Update app.py

app.py

@@ -268,10 +268,16 @@ if user_prompt := st.chat_input():
     with st.chat_message("assistant", avatar="🧠"):
         with st.spinner("Math Mentor is thinking... 🤔"):
             try:
-                chat_session = model.start_chat(history=[
-                    {'role': msg['role'], 'parts': [msg['content']]} 
-                    for msg in active_chat[:-1]
-                ])
+                 def convert_role_for_gemini(role):
+    """Convert Streamlit chat roles to Gemini API roles"""
+    if role == "assistant":
+        return "model"
+    return role  # "user" stays the same
+
+chat_session = model.start_chat(history=[
+    {'role': convert_role_for_gemini(msg['role']), 'parts': [msg['content']]} 
+    for msg in active_chat[:-1]
+])
                 response = chat_session.send_message(user_prompt)
                 ai_response_text = response.text
                 st.markdown(ai_response_text)