diff --git a/backend/package/yuxi/utils/trace_context.py b/backend/package/yuxi/utils/trace_context.py
index 3687ef81..2c6475fe 100644
--- a/backend/package/yuxi/utils/trace_context.py
+++ b/backend/package/yuxi/utils/trace_context.py
@@ -7,14 +7,13 @@
 ContextVar（server 层 ``_trace_id_var`` 与 channels 层 ``_current_span``）
 保持同步。
 """
+
 from __future__ import annotations
 
 import uuid
 from contextvars import ContextVar
 
-_trace_id_var: ContextVar[str | None] = ContextVar(
-    "yuxi_request_trace_id", default=None
-)
+_trace_id_var: ContextVar[str | None] = ContextVar("yuxi_request_trace_id", default=None)
 
 
 def set_trace_id(trace_id: str) -> None: