@@ -0,0 +1,17 @@
+---
+'@objectstack/plugin-auth': patch
+---
+
+fix(plugin-auth): the invitation role cap's refusals on `POST /organization/invite-member` carry an error code, and a membership read that fails answers `503` instead of a refusal
+
+Clause-②: no
+
+The role cap in `beforeCreateInvitation` refused with `403` and a message but no `code`, while better-auth's own `owner` refusal on the same endpoint carries one. A client, the console's Invite User dialog among them, could not tell the refusals apart without reading English prose. Each refusal now carries the code the error-code ledger registers for it under `@objectstack/plugin-auth`, in the same `{ message, code }` body:
+
+- `INVITE_ROLE_ABOVE_ISSUER`: the requested role grades above the issuer's own, for example a `delegated_admin` inviting as `admin`.
+- `INVITE_ISSUER_MEMBER_ONLY`: an issuer below admin grade asked for a role other than a plain `member`, for example a `delegated_admin` inviting as `delegated_admin`.
+- `INVITE_ISSUER_UNVERIFIED`: fail-closed. The issuer's membership role was not established: the read found no usable `sys_member` row, or the `AuthManager` has no data engine to read from.
+
+A membership read that throws is a store outage, not a verdict about the issuer. It used to answer the same `403` as an unverified issuer. It now answers `503` with the code `SERVICE_UNAVAILABLE`, as the organization slug guard does for its own read faults. No invitation is created either way.
+
+Unchanged: which invitations are admitted, the status of every refusal (`403`), better-auth's own `owner` refusal, and the exports.
@@ -1198,20 +1198,49 @@ describe('AuthManager', () => {
       expect(roles.sales_rep).toBeUndefined();
     });
 
+    /**
+     * [#23945] A cap refusal asserted on its envelope (ADR-0112): the status
+     * and the `code` better-auth serialises into the body — never the bare
+     * throw, which a codeless `FORBIDDEN` passes just as well.
+     */
+    const capAnswer = async (attempt: Promise<unknown>) => {
+      const err = (await attempt.then(
+        () => undefined,
+        (e: unknown) => e,
+      )) as
+        | { status?: unknown; statusCode?: unknown; body?: { code?: unknown; message?: unknown }; cause?: unknown }
+        | undefined;
+      expect(err, 'the invitation was admitted').toBeTruthy();
+      return err;
+    };
+    const inviteAs = (orgPlugin: any, role: string, inviterId = 'u_delegate') =>
+      orgPlugin._opts.organizationHooks.beforeCreateInvitation({
+        invitation: { organizationId: 'org-42', email: 'e@x.test', role },
+        inviter: { id: inviterId },
+        organization: { id: 'org-42' },
+      });
+
     it('role cap: a delegate inviting an `admin` is REFUSED (the escalation chain)', async () => {
       // delegate invites admin → sys_member(role='admin') → auto-org-admin-grant
       // → organization_admin → wildcard modifyAllRecords → isTenantAdmin().
       const orgPlugin = await bootOrgPlugin({
         dataEngine: engineWithMemberRole('delegated_admin') as never,
       });
 
-      await expect(
-        orgPlugin._opts.organizationHooks.beforeCreateInvitation({
-          invitation: { organizationId: 'org-42', email: 'e@x.test', role: 'admin' },
-          inviter: { id: 'u_delegate' },
-          organization: { id: 'org-42' },
-        }),
-      ).rejects.toThrow(/never confer a role above the issuer/);
+      const err = await capAnswer(inviteAs(orgPlugin, 'admin'));
+      expect(err?.statusCode).toBe(403);
+      expect(err?.status).toBe('FORBIDDEN');
+      expect(err?.body?.code).toBe('INVITE_ROLE_ABOVE_ISSUER');
+    });
+
+    it('role cap: a delegate minting another delegate is REFUSED as member-only, not as outranked', async () => {
+      const orgPlugin = await bootOrgPlugin({
+        dataEngine: engineWithMemberRole('delegated_admin') as never,
+      });
+
+      const err = await capAnswer(inviteAs(orgPlugin, 'delegated_admin'));
+      expect(err?.statusCode).toBe(403);
+      expect(err?.body?.code).toBe('INVITE_ISSUER_MEMBER_ONLY');
     });
 
