@@ -0,0 +1,23 @@
+---
+'@objectstack/plugin-hono-server': minor
+'@objectstack/hono': minor
+'@objectstack/plugin-auth': minor
+---
+
+fix(cors)!: every CORS door reads one admission rule; a loopback origin beside a list is admitted on a development boot only; an all-host pattern is refused with credentials, as `'*'` is
+
+Clause-②: yes (narrowing)
+
+<!-- adr-0087: not-required (no-migration-prescription) a narrowing of CORS admission at three doors plus a boot refusal of one more configuration class: no authorable metadata key, spelling, type or stored shape moves, so `objectstack migrate meta` has nothing to rewrite. The remedy is a deployment variable or the door's own origin option, which no ledger entry can derive. The other categories are closed on facts: the packages publish (not unpublished); no ADR-0087 id covers these doors (not already-registered); and the change is an admission verdict, not an interface, a type or an export retirement (not runtime-interface-only, type-surface-only or runtime-export-retired). -->
+
+**BREAKING** — an admission narrowing at three doors, shipped as `minor` under the launch-window convention for accept-set narrowings. The governing text is `docs/HARDENING.md` § CORS: never `'*'` with credentials, and an explicit origin list. It finishes what the `HonoServerPlugin` default change that `18.0.0` shipped (#24738) began.
+
+- **One rule.** `@objectstack/plugin-hono-server` exports `resolveCorsAdmission`, and both transport doors read it: `HonoServerPlugin` (the server `os serve`, `os dev` and `os start` mount) and `@objectstack/hono`'s `createHonoApp`. One configuration now gets one answer at both. That one rule shared by two published doors is why the public surface grows: `resolveCorsAdmission` with its types `CorsAdmission`, `CorsAdmissionInput` and `CorsAdmissionDoor`, `isAllHostOriginPattern`, `OriginMatcherOptions`, and an optional second parameter on `createOriginMatcher`.
+- **`createHonoApp`, before.** With no origin list (no `cors.origin` option and no `OS_CORS_ORIGIN`), every origin was admitted for credentialed cross-origin requests, and a configured `'*'` with credentials on was accepted the same way. **Now** it answers as `HonoServerPlugin` does: no list admits no cross-origin caller (a loopback origin excepted, on a development boot), and `'*'` with credentials on is refused when the app is created.
+- **`createHonoApp`'s `cors.origin` as one comma-separated string, before.** A `cors.origin` written as one comma-separated string of exact origins (`'https://a.example.com,https://b.example.com'`) admitted no origin. **Now** each listed origin is admitted, as `OS_CORS_ORIGIN` written the same way already was: a widening only toward what the operator listed, which the option's TSDoc already promised ("Comma-separated string or array").
+- **Loopback beside a list, before.** A configured list also admitted every loopback origin (`localhost`, `127.0.0.1`, `[::1]`, any port), in every mode, at both doors that used the pattern matcher. **Now** that happens on a development boot only (`NODE_ENV` exactly `development`, read through `isDevelopmentBoot` from `@objectstack/core`). Elsewhere a list admits what it names; a list that names `http://localhost:*` still admits it. One door gains on a development boot: `createHonoApp` with a list of exact origins never admitted a loopback origin, and now does there, as `HonoServerPlugin` already did. `matchOriginPattern` now matches the pattern and nothing else, and `createOriginMatcher` takes an optional `{ developmentBoot }`, read from `NODE_ENV` when the matcher is created if it is not passed, so a consumer that applies the matcher outside the Hono pipeline answers as the doors do on the same boot.
+- **All-host patterns, before.** Only a literal `'*'` was refused with credentials. **Now** a pattern whose host part is the bare `*` (`https://*`, `*://*`, `http://*:*`; `isAllHostOriginPattern`) is refused with credentials at both transport doors exactly as `'*'` is, and the message names the entry.
+- **Auth's trusted origins, before.** `@objectstack/plugin-auth` tested the whole `OS_CORS_ORIGIN` value against `'*'` and then split it, so a `'*'` entry among real origins, or an all-host pattern, entered better-auth's trusted origins. **Now** each entry is judged on its own, and an entry that admits every host never enters the trusted set.
+- **Unchanged.** Same-origin requests need no CORS answer. An exact origin or a pattern that names part of the host (`https://*.example.com`) is admitted as before, credentials included; the one exception is the comma-separated `cors.origin` string above, which now admits what it lists. `'*'` with credentials off is still served. `cors: false` and `OS_CORS_ENABLED=false` still disable the middleware. Headers, methods and max-age are unchanged. `OS_TRUSTED_ORIGINS` still admits nothing to CORS.
+
+**What an operator does.** A host composing `createHonoApp` for a cross-origin front-end names its origins, in `OS_CORS_ORIGIN` or the `cors.origin` option. A deployment that reached the server from a loopback origin outside development names that origin in its list. A list holding `'*'` or an all-host pattern while credentials are on either names its origins or sets `OS_CORS_CREDENTIALS=false`.
@@ -200,8 +200,8 @@ origins you name:
 | Configuration | What is admitted |
 | --- | --- |
 | No origin list (neither `OS_CORS_ORIGIN` nor the plugin's `cors.origins`) | **No cross-origin caller.** On a development boot (`NODE_ENV=development`, which `os dev` and `os serve --dev` set), loopback origins (`localhost`, `127.0.0.1`, `[::1]`, any port) are admitted too. |
-| A list (`OS_CORS_ORIGIN=https://app.example.com`, comma-separated; exact origins or patterns such as `https://*.example.com`) | Those origins, with credentials unless `OS_CORS_CREDENTIALS=false`. Loopback origins are admitted alongside any list. |
-| `*` while credentials are on | **Refused at boot** — the boot fails with a message naming the two remedies. |
+| A list (`OS_CORS_ORIGIN=https://app.example.com`, comma-separated; exact origins or patterns such as `https://*.example.com`) | Those origins, with credentials unless `OS_CORS_CREDENTIALS=false`. On a development boot, loopback origins are admitted beside the list too; on any other boot, only what the list names. |
+| `*`, or a pattern whose host part is the bare `*` (`https://*`, `*://*`), while credentials are on | **Refused at boot** — the boot fails with a message naming the entry and the two remedies. |
 
