@@ -0,0 +1,12 @@
+---
+'@objectstack/spec': patch
+---
+
+feat(spec): `IOwnershipQueueService` lets a caller ask for a refusal on a failed member read (`onFailedRead`), the call-time signal ADR-0142 D2 asks each consumer to send
+
+Clause-②: yes (widening: an optional `onFailedRead` on `expandMembers`' options and an optional options argument on `isMember`; precedent PR #30015)
+Metadata-protocol: none
+
+- **New type `OwnershipQueueFailedReadAnswer`** (`'nobody' | 'refuse'`, `@objectstack/spec/contracts`): what a membership read answers when a read behind the queue fails (`sys_queue`, `sys_queue_member`, `sys_team_member`, `sys_user_position`, `sys_member` through the position transition limb, the business-unit membership and tree).
+- **`expandMembers(name, organizationId, { purpose?, onFailedRead? })`** and **`isMember(userId, name, organizationId, { onFailedRead? })`**. `'nobody'` is the default and the answer every caller had before: a failed read is logged at `warn` and contributes nobody. Under `'refuse'` a failed read rejects with a failure that names the read, never `[]`, a partial set or `false`; an empty queue is still `[]`. The docblock names who takes which: the access path (D3), the claim admission (D4) and the assignment pool (D5) take `'nobody'`; the approver slate (D6) and the sharing-recipient grant recompute (D7) take `'refuse'`. The key is independent of `purpose`.
+- **Contract only.** Every existing call and implementation compiles unchanged and behaves as today; the producer in `@objectstack/plugin-sharing` and the D6/D7 callers that pass `'refuse'` land with #29604.
@@ -241,6 +241,7 @@
     "OWNERSHIP_QUEUE_SERVICE (const)",
     "ObjectDraft (interface)",
     "OwnershipFloorAlternate (interface)",
+    "OwnershipQueueFailedReadAnswer (type)",
     "PRINCIPAL_SESSION_MAX_TTL_SECONDS (const)",
     "PendingActionRow (interface)",
     "PendingActionStatus (type)",
 
@@ -241,6 +241,7 @@
     "OWNERSHIP_QUEUE_SERVICE": "src/contracts/ownership-queue-service.ts#OWNERSHIP_QUEUE_SERVICE (const)",
     "ObjectDraft": "src/contracts/external-datasource-service.ts#ObjectDraft (interface)",
     "OwnershipFloorAlternate": "src/contracts/security-service.ts#OwnershipFloorAlternate (interface)",
+    "OwnershipQueueFailedReadAnswer": "src/contracts/ownership-queue-service.ts#OwnershipQueueFailedReadAnswer (type)",
     "PRINCIPAL_SESSION_MAX_TTL_SECONDS": "src/contracts/auth-service.ts#PRINCIPAL_SESSION_MAX_TTL_SECONDS (const)",
     "PendingActionRow": "src/contracts/ai-service.ts#PendingActionRow (interface)",
     "PendingActionStatus": "src/contracts/ai-service.ts#PendingActionStatus (type)",
 
@@ -0,0 +1,84 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#30251] `onFailedRead` on {@link IOwnershipQueueService}: the call-time
+ * signal ADR-0142 D2 (as amended) asks each consumer to send, so a recompute
+ * consumer reached only through this contract (the D6 approver slate in
+ * `@objectstack/plugin-approvals`) can ask for a refusal on a failed read.
+ *
+ * Pinned at the type level, under `check:test-typecheck` (this file compiles
+ * under `tsconfig.test.json`):
+ *
+ *  1. **A widening, not a narrowing.** A call with no options, and the
+ *     three-argument `isMember` call, compile exactly as before; so does an
+ *     implementation written before the key existed.
+ *  2. **Both members read one value type.** `expandMembers`' and `isMember`'s
+ *     `onFailedRead` are both {@link OwnershipQueueFailedReadAnswer}, which is
+ *     exactly `'nobody' | 'refuse'`; an unknown value does not compile.
+ *  3. **Independent of `purpose`.** The two keys sit side by side; neither
+ *     value set leaks into the other.
+ *
+ * ⛔ Not pinned: what any implementation DOES under `'refuse'` — that is the
+ * producer half (#29604, `@objectstack/plugin-sharing`).
+ */
+
+import { describe, it, expect } from 'vitest';
+
+import type {
+  IOwnershipQueueService,
+  OwnershipQueueFailedReadAnswer,
+  QueueExpansionPurpose,
+} from './ownership-queue-service';
+
+/** Type-level identity: true iff A and B are the same type. */
+type Eq<A, B> = (<T>() => T extends A ? 1 : 2) extends (<T>() => T extends B ? 1 : 2) ? true : false;
+/** Compile error when the argument is not `true`. */
+type Assert<T extends true> = T;
+
+type ExpandOptions = NonNullable<Parameters<IOwnershipQueueService['expandMembers']>[2]>;
+type IsMemberOptions = NonNullable<Parameters<IOwnershipQueueService['isMember']>[3]>;
+
+export type _AnswerIsExactlyTwoValues = Assert<Eq<OwnershipQueueFailedReadAnswer, 'nobody' | 'refuse'>>;
+export type _ExpandReadsTheAnswerType = Assert<Eq<ExpandOptions['onFailedRead'], OwnershipQueueFailedReadAnswer | undefined>>;
+export type _IsMemberReadsTheAnswerType = Assert<Eq<IsMemberOptions['onFailedRead'], OwnershipQueueFailedReadAnswer | undefined>>;
+export type _PurposeUnchanged = Assert<Eq<ExpandOptions['purpose'], QueueExpansionPurpose | undefined>>;
+export type _ExpandOptionKeys = Assert<Eq<keyof ExpandOptions, 'purpose' | 'onFailedRead'>>;
+export type _IsMemberOptionKeys = Assert<Eq<keyof IsMemberOptions, 'onFailedRead'>>;
+/** The axes stay apart: no failed-read answer is a purpose, and no purpose is a failed-read answer. */
+export type _AxesDisjoint = Assert<Eq<Extract<OwnershipQueueFailedReadAnswer, QueueExpansionPurpose>, never>>;
+
+/** An implementation written before the key existed still satisfies the contract (method bivariance on an optional trailing argument). */
+const legacy: IOwnershipQueueService = {
+  resolveQueue: async () => null,
+  expandMembers: async (_name: string, _org: string | null, _options?: { purpose?: QueueExpansionPurpose }) => [],
+  isMember: async (_user: string, _name: string, _org: string | null) => false,
+  queuesOf: async () => [],
+};
+
+/** Every call shape the card's acceptance names; the unknown values must NOT compile. */
+async function callShapes(svc: IOwnershipQueueService): Promise<unknown[]> {
+  return [
+    await svc.expandMembers('q', 'org_a'),
+    await svc.expandMembers('q', null, {}),
+    await svc.expandMembers('q', 'org_a', { purpose: 'addressing' }),
+    await svc.expandMembers('q', 'org_a', { onFailedRead: 'refuse' }),
+    await svc.expandMembers('q', 'org_a', { purpose: 'addressing', onFailedRead: 'refuse' }),
+    await svc.expandMembers('q', 'org_a', { onFailedRead: 'nobody' }),
+    await svc.isMember('u', 'q', 'org_a'),
+    await svc.isMember('u', 'q', 'org_a', { onFailedRead: 'refuse' }),
+    // @ts-expect-error — not a failed-read answer
+    await svc.expandMembers('q', 'org_a', { onFailedRead: 'throw' }),
+    // @ts-expect-error — not a failed-read answer
+    await svc.isMember('u', 'q', 'org_a', { onFailedRead: 'empty' }),
+    // @ts-expect-error — `purpose` is the other axis, and `isMember` does not take it
+    await svc.isMember('u', 'q', 'org_a', { purpose: 'addressing' }),
+    // @ts-expect-error — a purpose value is not a failed-read answer
+    await svc.expandMembers('q', 'org_a', { onFailedRead: 'addressing' }),
+  ];
+}
+
+describe('IOwnershipQueueService onFailedRead (#30251)', () => {
+  it('every call shape compiles against an implementation written before the key, and answers as it did', async () => {
+    expect(await callShapes(legacy)).toEqual([[], [], [], [], [], [], false, false, [], false, false, []]);
+  });
+});
@@ -35,6 +35,9 @@
  * answers `[]`. Each consumer says what it does with that (ADR-0142 D5, D6,
  * D7) — and every queue-dependent ADMISSION fails closed when the service is
  * not registered at all.
+ *
+ * A read that FAILS is not absence. What the expander answers then is the
+ * caller's to say, per call — see {@link OwnershipQueueFailedReadAnswer}.
  */
 
 import type { QueueMemberType } from '../security/queue.zod.js';
@@ -45,6 +48,47 @@ export const OWNERSHIP_QUEUE_SERVICE = 'ownership-queue';
 /** Which reader an expansion is for — see {@link IOwnershipQueueService.expandMembers}. */
 export type QueueExpansionPurpose = 'access' | 'addressing';
 
