@@ -0,0 +1,13 @@
+---
+'@object-ui/app-shell': patch
+'@object-ui/i18n': patch
+---
+
+fix(app-shell): Studio's Automations, App and Data creates refuse an identifier a published or draft item of that type already holds
+
+Clause-②: no
+Metadata-protocol: none
+
+- **Before.** "New automation", "Create app" and "New object" saved their blank skeleton as a draft under the first-write pin (`If-None-Match: *` with `?mode=draft`), which the door refuses only where a DRAFT row exists. An identifier a published flow, app or object already held therefore got the skeleton written as that item's pending draft, and publishing the package would have replaced the live item with the blank one. The Data create checked only the objects on its own rail; the other two checked nothing.
+- **Now.** Before anything is written, each create reads the published items and the drafts of its type across every package, the read the Interfaces and Access creates already make (now one shared helper). An identifier one of them holds is refused in the dialog with a sentence naming the item; when the item is on the pillar's own rail (a flow or an object of this package), the dialog offers to open it instead. A fresh identifier is created as before, and the door's first-write pin still refuses a draft that lands between the check and the save.
+- **Strings** (`@object-ui/i18n`). Five new rows in the `studio` namespace (`en` and `zh`) for the refusals; the Access refusal's "Open" row becomes `engine.studio.create.openExisting`, shared by every create, and the Data pillar's `engine.studio.data.idExists`, which the new refusal replaces, is removed.
@@ -0,0 +1,382 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * objectstack#26917 — Studio's Automations, App and Data creates over an
+ * identifier a published item of that type already holds.
+ *
+ * Each create saves its blank skeleton under the first-write pin
+ * (`If-None-Match: *` with `?mode=draft`), which asserts that no DRAFT row
+ * exists: the spec's `parentVersion: null` is lifecycle-scoped. Over a
+ * PUBLISHED flow, app or object of the same identifier the door therefore
+ * wrote the skeleton as that item's pending draft, and publishing the package
+ * would have replaced the live item with the blank one. The Access create was
+ * fixed the same way by objectstack#26836.
+ *
+ *  - Automations: a published flow on this rail is refused with "Open"; one
+ *    another package holds is refused without it; nothing is written either way.
+ *  - Data: the same for objects (the namespace-prefixed identifier).
+ *  - App: an app another package holds is refused (Create app is offered only
+ *    to a package with no app, so there is nothing of its own to open).
+ *  - A fresh identifier is created as before, with the pin.
+ *
+ * The REAL pillars and dialogs, over a client double that keeps published and
+ * draft rows per package, writes a draft over a published row the way the
+ * door does, and refuses the pin over a draft row.
+ */
+
+import '@testing-library/jest-dom/vitest';
+import * as React from 'react';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { cleanup, fireEvent, render, screen, waitFor, within } from '@testing-library/react';
+import { MemoryRouter, Route, Routes } from 'react-router-dom';
+
+const PKG = 'com.acme.app';
+const OTHER_PKG = 'com.other.app';
+
+type Row = { pkg: string; body: Record<string, unknown> };
+
+const door = vi.hoisted(() => ({
+  /** `type/name` → the published row. */
+  published: new Map<string, { pkg: string; body: Record<string, unknown> }>(),
+  /** `type/name` → the pending draft row. */
+  drafts: new Map<string, { pkg: string; body: Record<string, unknown> }>(),
+}));
+
+const mockClient = vi.hoisted(() => {
+  const rows = (map: Map<string, { pkg: string; body: Record<string, unknown> }>, type: string | undefined, pkg?: string | null) =>
+    [...map.entries()]
+      .filter(([key, row]) => (!type || key.startsWith(`${type}/`)) && (!pkg || row.pkg === pkg))
+      .map(([key, row]) => ({ key, ...row }));
+  const client: Record<string, unknown> = {
+    list: vi.fn(async (type: string, opts: { packageId?: string | null } = {}) =>
+      rows(door.published, type, opts?.packageId).map((r) => ({ ...r.body, _packageId: r.pkg })),
+    ),
+    listDrafts: vi.fn(async (opts: { packageId?: string | null; type?: string } = {}) =>
+      rows(door.drafts, opts?.type, opts?.packageId).map((r) => ({
+        type: r.key.split('/')[0],
+        name: r.body.name,
+        label: r.body.label,
+        packageId: r.pkg,
+      })),
+    ),
+    listTypes: vi.fn(async () => ({ entries: [] })),
+    get: vi.fn(async (type: string, name: string) => door.published.get(`${type}/${name}`)?.body ?? null),
+    references: vi.fn(async () => []),
+    layered: vi.fn(async (type: string, name: string) => {
+      const effective = door.published.get(`${type}/${name}`)?.body ?? null;
+      return { effective, code: null, overlay: null, overlayScope: null, editable: true, deletable: true, resettable: false, lock: 'none' };
+    }),
+    getDraft: vi.fn(async (type: string, name: string) => {
+      const row = door.drafts.get(`${type}/${name}`);
+      return row ? { type, name, item: JSON.parse(JSON.stringify(row.body)) } : null;
+    }),
+    // The door: a draft-mode first-write pin refuses a DRAFT row only, and
+    // writes over a published one.