     it('role cap: a delegate inviting a plain `member` passes — and costs no lookup', async () => {
@@ -1244,17 +1273,50 @@ describe('AuthManager', () => {
     });
 
     it('role cap: an unresolvable issuer membership fails CLOSED', async () => {
+      // Pinned HERE, not on the wire: through `POST /organization/invite-member`
+      // this input is not reachable. better-auth reads the inviter's membership
+      // before the hook runs and refuses a non-member (`MEMBER_NOT_FOUND`, 400)
+      // or a role without `invitation:create` (403) first, and the cap re-reads
+      // the same `sys_member` rows in system context — so a read that answers
+      // "no usable row" needs the row to vanish between the two reads.
       const orgPlugin = await bootOrgPlugin({
         dataEngine: engineWithMemberRole(null) as never,
       });
 
-      await expect(
-        orgPlugin._opts.organizationHooks.beforeCreateInvitation({
-          invitation: { organizationId: 'org-42', email: 'e@x.test', role: 'admin' },
-          inviter: { id: 'u_ghost' },
-          organization: { id: 'org-42' },
-        }),
-      ).rejects.toThrow(/could not be verified/);
+      const err = await capAnswer(inviteAs(orgPlugin, 'admin', 'u_ghost'));
+      expect(err?.statusCode).toBe(403);
+      expect(err?.body?.code).toBe('INVITE_ISSUER_UNVERIFIED');
+    });
+
+    it('role cap: NO data engine to read fails CLOSED too — "cannot check" is never "does not apply"', async () => {
+      // Not reachable through `AuthPlugin`, which hard-depends on ObjectQL and
+      // always passes its `data` service; only a bare `AuthManager` built
+      // without `dataEngine` (better-auth then runs on its in-memory adapter)
+      // reaches the hook with nothing to read.
+      const orgPlugin = await bootOrgPlugin();
+
+      const err = await capAnswer(inviteAs(orgPlugin, 'admin', 'u_any'));
+      expect(err?.statusCode).toBe(403);
+      expect(err?.body?.code).toBe('INVITE_ISSUER_UNVERIFIED');
+    });
+
+    it('role cap: a membership read that THROWS is an outage (503 SERVICE_UNAVAILABLE), not a refusal', async () => {
+      // An owner's invitation, so the only thing between it and admission is
+      // the read: the verdict the store would have given is "admitted".
+      const engine = engineWithMemberRole('owner');
+      engine.find.mockImplementation(async () => {
+        throw new Error('store unavailable');
+      });
+      const orgPlugin = await bootOrgPlugin({ dataEngine: engine as never });
+
+      const err = await capAnswer(inviteAs(orgPlugin, 'admin', 'u_owner'));
+      expect(err?.statusCode).toBe(503);
+      expect(err?.status).toBe('SERVICE_UNAVAILABLE');
+      expect(err?.body?.code).toBe('SERVICE_UNAVAILABLE');
+      expect(err?.body?.code).not.toBe('INVITE_ISSUER_UNVERIFIED');
+      // The driver's own failure is kept for the operator.
+      expect((err?.cause as Error | undefined)?.message).toBe('store unavailable');
+      expect(engine.find).toHaveBeenCalledTimes(1);
     });
 
     it('role cap: it runs BEFORE the placement gate and applies without placement intent', async () => {
@@ -1278,7 +1340,7 @@ describe('AuthManager', () => {
           inviter: { id: 'u_delegate' },
           organization: { id: 'org-42' },
         }),
-      ).rejects.toThrow(/never confer a role above the issuer/);
+      ).rejects.toMatchObject({ statusCode: 403, body: { code: 'INVITE_ROLE_ABOVE_ISSUER' } });
       // Refused before the placement gate was ever consulted.
       expect(assertIssuable).not.toHaveBeenCalled();
     });
 