+/**
+ * What a membership read answers when a read behind the queue FAILS — the
+ * `onFailedRead` option of {@link IOwnershipQueueService.expandMembers} and
+ * {@link IOwnershipQueueService.isMember} (ADR-0142, D2 "Membership", the
+ * amended paragraph "An empty expansion is a fact; a failed read is a fault").
+ *
+ * The tables behind a queue are its own row (`sys_queue`, through which an
+ * authored queue resolves), its member rows (`sys_queue_member`), and the
+ * member tables a specification reads: `sys_team_member`, `sys_user_position`,
+ * `sys_member` (through the position transition limb), `sys_business_unit_member`
+ * and the business-unit tree (`sys_business_unit`). A table the composition
+ * does not carry is absence, not failure. The activation-ledger read
+ * (`sys_metadata_activation`, which says whether a declared queue or a position
+ * is switched off) is NOT a failed read in this sense: under either answer its
+ * failure reads "switched on", as it did before the key existed; whether that
+ * posture moves is #29604's code half to decide.
+ *
+ * - `'nobody'` — the default and the answer every caller had before the key
+ *   existed. A failed read is logged at `warn`, and what sat behind it
+ *   contributes nobody. The admission consumers take it, because for them
+ *   nobody denies: the sitting-record access path (D3), the claim admission
+ *   (D4) and the assignment pool (D5).
+ * - `'refuse'` — a failed read rejects the call with a failure that names the
+ *   read, never `[]`, a partial set or `false`. The recompute consumers take
+ *   it, because they turn the member set into routed work or materialised
+ *   grants and "nobody" there revokes: the approver slate (D6) and the
+ *   sharing-recipient grant recompute (D7). An implementation written before
+ *   this key existed ignores it and answers `'nobody'`; the registered one,
+ *   `@objectstack/plugin-sharing`'s, honours `'refuse'` from #29604's code half
+ *   on, so until then a caller passing `'refuse'` still gets `'nobody'`.
+ *
+ * Under either answer an EMPTY queue — every read succeeded and reached
+ * nobody — is still `[]`, and a name that resolves nowhere is still `[]` /
+ * `false`: those are facts, not faults.
+ *
+ * ⛔ An axis independent of {@link QueueExpansionPurpose}: which holders an
+ * answer keeps and whether a failed read refuses are two questions, and one
+ * value never answers both.
+ */
+export type OwnershipQueueFailedReadAnswer = 'nobody' | 'refuse';
+
 /** One member specification: a recipient kind and the value that kind takes in a sharing rule. */
 export interface QueueMemberSpec {
   type: QueueMemberType;
@@ -92,15 +136,35 @@ export interface IOwnershipQueueService {
    * off — the sitting-record path, the claim, the assignment pool and the
    * sharing recipient all confer access. `'addressing'` keeps them — the
    * approver slate routes work, and dropping holders there is fail-open.
+   *
+   * `onFailedRead` says what the call is owed when a read behind the queue
+   * fails: `'nobody'`, the default, or `'refuse'`, under which the call
+   * rejects with a failure naming the read. An empty queue is still `[]`.
+   * See {@link OwnershipQueueFailedReadAnswer} for the tables and for which
+   * ADR-0142 consumer takes which answer; it is independent of `purpose`.
    */
   expandMembers(
     name: string,
     organizationId: string | null,
-    options?: { purpose?: QueueExpansionPurpose },
+    options?: { purpose?: QueueExpansionPurpose; onFailedRead?: OwnershipQueueFailedReadAnswer },
   ): Promise<string[]>;
 
-  /** Is `userId` a member of the queue named `name` in `organizationId`? `false` when the name resolves nowhere. */
-  isMember(userId: string, name: string, organizationId: string | null): Promise<boolean>;
+  /**
+   * Is `userId` a member of the queue named `name` in `organizationId`?
+   * `false` when the name resolves nowhere.
+   *
+   * `onFailedRead` is {@link expandMembers}' key with the same meaning:
+   * under `'nobody'`, the default, a failed read counts as not reaching
+   * `userId`; under `'refuse'`, `false` is answered only when every read
+   * behind it succeeded, and a failed read rejects with a failure naming it.
+   * The options argument is optional, so a three-argument call is today's.
+   */
+  isMember(
+    userId: string,
+    name: string,
+    organizationId: string | null,
+    options?: { onFailedRead?: OwnershipQueueFailedReadAnswer },
+  ): Promise<boolean>;
 
   /**
    * The machine names of every queue `userId` is a member of in