refactor: 重构图为标准 agent/tools 分离结构

backend/app/main_graph/main_graph_builder.py

@@ -1,12 +1,15 @@
 """
-极简 Agent 主图 - 简化版本！
-因为完整的 ReAct 循环已经在 agent.py 里了！
+Agent 主图 - 标准 LangGraph 结构
+将 ReAct 循环分离为独立的 agent/tools 节点
 """
 
+from typing import Literal
 from langgraph.graph import StateGraph, START, END
 from backend.app.main_graph.state import AgentState
 from backend.app.main_graph.nodes.memory_trigger import memory_trigger_node, set_mem0_client
 from backend.app.main_graph.nodes.agent import create_agent_node
+from backend.app.main_graph.nodes.tools import tools_node
+from backend.app.main_graph.nodes.finalize import finalize_node
 from backend.app.logger import info
 
 
@@ -16,7 +19,20 @@ def build_agent_graph(
     max_steps: int = 10
 ):
     """
-    构建简化的 Agent 图（ReAct 循环在 agent 节点内）
+    构建标准 Agent 图
+
+    节点:
+    - init_state: 初始化状态
+    - memory_trigger: 记忆触发
+    - agent: 单步推理
+    - tools: 工具执行
+    - finalize: 后处理
+
+    边:
+    - START -> init_state -> memory_trigger -> agent
+    - agent -> (条件边) -> tools 或 finalize
+    - tools -> agent (循环)
+    - finalize -> END
 
     Args:
         chat_services: 模型服务字典
@@ -26,57 +42,70 @@ def build_agent_graph(
     Returns:
         构建好的 StateGraph（未编译）
     """
-    # ========== 设置全局客户端 ==========
+    # 设置全局客户端
     if mem0_client:
         set_mem0_client(mem0_client)
 
-    # ========== 1. 初始化节点：重置步数 ==========
+    # ========== 1. init_state 节点 ==========
     async def init_state_node(state: AgentState):
-        info("[Init State] 初始化状态，重置步数")
+        info("[Init State] 初始化状态")
         return {
             "current_step": 0,
-            "max_steps": max_steps
+            "max_steps": max_steps,
+            "tool_call_history": [],
+            "tool_result_history": [],
+            "tools_used": [],
+            "stop": False,
+            "stop_reason": "",
         }
 
-    # ========== 2. 记忆节点（可选） ==========
-    retrieve_memory_node = None
-    if mem0_client:
-        try:
-            from ..nodes.retrieve_memory import create_retrieve_memory_node
-            retrieve_memory_node = create_retrieve_memory_node(mem0_client)
-        except Exception as e:
-            info(f"[Graph Builder] 记忆节点初始化失败: {e}")
-
-    # ========== 3. Agent 节点（包含完整 ReAct 循环，支持动态模型切换） ==========
+    # ========== 2. Agent 节点 ==========
     agent_node_fn = create_agent_node(chat_services)
 
-    # ========== 4. 完成节点 ==========
-    async def finalize_node_simple(state: AgentState):
-        info("[Finalize] 进入完成节点")
-        return {}
+    # ========== 3. 条件边函数 ==========
+    def should_continue(state: AgentState) -> Literal["tools", "finalize"]:
+        """根据 agent 节点输出决定下一步"""
+        # 手动停止标志
+        if getattr(state, "stop", False):
+            return "finalize"
 
-    # ========== 5. 构建图 ==========
+        # 检查是否有工具调用
+        last_msg = state.messages[-1]
+        if hasattr(last_msg, 'tool_calls') and last_msg.tool_calls:
+            return "tools"
+
+        return "finalize"
+
+    # ========== 4. 构建图 ==========
     graph = StateGraph(AgentState)
 
+    # 添加节点
     graph.add_node("init_state", init_state_node)
-    if retrieve_memory_node:
-        graph.add_node("retrieve_memory", retrieve_memory_node)
     graph.add_node("memory_trigger", memory_trigger_node)
     graph.add_node("agent", agent_node_fn)
-    graph.add_node("finalize", finalize_node_simple)
+    graph.add_node("tools", tools_node)
+    graph.add_node("finalize", finalize_node)
 
-    # ========== 6. 边的连接 ==========
+    # 边的连接
     graph.add_edge(START, "init_state")
-
-    if retrieve_memory_node:
-        graph.add_edge("init_state", "retrieve_memory")
-        graph.add_edge("retrieve_memory", "memory_trigger")
-    else:
-        graph.add_edge("init_state", "memory_trigger")
-
+    graph.add_edge("init_state", "memory_trigger")
     graph.add_edge("memory_trigger", "agent")
-    graph.add_edge("agent", "finalize")
+
+    # 条件边: agent -> tools 或 finalize
+    graph.add_conditional_edges(
+        "agent",
+        should_continue,
+        {
+            "tools": "tools",
+            "finalize": "finalize"
+        }
+    )
+
+    # 循环回边: tools -> agent
+    graph.add_edge("tools", "agent")
+
+    # 结束
     graph.add_edge("finalize", END)
 
-    info("✅ [Graph Builder] 简化 Agent 图构建完成（ReAct 在节点内）")
+    info("✅ [Graph Builder] 标准 Agent 图构建完成")
     return graph