def initialize_session() -> None:
    if "graph" in st.session_state:
        return

    llm = ChatOpenAI(
        model=os.getenv("OPENAI_MODEL", "gpt-4o-mini"),
        temperature=0,
    )

    handler = create_langfuse_handler()

    st.session_state.graph = build_graph(llm)
    st.session_state.handler = handler
    st.session_state.config = graph_config(
        str(uuid4()),
        handler,
    )
    st.session_state.agent_state = INITIAL_STATE.copy()
    st.session_state.started = False