@@ -0,0 +1,19 @@
+---
+'@objectstack/runtime': minor
+---
+
+fix(runtime)!: an app-authored body may not read the stored-metadata tables either; it reaches them through the metadata API only (#21594)
+
+Clause-②: yes (narrowing)
+
+<!-- adr-0087: not-required (no-migration-prescription) no metadata body, authorable key, spelling, export or stored shape moves; what changes is which reads a sandboxed hook, action or job body may make of the two stored-metadata tables, so `objectstack migrate meta` has nothing to rewrite. The other categories are closed on facts: the package publishes (not `unpublished`); no ADR-0087 id covers a refused read (not `registered` / `already-registered`); and the change is runtime behaviour, not a declaration (not `runtime-interface-only` / `type-surface-only`). -->
+
+**BREAKING**: this narrows what an app-authored body may do with the two stored-metadata tables, `sys_metadata` and `sys_metadata_history`. With the binding and write refusals already in this release, an app-authored body now reaches them through the metadata API only.
+
+- **Reading.** A sandboxed hook, action or job body's read of either table through `ctx.api` answers `PERMISSION_DENIED` / 403 before the read runs. That covers `find`, `findOne`, `count` and `aggregate`, inside a transaction or not, with or without elevation, and whatever filter, sort, grouping, search or projection the read carries. A body is served nothing of these tables, neither the stored row nor a projection of it, and the answer does not depend on what the read asks. A hook body that reads them fails the write that fired it.
+- **Subject record.** An action body is not handed a row of either table as its subject record either. The `/actions` door loads an action's subject row before it dispatches. When that row is from either table, the call answers the same `PERMISSION_DENIED` / 403 before the body runs, instead of handing the body the row as `ctx.record`. That covers an action declared on either table (through a bundle, an installed package or the metadata door) and an object-less action addressed under one. A call that carries no record hands the body nothing and runs as before.
+- **The route.** A body that read either table through `ctx.api.object(...)` was served the body projected and the content hash keyed; read metadata through the metadata API instead: `GET /api/v1/meta/:type/:name` for a definition, and `GET /api/v1/meta/:type/:name/history` for its versions. The refusal names that route. No shipped example reads either table from a body.
+- **This supersedes, for bodies, two earlier entries of this release:** the served read of these tables, and the evaluate-shape refusals (`INVALID_FIELD` / 400) and default-search narrowing of that read. For a body, all of these now give way to this refusal. It also supersedes the binding-and-write entry's note that a body's reads are unchanged.
+- **Unchanged:** host code that registers its own action handlers (its `ctx.api`, `ctx.engine.find` and subject record are still served as the generic data door serves these tables, with the door's evaluate refusals); the binding and write refusals; the platform's own readers; the generic data door and the metadata API; and every other object.
+
+It ships as `minor` under the launch-window convention for accept-set narrowings.
@@ -1500,9 +1500,11 @@ export function buildActionExecutionContext(ec: any): Record<string, unknown> {
  *
  * [#21454] Served through the stored-metadata reader seam
  * (`stored-metadata-reader-seam.ts`): this context is elevated, and it is the
- * `ctx.api` a host code handler receives as well as an action body, so a read
- * of the stored-metadata-body family answers the generic data door's form
- * (the body projected, the content hash keyed) and never the stored row.
+ * `ctx.api` a host code handler receives, so a read of the stored-metadata-body
+ * family answers the generic data door's form (the body projected, the content
+ * hash keyed) and never the stored row. [#21594] An action BODY's API is built
+ * over this one by the sandbox (`buildSandboxApi`), whose body layers refuse a
+ * family read or write before it reaches this seam.
  */
 export function buildActionApi(_deps: ActionExecutionDeps, ql: any, ec: any): any | undefined {
     if (!ql || typeof ql.createContext !== 'function') return undefined;
 
