@@ -0,0 +1,8 @@
+---
+"@objectstack/spec": minor
+"@objectstack/metadata-protocol": patch
+---
+
+Declare `MetadataProtocol.getMetaItemLayered` — the layered three-way diagnostic read (`GET /api/v1/meta/:type/:name/layers`) now appears on the protocol interface, typed against the already-declared `GetMetaItemLayeredRequestSchema` / `GetMetaItemLayeredResponseSchema`, so callers no longer reach the verb through `any`. Declared optional like its `getMetaItemCached` / `deleteMetaItem` siblings: a declared-surface catch-up to a shipped verb, not a new capability.
+
+In `@objectstack/metadata-protocol`, the implementation's inline return-type annotation for `getMetaItemLayered` drops its dead `'overlay'` arm on `lockSource` and annotates with `MetadataLockSource` directly — the only producer feeding that field on the layered read path is `resolveLockState`, whose return is already typed `MetadataLockSource | undefined` (`'artifact' | 'package' | 'env-forced'`); the `'overlay'` literal in the file belongs to `getEffectiveLock`, a write/delete-door helper that never feeds this response. Type-level change only; no runtime behaviour or wire vocabulary changes.
@@ -73,6 +73,7 @@ import {
     evaluateLockForDelete,
     resolveLockState,
     type MetadataLock,
+    type MetadataLockSource,
     type MetadataProvenance,
 } from '@objectstack/spec/kernel';
 import { validateObjectNamespacePrefix, deriveNamespaceFromPackageId } from '@objectstack/spec/kernel';
@@ -6081,7 +6082,14 @@ export class ObjectStackProtocolImplementation implements
         // ── ADR-0010 protection envelope ──
         lock: MetadataLock;
         lockReason?: string;
-        lockSource?: 'artifact' | 'package' | 'env-forced' | 'overlay';
+        // `MetadataLockSource` (artifact | package | env-forced) — the only
+        // producer feeding this field on this path is `resolveLockState`,
+        // whose return is typed `MetadataLockSource | undefined`. The
+        // `'overlay'` arm this annotation used to carry was dead: the one
+        // `lockSource: 'overlay'` producer in this file belongs to
+        // `getEffectiveLock`, a write/delete-door helper that never feeds
+        // this response (#9740).
+        lockSource?: MetadataLockSource;
         lockDocsUrl?: string;
         provenance?: MetadataProvenance;
         packageId?: string;
 
@@ -59,6 +59,12 @@ import {
   GetFieldLabelsResponseSchema,
 } from './protocol.zod';
 import type { ListNotificationsRequest } from './protocol.zod';
+import { expectTypeOf } from 'vitest';
+import type {
+  MetadataProtocol,
+  GetMetaItemLayeredRequest,
+  GetMetaItemLayeredResponse,
+} from './protocol.zod';
 
 describe('ObjectStack Protocol', () => {
 
@@ -1350,3 +1356,31 @@ describe('meta-read request schemas declare organizationId (#9726 — declared =
     expect(GetMetaItemLayeredRequestSchema.safeParse({ name: 'account_list' }).success).toBe(false);
   });
 });
+
+describe('MetadataProtocol declares getMetaItemLayered (#9740)', () => {
+  // Type-level pins (compiled by the spec test typecheck, the
+  // translation-typegen.test.ts pattern). The member is an interface
+  // declaration with no runtime shadow, so its presence and shape are only
+  // observable to tsc — these pins are what turns red if the member is
+  // dropped again or drifts off the layered schemas.
+
+  it('declares the member optional, against the layered request/response schemas', () => {
+    // Optional like its `getMetaItemCached` / `deleteMetaItem` siblings:
+    // additive to a shipped contract, implementation predating declaration.
+    expectTypeOf<MetadataProtocol['getMetaItemLayered']>().toEqualTypeOf<
+      ((request: GetMetaItemLayeredRequest) => Promise<GetMetaItemLayeredResponse>) | undefined
+    >();
+  });
+
+  it("keeps the layered lockSource vocabulary closed — no 'overlay' arm", () => {
+    // The drift this card closed: the implementation's inline annotation
+    // carried an 'overlay' arm no producer on the layered read path can emit
+    // (the only `lockSource: 'overlay'` producer is `getEffectiveLock`, a
+    // write/delete-door helper). The declared wire enum stays
+    // artifact | package | env-forced; widening it without a producer is the
+    // declared-but-unenforced direction Prime Directive #10 forbids.
+    expectTypeOf<GetMetaItemLayeredResponse['lockSource']>().toEqualTypeOf<
+      'artifact' | 'package' | 'env-forced' | undefined
+    >();
+  });
+});
@@ -2337,17 +2337,17 @@ export interface MetadataProtocol {
    */
   deleteMetaItem?(request: DeleteMetaItemRequest): Promise<DeleteMetaItemResponse>;
   getMetaItemCached?(request: GetMetaItemCachedRequest): Promise<GetMetaItemCachedResponse>;
-  // `getMetaItemLayered` is deliberately NOT declared here yet, although both
-  // its request and response schemas are (see them above). Declaring the
-  // member makes tsc check `metadata-protocol`'s implementation against
-  // `GetMetaItemLayeredResponse`, and that check currently fails on one
-  // member: the implementation's inline return type annotates `lockSource`
-  // with an `'overlay'` arm that its only producer (`resolveLockState`, whose
-  // return is typed `MetadataLockSource | undefined`) can never emit — an
-  // over-wide annotation, not enforced behaviour. Until that annotation is
-  // corrected at the implementation, adding the member here would either lie
-  // about the wire enum or hard-break the implementing class. Tracked as its
-  // own card (filed from #9726).
+  /**
+   * Three-layer diagnostic read (`GET /api/v1/meta/:type/:name/layers`) —
+   * packaged baseline, tenant overlay row and merged result side by side; see
+   * {@link GetMetaItemLayeredResponseSchema} for the shape and its #5882
+   * route-separation rationale. A declared-surface catch-up, not a new
+   * capability: `metadata-protocol` has shipped this verb since the layered
+   * route landed. Declared optional like its `getMetaItemCached` /
+   * `deleteMetaItem` siblings — additive to a shipped contract, with the
+   * implementation predating the declaration.
+   */
+  getMetaItemLayered?(request: GetMetaItemLayeredRequest): Promise<GetMetaItemLayeredResponse>;
   getUiView?(request: GetUiViewRequest): Promise<GetUiViewResponse>;
 }