@@ -0,0 +1,12 @@
+---
+'@object-ui/i18n': patch
+---
+
+fix(i18n): the Studio landing page tells users to customize a read-only package in its `.custom` customization package, not with an environment overlay
+
+Clause-②: no
+Metadata-protocol: none
+
+The App Builder landing page's description (`engine.studio.landing.description`) and its read-only section hint (`engine.studio.landing.readonlyHint`) told users to customize a code or installed package "with an environment overlay". A write naming no package onto an item a read-only package ships is now refused with `403 NOT_OVERRIDABLE`, and the refusal names the package's `.custom` pair. Both strings, in English and Chinese, now name the route that is open: open an item and choose Customize or New similar; the change is saved in the package's `.custom` customization package, and upgrades keep reaching the installed package.
+
+Only the two values change. No key is added or removed, and nothing else on the page changes.
@@ -0,0 +1,125 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * objectstack#29489 — the Studio landing teaches the customization route that
+ * is open, not the package-less overlay objectstack ADR-0146 D11 closed.
+ *
+ * A package-less write onto an item a read-only package ships answers 403
+ * NOT_OVERRIDABLE and names the base's `.custom` pair. The landing's page
+ * description and its read-only section hint used to send the user there
+ * ("customize them with an environment overlay"). They now name Customize and
+ * New similar, saved in the package's `.custom` customization package.
+ *
+ * Read off the real `BuilderLanding`, rendered in English and in Chinese with a
+ * read-only package listed, so both strings are on the page. The expected
+ * words are the tables' own: the Customize and New similar action labels.
+ */
+
+import '@testing-library/jest-dom/vitest';
+import * as React from 'react';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { cleanup, render, screen } from '@testing-library/react';
+import { MemoryRouter, Route, Routes } from 'react-router-dom';
+import { I18nProvider, createI18n } from '@object-ui/i18n';
+import { t } from '../metadata-admin/i18n';
+import { initRuntimeConfig, resetRuntimeConfigForTesting } from '../../runtime-config';
+// The landing's rows live in `@object-ui/i18n`'s `studio` namespace, whose `zh`
+// catalogue is fetched on demand: resident before any case.
+import { loadStudioCatalogue } from '@object-ui/i18n/namespaces/studio';
+await loadStudioCatalogue('zh');
+
+const packages = vi.hoisted(() => ({ list: [] as Array<Record<string, unknown>> }));
+
+vi.mock('./packages-io', async (importOriginal) => {
+  const mod = await importOriginal<typeof import('./packages-io')>();
+  return { ...mod, fetchPackages: vi.fn(async () => packages.list) };
+});
+
+// The create dialog is closed throughout; its form stack is not under test.
+vi.mock('../metadata-admin/PackageFormDialog', () => ({ PackageFormDialog: () => null }));
+
+import { BuilderLanding } from './BuilderLanding';
+
+const READ_ONLY = { id: 'com.example.showcase', name: 'Showcase', writable: false, namespace: 'showcase' };
+
+type Locale = 'en-US' | 'zh-CN';
+const LOCALES: ReadonlyArray<readonly [Locale, 'en' | 'zh']> = [
+  ['en-US', 'en'],
+  ['zh-CN', 'zh'],
+];
+
+/** The retired route, in both languages the tables speak. */
+const ENVIRONMENT_OVERLAY = /environment overlay|环境覆盖/iu;
+
+afterEach(() => {
+  cleanup();
+  packages.list = [];
+  vi.unstubAllGlobals();
+  resetRuntimeConfigForTesting();
+});
+
+/** The row for `key` in `locale`, which must exist: `t` echoes a missing key. */
+function row(key: string, locale: Locale): string {
+  const text = t(key, locale);
+  expect(text, `no ${locale} row for ${key}`).not.toBe(key);
+  return text;
+}
+
+async function renderLanding(lang: 'en' | 'zh') {
+  resetRuntimeConfigForTesting();
+  vi.stubGlobal(
+    'fetch',
+    vi.fn(async () => {
+      const body = { features: { installLocal: false, marketplace: false } };
+      return { ok: true, status: 200, json: async () => body, text: async () => JSON.stringify(body) } as Response;
+    }),
+  );
+  await initRuntimeConfig();
+  packages.list = [READ_ONLY];
+  const landing = (
+    <MemoryRouter initialEntries={['/studio']}>
+      <Routes>
+        <Route path="/studio" element={<BuilderLanding />} />
+      </Routes>
+    </MemoryRouter>
+  );
+  if (lang === 'en') return render(landing);
+  const zh = createI18n({ defaultLanguage: 'zh', detectBrowserLanguage: false, resources: { zh: {} } });
+  return render(<I18nProvider instance={zh}>{landing}</I18nProvider>);
+}
+
+/** The page description: the paragraph right under the title row. */
+function descriptionElement(): HTMLElement {
+  const titleRow = screen.getByRole('heading', { level: 1 }).parentElement;
+  const description = titleRow?.nextElementSibling;
+  if (!(description instanceof HTMLElement)) throw new Error('no description under the landing title');
+  return description;
+}
+
+describe('Studio landing: a read-only package is customized in its .custom package (objectstack#29489)', () => {
+  for (const [locale, lang] of LOCALES) {
+    it(`${locale}: the description and the read-only hint name Customize, New similar and the .custom package, never an overlay`, async () => {
+      await renderLanding(lang);
+      await screen.findByText('Showcase');
+
+      const customize = row('engine.studio.customize.action', locale);
+      const newSimilar = row('engine.studio.auto.newSimilar.action', locale);
+      const shown = [
+        descriptionElement().textContent ?? '',
+        screen.getByTestId('studio-landing-readonly-hint').textContent ?? '',
+      ];
+
+      // The rendered text is the table's row, so the landing reads these keys.
+      expect(shown).toEqual([
+        row('engine.studio.landing.description', locale),
+        row('engine.studio.landing.readonlyHint', locale),
+      ]);
+      for (const text of shown) {
+        expect(text).not.toMatch(ENVIRONMENT_OVERLAY);
+        expect(text).toContain('.custom');
+        expect(text).toContain(customize);
+        expect(text).toContain(newSimilar);
+      }
+    });
+  }
+});
@@ -1,7 +1,8 @@
 // Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
 
