autorefine_triangle_soup and self-union

[pentacular]

I was reading https://www.cgal.org/2025/06/13/autorefine-and-snap/

I can confirm that autorefine_triangle_soup preserves the interpenetrating part of the geometry, which is what I expected.

But I don't see a good option for doing the self-union on the triangle soup.

I also found https://inria.hal.science/hal-04907149/file/Snap-HAL.pdf but it doesn't shed any light on the removing of the interpenetrating parts.

What am I missing?