@@ -61,11 +61,12 @@ import {
   resolveRecordTitle,
   resolveRelatedTitleTarget,
 } from '@objectstack/objectql';
-import { refuseStoredMetadataBodyWrites, serveStoredMetadataReadsThrough } from '../stored-metadata-reader-seam.js';
+import { refuseStoredMetadataBodyReads, refuseStoredMetadataBodyWrites } from '../stored-metadata-reader-seam.js';
 import { isStoredMetadataBodyObject } from '@objectstack/spec/kernel';
 import {
   isWildcardHookTarget,
   storedMetadataBodyHookBindingRefusal,
+  storedMetadataBodySubjectRecordRefusal,
   storedMetadataFamilyTableList,
 } from '../stored-metadata-body-boundary.js';
 
@@ -448,6 +449,11 @@ export function actionBodyRunnerFactory(
     const body = parsed.data;
 
     return async function boundActionHandler(actionCtx: any): Promise<unknown> {
+      // [#21594] A body is handed nothing of the stored-metadata family: an
+      // action whose subject record is a family row is refused here, before
+      // the body runs and before its sandbox context is built.
+      const subjectRefusal = actionSubjectRecordRefusal(actionCtx, action);
+      if (subjectRefusal) throw subjectRefusal;
       const sandboxCtx = buildActionSandboxContext(
         actionCtx,
         opts.ql,
@@ -478,6 +484,38 @@ export function actionBodyRunnerFactory(
   };
 }
 
+/**
+ * [#21594] The refusal for an action body about to be handed a row of the
+ * stored-metadata family as its subject record, or `undefined`.
+ *
+ * Both action doors (REST `/actions` and MCP `run_action`) load the subject
+ * record before they dispatch, through the generic data door, and stamp the
+ * routed object and record id into `params` AFTER the caller's own params, so
+ * `params.objectName` is the door's routed object, never the caller's. That
+ * object is the subject: an action declared on a family table is routed under
+ * it, and so is an object-less action a caller addresses under it
+ * (`/actions/<family table>/<action>/<id>`), which no binding-time refusal
+ * could see. Absent a routed object (an engine `execute` call from host code),
+ * the action's declared object stands in.
+ *
+ * Judged here — the action body's own handler, the one point every action
+ * body passes through to run, whichever door bound it — because only here is
+ * the handler known to be a body: the doors dispatch body and host handlers
+ * alike, and a host code handler's subject record is outside the boundary.
+ * A record is "handed" when the call carries a record id or a non-empty
+ * record; a family-routed call with neither hands the body nothing and runs.
+ */
+function actionSubjectRecordRefusal(actionCtx: any, action: { name: string; object?: string }): Error | undefined {
+  const params = actionCtx?.params;
+  const routed = typeof params?.objectName === 'string' && params.objectName.length > 0 ? params.objectName : undefined;
+  const subject = routed ?? action.object;
+  if (typeof subject !== 'string' || !isStoredMetadataBodyObject(subject)) return undefined;
+  const record = actionCtx?.record;
+  const handed = (typeof params?.recordId === 'string' && params.recordId.length > 0)
+    || (record !== null && typeof record === 'object' && Object.keys(record).length > 0);
+  return handed ? storedMetadataBodySubjectRecordRefusal(subject, action.name) : undefined;
+}
+
 /** What {@link judgeJobBody} answers for a `body` that binds, and for one that does not. */
 export type JobBodyJudgement =
   | { binds: true; body: ScriptBodyParsed }
@@ -970,24 +1008,29 @@ function buildEngineRepoFacade(ql: any, objectName: string, context?: any) {
 }
 