+    save: vi.fn(
+      async (type: string, name: string, body: Record<string, unknown>, opts: { packageId?: string | null; ifNoneMatch?: string } = {}) => {
+        const key = `${type}/${name}`;
+        if (opts?.ifNoneMatch === '*' && door.drafts.has(key)) {
+          throw Object.assign(new Error(`${key}: this save asserted that no draft row exists (If-None-Match: *)`), {
+            status: 409,
+            code: 'METADATA_CONFLICT',
+          });
+        }
+        door.drafts.set(key, { pkg: opts?.packageId ?? '', body: JSON.parse(JSON.stringify(body)) });
+        return { type, name, item: body };
+      },
+    ),
+    publish: vi.fn(async () => ({ success: true })),
+    reset: vi.fn(async () => ({})),
+  };
+  client.withPreviewDrafts = () => client;
+  return client;
+});
+
+vi.mock('../metadata-admin/useMetadata', async (importOriginal) => {
+  const mod = await importOriginal<typeof import('../metadata-admin/useMetadata')>();
+  return {
+    ...mod,
+    useMetadataClient: () => mockClient,
+    useMetadataTypes: () => ({ loading: false, error: null, entries: [] }),
+  };
+});
+
+vi.mock('./packages-io', async (importOriginal) => {
+  const mod = await importOriginal<typeof import('./packages-io')>();
+  return {
+    ...mod,
+    fetchPackages: vi.fn(async () => [{ id: PKG, name: 'Acme', writable: true, namespace: 'acme' }]),
+  };
+});
+
+vi.mock('@object-ui/react', async (importOriginal) => {
+  const mod = await importOriginal<typeof import('@object-ui/react')>();
+  return { ...mod, useAdapter: () => dataSource };
+});
+
+vi.mock('sonner', () => ({ toast: { success: vi.fn(), error: vi.fn(), message: vi.fn() } }));
+vi.mock('../../components/SuggestedBindingsPanel', () => ({ SuggestedBindingsPanel: () => null }));
+vi.mock('../metadata-admin/AccessExplainPanel', () => ({ AccessExplainPanel: () => null }));
+vi.mock('./StudioAiCopilot', () => ({ StudioChatDock: () => null }));
+vi.mock('../../preview/DraftChangesPanel', () => ({ DraftChangesPanel: () => null }));
+
+import { AutomationsPillar, DataPillar, StudioDesignSurface } from './StudioDesignSurface';
+import { createEmptyDataSource } from './__tests__/emptyDataSource';
+import { t, tFormat } from '../metadata-admin/i18n';
+
+const dataSource = createEmptyDataSource();
+
+window.matchMedia = ((query: string) => ({
+  matches: false,
+  media: query,
+  onchange: null,
+  addEventListener: () => {},
+  removeEventListener: () => {},
+  addListener: () => {},
+  removeListener: () => {},
+  dispatchEvent: () => false,
+})) as unknown as typeof window.matchMedia;
+
+(globalThis as { ResizeObserver?: unknown }).ResizeObserver =
+  (globalThis as { ResizeObserver?: unknown }).ResizeObserver ??
