@@ -0,0 +1,29 @@
+---
+'@objectstack/core': minor
+'@objectstack/runtime': minor
+'@objectstack/cloud-connection': minor
+'@objectstack/mcp': minor
+'@objectstack/service-storage': patch
+---
+
+fix(core,cloud-connection,mcp)!: every API-key admission names its owner-posture source, so a held owner's key is refused at the marketplace install-local doors and on every MCP stdio call
+
+Clause-②: no (narrowing) — no published accept-set widens; two more seams refuse a key whose owner holds an account-scope posture, the owner-posture input of the shared key-admission seam becomes required, and `resolveApiKeyPrincipal` no longer answers a held owner's key with a principal.
+
+<!-- adr-0087: not-required (runtime-interface-only packages/core/src/security/resolve-authz-context.ts#ResolveAuthzInput) An authentication-policy change at runtime TypeScript call sites, not a metadata change. No authorable spec key, stored shape or metadata surface moves, so `objectstack migrate meta` has nothing to rewrite. The input that becomes required lives on a runtime interface and on two runtime functions of `@objectstack/core` (`resolveApiKeyAdmission`, `resolveApiKeyPrincipal`), none of them a metadata surface; the affected party is a TypeScript caller, and the compiler names its call site. The packages publish (not unpublished), no ADR-0087 id covers this and none is added (not registered or already-registered). -->
+
+**BREAKING** (an accept-set narrowing at two API-key doors, and a required input on the shared key-admission seam), shipped as `minor` under the launch-window convention for breaking changes.
+
+Ruling C′ on #23287, item 1: "a held user's API key is refused at every seam with the same code". Item 4: "The refusal is not a revocation: the key resumes the moment the user enrols (or the account posture clears)". `AUTH_GATE_SCOPES` decides which posture holds a key: `MFA_REQUIRED` (scope `account`) holds it; `PASSWORD_EXPIRED` and `PASSWORD_RESET_REQUIRED` (scope `credential`) do not.
+
+- **The marketplace install-local doors (`@objectstack/cloud-connection`).** The resolver behind all five doors now hands the shared resolver the auth service's per-user posture computation and refuses on the posture it decided for whichever credential admitted the caller. A key whose owner holds `MFA_REQUIRED` gets `403 MFA_REQUIRED` with the session's message, before any effect. It used to be served there.
+- **The MCP stdio transport (`@objectstack/mcp`).** `OS_MCP_STDIO_API_KEY` is resolved with the owner's posture on every call of a live session, and a held owner's call is refused before any read or write with the envelope REST answers (`code` `MFA_REQUIRED`, `status` 403, the session's remediation message). A data tool's error and the record resource carry that message, as they carry every other refusal on this transport. A held key still starts the transport and says so once in a warning: the key is valid, and the next call after the owner enrols is served with no restart.
+- **The owner-posture input is required (`@objectstack/core`).** `ResolveAuthzInput.userAuthGates`, and the `tenancyPosture` and `userAuthGates` parameters of `resolveApiKeyAdmission` and `resolveApiKeyPrincipal`, are now required; `undefined` is a value passed on purpose. A seam that forgets the source no longer compiles, which is how the two seams above were missed. `@objectstack/runtime` re-exports these, so its importers see the same change.
+- **`resolveApiKeyPrincipal` collapses a held owner's key to no principal.** A principal-or-nothing answer cannot carry the posture's code, so a host that answers requests should read `resolveApiKeyAdmission` and refuse its `held` outcome with `gate.code`.
+- **The storage download authorizer (`@objectstack/service-storage`)** names the same source. The storage family's door already refused a held owner's key on the same request, so nothing changes on the wire.
+
+What changes for you:
+
+- **Refused now:** an API key whose owner owes MFA enrolment past the grace window gets `403 MFA_REQUIRED` at the install-local doors, and every principal-bound MCP stdio call it makes is refused with the same code and message. It works again the moment the owner enrols, with nothing reissued.
+- **Unchanged:** a key whose owner's password expired, or whose administrator forced a password change, keeps working on both.
+- **Code that calls `resolveAuthzContext`, `resolveApiKeyAdmission` or `resolveApiKeyPrincipal` directly** now passes the owner-posture source explicitly: `userAuthGates: userAuthGateSourceOf(authService)` wherever the kernel's `auth` service is reachable, or `undefined` on a kernel composed without `plugin-auth`. The two positional functions also take `tenancyPosture` explicitly (`undefined` when no `tenancy` service is registered).
