Function clamp_trainable_to_vocab 

pub fn clamp_trainable_to_vocab(
    trainable: &[u32],
    r: usize,
    vocab: usize,
) -> Result<(Vec<u32>, usize)>

2026-09-25: Split trainable ids at the served vocab, keeping list order, since delta row k belongs to the k-th id. Returns (kept_ids, skipped_count):

• idx >= r (outside the adapter’s [R, h] table) is an error;
• vocab <= idx < r is dropped and counted;
• idx < vocab is kept.

Also an error: a kept id after a dropped one (dropped ids must be one trailing run, so kept id k still matches delta row k), and a kept id not greater than the previous kept id.