+  class {
+    observe() {}
+    unobserve() {}
+    disconnect() {}
+  };
+
+const en = (key: string) => t(key, 'en');
+const save = mockClient.save as ReturnType<typeof vi.fn>;
+const getDraft = mockClient.getDraft as ReturnType<typeof vi.fn>;
+
+function publish(type: string, pkg: string, body: Record<string, unknown>) {
+  door.published.set(`${type}/${String(body.name)}`, { pkg, body } satisfies Row);
+}
+
+/** The published body, as a deep copy, so "unchanged" compares against what was seeded. */
+const publishedBody = (type: string, name: string) => JSON.parse(JSON.stringify(door.published.get(`${type}/${name}`)!.body));
+
+const FLOW_ALPHA = { name: 'alpha_intake', label: 'Alpha intake', type: 'autolaunched', nodes: [], edges: [] };
+const FLOW_ESCALATE = {
+  name: 'escalate',
+  label: 'Escalate',
+  type: 'autolaunched',
+  status: 'active',
+  nodes: [
+    { id: 'start', type: 'start', label: 'Start', config: { triggerType: 'record-after-update', objectName: 'acme_ticket' } },
+    { id: 'notify', type: 'notify', label: 'Notify' },
+    { id: 'end', type: 'end', label: 'End' },
+  ],
+  edges: [],
+};
+const OBJ_ACCOUNT = { name: 'acme_account', label: 'Account', fields: { name: { type: 'text', label: 'Name' } } };
+const OBJ_TICKET = { name: 'acme_ticket', label: 'Ticket', fields: { subject: { type: 'text', label: 'Subject' } } };
+const APP_FIELD = { name: 'field_service', label: 'Field Service', active: true, navigation: [{ id: 'nav_x', type: 'object', objectName: 'other_x' }] };
+
+beforeEach(() => {
+  door.published.clear();
+  door.drafts.clear();
+  window.confirm = vi.fn(() => true) as unknown as typeof window.confirm;
+  vi.stubGlobal(
+    'fetch',
+    vi.fn(async () => new Response('null', { status: 404, headers: { 'content-type': 'application/json' } })),
+  );
+});
+
+afterEach(() => {
+  cleanup();
+  vi.clearAllMocks();
+  vi.unstubAllGlobals();
+});
+
+/** Fill the create dialog's label (the identifier derives from it) and submit. */
+function submitCreate(dialog: HTMLElement, label: string) {
+  fireEvent.change(dialog.querySelectorAll('input')[0], { target: { value: label } });
+  fireEvent.click(within(dialog).getByRole('button', { name: en('engine.studio.createDraft') }));
+}
+
+describe('objectstack#26917 — Automations: New automation over a taken identifier', () => {
+  async function openNewAutomation() {
+    render(
+      <MemoryRouter initialEntries={[`/studio/${PKG}/automations`]}>
+        <AutomationsPillar packageId={PKG} />
+      </MemoryRouter>,
+    );
+    await screen.findByTestId('auto-rail-row-alpha_intake', undefined, { timeout: 8000 });
+    fireEvent.click(screen.getByTitle(en('engine.studio.auto.newTitle')));
+    const dialog = await screen.findByRole('dialog');
+    // The manual preset: the record ones hold Create until an object is named.