@@ -98,6 +98,7 @@ async function boot(kind: Kind, dbFile: string, rootDir: string, app: any): Prom
 /** Read `echo_doc` as `userId`, with the context the request path builds. */
 async function readAs(ql: any, userId: string, org: string): Promise<'granted' | 'refused'> {
   const authz = await resolveAuthzContext({
+    userAuthGates: undefined,
     ql,
     headers: {},
     getSession: () => ({ user: { id: userId }, session: { userId, activeOrganizationId: org } }),
 
@@ -0,0 +1,266 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#23455 — ruling C′ items 1 and 4] The install-local doors judge an API key
+ * by the answer the shared key-admission seam gives for its OWNER.
+ *
+ * ## What was open
+ *
+ * `MarketplaceInstallLocalPlugin.resolveInstallPrincipal` called
+ * `resolveAuthzContext` with no owner-posture source and asked the ADR-0069
+ * gate about the session user alone. An API key admits its owner without a
+ * session, so a key whose owner owes MFA enrolment carried no posture here and
+ * all five doors served it, while REST and every face ruling C′ built refuse
+ * the same key with `403 MFA_REQUIRED`.
+ *
+ * ## What is pinned, through the booted plugin's own doors
+ *
+ *  - a key whose owner holds `MFA_REQUIRED` (scope `account`) → all five doors
+ *    answer `403 MFA_REQUIRED` with the session's message, before any effect;
+ *  - a key whose owner holds only `PASSWORD_RESET_REQUIRED` (scope
+ *    `credential`) → served;
+ *  - the refusal is not a revocation: the same key is served again once the
+ *    posture clears, with nothing rewritten.
+ *
+ * The harness is `cloud-connection-auth-gate.pin.test.ts`'s install-local
+ * half, with a data engine that knows the key and an auth service that answers
+ * a per-user posture (`resolveUserAuthGates`, the computation plugin-auth's
+ * `AuthManager` exposes).
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { mkdtempSync, rmSync, existsSync } from 'node:fs';
+import { join } from 'node:path';
+import { tmpdir } from 'node:os';
+import { hashApiKey } from '@objectstack/core';
+
+const seedCalls: unknown[] = [];
+vi.mock('@objectstack/runtime', () => ({
+    SeedLoaderService: class {
+        async load(request: unknown) {
+            seedCalls.push(request);
+            return { summary: { totalInserted: 2, totalUpdated: 0, totalSkipped: 0 }, errors: [] };
+        }
+        async buildDependencyGraph(objectNames: string[]) {
+            return {
+                nodes: objectNames.map((object) => ({ object, dependsOn: [], references: [] })),
+                insertOrder: objectNames,
+                circularDependencies: [],
+            };
+        }
+    },
+    recordSeedOutcome: vi.fn(),
+}));
+
+import { assertEngineDeleteDispatch } from '@objectstack/metadata-core';
+import { MarketplaceInstallLocalPlugin } from './marketplace-install-local-plugin.js';
+import { bindCatalogFromTables } from './__tests__/security-catalog.testkit.js';
+
+const IL = '/api/v1/marketplace/install-local';
+const KEY = 'osk_install_local_account_posture_pin';
+const OWNER = 'u_key_owner';
+
+const MFA_REQUIRED = {
+    code: 'MFA_REQUIRED',
+    message: 'Multi-factor authentication is required. Please set up an authenticator app to continue.',
+};
+const PASSWORD_RESET_REQUIRED = { code: 'PASSWORD_RESET_REQUIRED', message: 'You must change your password before continuing.' };
+
+type Posture = { code: string; message: string };
+
+const APP = {
+    id: 'com.acme.keyheld',
+    namespace: 'keyheld',
+    version: '1.0.0',
+    objects: [{ name: 'widget', fields: { code: { type: 'text' } } }],
+    data: [{ object: 'widget', externalId: 'code', records: [{ code: 'a' }, { code: 'b' }] }],
+};
+const LEDGER_FILE = 'com.acme.keyheld.json';
+
+/** Equality and `$in` — the two shapes the shared resolver issues — and nothing else, loudly. */
+function matchesWhere(row: Record<string, unknown>, where: unknown): boolean {
+    for (const [field, cond] of Object.entries((where ?? {}) as Record<string, unknown>)) {
+        if (field.startsWith('$')) throw new Error(`fixture where-matcher: unsupported combinator '${field}'`);
+        if (cond !== null && typeof cond === 'object') {
