diff --git a/AGENTS.md b/AGENTS.md
index a9d0fe4..f04ba95 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -179,6 +179,12 @@ docker compose start redis                              # app reconnects on its
 Verify Redis state through `GET /api/system-info` → `cache` (`driver`, `ready`, `hits`, `misses`,
 `fallbackOps`, `used_memory_human`, `keys`).
 
+`api.smoketest.js` also locks the auth contract: only `X-Auth-Token` with a session token
+authenticates, while `X-Admin-Token`, `Authorization: Bearer` and `ADMIN_PASSWORD` used as a
+token must all be rejected with 401. If you change the auth scheme, update this test and the
+Auth notes in this file together — a doc that drifts from the code is the failure mode this
+guards against.
+
 ---
 
 ## Security Checklist (before any change)
@@ -187,6 +193,7 @@ Verify Redis state through `GET /api/system-info` → `cache` (`driver`, `ready`
 - [ ] File I/O через `storage.*`, ключи объектов не выходят за пределы бакета/`uploads/`
 - [ ] Rate limiter on new public routes
 - [ ] Admin routes behind `requireAdmin`
+- [ ] New auth paths checked against the contract in `api.smoketest.js`, docs updated in the same change
 - [ ] No secrets in code — only via env vars
 - [ ] Helmet headers present (already global)
 - [ ] CORS disabled (no `cors` middleware)
diff --git a/api.smoketest.js b/api.smoketest.js
index ad07c70..2085ea9 100644
--- a/api.smoketest.js
+++ b/api.smoketest.js
@@ -11,10 +11,11 @@ function loadEnv() {
 
 const BASE = process.env.BASE || 'http://localhost:3003';
 
-async function api(pathname, { token, method = 'GET', body } = {}) {
+async function api(pathname, { token, method = 'GET', body, headers: extra } = {}) {
   const headers = {};
   if (token) headers['X-Auth-Token'] = token;
   if (body) headers['Content-Type'] = 'application/json';
+  Object.assign(headers, extra || {});
   const res = await fetch(BASE + pathname, {
     method,
     headers,
@@ -46,6 +47,28 @@ async function main() {
   const me1 = await api('/api/auth/me', { token });
   ok('auth/me', me1.status === 200 && me1.data.id > 0 && me1.data.is_active === true, { status: me1.status, id: me1.data && me1.data.id });
 
+  // Контракт авторизации. Держим в синхроне с AGENTS.md/README: доступ даёт только
+  // X-Auth-Token с токеном сессии. Никакой статический токен (в т.ч. ранее
+  // документированный X-Admin-Token = ADMIN_PASSWORD) доступа не даёт, и
+  // ADMIN_PASSWORD не является паролем для входа, кроме случая пустой БД,
+  // где он задаётся через login.
+  const PROTECTED = '/api/auth/me';
+  const ADMIN_ONLY = '/api/users';
+  const noAuth = await api(PROTECTED);
+  ok('auth: защищённый маршрут без токена -> 401', noAuth.status === 401, noAuth.status);
+  const garbage = await api(PROTECTED, { token: 'deadbeef' });
+  ok('auth: мусорный X-Auth-Token -> 401', garbage.status === 401, garbage.status);
+  const legacy = await api(PROTECTED, { headers: { 'X-Admin-Token': pass } });
+  ok('auth: X-Admin-Token не авторизует -> 401', legacy.status === 401, legacy.status);
+  const bearer = await api(PROTECTED, { headers: { Authorization: 'Bearer ' + token } });
+  ok('auth: Authorization Bearer не поддерживается -> 401', bearer.status === 401, bearer.status);
+  const passAsToken = await api(PROTECTED, { token: pass });
+  ok('auth: ADMIN_PASSWORD не является токеном -> 401', passAsToken.status === 401, passAsToken.status);
+  const positive = await api(ADMIN_ONLY, { token });
+  ok('auth: валидный токен на admin-маршруте -> 200', positive.status === 200, positive.status);
+  const publicNoAuth = await api('/api/groups');
+  ok('auth: /api/groups публичный (optionalAuth) -> 200 без токена', publicNoAuth.status === 200, publicNoAuth.status);
+
   const groups = await api('/api/groups', { token });
   ok('groups', groups.status === 200 && Array.isArray(groups.data), groups.status);