Update vlm.py

vlm.py

@@ -49,6 +49,14 @@ def encode_image(image_path):
 #
 # Build messages
 #
+def normalize_message_content(msg: dict) -> dict:
+    if isinstance(msg.get("content"), str):
+        return {
+            "role": msg["role"],
+            "content": [{"type": "text", "text": msg["content"]}]
+        }
+    return msg
+
 def build_messages(message: dict, history: list[dict]):
     """Build messages given message & history from a **multimodal** chat interface.
     Args:
@@ -77,13 +85,16 @@ def build_messages(message: dict, history: list[dict]):
             }
         )
 
-    # Append to the history to create the new messages
-    messages = history
+    # Normalize existing history content
+    messages = [normalize_message_content(msg) for msg in history]
+    
+    # Append new user message
     messages.append({'role': 'user', 'content': user_content})
     logger.info(f"{messages=}")
 
     return messages
 
+
 #
 # stream response
 #