采用向量数据库实现长期记忆

app/nodes/retrieve_memory.py

@@ -0,0 +1,75 @@
+"""
+记忆检索节点模块
+负责从 Mem0 检索相关长期记忆
+"""
+
+from typing import Any, Dict
+from langgraph.runtime import Runtime
+
+# 本地模块
+from app.state import MessagesState, GraphContext
+from app.memory.mem0_client import Mem0Client
+from app.utils.logging import log_state_change
+from app.logger import debug
+
+
+def create_retrieve_memory_node(mem0_client: Mem0Client):
+    """
+    工厂函数：创建记忆检索节点
+    
+    Args:
+        mem0_client: Mem0 客户端实例
+        
+    Returns:
+        异步节点函数
+    """
+    
+    async def retrieve_memory(state: MessagesState, runtime: Runtime[GraphContext]) -> Dict[str, Any]:
+        """
+        记忆检索节点 - 使用 Mem0
+        
+        Args:
+            state: 当前对话状态
+            runtime: LangGraph 运行时上下文
+            
+        Returns:
+            包含 memory_context 的状态更新
+        """
+        log_state_change("retrieve_memory", state, "进入")
+
+        user_id = runtime.context.user_id
+        
+        # 兼容 dict 和对象两种消息格式
+        last_msg = state["messages"][-1]
+        if isinstance(last_msg, dict):
+            query = str(last_msg.get("content", ""))
+        else:
+            query = str(last_msg.content)
+        memory_text_parts = []
+
+        # 确保 Mem0 已初始化（懒加载）
+        if not mem0_client._initialized:
+            await mem0_client.initialize()
+
+        if mem0_client.mem0:
+            try:
+                # 异步调用 Mem0 语义检索
+                facts = await mem0_client.search_memories(query, user_id=user_id, limit=5)
+                
+                if facts:
+                    memory_text_parts.append(f"【相关长期记忆】\n" + "\n".join(f"- {f}" for f in facts))
+                else:
+                    debug("🔍 [记忆检索] 未找到相关记忆")
+            except Exception as e:
+                from app.logger import warning
+                warning(f"⚠️ Mem0 检索失败: {e}")
+        else:
+            from app.logger import warning
+            warning("⚠️ Mem0 未初始化，跳过记忆检索")
+
+        memory_context = "\n\n".join(memory_text_parts) if memory_text_parts else "暂无用户信息"
+        result = {"memory_context": memory_context}
+        log_state_change("retrieve_memory", {**state, **result}, "离开")
+        return result
+    
+    return retrieve_memory