diff --git a/tests/unit/test_agent_loop.py b/tests/unit/test_agent_loop.py
index 3d9ae7a..343914b 100644
--- a/tests/unit/test_agent_loop.py
+++ b/tests/unit/test_agent_loop.py
@@ -303,4 +303,5 @@ class TestParseNormalization:
         assert self._parse(content) is None
 
     def test_empty_content_still_rejected(self) -> None:
+        """空 content 照旧拒绝，归一化不改变该边界。"""
         assert self._parse("") is None