diff --git a/main.py b/main.py
index 94fbb87..2534824 100644
--- a/main.py
+++ b/main.py
@@ -261,27 +261,32 @@ def get_node_base(node: Dict[str, Any]) -> str:
     return f"http://{host}:{port}".rstrip("/")
 
 
+def _runtime_unlocked(nid: str) -> Dict[str, Any]:
+    """获取节点运行时状态（调用方已持有 _nodes_lock 时使用）。"""
+    if nid not in _node_runtime:
+        _node_runtime[nid] = {
+            "in_flight": 0,
+            "healthy": None,
+            "last_check": None,
+            "last_error": "",
+        }
+    return _node_runtime[nid]
+
+
 def _runtime(nid: str) -> Dict[str, Any]:
     with _nodes_lock:
-        if nid not in _node_runtime:
-            _node_runtime[nid] = {
-                "in_flight": 0,
-                "healthy": None,
-                "last_check": None,
-                "last_error": "",
-            }
-        return _node_runtime[nid]
+        return _runtime_unlocked(nid)
 
 
 def node_in_flight_inc(nid: str) -> None:
     with _nodes_lock:
-        rt = _runtime(nid)
+        rt = _runtime_unlocked(nid)
         rt["in_flight"] = int(rt.get("in_flight", 0)) + 1
 
 
 def node_in_flight_dec(nid: str) -> None:
     with _nodes_lock:
-        rt = _runtime(nid)
+        rt = _runtime_unlocked(nid)
         rt["in_flight"] = max(0, int(rt.get("in_flight", 0)) - 1)
 
 
@@ -362,7 +367,7 @@ async def refresh_all_node_health(client: httpx.AsyncClient) -> None:
             continue
         ok, err = await probe_node(client, node)
         with _nodes_lock:
-            rt = _runtime(nid)
+            rt = _runtime_unlocked(nid)
             rt["healthy"] = ok
             rt["last_error"] = err
             rt["last_check"] = datetime.now(timezone.utc).isoformat()
@@ -1494,7 +1499,6 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
     timeout = httpx.Timeout(600.0, connect=30.0)
     app.state.http = httpx.AsyncClient(timeout=timeout)
     global _health_task
-    await refresh_all_node_health(app.state.http)
     _health_task = asyncio.create_task(_health_loop(app.state.http))
     try:
         yield
@@ -1636,7 +1640,7 @@ async def api_nodes_test(
     client: httpx.AsyncClient = request.app.state.http
     ok, err = await probe_node(client, node)
     with _nodes_lock:
-        rt = _runtime(node_id)
+        rt = _runtime_unlocked(node_id)
         rt["healthy"] = ok
         rt["last_error"] = err
         rt["last_check"] = datetime.now(timezone.utc).isoformat()