We're launching P2P transfer limits in mobile banking: max $1,000 per transaction and $2,500 cumulative per day. A customer has already sent $1,800 today and now initiates an $800 transfer. Write the key acceptance criteria for this story, tell me what happens to this transfer, and what boundary tests you would design.

手机银行要上线 P2P 转账限额：单笔不超过 $1,000，单日累计不超过 $2,500。某客户今天已经转出 $1,800，现在又发起一笔 $800。请写出这条 story 的关键验收标准，并说说这笔交易会是什么结果、你会设计哪些边界测试。