I think I read in another HN discussion that all of that code is written using Claude Code. Could be a strict dogfood diet to (try to) force themselves to improve their product. Which would be strangely principled (or stupid) in such a competitive market. Like a 3D printer company insisting on 3D-printing its 3D printers.

It's not crazy if you know that your customers ARE buying your 3D printer to make other 3D printers.