Code Editor for app.py

import streamlit as st

st.title("Chat with fixed height")

# Initialize chat history
if "messages" not in st.session_state:
    st.session_state.messages = []

# Create a fixed height container for the chat messages
chat_container = st.container(height=400, border=True)

# Display chat messages from history on app rerun
with chat_container:
    for message in st.session_state.messages:
        with st.chat_message(message["role"]):
            st.markdown(message["content"])

# Accept user input
if prompt := st.chat_input("What is up?"):
    # Add user message to chat history
    st.session_state.messages.append({"role": "user", "content": prompt})
    # Display user message in chat message container
    with chat_container:
        with st.chat_message("user"):
            st.markdown(prompt)
        
        # Display assistant response in chat message container
        with st.chat_message("assistant"):
            response = f"You said: {prompt}"
            st.markdown(response)
        # Add assistant response to chat history
        st.session_state.messages.append({"role": "assistant", "content": response})