Show HN: Formally verified 3D CSG: Trust 93 lines spec, not 1000 lines AI code

A developer has created the first formally verified 3D mesh intersection implementation in Lean 4, where a human only needs to review a 93-line formal specification rather than 1000+ lines of AI-generated code, while an AI agent autonomously wrote 60,000+ lines of verified proofs. The project demonstrates how formal verification can eliminate the need to trust AI-written code, with a working web demo available, though the implementation is significantly slower than conventional mesh intersection algorithms.