pub fn tail_split_point(total: usize, block_size: usize) -> Option<usize>Expand description
2026-09-27: The tail split point of a total-token prompt: one block below the last
block boundary strictly under total, or None when that is not above token 0. A
warm next turn’s block-floored match lands at or one block below that boundary, so a
snapshot here is restorable by both.