Function budget_exhausted 

pub fn budget_exhausted(
    restarts: &mut Vec<Instant>,
    now: Instant,
    window: Duration,
    budget: usize,
) -> bool

Crash-budget bookkeeping, factored out so it is unit-testable. Retains only restarts within window of now; if the surviving count is already at budget, returns true (exhausted — caller gives up) WITHOUT recording. Otherwise records now and returns false. Matches the existing inline wedged-host budget semantics (check-before-push).