class GraphState(TypedDict, total=False):
    user_id: int              # 用户 ID
    conversation_id: int      # 当前会话 ID
    user_setup_stage: int     # 用户引导阶段（0-3，< 3 表示未完成新手引导）
    message: UnifiedMessage   # 标准化消息对象（含 content、image_urls 等）
    responses: List[str]      # 节点生成的回复列表
    intent: str               # Router 分类的意图标识
    extra: dict[str, Any]     # 扩展上下文（记忆、会话摘要、图片分析等）

render_conversation_context(
    state,
    max_messages=8,         # 最多包含的历史消息数
    include_summary=True,   # 是否包含会话摘要
    include_assistant_messages=True,  # 是否包含助手回复
    include_long_term_memories=True,  # 是否包含长期记忆
)

def _build_graph(checkpointer):
    graph = StateGraph(GraphState)

    # 注册所有节点
    graph.add_node("router", router_node)
    graph.add_node("onboarding", onboarding_node)
    graph.add_node("complex_task", complex_task_node)
    graph.add_node("ledger_manager", ledger_manager_node)
    graph.add_node("schedule_manager", schedule_manager_node)
    graph.add_node("chat_manager", chat_manager_node)
    graph.add_node("skill_manager", skill_manager_node)
    graph.add_node("help_center", help_center_node)

    # 设置入口点
    graph.set_entry_point("router")

    # Router 条件路由
    graph.add_conditional_edges("router", route_intent, { ... })

    # Ledger 条件后续路由（可继续到 chat_manager）
    graph.add_conditional_edges("ledger_manager", _route_after_ledger, { ... })

    # 其他节点直接到 END
    graph.add_edge("onboarding", END)
    graph.add_edge("chat_manager", END)
    # ...

    return graph.compile(checkpointer=checkpointer)

_graph = None
_graph_lock = asyncio.Lock()

async def get_graph():
    global _graph
    if _graph is not None:
        return _graph
    async with _graph_lock:
        if _graph is not None:
            return _graph
        # 初始化检查点 → 构建图 → 缓存
        _graph = _build_graph(checkpointer)
        return _graph