Fix multi-turn conversation: handle dict history format

app.py

@@ -79,11 +79,9 @@ def chat_fn(message, history, system_prompt, max_new_tokens, temperature, top_p)
     if system_prompt:
         messages.append({"role": "system", "content": system_prompt})
 
-    for user_msg, assistant_msg in (history or []):
-        if user_msg:
-            messages.append({"role": "user", "content": user_msg})
-        if assistant_msg:
-            messages.append({"role": "assistant", "content": assistant_msg})
+    # History is already in dict format: [{"role": "user", "content": "..."}, ...]
+    for msg in (history or []):
+        messages.append(msg)
 
     if message:
         messages.append({"role": "user", "content": message})