fix error (#1562)

Author: lnhsingh

src/oss/langchain/context-engineering.mdx

@@ -408,7 +408,7 @@ Reference these files when answering questions.`;
 
           // Inject file context before recent messages
           const messages = [  // [!code highlight]
-            ...request.messages  // Rest of conversation
+            ...request.messages,  // Rest of conversation
             { role: "user", content: fileContext }
           ];
           request = request.override({ messages });  // [!code highlight]
@@ -1353,6 +1353,7 @@ Dynamic response format selection adapts schemas based on user preferences, conv
         // request.state is a shortcut for request.state.messages
         const messageCount = request.messages.length;  // [!code highlight]
 
+        let responseFormat;
         if (messageCount < 3) {
           // Early conversation - use simple format
           responseFormat = simpleResponse; // [!code highlight]
@@ -1552,6 +1553,7 @@ Dynamic response format selection adapts schemas based on user preferences, conv
         const userRole = request.runtime.context.userRole;  // [!code highlight]
         const environment = request.runtime.context.environment;  // [!code highlight]
 
+        let responseFormat;
         if (userRole === "admin" && environment === "production") {
           responseFormat = adminResponse;  // [!code highlight]
         } else {