 /**
- * objectui#12171 — the Studio landing names the overlay axis that exists.
+ * objectui#12171 — the Studio landing names the overlay axis that exists;
+ * objectstack#29489 — and the landing no longer offers that overlay at all.
  *
  * ADR-0131 D6 (objectstack) retired ADR-0005's per-organization overlay axis.
  * The registry flag the landing points at is `allowEnvironmentOverlay`: may an
@@ -12,6 +13,12 @@
  * (`perm.readOnly.artifact.hint`), said "per-org overlay" (zh 「按组织覆盖」)
  * in its parenthetical; the card's claim amendment added it to this pin.
  *
+ * objectstack ADR-0146 D11 then closed the package-less write onto a packaged
+ * item (403 NOT_OVERRIDABLE, naming the base's `.custom` pair). The landing's
+ * two strings now teach the route that is open: Customize or New similar,
+ * saved in the package's `.custom` customization package. The permission hint
+ * still names the environment overlay, because it says that overlay is refused.
+ *
  * ## The population
  *
  * Every designer string table, read through their shared extractor
@@ -23,10 +30,14 @@
  *
  * 1. No value of these keys, in any table that carries them, names the
  *    organization axis.
- * 2. Lit control on the matcher: every one of those values names the
- *    environment overlay. A table in a language neither pattern speaks fails
- *    here, so pin 1 cannot pass on it by matching nothing.
- * 3. Lit control on the reader: for every locale the module's own
+ * 2. No landing value names the environment overlay, and every landing value
+ *    names the route that exists: the `.custom` package and the table's own
+ *    Customize label, read from the same table, so the check speaks every
+ *    language a table is written in.
+ * 3. Lit control on the matchers: the permission hint names the environment
+ *    overlay in every table. A table in a language neither pattern speaks
+ *    fails here, so pins 1 and 2 cannot pass on it by matching nothing.
+ * 4. Lit control on the reader: for every locale the module's own
  *    `SupportedLocale` union declares, the value `t()` serves is the one the
  *    extractor read, so an extractor that read some other table cannot pass.
  */
@@ -49,21 +60,27 @@ const readTables: (root: string) => Map<string, Map<string, string>> = readDesig
 const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../../../../..');
 
 /**
- * The keys that name the overlay axis: the two `BuilderLanding` renders, and
- * the hint `PermissionMatrixEditor` shows on a set a code package ships. The
- * third landing string, the overlay link's tooltip, retired with the link: the
+ * The two strings `BuilderLanding` renders about a read-only package. The third
+ * landing string, the overlay link's tooltip, retired with the link: the
  * landing no longer links into Setup (objectstack ADR-0146 D1, N-28).
  */
-const KEYS = [
-  'engine.studio.landing.description',
-  'engine.studio.landing.readonlyHint',
-  'perm.readOnly.artifact.hint',
-] as const;
+const LANDING_KEYS = ['engine.studio.landing.description', 'engine.studio.landing.readonlyHint'] as const;
+
+/** The hint `PermissionMatrixEditor` shows on a set a code package ships: it names the overlay it refuses. */
+const PERMISSION_HINT = 'perm.readOnly.artifact.hint';
+
+const KEYS = [...LANDING_KEYS, PERMISSION_HINT] as const;
+
+/** The Customize action's own label, read from each table beside the landing strings. */
+const CUSTOMIZE_ACTION = 'engine.studio.customize.action';
+
+/** The customization package a read-only package is paired with (objectstack ADR-0146 D3). */
+const CUSTOM_PAIR = /\.custom\b/u;
 
