ailine/app/graph_builder.py

"""
LangGraph 状态图构建模块 - 精简版，仅负责组装图
所有节点逻辑已拆分到独立模块
"""

from langchain_core.language_models import BaseLLM
from langgraph.graph import StateGraph, START, END

# 本地模块
from app.graph.state import MessagesState, GraphContext
from app.nodes import (
    create_llm_call_node,
    create_tool_call_node,
    create_retrieve_memory_node,
    create_summarize_node,
    should_continue
)
from app.memory import Mem0Client
from app.nodes.finalize import finalize_node


class GraphBuilder:
    """LangGraph 状态图构建器 - 仅负责组装图"""

    def __init__(self, llm: BaseLLM, tools: list, tools_by_name: dict):
        """
        初始化构建器
        
        Args:
            llm: 大语言模型实例
            tools: 工具列表
            tools_by_name: 名称到工具函数的映射
        """
        self.llm = llm
        self.tools = tools
        self.tools_by_name = tools_by_name
        
        # ⭐ 创建 Mem0 客户端（懒加载，首次使用时初始化）
        self.mem0_client = Mem0Client(llm)

    def build(self) -> StateGraph:
        """
        构建未编译的状态图
        
        Returns:
            StateGraph 实例
        """
        builder = StateGraph(MessagesState, context_schema=GraphContext)
        
        # ⭐ 通过工厂函数创建节点（依赖注入）
        retrieve_memory_node = create_retrieve_memory_node(self.mem0_client)
        llm_call_node = create_llm_call_node(self.llm, self.tools)
        tool_call_node = create_tool_call_node(self.tools_by_name)
        summarize_node = create_summarize_node(self.mem0_client)
        
        # 添加节点
        builder.add_node("retrieve_memory", retrieve_memory_node)
        builder.add_node("llm_call", llm_call_node)
        builder.add_node("tool_node", tool_call_node)
        builder.add_node("summarize", summarize_node)
        builder.add_node("finalize", finalize_node)

        # 添加边
        builder.add_edge(START, "retrieve_memory")
        builder.add_edge("retrieve_memory", "llm_call")
        builder.add_conditional_edges(
            "llm_call",
            should_continue,
            {
                "tool_node": "tool_node",
                "summarize": "summarize",
                "finalize": "finalize"
            }
        )
        builder.add_edge("tool_node", "llm_call")
        builder.add_edge("summarize", "finalize")
        builder.add_edge("finalize", END)
        
        return builder