Our digital account opening flow is going to call a third-party identity verification API. The vendor says the average response time is 2 seconds with 99.5% availability, and we get about 3,000 applications a day. Before you write the stories, what would you confirm with the vendor, and what should happen to the customer when the API is down?

数字开户要接一个第三方身份核验接口，对方说平均 2 秒返回、可用率 99.5%，我们每天大约有 3,000 个开户申请。写 story 之前，你会跟接口方确认哪些东西？接口不可用的时候，客户这边应该怎么处理？