Function pool_counts_with 

pub fn pool_counts_with(
    shape: &PoolShape,
    mtp_slots: usize,
    slot_h: impl Fn(usize) -> usize,
) -> PoolCounts

2026-09-30: Pure: the counts for mtp_slots verify slots, slot s tiered to slot_h(s) h intermediates (capped at K - 1). The verify dummy, at index mtp_slots, always gets K - 1: batched-verify padding rows may write any live token index. Replay keeps no intermediates, only the checkpoints.