Function legacy_splits 

pub fn legacy_splits(sm_count: u32, num_q_heads: u32, ref_seqs: u32) -> u32

2026-09-25: The SplitkPolicy::Legacy rule. The dispatch passes ref_seqs = split_ref_seqs(num_seqs, max_decode_seqs), which is max(max_decode_seqs, num_seqs).