While it's true that the "state" of a future is only mutated in the poll() implementation, it's up to the author of the future implementation to clone/send/call

While it's true that the "state" of a future is only mutated in the poll() implementation, it's up to the author of the future implementation to clone/send/call the Waker provided in the context argument to signal to the executor that poll() should be called again by the executor, which I believe is how one should handle this case.