feat: 完善子图，添加路由函数和审核节点

backend/app/agent_subgraphs/contact/nodes.py

@@ -172,5 +172,59 @@ def format_result(state: ContactState) -> ContactState:
     state.final_result = "\n".join(output_lines)
     state.success = True
     state.current_phase = "completed"
-    
+
     return state
+
+
+def human_review(state: ContactState) -> ContactState:
+    """
+    人工审核节点（用于邮件草稿）
+    """
+    state.current_phase = "reviewing"
+    # 标记需要审核，等待用户决定
+    state.needs_approval = True
+    return state
+
+
+def send_email(state: ContactState) -> ContactState:
+    """
+    发送邮件节点
+    """
+    state.current_phase = "executing"
+    # 使用 API 客户端发送邮件
+    success = contact_api.send_email(
+        state.user_id,
+        state.draft_recipient,
+        state.draft_subject,
+        state.draft_body
+    )
+    state.success = success
+    return state
+
+
+def should_continue(state: ContactState) -> str:
+    """
+    条件路由函数：根据 action 和状态决定下一个节点
+    """
+    # 如果是从 human_review 来的，根据审核状态决定
+    if state.current_phase == "reviewing":
+        if state.needs_approval:
+            # 这里会等待用户操作，实际运行时通过 checkpointer 或后端 API 处理
+            return "format_result"
+        else:
+            return "send_email"
+
+    # 普通路由
+    action = state.action
+    if action == ContactAction.CONTACT_LIST:
+        return "list_contacts"
+    elif action == ContactAction.CONTACT_ADD:
+        return "add_contact"
+    elif action == ContactAction.EMAIL_LIST:
+        return "list_emails"
+    elif action == ContactAction.EMAIL_SEND:
+        return "generate_email_draft"
+    elif action == ContactAction.SNIFF_CONTACTS:
+        return "sniff_contacts"
+    else:
+        return "format_result"