+    fireEvent.click(within(dialog).getByTestId('create-flow-preset-manual'));
+    return dialog;
+  }
+
+  it("a published flow on this package's rail: refused, nothing written, and Open opens it", async () => {
+    publish('flow', PKG, FLOW_ALPHA);
+    publish('flow', PKG, FLOW_ESCALATE);
+    const before = publishedBody('flow', 'escalate');
+    const dialog = await openNewAutomation();
+    submitCreate(dialog, 'Escalate');
+
+    const taken = await within(dialog).findByTestId('flow-create-taken');
+    expect(taken).toHaveTextContent(
+      tFormat('engine.studio.auto.createTaken', 'en', { name: 'escalate', label: 'Escalate' }),
+    );
+    expect(save).not.toHaveBeenCalled();
+    expect(door.drafts.size).toBe(0);
+    expect(door.published.get('flow/escalate')!.body).toEqual(before);
+
+    expect(getDraft.mock.calls.some(([, name]) => name === 'escalate')).toBe(false);
+    fireEvent.click(within(taken).getByTestId('flow-create-open-existing'));
+    await waitFor(() => expect(screen.queryByRole('dialog')).toBeNull());
+    await waitFor(() => expect(getDraft.mock.calls.some(([, name]) => name === 'escalate')).toBe(true));
+    expect(save).not.toHaveBeenCalled();
+  });
+
+  it('a published flow another package holds: refused, nothing written, and no Open', async () => {
+    publish('flow', PKG, FLOW_ALPHA);
+    publish('flow', OTHER_PKG, FLOW_ESCALATE);
+    const before = publishedBody('flow', 'escalate');
+    const dialog = await openNewAutomation();
+    submitCreate(dialog, 'Escalate');
+
+    const taken = await within(dialog).findByTestId('flow-create-taken');
+    expect(taken).toHaveTextContent(
+      tFormat('engine.studio.auto.createTakenElsewhere', 'en', { name: 'escalate', label: 'Escalate' }),
+    );
+    expect(within(taken).queryByTestId('flow-create-open-existing')).toBeNull();
+    expect(save).not.toHaveBeenCalled();
+    expect(door.drafts.size).toBe(0);
+    expect(door.published.get('flow/escalate')!.body).toEqual(before);
+  });
+
+  it('a fresh identifier is created as before, under the first-write pin', async () => {
+    publish('flow', PKG, FLOW_ALPHA);
+    publish('flow', OTHER_PKG, FLOW_ESCALATE);
+    const dialog = await openNewAutomation();
+    submitCreate(dialog, 'Close stale');
+
+    await waitFor(() => expect(save).toHaveBeenCalledTimes(1));
+    const [type, name, , opts] = save.mock.calls[0]!;
+    expect([type, name, opts]).toEqual([
+      'flow',
+      'close_stale',
+      { mode: 'draft', packageId: PKG, ifNoneMatch: '*', surface: 'studio' },
+    ]);
+    expect(door.drafts.has('flow/close_stale')).toBe(true);
+    expect(screen.queryByTestId('flow-create-taken')).toBeNull();
+  });
+});
+
+describe('objectstack#26917 — Data: New object over a taken identifier', () => {
+  async function openNewObject() {
+    render(
+      <MemoryRouter initialEntries={[`/studio/${PKG}/data`]}>
+        <DataPillar packageId={PKG} />
+      </MemoryRouter>,
+    );
+    fireEvent.click(await screen.findByRole('button', { name: en('engine.studio.data.newObject') }, { timeout: 8000 }));
+    const dialog = await screen.findByRole('dialog');
+    // The identifier is stored with the package's namespace prefix
+    // (`prefixObjectName`): wait until the dialog previews it.
