Function style_finishes_for_ids 

pub fn style_finishes_for_ids(
    ids: &[u32],
    finish_of: impl FnMut(u32) -> Option<SpecularMaterial>,
) -> Vec<f32>

The styleFinishes wire for an already-ordered id list: finish_of(id)’s finish_to_wire pair per id, in ids order. Shared by the serial flatten and the sharded finalize so both encode identically.