diff --git a/src/oss/langchain/context-engineering.mdx b/src/oss/langchain/context-engineering.mdx
index 3c4299a53..f4b73cecd 100644
--- a/src/oss/langchain/context-engineering.mdx
+++ b/src/oss/langchain/context-engineering.mdx
@@ -366,7 +366,7 @@ Reference these files when answering questions."""
 
             # Inject file context before recent messages
             messages = [  # [!code highlight]
-                *request.messages
+                *request.messages,
                 {"role": "user", "content": file_context},
             ]
             request = request.override(messages=messages)  # [!code highlight]