Fix empty tool-use response handling

s09_memory/README.zh.md

@@ -96,7 +96,10 @@ system = build_system(relevant_memories)
 用户不一定会明确说“请记住”。`extract_memories()` 在 Agent 完成本轮回答后检查当前对话，只提取以后仍可能有用的信息：
 
 ```python
-if response.stop_reason != "tool_use":
+tool_calls = [
+    block for block in response.content if block.type == "tool_use"
+]
+if not tool_calls:
     force = trigger_hooks("Stop", messages)
     if force:
         messages.append({"role": "user", "content": force})