 Same-origin requests need no CORS answer, so the Console under
 `/_console` and any page the server itself serves work with no list at
@@ -219,7 +219,10 @@ variable covers a cross-origin front-end that signs in. A list given
 through the plugin's `cors.origins` option instead is not seen by
 auth, so such a front-end is then also named in `OS_TRUSTED_ORIGINS`.
 
-Composing the Hono adapter yourself, name the origins there as well:
+Composing the Hono adapter yourself, `createHonoApp` answers by the
+same rule — the table above holds for it too, with its own `cors.origin`
+option in place of `cors.origins` — so with no list it admits no
+cross-origin caller. Name the origins there:
 
 ```ts
 import { createHonoApp } from '@objectstack/hono';
@@ -235,9 +238,12 @@ const app = createHonoApp({
 ```
 
 Do **not** use `origin: '*'` with `credentials: true`: together they
-admit every origin for credentialed requests. `HonoServerPlugin`
-refuses the combination at boot; `*` is accepted only with credentials
-off (`OS_CORS_CREDENTIALS=false`), for an API that takes no cookies.
+admit every origin for credentialed requests. Both doors refuse the
+combination, and a pattern whose host part is the bare `*` with it —
+`HonoServerPlugin` at boot, `createHonoApp` when the app is created;
+such an entry is accepted only with credentials off
+(`OS_CORS_CREDENTIALS=false`), for an API that takes no cookies, and
+auth never trusts it from `OS_CORS_ORIGIN`.
 
 ## Auditing
 
 
@@ -33,6 +33,16 @@ const app = createHonoApp({
 export default app; // Cloudflare Workers / Bun / Deno / Vercel Edge
 ```
 
+### CORS
+
+`createHonoApp` admits by the same rule as `@objectstack/plugin-hono-server`'s
+`HonoServerPlugin` (`resolveCorsAdmission`), so one configuration gets one answer at
+both: a list admits what it names; no list admits no cross-origin caller; a loopback
+origin is admitted, beside a list or without one, on a development boot only
+(`NODE_ENV=development`). `'*'`, or a pattern whose host part is the bare `*`
+(`https://*`), while credentials are on is refused when the app is created; turn
+credentials off to serve it to callers that send no cookies.
+
 ### Embed into an existing Hono app
 
 ```typescript
@@ -59,8 +69,8 @@ app.use('/api/*', objectStackMiddleware(kernel));
 | `kernel` | `ObjectKernel` | — | Bootstrapped kernel. |
 | `prefix` | `string` | `'/api'` | Base path. |
 | `cors` | `ObjectStackHonoCorsOptions \| false` | Enabled | Set to `false` to disable. |
-| `cors.origin` | `string \| string[]` | env `CORS_ORIGIN` or `'*'` | Supports wildcard patterns. |
-| `cors.credentials` | `boolean` | `false` | Required for cookie sessions. |
+| `cors.origin` | `string \| string[]` | env `OS_CORS_ORIGIN`, else no list | Supports wildcard patterns. With no list, no cross-origin caller is admitted. |
+| `cors.credentials` | `boolean` | env `OS_CORS_CREDENTIALS !== 'false'` (on) | Required for cookie sessions. |
 | `cors.exposeHeaders` | `string[]` | `['set-auth-token']` merged | Always includes `set-auth-token` for better-auth. |
 