+    await waitFor(() => {
+      fireEvent.change(dialog.querySelectorAll('input')[0], { target: { value: 'Ticket' } });
+      expect(within(dialog).getByTestId('create-item-stored-name')).toHaveTextContent('acme_ticket');
+    });
+    return dialog;
+  }
+
+  it('a published object another package holds: refused, nothing written, and no Open', async () => {
+    publish('object', PKG, OBJ_ACCOUNT);
+    publish('object', OTHER_PKG, OBJ_TICKET);
+    const before = publishedBody('object', 'acme_ticket');
+    const dialog = await openNewObject();
+    submitCreate(dialog, 'Ticket');
+
+    const taken = await within(dialog).findByTestId('object-create-taken');
+    expect(taken).toHaveTextContent(
+      tFormat('engine.studio.data.createTakenElsewhere', 'en', { name: 'acme_ticket', label: 'Ticket' }),
+    );
+    expect(within(taken).queryByTestId('object-create-open-existing')).toBeNull();
+    expect(save).not.toHaveBeenCalled();
+    expect(door.drafts.size).toBe(0);
+    expect(door.published.get('object/acme_ticket')!.body).toEqual(before);
+  });
+
+  it("an object on this package's rail: refused, nothing written, and Open opens it", async () => {
+    publish('object', PKG, OBJ_ACCOUNT);
+    publish('object', PKG, OBJ_TICKET);
+    const dialog = await openNewObject();
+    submitCreate(dialog, 'Ticket');
+
+    const taken = await within(dialog).findByTestId('object-create-taken');
+    expect(taken).toHaveTextContent(
+      tFormat('engine.studio.data.createTaken', 'en', { name: 'acme_ticket', label: 'Ticket' }),
+    );
+    expect(save).not.toHaveBeenCalled();
+
+    fireEvent.click(within(taken).getByTestId('object-create-open-existing'));
+    await waitFor(() => expect(screen.queryByRole('dialog')).toBeNull());
+    await waitFor(() => expect(getDraft.mock.calls.some(([type, name]) => type === 'object' && name === 'acme_ticket')).toBe(true));
+    expect(save).not.toHaveBeenCalled();
+  });
+
+  it('a fresh identifier is created as before, under the first-write pin', async () => {
+    publish('object', PKG, OBJ_ACCOUNT);
+    const dialog = await openNewObject();
+    submitCreate(dialog, 'Ticket');
+
+    await waitFor(() => expect(save).toHaveBeenCalledTimes(1));
+    const [type, name, , opts] = save.mock.calls[0]!;
+    expect([type, name, opts]).toEqual([
+      'object',
+      'acme_ticket',
+      { mode: 'draft', packageId: PKG, ifNoneMatch: '*', surface: 'studio' },
+    ]);
+  });
+});
+
+describe('objectstack#26917 — Create app over a taken identifier', () => {
+  async function openCreateApp() {
+    render(
+      <MemoryRouter initialEntries={[`/studio/${PKG}/automations`]}>
+        <Routes>
+          <Route path="/studio/:packageId/:tab" element={<StudioDesignSurface />} />
+        </Routes>
+      </MemoryRouter>,
+    );
+    const toolbar = await screen.findByTestId('studio-shell-header', undefined, { timeout: 8000 });
+    await waitFor(() => expect(within(toolbar).getByRole('button', { name: en('engine.studio.app.create') })).toBeInTheDocument());
+    fireEvent.click(within(toolbar).getByRole('button', { name: en('engine.studio.app.create') }));
+    return await screen.findByRole('dialog');
+  }
+
+  it('a published app another package holds: refused, nothing written', async () => {
+    publish('app', OTHER_PKG, APP_FIELD);
+    const before = publishedBody('app', 'field_service');
+    const dialog = await openCreateApp();
+    submitCreate(dialog, 'Field Service');
+
+    const taken = await within(dialog).findByTestId('app-create-taken');
+    expect(taken).toHaveTextContent(
+      tFormat('engine.studio.app.createTaken', 'en', { name: 'field_service', label: 'Field Service' }),
+    );
+    expect(within(taken).queryByTestId('app-create-open-existing')).toBeNull();
+    expect(save).not.toHaveBeenCalled();
+    expect(door.drafts.size).toBe(0);
+    expect(door.published.get('app/field_service')!.body).toEqual(before);
+  });
+
+  it('a fresh identifier is created as before, under the first-write pin', async () => {
+    publish('app', OTHER_PKG, APP_FIELD);
+    const dialog = await openCreateApp();
+    submitCreate(dialog, 'Dispatch');
+
+    await waitFor(() => expect(save).toHaveBeenCalledTimes(1));
+    const [type, name, , opts] = save.mock.calls[0]!;
+    expect([type, name, opts]).toEqual([
+      'app',
+      'dispatch',
+      { mode: 'draft', packageId: PKG, ifNoneMatch: '*', surface: 'studio' },
+    ]);
+  });
+});