@@ -73,6 +73,7 @@ import {
 } from '@objectstack/spec';
 import { postureEnforcesWall, type TenancyPosture } from '@objectstack/spec/security';
 import { MCP_OAUTH_SCOPES } from '@objectstack/spec/ai';
+import type { StandardErrorCode } from '@objectstack/spec/api';
 import { createObjectQLAdapterFactory, withSystemContext, withSystemReadContext } from './objectql-adapter.js';
 import { permissionSetInEffect } from './catalog-set-in-effect.js';
 import { recoverInternalFieldsForSystemRead } from './internal-field-readback.js';
@@ -1364,6 +1365,34 @@ async function slugGuardReadFaultApiError(object: string, cause: unknown): Promi
   return err;
 }
 
+/** [#23945] The standard ADR-0112 code a store outage answers with — the status's own name. */
+const INVITATION_ROLE_CAP_READ_FAULT_CODE: StandardErrorCode = 'SERVICE_UNAVAILABLE';
+
+/**
+ * [#23945] The invitation role cap's answer when its one read — the issuer's
+ * `sys_member` rows — cannot answer: `503 SERVICE_UNAVAILABLE`, as the slug
+ * guard's read fault answers ({@link slugGuardReadFaultApiError}).
+ *
+ * Not the cap's `403 INVITE_ISSUER_UNVERIFIED`: that code is a verdict — the
+ * store answered and established no role — while a read that threw reached no
+ * verdict, so it must not wear the refusal's code. Still fail-closed: the
+ * throw ends the endpoint, so no invitation row is written. Unlike the slug
+ * guard's body, this one carries the code too, so every answer from the
+ * invitation endpoint has one. The driver's own failure rides `cause`.
+ */
+async function invitationRoleCapReadFaultApiError(cause: unknown): Promise<Error> {
+  const { APIError } = await import('better-auth/api');
+  const err = new APIError('SERVICE_UNAVAILABLE', {
+    message:
+      'The invitation role cap could not read `sys_member`, so the role the issuer holds was never ' +
+      'determined, and no invitation was created. This is a server-side outage, not a refusal of the ' +
+      'invitation: retry once the data store is reachable.',
+    code: INVITATION_ROLE_CAP_READ_FAULT_CODE,
+  });
+  (err as { cause?: unknown }).cause = cause;
+  return err;
+}
+
 /**
  * [#24166, ruling 6232069920 A] The access-token claim that carries the
  * organization an OAuth consent bound. Minted by `customAccessTokenClaims` on
@@ -3487,13 +3516,18 @@ export class AuthManager {
             // placement intent at all. Skipped for a plain `member` invitation,
             // which can never trip the cap — so the ordinary path pays nothing.
             if (!isPlainMemberInvitation(invitation?.role)) {
-              const capFailure = invitationRoleCapFailure(
+              // [#23945] Each refusal carries its ADR-0112 code beside its
+              // message, the way better-auth's own `owner` refusal on this
+              // endpoint does. A membership read that THROWS never reaches
+              // this verdict: `resolveMembershipRole` answers it as an outage
+              // (503 `SERVICE_UNAVAILABLE`), not as a refusal.
+              const refusal = invitationRoleCapFailure(
                 invitation?.role,
                 await this.resolveMembershipRole(inviterUserId, organizationId),
               );
-              if (capFailure) {
+              if (refusal) {
                 const { APIError } = await import('better-auth/api');
-                throw new APIError('FORBIDDEN', { message: capFailure });
+                throw new APIError('FORBIDDEN', { message: refusal.message, code: refusal.code });
               }
             }
 
