Cloud Functions（第二代）部署的Google Chat应用回复失败问题求助

我现在用Python在Cloud Functions（第二代）上搭一个超简单的Google Chat应用，需求特别简单——就是在mail.google.com/chat发消息的时候，应用能回复一句"OK"就行。但现在每次发消息，日志里都会弹出错误，完全没法正常回复，折腾好半天都没搞定，来求助各位大佬！

遇到的错误信息： #

Can't post a reply. The Chat app didn't respond or its response was invalid. If your Chat app is configured as an add-on, see "Build Google Chat interfaces" in the Google Workspace add-ons documentation. Otherwise, see "Receive and respond to Google Chat events" in the Chat API documentation.

我的代码实现： #

import functions_framework

@functions_framework.http
def mi_app_de_chat(request):
    event = request.get_json(silent=True)
    if event and event.get("type") == "ADDED_TO_SPACE":
        return {"text": "Your Welcome"}
    return {"text": "OK"}

我感觉逻辑上没什么毛病啊，有没有大佬能帮我排查下问题出在哪？

内容来源于stack exchange