 ## Edge runtime notes
 
@@ -0,0 +1,188 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * What `createHonoApp`'s CORS answer ADMITS — through the real `hono/cors`
+ * middleware (`app.request`), never a captured config.
+ *
+ * The governing text is `docs/HARDENING.md` § CORS: "Do **not** use
+ * `origin: '*'` with `credentials: true`", and the go-live checklist's "CORS
+ * origin list is explicit, not `*`". This door reads the same rule
+ * `HonoServerPlugin` does (`resolveCorsAdmission` in
+ * `@objectstack/plugin-hono-server`, which this package's vitest config
+ * resolves to SOURCE), so a configuration gets the same answer here as there:
+ *
+ *  1. no origin list (neither `cors.origin` nor `OS_CORS_ORIGIN`): no
+ *     cross-origin caller is admitted; a loopback origin is admitted on a
+ *     development boot only;
+ *  2. a configured list is admitted with credentials, and nothing else is — a
+ *     loopback origin beside it on a development boot only;
+ *  3. `'*'`, or a pattern whose host part is the bare `*`, together with
+ *     credentials is refused when the app is created; without credentials it
+ *     is served.
+ *
+ * "Admitted" is read off `Access-Control-Allow-Origin` — the one header a
+ * browser checks before handing a cross-origin response to the page.
+ */
+
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import type { Hono } from 'hono';
+
+// `@objectstack/runtime` resolves to `src/__mocks__/runtime.ts` (this
+// package's vitest alias): the dispatcher is never reached on `/probe`.
+import { createHonoApp, type ObjectStackHonoOptions } from './index';
+
+const FOREIGN = 'https://other.example';
+const CONFIGURED = 'https://app.example.com';
+const LOOPBACK = 'http://localhost:5173';
+
+/** Every variable the CORS block reads, canonical and legacy spellings. */
+const CORS_ENV = [
+  'OS_CORS_ENABLED', 'CORS_ENABLED',
+  'OS_CORS_ORIGIN', 'CORS_ORIGIN',
+  'OS_CORS_CREDENTIALS', 'CORS_CREDENTIALS',
+  'OS_CORS_MAX_AGE', 'CORS_MAX_AGE',
+  'NODE_ENV',
+] as const;
+
+let saved: Record<string, string | undefined> = {};
+
+beforeEach(() => {
+  saved = {};
+  for (const name of CORS_ENV) {
+    saved[name] = process.env[name];
+    delete process.env[name];
+  }
+  // Not a development boot unless a case says so.
+  process.env.NODE_ENV = 'production';
+});
+
+afterEach(() => {
+  for (const name of CORS_ENV) {
+    if (saved[name] === undefined) delete process.env[name];
+    else process.env[name] = saved[name];
+  }
+});
+
+const kernel = { name: 'cors-admission-kernel' } as unknown as ObjectStackHonoOptions['kernel'];
+
+/** The real `createHonoApp`, with one probe route behind its middleware. */
+function app(cors?: ObjectStackHonoOptions['cors']): Hono {
+  const created = createHonoApp({ kernel, prefix: '/api/v1', ...(cors === undefined ? {} : { cors }) });
+  created.get('/probe', (c) => c.text('ok'));
+  return created;
+}
+
+/** The `Access-Control-Allow-Origin` a credentialed GET from `origin` is answered with. */
+async function allowedOnGet(target: Hono, origin: string): Promise<string | null> {
+  const res = await target.request('/probe', { headers: { Origin: origin, Cookie: 'session=1' } });
+  expect(res.status).toBe(200);
+  return res.headers.get('access-control-allow-origin');
+}
+
+/** The same, for the preflight a browser sends ahead of a non-simple request. */
+async function allowedOnPreflight(target: Hono, origin: string): Promise<string | null> {
+  const res = await target.request('/probe', {
+    method: 'OPTIONS',
+    headers: {
+      Origin: origin,
+      'Access-Control-Request-Method': 'POST',
+      'Access-Control-Request-Headers': 'content-type',
+    },
+  });
+  return res.headers.get('access-control-allow-origin');
+}
+
+/** What `createHonoApp` threw; an app that was created fails the case. */
+function refusal(cors?: ObjectStackHonoOptions['cors']): Error {
+  let thrown: unknown = null;
+  try {
