Function fragment_face 

pub fn fragment_face(
    solid: &BrepSolid,
    operand: u8,
    face: &FaceRecord,
    imprint: &ImprintResultRecord,
) -> Result<Vec<FaceFragmentRecord>, String>

Back-compat entry point: builds the imprint index for this single face. fragment_solid builds it once and calls fragment_face_indexed directly.