Function mesh_regions_to_brep 

pub fn mesh_regions_to_brep(
    positions: &[f64],
    indices: &[u32],
    options: &SegmentOptions,
) -> Result<BrepSolid, String>

Rebuild a BrepSolid whose faces are the mesh’s segmented regions. The result always passes full topology validation (watertight edge pairing, Euler accounting, pcurve consistency) or the call returns Err — an invalid solid is never returned. See the module-level v1 scope notes.