+        if ( can_write_any ) {
+            return;
+        }
+
+        // Otherwise verify the app owns this entity
+        const app = actor.type.app;
+        const app_owner = old_app.app_owner;
+        const app_owner_uid = app_owner?.uid;
+
+        if ( ! app_owner_uid || app_owner_uid !== app.uid ) {
+            throw APIError.create('forbidden');
+        }
+    }
+
     async #update ({ object, id, options }) {
         const old_app = await this.#read({
             uid: object.uid,
@@ -515,6 +535,11 @@ export default class AppService extends BaseService {
         // Check owner permission (WriteByOwnerOnlyES behavior)
         await this.#check_owner_permission(old_app);
 
+        // If actor is AppUnderUserActorType, check app_owner (AppLimitedES behavior)
+        if ( actor.type instanceof AppUnderUserActorType ) {
+            await this.#check_app_owner_permission(old_app, actor);
+        }
+
         // Remove protected/read_only fields from the update (ValidationES behavior)
         {
             object = { ...object };

src/backend/src/modules/data-access/AppService.test.js

@@ -1195,6 +1195,62 @@ describe('AppService', () => {
                 expect.arrayContaining(['https://mysite.puter.site'])
             );
         });
+
+        it('should throw forbidden when app actor does not own the entity (AppLimitedES behavior)', async () => {
+            // App actor trying to update an app it didn't create
+            setupContextForWrite(createMockAppUnderUserActor(1, 999));
+            mockDb.read.mockResolvedValue([createMockAppRow({
+                owner_user_id: 1,
+                app_owner_uid: 'different-app-uid',
+            })]);
+
+            const crudQ = AppService.IMPLEMENTS['crud-q'];
+
+            await expect(crudQ.update.call(appService, {
+                object: { uid: 'app-uid-123', title: 'Hacked Title' },
+            })).rejects.toThrow();
+        });
+
+        it('should allow app actor to update entity it owns (AppLimitedES behavior)', async () => {
+            // App actor updating an app it created
+            const actor = createMockAppUnderUserActor(1, 100);
+            actor.type.app.uid = 'creator-app-uid';
+            setupContextForWrite(actor);
+            mockDb.read.mockResolvedValue([createMockAppRow({
+                owner_user_id: 1,
+                app_owner_uid: 'creator-app-uid',
+            })]);
+
+            const crudQ = AppService.IMPLEMENTS['crud-q'];
+            await crudQ.update.call(appService, {
+                object: { uid: 'app-uid-123', title: 'Updated by App' },
+            });
+
+            expect(mockDbWrite.write).toHaveBeenCalledWith(
+                expect.stringContaining('UPDATE apps SET'),
+                expect.arrayContaining(['Updated by App'])
+            );
+        });
+
+        it('should allow app actor with write permission to update any entity (AppLimitedES behavior)', async () => {
+            setupContextForWrite(createMockAppUnderUserActor(1, 999));
+            mockDb.read.mockResolvedValue([createMockAppRow({
+                owner_user_id: 1,
+                app_owner_uid: 'different-app-uid',
+            })]);
+            // Grant write permission
+            mockPermissionService.check.mockResolvedValue(true);
+
+            const crudQ = AppService.IMPLEMENTS['crud-q'];
+            await crudQ.update.call(appService, {
+                object: { uid: 'app-uid-123', title: 'Admin Update' },
+            });
+
+            expect(mockDbWrite.write).toHaveBeenCalledWith(
+                expect.stringContaining('UPDATE apps SET'),
+                expect.arrayContaining(['Admin Update'])
+            );
+        });
     });
 
     describe('#upsert', () => {