Function settle_with 

pub fn settle_with<H>(
    host: &H,
    caller: &Caller,
    invocation: InvocationId,
    seen: Option<UpdateMark>,
    until: Instant,
) -> Pending<Option<InvocationState>> 
where
    H: ActionHost + Clone + Send + 'static,

The state of invocation, as ActionHost::observe reports it to caller, once it has moved past seen — or, with no seen, once it settles — or at until, whichever comes first.

It answers at once when the invocation is already there, when caller may not see it (None), when the host cannot signal changes, or when caller’s execution has ended. Otherwise it waits on ActionHost::next_change and looks again each time that fires; the deadline is checked then, so a host’s bounded change interval bounds how far past until an answer can come.