Update app.py

app.py

@@ -107,7 +107,10 @@ def retrieve_context(query, max_results=6, max_chars=600):
 
 def format_conversation(history, system_prompt, tokenizer):
     if hasattr(tokenizer, "chat_template") and tokenizer.chat_template:
-        messages = [{"role": "system", "content": system_prompt.strip()}] + history
+        if len(history) > 0:
+            messages = [{"role": "system", "content": system_prompt.strip()}] + history
+        else:
+            messages = [{"role": "system", "content": system_prompt.strip()}]
         return tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True, enable_thinking=True)
     else:
         # Fallback for base LMs without chat template