Function mtp_ladder_drafts 

pub fn mtp_ladder_drafts(n_active: usize, num_drafts: usize) -> usize

The per-step draft count for n_active concurrent sequences.

num_drafts is the configured ceiling (CLI --num-drafts); the return value is always in [1, num_drafts] (or 0 when num_drafts is 0, i.e. speculation off). Ladder disabled -> fixed num_drafts (pre-ladder behavior). n_active beyond the last ladder step uses the last step’s draft count (the cap gates dispatch anyway).