 /**
- * The `ctx.api` a sandboxed body (hook or action) reads and writes through.
- *
- * [#21454] Served through the stored-metadata reader seam: a read of the
- * stored-metadata-body family answers the generic data door's form (the body
- * projected, the content hash keyed), never the stored row. This is the one
- * place both body faces get their API, so the hook face, the action face and
- * every fallback below are served alike, and a body can copy only what it was
- * served.
- *
- * [#21520] And, layered over that, a body may not WRITE a stored-metadata table
- * at all: every write of one is refused before it runs, whatever the body's
- * elevation. Applied HERE and nowhere else because this is the one place a
- * body gets its API — a host code handler's `ctx.api` is served by the read
- * seam but keeps its writes (deployer code, outside the boundary).
+ * The `ctx.api` a sandboxed body (hook, action or job) reads and writes through.
+ *
+ * For an app-authored body, the stored-metadata family is reached through the
+ * metadata API only, so this API refuses every touch of a family table before
+ * it runs, whatever the body's elevation, with `PERMISSION_DENIED` / 403 and a
+ * prescription naming the metadata API:
+ *
+ * - [#21594] a READ (`find`, `findOne`, `count`, `aggregate`, and every filter,
+ *   sort, grouping or search one can carry): the body is served nothing of the
+ *   family, neither the stored row nor a projection of it, so it can copy
+ *   nothing of it either;
+ * - [#21520] a WRITE (every write verb, and any verb not known to be a read).
+ *
+ * This is the one place every body face gets its API, so the hook face, the
+ * action face, the job face and every fallback below are refused alike.
+ * Applied HERE and nowhere else: a host code handler's `ctx.api` is not a
+ * body's, and is served by the reader-context seam
+ * (`serveStoredMetadataReadsThrough`) with its writes kept (deployer code,
+ * outside the boundary).
  */
 function buildSandboxApi(engineCtx: any, ql: any, errLabel: string) {
   return refuseStoredMetadataBodyWrites(
-    serveStoredMetadataReadsThrough(buildSandboxApiSource(engineCtx, ql, errLabel), ql),
+    refuseStoredMetadataBodyReads(buildSandboxApiSource(engineCtx, ql, errLabel)),
   );
 }
 
 
@@ -1,29 +1,39 @@
 // Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
 
 /**
- * [#21520] The stored-metadata family's WRITE boundary for app-authored bodies.
+ * [#21520, #21594] The stored-metadata family's boundary for app-authored bodies.
  *
  * The family's tables (`sys_metadata` / `sys_metadata_history`, the set
- * `isStoredMetadataBodyObject` answers for) have one writer for an app-authored
- * body: the metadata protocol, where a change is validated and its provenance
- * recorded. A sandboxed body — a hook body or an action body, whether it came
- * from a code bundle, an installed artifact or the metadata door — may not
- * touch those tables any other way:
+ * `isStoredMetadataBodyObject` answers for) are reached by an app-authored body
+ * through the metadata API only: the metadata protocol is their one writer,
+ * where a change is validated and its provenance recorded, and their one
+ * reader, which serves each definition in its read projection. A sandboxed
+ * body — a hook body, an action body or a job body, whether it came from a
+ * code bundle, an installed artifact or the metadata door — may not touch
+ * those tables any other way:
  *
  *  - **Binding** a body hook to a family table is refused at registration
  *    ({@link storedMetadataBodyHookBindingRefusal}, consulted by
  *    `hookBodyRunnerFactory` — the one point every body hook passes through
  *    to become a handler, whichever door bound it).
  *  - **Writing** a family table through a body's `ctx.api` is refused before
  *    the write runs ({@link storedMetadataBodyWriteRefusal}, consulted by the
- *    reader-context seam's body layer).
+ *    reader-context seam's body write layer).
+ *  - **Reading** a family table through a body's `ctx.api` is refused before
+ *    the read runs ({@link storedMetadataBodyReadRefusal}, consulted by the
+ *    seam's body read layer), whatever the read's query names.
+ *  - **Being handed** a family row as an action's subject record (`ctx.record`,
+ *    which the `/actions` door loads before dispatch) is refused before the
+ *    body runs ({@link storedMetadataBodySubjectRecordRefusal}, consulted by
+ *    `actionBodyRunnerFactory` — the one point every action body passes
+ *    through to run, whichever door bound it).
  *
  * Platform code is outside this boundary: the metadata protocol and its own
- * writers, the platform's internal hooks (registered as code, never as a
- * body) and host code a deployer registers all reach the store through their
- * own imports, never through a sandboxed body's API.
+ * readers and writers, the platform's internal hooks (registered as code,
+ * never as a body) and host code a deployer registers all reach the store
+ * through their own imports, never through a sandboxed body's API.
  *
- * Both refusals carry the standard catalog's `PERMISSION_DENIED` / 403: the
+ * Every refusal carries the standard catalog's `PERMISSION_DENIED` / 403: the
  * condition is that this author context is not permitted the operation on this
  * table, which is the catalog member's meaning, and the ledger's own admission
  * rule sends a generic permission condition to the standard member rather than
@@ -37,14 +47,20 @@ import { isStoredMetadataBodyObject, STORED_METADATA_BODY_OBJECTS } from '@objec
 export const STORED_METADATA_BODY_BOUNDARY_CODE = 'PERMISSION_DENIED';
 export const STORED_METADATA_BODY_BOUNDARY_STATUS = 403;
 
