Function loop_crossings_handle_native 

pub fn loop_crossings_handle_native(
    handle: u32,
) -> Result<LoopCrossingReport, String>

Face-loop self-crossing of a resident solid — the check no OTHER detector here can make. validate() is silent (the incidence is perfect), the face-versus-face scan has no pair to confirm (both triangles are on one face), connectivity and Euler parity count the same cells either way; the face’s AREA is the only other tell. Pure parameter-space work on the trims the face already carries — no tessellation — so it is cheap enough to be a default. Reads the solid in one registry borrow.