diff --git a/产品需求文档AI生成/application/utils/agent.py b/产品需求文档AI生成/application/utils/agent.py
index 9fe0662..fad668c 100644
--- a/产品需求文档AI生成/application/utils/agent.py
+++ b/产品需求文档AI生成/application/utils/agent.py
@@ -7,7 +7,6 @@ Pydantic AI 聊天智能体和相关模块
 from enum import StrEnum
 from typing import AsyncGenerator, List, Optional, Union
 from uuid import uuid4
-from numpy._core.numeric import str_
 from pydantic_ai import Agent
 from pydantic_ai.capabilities import AgentCapability
 from pydantic_ai.messages import (
@@ -258,7 +257,7 @@ class AIAgent:
                     ):
                         yield Event(
                             event_kind=event_kind,
-                            content=content,
+                            content=content if isinstance(content, str) else None,  # 
                             part_index=index,
                             part_kind=part_kind,
                             tool_name=tool_name,