These are just assumptions on your part - the synchronous/threading model doesn’t have to be that primitive, the Thread itself can take on the semantics of cancellation/timeouts just fine. While there are some ergonomic warts in java’s case, it does show that something like interrupts can work reasonably well (with a sufficiently good error handling system, e.g. exceptions).

With “structured concurrency”/nurseries it can be much more readable than manually checking interruptions, and you can just do something like fire a bunch of requests with a given timeline, and join them at the end of the “block”.