-/** The one prescription both refusals end with: the door an author uses instead. */
+/** The prescription the binding and write refusals end with: the door an author changes metadata through. */
 const PRESCRIPTION =
     'Change metadata through the metadata API (`PUT /api/v1/meta/:type/:name`, the metadata protocol), '
     + 'where it is validated and its provenance is recorded. Elevation (`runAs`, a system context) does not '
     + 'change this.';
 
-function refusal(message: string, object: string, operation: string): Error {
-    const err = new Error(`${message} ${PRESCRIPTION}`) as Error & Record<string, unknown>;
+/** The prescription the read refusal ends with: the door an author reads metadata through. */
+const READ_PRESCRIPTION =
+    'Read metadata through the metadata API (`GET /api/v1/meta/:type/:name`, the metadata protocol, and '
+    + '`GET /api/v1/meta/:type/:name/history` for its versions). Elevation (`runAs`, a system context) does not '
+    + 'change this.';
+
+function refusal(message: string, object: string, operation: string, prescription: string = PRESCRIPTION): Error {
+    const err = new Error(`${message} ${prescription}`) as Error & Record<string, unknown>;
     err.code = STORED_METADATA_BODY_BOUNDARY_CODE;
     err.status = STORED_METADATA_BODY_BOUNDARY_STATUS;
     err.object = object;
@@ -105,6 +121,44 @@ export function storedMetadataBodyWriteRefusal(object: string, verb: string): Er
     );
 }
 
+/**
+ * [#21594] The refusal for a sandboxed body's read verb on a family table, or
+ * `undefined` for any other object. Thrown before the read runs, whatever its
+ * query names (a filter, a sort, a grouping, a search, a projection, or none),
+ * so a refused read reaches no row and answers the same way whatever it asks:
+ * it serves nothing, and it is no oracle on what the table holds.
+ */
+export function storedMetadataBodyReadRefusal(object: string, verb: string): Error | undefined {
+    if (!isStoredMetadataBodyObject(object)) return undefined;
+    return refusal(
+        `Cannot ${verb} '${object}' from an app-authored body: the read was not run. '${object}' holds stored `
+        + 'metadata, and a body may not read it directly.',
+        object,
+        verb,
+        READ_PRESCRIPTION,
+    );
+}
+
+/**
+ * [#21594] The refusal for an action body that would be handed a family row as
+ * its subject record, or `undefined` for any other object. The `/actions` door
+ * loads an action's subject record before it dispatches, through the generic
+ * data door, so an action declared on a family table — or an object-less one
+ * addressed under it — would otherwise reach its body with a family row as
+ * `ctx.record`. Thrown before the body runs, so the body is handed nothing of
+ * the row; a host code handler's subject record is not judged here.
+ */
+export function storedMetadataBodySubjectRecordRefusal(object: string, action: string): Error | undefined {
+    if (!isStoredMetadataBodyObject(object)) return undefined;
+    return refusal(
+        `Action '${action}' was not run: its subject record is a row of '${object}', which holds stored `
+        + 'metadata, and an app-authored body may not be handed one.',
+        object,
+        'record',
+        READ_PRESCRIPTION,
+    );
+}
+
 /** The family's table names, for messages and logs that list them. */
 export function storedMetadataFamilyTableList(): string {
     return [...STORED_METADATA_BODY_OBJECTS].map((n) => `'${n}'`).join(', ');