@@ -29,6 +29,8 @@ import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { loadStudioCatalogue } from '@object-ui/i18n/namespaces/studio';
 import { t, tOptional } from '../i18n';
+// The i18n pin's own family list (a test-support module, not a package export).
+import { STUDIO_ZH_ONLY_FAMILIES } from '../../../../../i18n/src/__tests__/studio-zh-only-families';
 
 const EN = await loadStudioCatalogue('en');
 // Resident before any case, so the zh lookups below read synchronously.
@@ -152,6 +154,8 @@ const ZH_ONLY_FLOOR: Readonly<Record<string, number>> = Object.freeze({
  * here from the retired `check:i18n-designer-parity` gate with slice S7. A
  * citation is `{ file, anchor }`, the anchor is TEXT and never a line number,
  * and it must occur exactly once in its file or it stops locating anything.
+ * Its prefixes are held equal to `STUDIO_ZH_ONLY_FAMILIES`, the list the i18n
+ * pin `studio-namespace.test.ts` allows, so neither can widen alone.
  */
 const ZH_ONLY_REASONS = Object.freeze([
   {
@@ -248,6 +252,10 @@ describe('the namespace is the only home (objectstack#25922 slice S7)', () => {
     expect(wrong).toEqual([]);
   });
 
+  it('a reason is given for exactly the families the i18n pin allows', () => {
+    expect(ZH_ONLY_REASONS.map((f) => f.prefix).sort()).toEqual([...STUDIO_ZH_ONLY_FAMILIES].sort());
+  });
+
   it.each(ZH_ONLY_REASONS.map((f) => [f.prefix, f] as const))('%s: its citation anchor occurs exactly once', (_prefix, family) => {
     const text = readFileSync(path.join(here, family.file), 'utf8');
     expect(text.split(family.anchor).length - 1).toBe(1);
 
@@ -30,18 +30,13 @@ import {
   resolveStudioLanguage,
   studioString,
 } from '../namespaces/studio/index.js';
+// The `zh`-only families, each one-sided on purpose; the list's one home.
+import { STUDIO_ZH_ONLY_FAMILIES } from './studio-zh-only-families.js';
 
 /** `tFormat()`'s own placeholder pattern (app-shell `views/metadata-admin/i18n.ts`). */
 const PLACEHOLDER = /\{(\w+)\}/g;
 const placeholders = (value: string) => [...new Set(Array.from(value.matchAll(PLACEHOLDER), (m) => m[1]))].sort();
 
-/**
- * The `zh`-only families, each one-sided on purpose. `ZH_ONLY_REASONS` in
- * app-shell's `inspectorStrings.studioNamespace-25922.test.ts` carries the
- * reason and the consumer for each, and checks that its citation still locates it.
- */
-const ZH_ONLY_FAMILIES = ['engine.flowNode.', 'engine.enum.type.', 'engine.packages.form.help.'];
-
 function flatKeys(node: unknown, prefix = ''): string[] {
   if (typeof node !== 'object' || node === null) return [prefix];
   return Object.entries(node).flatMap(([k, v]) => flatKeys(v, prefix ? `${prefix}.${k}` : k));
@@ -69,7 +64,7 @@ describe('studio namespace — scoped parity', () => {
 
   it('a zh-only key belongs to a documented family', () => {
     const stray = zhKeys.filter(
-      (key) => !(key in STUDIO_EN) && !ZH_ONLY_FAMILIES.some((family) => key.startsWith(family)),
+      (key) => !(key in STUDIO_EN) && !STUDIO_ZH_ONLY_FAMILIES.some((family) => key.startsWith(family)),
     );
     expect(stray).toEqual([]);
   });
 
@@ -0,0 +1,15 @@
+/**
+ * The `studio` namespace's `zh`-only key families, the one list.
+ *
+ * Two pins read it: `studio-namespace.test.ts` here, which reds on a `zh`-only
+ * key outside these prefixes, and app-shell's
+ * `inspectorStrings.studioNamespace-25922.test.ts`, whose `ZH_ONLY_REASONS`
+ * carries the reason and consumer for each family and asserts its prefixes
+ * equal this list. A test-support module, not an export of the package entry:
+ * `__tests__/` is excluded from the build, so nothing here ships.
+ */
+export const STUDIO_ZH_ONLY_FAMILIES: readonly string[] = Object.freeze([
+  'engine.flowNode.',
+  'engine.enum.type.',
+  'engine.packages.form.help.',
+]);