diff --git a/offline-backend-20260512/backend/app/gateway/auth_middleware.py b/offline-backend-20260512/backend/app/gateway/auth_middleware.py
index e6c84b4d..9c039c50 100644
--- a/offline-backend-20260512/backend/app/gateway/auth_middleware.py
+++ b/offline-backend-20260512/backend/app/gateway/auth_middleware.py
@@ -9,6 +9,7 @@ owner filtering works automatically via the sentinel pattern.
 Fine-grained permission checks remain in authz.py decorators.
 """
 
+import re
 from collections.abc import Callable
 
 from fastapi import HTTPException, Request, Response
@@ -64,6 +65,20 @@ def _is_public(path: str) -> bool:
     return any(path.startswith(prefix) for prefix in _PUBLIC_PATH_PREFIXES)
 
 
+# 「发起问答」的 run 创建接口(会真正调用大模型):
+#   POST /api/threads/{id}/runs[/stream|/wait]
+#   POST /api/runs/{stream|wait}
+#   （含 nginx 未改写到的 /api/langgraph/... 前缀,双保险)
+# 只匹配这些「提交问答」的 POST,不碰 GET 列表 / join / cancel / feedback 等,
+# 这样登录白名单开启后,未放行用户(凭旧 token)无法再用接口问答,但普通浏览不受影响。
+_QA_RUN_RE = re.compile(r"^/api/(?:langgraph/)?(?:threads/[^/]+/)?runs(?:/stream|/wait)?$")
+
+
+def _is_qa_run_request(method: str, path: str) -> bool:
+    """True for an authenticated「发起问答」run-creation request (see ``_QA_RUN_RE``)."""
+    return method.upper() == "POST" and bool(_QA_RUN_RE.match(path.rstrip("/")))
+
+
 class AuthMiddleware(BaseHTTPMiddleware):
     """Strict auth gate: reject requests without a valid session.
 
@@ -148,6 +163,18 @@ class AuthMiddleware(BaseHTTPMiddleware):
         # JWT-decode + DB-lookup pipeline a second time per request).
         request.state.user = user
         request.state.auth = AuthContext(user=user, permissions=_ALL_PERMISSIONS)
+
+        # 登录白名单:开关开启时,未放行用户(非 admin)不仅被拦在登录外,连「接口
+        # 问答」也封掉——已拿到 token 的未放行用户用旧会话直接调问答接口同样被拒。
+        # 仅作用于「发起问答」的 run 接口;内部/渠道调用(internal_user)不受限。
+        if internal_user is None and _is_qa_run_request(request.method, app_relative_path(request)):
+            from app.gateway.routers.auth import enforce_user_approved
+
+            try:
+                enforce_user_approved(user)
+            except HTTPException as exc:
+                return JSONResponse(status_code=exc.status_code, content={"detail": exc.detail})
+
         token = set_current_user(user)
         try:
             return await call_next(request)