Function evaluate_for_dispatch 

pub fn evaluate_for_dispatch(
    fleet_state: &FleetState,
    manifests: &SignedManifestSet,
    quarantines: &QuarantineSet,
    rollout_id: &RolloutId,
    host: &HostId,
    target_closure: &ClosureHash,
    channel: &ChannelId,
    tick_dispatched: &HashMap<BudgetId, u32>,
) -> Option<GateBlock>

First block wins. Cheapest-first; quarantine is FIRST for the anti-thrash property (see module docstring).

tick_dispatched is the per-budget counter the planner maintains across a single plan_next() call so within-tick over-commit is caught (see planner_gates::disruption_budget for the rationale). Empty map = first host in the tick.