Function reconstruct_spherical_mesh_union 

pub fn reconstruct_spherical_mesh_union(
    positions: &[f64],
    indices: &[u32],
    seg: &MeshSegmentation,
    options: &SegmentOptions,
) -> Option<BrepSolid>

Attempt a small union of outward spheres and, optionally, one orthogonal box. Returns None for unsupported geometry or insufficient evidence.

The caller supplies a consistently wound closed component and its kernel segmentation. This does not relax segmentation tolerances: carriers need near-precision support, all source facets must agree with the exposed union boundary, and that boundary must also be covered by the source. The distance allowance for cut vertices is bounded by the measured chordal deflection of intact sphere facets (at most 2% of the radius).