@@ -7813,10 +7847,18 @@ export class AuthManager {
    * org-scoped RLS read performed as a non-privileged delegate could return
    * nothing and silently grade them as unresolved.
    *
-   * Returns `null` when the role cannot be established — missing keys, no
-   * engine, no membership row, or a lookup error. That grades BELOW a plain
-   * member, so the cap refuses anything above a `member` invitation: this
-   * backs a security gate, and an unverifiable issuer must confer nothing.
+   * Returns `null` when the role is not established — missing keys, no
+   * engine, or a read that answered with no usable membership row. That
+   * grades BELOW a plain member, so the cap refuses anything above a `member`
+   * invitation with `INVITE_ISSUER_UNVERIFIED`: this backs a security gate,
+   * and an issuer it cannot check confers nothing — "no engine to read" is
+   * "cannot check", never "the cap does not apply".
+   *
+   * [#23945] A read that THROWS is not one of those answers: it throws
+   * `503 SERVICE_UNAVAILABLE` ({@link invitationRoleCapReadFaultApiError}), so
+   * an outage is never reported as a verdict about the issuer. Still no
+   * invitation is created.
+   *
    * Multiple membership rows (legacy duplicates) are joined so the highest
    * grade among them wins — the cap must judge the authority they actually
    * hold, not whichever row came back first.
@@ -7830,18 +7872,19 @@ export class AuthManager {
     if (!uid || !oid) return null;
     const engine = this.getDataEngine();
     if (!engine) return null;
+    let members: unknown;
     try {
-      const members = await withSystemReadContext(engine).find('sys_member', {
+      members = await withSystemReadContext(engine).find('sys_member', {
         where: { user_id: uid, organization_id: oid },
         limit: 10,
       });
-      const roles = (Array.isArray(members) ? members : [])
-        .map((m: any) => (typeof m?.role === 'string' ? m.role : ''))
-        .filter((r: string) => r.length > 0);
-      return roles.length > 0 ? roles.join(',') : null;
-    } catch {
-      return null;
+    } catch (err) {
+      throw await invitationRoleCapReadFaultApiError(err);
     }
+    const roles = (Array.isArray(members) ? members : [])
+      .map((m: any) => (typeof m?.role === 'string' ? m.role : ''))
+      .filter((r: string) => r.length > 0);
+    return roles.length > 0 ? roles.join(',') : null;
   }
 
   /**
 
@@ -14,6 +14,9 @@
 
 import { describe, expect, it } from 'vitest';
 import {
+  INVITE_ISSUER_MEMBER_ONLY_CODE,
+  INVITE_ISSUER_UNVERIFIED_CODE,
+  INVITE_ROLE_ABOVE_ISSUER_CODE,
   invitationRoleCapFailure,
   isPlainMemberInvitation,
   orgRoleGrade,
@@ -22,6 +25,9 @@ import {
 
 const DELEGATE = 'delegated_admin';
 
+/** The refusal's ADR-0112 code — what a client branches on (#23945). */
+const codeOf = (requested: unknown, issuer: unknown) => invitationRoleCapFailure(requested, issuer)?.code;
+
 describe('parseOrgRoles', () => {
   it('accepts better-auth’s three role shapes', () => {
     expect(parseOrgRoles('admin')).toEqual(['admin']);
@@ -79,16 +85,15 @@ describe('isPlainMemberInvitation', () => {
 
 describe('invitationRoleCapFailure — the escalation chain', () => {
   it('REFUSES the chain: a delegate inviting an admin', () => {
-    const failure = invitationRoleCapFailure('admin', DELEGATE);
-    expect(failure).toMatch(/never confer a role above the issuer/);
+    expect(codeOf('admin', DELEGATE)).toBe(INVITE_ROLE_ABOVE_ISSUER_CODE);
   });
 
   it('REFUSES a delegate inviting an owner', () => {
-    expect(invitationRoleCapFailure('owner', DELEGATE)).toMatch(/above the issuer/);
+    expect(codeOf('owner', DELEGATE)).toBe(INVITE_ROLE_ABOVE_ISSUER_CODE);
   });
 
   it('REFUSES admin smuggled inside a comma list', () => {
-    expect(invitationRoleCapFailure('member,admin', DELEGATE)).toMatch(/above the issuer/);
+    expect(codeOf('member,admin', DELEGATE)).toBe(INVITE_ROLE_ABOVE_ISSUER_CODE);
   });
 
