feat(app-dev): add dry-run preview to dev sync (#21251)

Split out of #21240. Stacked on #21250 (review/merge that first).

`yarn twenty dev --once --dry-run` computes the migration plan and
prints the diff **without applying anything** (no migration, no
app-record update, no SDK generation). Also renders the diff on a normal
`dev --once` sync.

<img width="646" height="179" alt="image"
src="https://github.com/user-attachments/assets/59f3ddcd-2a5b-4b8a-b21a-c659abe16af0"
/>

packages/twenty-server/test/integration/metadata/suites/application/dry-run-manifest-sync.integration-spec.ts

@@ -0,0 +1,84 @@
+import { buildBaseManifest } from 'test/integration/metadata/suites/application/utils/build-base-manifest.util';
+import { buildDefaultObjectManifest } from 'test/integration/metadata/suites/application/utils/build-default-object-manifest.util';
+import { cleanupApplicationAndAppRegistration } from 'test/integration/metadata/suites/application/utils/cleanup-application-and-app-registration.util';
+import { setupApplicationForSync } from 'test/integration/metadata/suites/application/utils/setup-application-for-sync.util';
+import { syncApplication } from 'test/integration/metadata/suites/application/utils/sync-application.util';
+import { findManyObjectMetadata } from 'test/integration/metadata/suites/object-metadata/utils/find-many-object-metadata.util';
+import { type Manifest } from 'twenty-shared/application';
+import { v4 as uuidv4 } from 'uuid';
+
+const TEST_APP_ID = uuidv4();
+const TEST_ROLE_ID = uuidv4();
+
+const buildManifest = (
+  overrides?: Partial<Pick<Manifest, 'objects' | 'fields'>>,
+) => buildBaseManifest({ appId: TEST_APP_ID, roleId: TEST_ROLE_ID, overrides });
+
+const findCustomObjectNames = async (): Promise<string[]> => {
+  const { objects } = await findManyObjectMetadata({
+    input: {
+      filter: { isCustom: { is: true } },
+      paging: { first: 100 },
+    },
+    gqlFields: 'id nameSingular',
+    expectToFail: false,
+  });
+
+  return objects.map((object) => object.nameSingular);
+};
+
+describe('Manifest sync - dry run', () => {
+  beforeEach(async () => {
+    await setupApplicationForSync({
+      applicationUniversalIdentifier: TEST_APP_ID,
+      name: 'Dry Run Test Application',
+      description: 'App for testing dry-run manifest sync',
+      sourcePath: 'dry-run-manifest-sync',
+    });
+  }, 60000);
+
+  afterEach(async () => {
+    await cleanupApplicationAndAppRegistration({
+      applicationUniversalIdentifier: TEST_APP_ID,
+    });
+  });
+
+  it('returns the planned actions without applying them', async () => {
+    const ticketObject = buildDefaultObjectManifest({
+      nameSingular: 'dryRunTicket',
+      namePlural: 'dryRunTickets',
+      labelSingular: 'Dry Run Ticket',
+      labelPlural: 'Dry Run Tickets',
+      description: 'A support ticket',
+    });
+
+    await syncApplication({
+      manifest: buildManifest({ objects: [ticketObject] }),
+      expectToFail: false,
+    });
+
+    const invoiceObject = buildDefaultObjectManifest({
+      nameSingular: 'dryRunInvoice',
+      namePlural: 'dryRunInvoices',
+      labelSingular: 'Dry Run Invoice',
+      labelPlural: 'Dry Run Invoices',
+      description: 'A billing invoice',
+    });
+
+    const dryRunResponse = await syncApplication({
+      manifest: buildManifest({ objects: [ticketObject, invoiceObject] }),
+      dryRun: true,
+      expectToFail: false,
+    });
+
+    expect(dryRunResponse.errors).toBeUndefined();
+    expect(dryRunResponse.data.syncApplication.actions.length).toBeGreaterThan(
+      0,
+    );
+
+    const customObjectNames = await findCustomObjectNames();
+
+    expect(customObjectNames).toContain('dryRunTicket');
+    expect(customObjectNames).not.toContain('dryRunInvoice');
+  }, 60000);
+});

packages/twenty-server/test/integration/metadata/suites/application/utils/sync-application-query-factory.util.ts

@@ -3,12 +3,14 @@ import { type Manifest } from 'twenty-shared/application';
 
 export const syncApplicationQueryFactory = ({
   manifest,
+  dryRun,
 }: {
   manifest: Manifest;
+  dryRun?: boolean;
 }) => ({
   query: gql`
-    mutation SyncApplication($manifest: JSON!) {
-      syncApplication(manifest: $manifest) {
+    mutation SyncApplication($manifest: JSON!, $dryRun: Boolean) {
+      syncApplication(manifest: $manifest, dryRun: $dryRun) {
         applicationUniversalIdentifier
         actions
       }
@@ -16,5 +18,6 @@ export const syncApplicationQueryFactory = ({
   `,
   variables: {
     manifest,
+    dryRun,
   },
 });

packages/twenty-server/test/integration/metadata/suites/application/utils/sync-application.util.ts

@@ -14,15 +14,18 @@ export const syncApplication = async ({
   manifest,
   expectToFail = false,
   token,
+  dryRun,
 }: {
   manifest: Manifest;
   expectToFail?: boolean;
   token?: string;
+  dryRun?: boolean;
 }): CommonResponseBody<{
   syncApplication: WorkspaceMigration;
 }> => {
   const graphqlOperation = syncApplicationQueryFactory({
     manifest,
+    dryRun,
   });
 
   const response = await makeMetadataAPIRequest(graphqlOperation, token);