+    app(cors);
+  } catch (e) {
+    thrown = e;
+  }
+  expect(thrown).toBeInstanceOf(Error);
+  return thrown as Error;
+}
+
+describe('1. with no origin list configured, no cross-origin caller is admitted', () => {
+  it('answers a foreign origin with no Access-Control-Allow-Origin, on a request and on a preflight', async () => {
+    const target = app();
+    expect(await allowedOnGet(target, FOREIGN)).toBeNull();
+    expect(await allowedOnPreflight(target, FOREIGN)).toBeNull();
+  });
+
+  it('does not admit a loopback origin either, outside a development boot', async () => {
+    const target = app();
+    expect(await allowedOnGet(target, LOOPBACK)).toBeNull();
+    expect(await allowedOnPreflight(target, LOOPBACK)).toBeNull();
+  });
+
+  it('admits a loopback origin, and still no foreign one, on a development boot', async () => {
+    process.env.NODE_ENV = 'development';
+    const target = app();
+    expect(await allowedOnGet(target, LOOPBACK)).toBe(LOOPBACK);
+    expect(await allowedOnGet(target, FOREIGN)).toBeNull();
+  });
+});
+
+describe('2. a configured list is admitted with credentials, and nothing else is', () => {
+  it('via the `cors.origin` option', async () => {
+    const target = app({ origin: [CONFIGURED] });
+    const res = await target.request('/probe', { headers: { Origin: CONFIGURED } });
+    expect(res.headers.get('access-control-allow-origin')).toBe(CONFIGURED);
+    expect(res.headers.get('access-control-allow-credentials')).toBe('true');
+    expect(await allowedOnGet(target, FOREIGN)).toBeNull();
+  });
+
+  it('via OS_CORS_ORIGIN, comma-separated, patterns included', async () => {
+    process.env.OS_CORS_ORIGIN = `${CONFIGURED}, https://*.example.net`;
+    const target = app();
+    expect(await allowedOnGet(target, CONFIGURED)).toBe(CONFIGURED);
+    expect(await allowedOnGet(target, 'https://tenant.example.net')).toBe('https://tenant.example.net');
+    expect(await allowedOnGet(target, FOREIGN)).toBeNull();
+  });
+
+  it('admits a loopback origin beside the list on a development boot only', async () => {
+    for (const origin of [[CONFIGURED], 'https://*.example.net']) {
+      process.env.NODE_ENV = 'production';
+      expect(await allowedOnGet(app({ origin }), LOOPBACK)).toBeNull();
+      process.env.NODE_ENV = 'development';
+      expect(await allowedOnGet(app({ origin }), LOOPBACK)).toBe(LOOPBACK);
+    }
+  });
+});
+
+describe("3. '*', or a pattern whose host part is the bare `*`, with credentials is refused when the app is created", () => {
+  it('from the `cors.origin` option, with credentials left at their default, naming the entry', () => {
+    for (const entry of ['*', 'https://*', '*://*', 'http://*:*']) {
+      const err = refusal({ origin: entry });
+      expect(err.message).toContain(`'${entry}'`);
+      expect(err.message).toContain('OS_CORS_ORIGIN');
+      expect(err.message).toContain('OS_CORS_CREDENTIALS');
+    }
+  });
+
+  it('from OS_CORS_ORIGIN, alone or inside a list', () => {
+    for (const value of ['*', ' * ', `${CONFIGURED},*`, 'https://*', `${CONFIGURED}, *://*`]) {
+      process.env.OS_CORS_ORIGIN = value;
+      refusal();
+    }
+  });
+
+  it('with credentials named explicitly, by option or by OS_CORS_CREDENTIALS', () => {
+    refusal({ origin: ['*'], credentials: true });
+    process.env.OS_CORS_ORIGIN = 'https://*';
+    process.env.OS_CORS_CREDENTIALS = 'true';
+    refusal();
+  });
+
+  it('serves them without credentials, admitting any origin with no credentials header', async () => {
+    process.env.OS_CORS_CREDENTIALS = 'false';
+    for (const value of ['*', 'https://*']) {
+      process.env.OS_CORS_ORIGIN = value;
+      const res = await app().request('/probe', { headers: { Origin: FOREIGN } });
+      expect(res.headers.get('access-control-allow-origin')).toBe(FOREIGN);
+      expect(res.headers.get('access-control-allow-credentials')).toBeNull();
+    }
+  });
+});