   it('REFUSES a delegate inviting an app role — membership roles are a capability channel too', () => {
@@ -97,13 +102,11 @@ describe('invitationRoleCapFailure — the escalation chain', () => {
     // them with nothing gating the hand-out. A delegate's channel for
     // capability is the invitation's PLACEMENT intent, which the D12 gate
     // allowlists position-by-position.
-    expect(invitationRoleCapFailure('sales_manager', DELEGATE)).toMatch(
-      /may invite only as 'member'/,
-    );
+    expect(codeOf('sales_manager', DELEGATE)).toBe(INVITE_ISSUER_MEMBER_ONLY_CODE);
   });
 
   it('REFUSES a delegate minting another delegate', () => {
-    expect(invitationRoleCapFailure(DELEGATE, DELEGATE)).toMatch(/may invite only as 'member'/);
+    expect(codeOf(DELEGATE, DELEGATE)).toBe(INVITE_ISSUER_MEMBER_ONLY_CODE);
   });
 
   it('ALLOWS a delegate inviting a plain member — the capability the fix exists to grant', () => {
@@ -123,22 +126,38 @@ describe('invitationRoleCapFailure — org owners and admins are unaffected', ()
     expect(invitationRoleCapFailure('admin', 'admin')).toBeNull();
     expect(invitationRoleCapFailure(DELEGATE, 'admin')).toBeNull();
     expect(invitationRoleCapFailure('sales_manager', 'admin')).toBeNull();
-    expect(invitationRoleCapFailure('owner', 'admin')).toMatch(/above the issuer/);
+    expect(codeOf('owner', 'admin')).toBe(INVITE_ROLE_ABOVE_ISSUER_CODE);
   });
 
   it('an issuer holding both roles is judged on the higher one', () => {
     expect(invitationRoleCapFailure('owner', 'member,owner')).toBeNull();
   });
 });
 
+describe('invitationRoleCapFailure — each refusal answers its own code (#23945)', () => {
+  it('the three codes, by value — the strings the error-code ledger registers under plugin-auth', () => {
+    expect([INVITE_ROLE_ABOVE_ISSUER_CODE, INVITE_ISSUER_MEMBER_ONLY_CODE, INVITE_ISSUER_UNVERIFIED_CODE]).toEqual([
+      'INVITE_ROLE_ABOVE_ISSUER',
+      'INVITE_ISSUER_MEMBER_ONLY',
+      'INVITE_ISSUER_UNVERIFIED',
+    ]);
+  });
+
+  it('a refusal carries its reason beside the code', () => {
+    for (const [requested, issuer] of [['admin', DELEGATE], [DELEGATE, DELEGATE], ['admin', null]] as const) {
+      const refusal = invitationRoleCapFailure(requested, issuer);
+      expect(refusal?.message, `${requested} by ${issuer}`).toEqual(expect.any(String));
+      expect(refusal?.message.length).toBeGreaterThan(0);
+    }
+  });
+});
+
 describe('invitationRoleCapFailure — fail-closed', () => {
   it('an unresolvable issuer role confers nothing above a plain member', () => {
     for (const unresolved of [null, undefined, '']) {
       // Reported as what it is — unverified, not outranked.
-      expect(invitationRoleCapFailure('admin', unresolved)).toMatch(/could not be verified/);
-      expect(invitationRoleCapFailure('sales_manager', unresolved)).toMatch(
-        /could not be verified/,
-      );
+      expect(codeOf('admin', unresolved)).toBe(INVITE_ISSUER_UNVERIFIED_CODE);
+      expect(codeOf('sales_manager', unresolved)).toBe(INVITE_ISSUER_UNVERIFIED_CODE);
       // …but the ordinary invitation still works: an unreadable membership row
       // must not take the whole invite surface down with it.
       expect(invitationRoleCapFailure('member', unresolved)).toBeNull();