diff --git a/python/packages/core/agent_framework/openai/_responses_client.py b/python/packages/core/agent_framework/openai/_responses_client.py
index 3cc69d2aaf..cdc6103636 100644
--- a/python/packages/core/agent_framework/openai/_responses_client.py
+++ b/python/packages/core/agent_framework/openai/_responses_client.py
@@ -678,7 +678,7 @@ class RawOpenAIResponsesClient(  # type: ignore[misc]
             if last_assistant_idx >= 0:
                 # Collect system/developer messages from before the last assistant
                 system_messages = [
-                    msg for msg in chat_messages[:last_assistant_idx] 
+                    msg for msg in chat_messages[:last_assistant_idx]
                     if msg.role in ("system", "developer")
                 ]
                 # Get all messages after the last assistant (new user messages)