+            const ops = Object.keys(cond as object);
+            if (ops.length !== 1 || ops[0] !== '$in' || !Array.isArray((cond as { $in?: unknown }).$in)) {
+                throw new Error(`fixture where-matcher: unsupported operator shape on '${field}'`);
+            }
+            if (!(cond as { $in: unknown[] }).$in.includes(row[field])) return false;
+            continue;
+        }
+        if (row[field] !== cond) return false;
+    }
+    return true;
+}
+
+/** The key's owner holds the authoring capability, so a refusal below is the gate's alone. */
+function grantRows(): Record<string, Array<Record<string, unknown>>> {
+    return {
+        sys_api_key: [{ id: 'key_1', key: hashApiKey(KEY), user_id: OWNER, revoked: false, scopes: '[]' }],
+        sys_user: [{ id: OWNER, email: 'owner@acme.test' }],
+        sys_member: [],
+        sys_user_position: [],
+        sys_position: [],
+        sys_metadata_activation: [],
+        sys_position_permission_set: [],
+        sys_user_permission_set: [
+            { id: 'ups1', user_id: OWNER, permission_set_id: 'ps1', permission_set: 'admin_full_access', organization_id: null },
+        ],
+        sys_permission_set: [{ id: 'ps1', name: 'admin_full_access', system_permissions: ['manage_metadata', 'studio.access', 'setup.access'] }],
+    };
+}
+
+type Handler = (c: any) => Promise<any>;
+
+/**
+ * Boot the plugin with an auth service whose per-user posture is read from
+ * `postures` on every ask, so a test can move it while the doors are live.
+ */
+async function mountInstallLocal(storageDir: string, postures: Record<string, Posture[]>) {
+    const register = vi.fn(async () => undefined);
+    const syncSchemas = vi.fn(async () => undefined);
+    const widgets = [{ id: 'w1', code: 'a' }, { id: 'w2', code: 'b' }];
+    const engineDelete = vi.fn(async (object: string, options?: any) => {
+        const dispatch = assertEngineDeleteDispatch(options);
+        if (object !== 'widget' || dispatch.kind !== 'by-id') return false;
+        const at = widgets.findIndex((w) => w.id === dispatch.id);
+        if (at < 0) return false;
+        widgets.splice(at, 1);
+        return true;
+    });
+    const routes = new Map<string, Handler>();
+    const rawApp = {
+        get: (p: string, h: Handler) => routes.set(`GET ${p}`, h),
+        post: (p: string, h: Handler) => routes.set(`POST ${p}`, h),
+        delete: (p: string, h: Handler) => routes.set(`DELETE ${p}`, h),
+    };
+    const hooks = new Map<string, any>();
+    const rows = grantRows();
+    const keyRowBefore = JSON.stringify(rows.sys_api_key);
+    const services: Record<string, any> = {
+        manifest: { register },
+        auth: {
+            // No session: every caller below presents the key alone.
+            api: { getSession: async () => null },
+            resolveUserAuthGates: async (userId: string) => postures[userId] ?? [],
+        },
+        objectql: bindCatalogFromTables({
+            syncSchemas,
+            find: async (object: string, q: any = {}) => {
+                if (object === 'widget') return widgets.map((w) => ({ ...w }));
+                const matched = (rows[object] ?? []).filter((row) => matchesWhere(row, q?.where));
+                return typeof q?.limit === 'number' ? matched.slice(0, q.limit) : matched;
+            },
+            delete: engineDelete,
+        }, rows),
+        metadata: { getObject: async () => ({ name: 'widget', fields: {} }) },
+    };
+    const ctx: any = {
+        hook: (e: string, h: any) => hooks.set(e, h),
+        getService: (name: string) => {
+            if (name === 'http-server') return { getRawApp: () => rawApp };
+            const svc = services[name];
+            if (svc === undefined) throw new Error(`no ${name}`);
+            return svc;
+        },
+        registerService: () => undefined,
+        logger: { info: vi.fn(), warn: vi.fn(), error: vi.fn() },
+    };
+    await new MarketplaceInstallLocalPlugin({ controlPlaneUrl: 'off', storageDir }).start(ctx);
+    await hooks.get('kernel:ready')?.();
+    // `kernel:ready` rehydrates the ledger, so every counter starts AFTER it.
