🗑️ 删除旧的 graph_builder.py

- 保留最新的 main_graph/utils/main_graph_builder.py
- agent_service.py 已在使用新文件
- 旧文件是没有混合路由的老版本

backend/app/main_graph/graph_builder.py

@@ -1,83 +0,0 @@
-"""
-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 app.main_graph.graph import StateGraph, START, END
-from app.main_graph.state import MessagesState, GraphContext
-from .nodes import (
-    should_continue,
-    create_llm_call_node,
-    create_tool_call_node,
-    create_retrieve_memory_node,
-    create_summarize_node,
-    finalize_node,
-)
-from app.main_graph.nodes.memory_trigger import memory_trigger_node, set_mem0_client
-from app.memory import Mem0Client
-
-
-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
-        """
-        # 注入全局客户端
-        set_mem0_client(self.mem0_client)
-        
-        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("memory_trigger", memory_trigger_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", "memory_trigger")
-        builder.add_edge("memory_trigger", "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