 /** The retired axis, in the languages the tables speak: "org", "per-org", "organization", 组织. */
 const ORGANIZATION_AXIS = /\borg(?:ani[sz]ation)?s?\b|组织/iu;
 
-/** The axis that exists, in the same languages. */
+/** The overlay axis, in the same languages: refused on a packaged item since objectstack ADR-0146 D11. */
 const ENVIRONMENT_OVERLAY = /\benvironment overlay\b|环境覆盖/iu;
 
 /**
@@ -77,7 +94,7 @@ function tablesCarryingKeys(): Array<[string, Map<string, string>]> {
   return [...readTables(REPO_ROOT)].filter(([, table]) => KEYS.some((key) => table.has(key)));
 }
 
-describe('the overlay copy names the environment overlay, not the organization axis (objectui#12171)', () => {
+describe('the read-only copy names no organization axis, and the landing offers no overlay (objectui#12171, objectstack#29489)', () => {
   it('reads the tables t() serves', () => {
     const read = tablesCarryingKeys();
     for (const locale of Object.keys(DECLARED_LOCALES)) {
@@ -104,14 +121,30 @@ describe('the overlay copy names the environment overlay, not the organization a
     expect(offenders).toEqual([]);
   });
 
-  it('every value of these keys names the environment overlay', () => {
-    const silent: string[] = [];
+  it('no landing value offers the environment overlay; each names Customize and the .custom package', () => {
+    const offenders: string[] = [];
     for (const [name, table] of tablesCarryingKeys()) {
-      for (const key of KEYS) {
+      const customize = table.get(CUSTOMIZE_ACTION);
+      if (!customize) {
+        offenders.push(`${name} ${CUSTOMIZE_ACTION}: missing`);
+        continue;
+      }
+      for (const key of LANDING_KEYS) {
         const value = table.get(key) ?? '';
-        if (!ENVIRONMENT_OVERLAY.test(value)) silent.push(`${name} ${key}: ${value}`);
+        if (ENVIRONMENT_OVERLAY.test(value)) offenders.push(`${name} ${key} offers the overlay: ${value}`);
+        if (!CUSTOM_PAIR.test(value)) offenders.push(`${name} ${key} names no .custom package: ${value}`);
+        if (!value.includes(customize)) offenders.push(`${name} ${key} names no "${customize}": ${value}`);
       }
     }
+    expect(offenders).toEqual([]);
+  });
+
+  it('lit control: the permission hint names the environment overlay in every table', () => {
+    const silent: string[] = [];
+    for (const [name, table] of tablesCarryingKeys()) {
+      const value = table.get(PERMISSION_HINT) ?? '';
+      if (!ENVIRONMENT_OVERLAY.test(value)) silent.push(`${name}: ${value}`);
+    }
     expect(silent).toEqual([]);
   });
 });
@@ -217,11 +217,11 @@ export function BuilderLanding(): React.ReactElement {
   // Duplicate (ADR-0070 D4) clones a writable BASE into a new writable package,
   // the "duplicate base" gesture, and drops the user straight into the copy's
   // builder. It is offered on writable bases only. A read-only code or
-  // installed package is not a duplicate source: ADR-0070 D2 customizes it by
-  // environment overlay, where the item's metadata type declares `allowEnvironmentOverlay`
-  // (ADR-0005), so its card points there instead (the read-only section
-  // below). Home's "Start with a template" is not this gesture either: it
-  // opens the marketplace.
+  // installed package is not a duplicate source: its items are customized in
+  // its paired `.custom` package through Customize or New similar (objectstack
+  // ADR-0146 D2, D3), never by a package-less overlay (D11), and the read-only
+  // section below says so. Home's "Start with a template" is not this gesture
+  // either: it opens the marketplace.
   const [dupFor, setDupFor] = React.useState<string | null>(null);
   const [dupName, setDupName] = React.useState('');
   const [dupId, setDupId] = React.useState('');
@@ -327,7 +327,7 @@ export function BuilderLanding(): React.ReactElement {
               {/* ADR-0070 D4 — Duplicate clones a writable base: the copy is a new
                 * writable package holding the base's sys_metadata rows. It is
                 * offered here, on writable bases only; a read-only package's card
-                * offers the routes that exist for it (environment overlay, the
+                * offers the routes that exist for it (its `.custom` pair, the
                 * marketplace). */}
               <button
                 type="button"
 