+    register.mockClear();
+    syncSchemas.mockClear();
+    engineDelete.mockClear();
+    seedCalls.length = 0;
+    return {
+        routes,
+        effects: () => register.mock.calls.length + syncSchemas.mock.calls.length + seedCalls.length + engineDelete.mock.calls.length,
+        keyRowUnchanged: () => JSON.stringify(rows.sys_api_key) === keyRowBefore,
+    };
+}
+
+function withKey(body: unknown = {}, manifestId?: string) {
+    const headers = new Headers({ 'x-api-key': KEY });
+    const url = `http://localhost${IL}`;
+    return {
+        req: {
+            url,
+            raw: new Request(url, { headers }),
+            header: (n: string) => headers.get(n) ?? undefined,
+            json: async () => body,
+            param: () => manifestId,
+        },
+        json: (payload: any, status?: number) => ({ payload, status: status ?? 200 }),
+    };
+}
+
+/** The five doors, addressed with what each needs to act. */
+const IL_DOORS = [
+    { route: `POST ${IL}`, body: { manifest: APP } },
+    { route: `GET ${IL}`, body: {} },
+    { route: `DELETE ${IL}/:manifestId`, body: {} },
+    { route: `POST ${IL}/:manifestId/reseed-sample-data`, body: {} },
+    { route: `POST ${IL}/:manifestId/purge-sample-data`, body: {} },
+] as const;
+
+let dir: string;
+beforeEach(() => {
+    dir = mkdtempSync(join(tmpdir(), 'il-key-posture-pin-'));
+    seedCalls.length = 0;
+});
+afterEach(() => {
+    rmSync(dir, { recursive: true, force: true });
+    vi.restoreAllMocks();
+});
+
+describe('install-local doors — a key answers as its owner\'s session does (#23455, ruling C′)', () => {
+    it('REFUSES a key whose owner holds MFA_REQUIRED on all five doors, with the session\'s 403 code and message, before any effect', async () => {
+        const postures: Record<string, Posture[]> = {};
+        const m = await mountInstallLocal(dir, postures);
+        // Installed by the same key while its owner is not held, so the
+        // follow-on doors have a target.
+        const seeded = await m.routes.get(`POST ${IL}`)!(withKey({ manifest: APP }));
+        expect(seeded.status, JSON.stringify(seeded.payload)).toBe(200);
+        expect(existsSync(join(dir, LEDGER_FILE))).toBe(true);
+        const effectsBefore = m.effects();
+
+        postures[OWNER] = [MFA_REQUIRED];
+        for (const door of IL_DOORS) {
+            const res = await m.routes.get(door.route)!(withKey(door.body, APP.id));
+            expect(res.status, door.route).toBe(403);
+            expect(res.payload, door.route).toEqual({ success: false, error: { code: MFA_REQUIRED.code, message: MFA_REQUIRED.message } });
+        }
+        expect(m.effects(), 'a held owner\'s key caused an effect').toBe(effectsBefore);
+        expect(existsSync(join(dir, LEDGER_FILE)), 'a held owner\'s key reached the uninstall').toBe(true);
+    });
+
+    it('SERVES a key whose owner holds only a credential-scope posture', async () => {
+        const m = await mountInstallLocal(dir, { [OWNER]: [PASSWORD_RESET_REQUIRED] });
+        const installed = await m.routes.get(`POST ${IL}`)!(withKey({ manifest: APP }));
+        expect(installed.status, JSON.stringify(installed.payload)).toBe(200);
+        expect(installed.payload.success).toBe(true);
+        expect(m.effects()).toBeGreaterThan(0);
+        const listed = await m.routes.get(`GET ${IL}`)!(withKey());
+        expect(listed.status).toBe(200);
+        expect(listed.payload.success).toBe(true);
+    });
+
+    it('the refusal is not a revocation: the same key is served once the posture clears', async () => {
+        const postures: Record<string, Posture[]> = { [OWNER]: [MFA_REQUIRED] };
+        const m = await mountInstallLocal(dir, postures);
+        const held = await m.routes.get(`POST ${IL}`)!(withKey({ manifest: APP }));
+        expect(held.status).toBe(403);
+        expect(held.payload?.error?.code).toBe('MFA_REQUIRED');
+        expect(m.effects()).toBe(0);
+
+        // The owner enrols; nothing about the key is rewritten or reissued.
+        postures[OWNER] = [];
+        const again = await m.routes.get(`POST ${IL}`)!(withKey({ manifest: APP }));
+        expect(again.status, JSON.stringify(again.payload)).toBe(200);
+        expect(again.payload.success).toBe(true);
+        expect(existsSync(join(dir, LEDGER_FILE))).toBe(true);
+        expect(m.keyRowUnchanged(), 'the hold wrote to the key row').toBe(true);
+    });
+});