diff --git a/server/app/model/chat/chat_step.py b/server/app/model/chat/chat_step.py
index a81e00ee..4694ff64 100644
--- a/server/app/model/chat/chat_step.py
+++ b/server/app/model/chat/chat_step.py
@@ -43,3 +43,4 @@ class ChatStepOut(BaseModel):
     task_id: str
     step: str
     data: Any
+    timestamp: float | None = None