@@ -3234,7 +3234,7 @@ const STUDIO_EN: Record<string, string> = {
     'Saved as a draft in this deployment’s customization of {baseName}, and opened on the canvas. The navigation of {baseName} stays as it was installed.',
   'engine.studio.app.scaffoldNav': "Add this package's objects as menu items",
   'engine.studio.landing.title': 'App Builder',
-  'engine.studio.landing.description': 'Design objects, forms, automations and interfaces inside a writable package; edits save as drafts and the whole package publishes in one release. Code and installed packages are read-only: browse them here, and customize them with an environment overlay.',
+  'engine.studio.landing.description': 'Design objects, forms, automations and interfaces inside a writable package; edits save as drafts and the whole package publishes in one release. Code and installed packages are read-only: browse them here, and change their items with Customize or New similar, which save into the package’s .custom customization package.',
   'engine.studio.landing.mineHeading': 'My packages (writable)',
   'engine.studio.landing.noneWritable': 'No writable packages yet — create one to start.',
   'engine.studio.landing.dup': 'Duplicate',
@@ -3245,9 +3245,10 @@ const STUDIO_EN: Record<string, string> = {
   'engine.studio.landing.dupGo': 'Duplicate and open the builder',
   'engine.studio.landing.dupCreated': 'Duplicated into writable package “{name}”',
   'engine.studio.landing.installedHeading': 'Installed (read-only · browsable)',
-  // objectui#11808 — the routes a read-only package does have (ADR-0070 D2,
-  // ADR-0005): an environment overlay, and the marketplace where the runtime has one.
-  'engine.studio.landing.readonlyHint': 'Code and installed packages are read-only, so they are not edited or duplicated here. Customize one with an environment overlay, for the metadata types that accept one.',
+  // The routes a read-only package does have (objectstack ADR-0146 D2, D3, D11):
+  // Customize or New similar into its paired `.custom` package, and the
+  // marketplace where the runtime has one. A package-less overlay is not one.
+  'engine.studio.landing.readonlyHint': 'Code and installed packages are read-only, so they are not edited or duplicated here. To change one, open an item and choose Customize or New similar: the change is saved in the package’s .custom customization package, and upgrades keep reaching the installed package.',
   'engine.studio.landing.marketplace': 'Or install a template app from the marketplace',
   // ADR-0146 D3 — a read-only base's card says what this deployment changed on
   // it, from the server's per-package customization read.
 
@@ -2862,7 +2862,7 @@ const STUDIO_ZH: Record<string, string> = {
   'engine.studio.interfaces.create.descriptionInPair': '存为本部署对 {baseName} 定制的草稿，并在画布上打开。{baseName} 的导航保持安装时的样子。',
   'engine.studio.app.scaffoldNav': '将本包的对象添加为菜单项',
   'engine.studio.landing.title': '应用构建',
-  'engine.studio.landing.description': '在一个可写软件包里设计对象、表单、自动化与界面;编辑存为草稿,整包一次发布。源码与已安装的软件包为只读：可在此浏览，并用环境覆盖进行定制。',
+  'engine.studio.landing.description': '在一个可写软件包里设计对象、表单、自动化与界面;编辑存为草稿,整包一次发布。源码与已安装的软件包为只读：可在此浏览，并用「自定义」或「新建类似」修改其条目，修改保存在该软件包的 .custom 定制包中。',
   'engine.studio.landing.mineHeading': '我的软件包(可写)',
   'engine.studio.landing.noneWritable': '还没有可写软件包 — 新建一个开始。',
   'engine.studio.landing.dup': '复制',
@@ -2874,7 +2874,7 @@ const STUDIO_ZH: Record<string, string> = {
   'engine.studio.landing.dupCreated': '已复制为可写软件包「{name}」',
   'engine.studio.landing.installedHeading': '已安装(只读 · 可浏览)',
   // objectui#11808 — the routes a read-only package does have.
-  'engine.studio.landing.readonlyHint': '源码与已安装的软件包为只读，不能在此编辑或复制。对于接受环境覆盖的元数据类型，可用环境覆盖（overlay）进行定制。',
+  'engine.studio.landing.readonlyHint': '源码与已安装的软件包为只读，不能在此编辑或复制。要修改其中一个，请打开条目并选择「自定义」或「新建类似」：修改保存在该软件包的 .custom 定制包中，升级仍会到达已安装的软件包。',
   'engine.studio.landing.marketplace': '或从应用市场安装一个模板应用',
   'engine.studio.landing.customizations.customized': '已定制 {customized} 项',
   'engine.studio.landing.customizations.separator': '，',