Building an exact, deterministic geometry kernel in Rust for an open-source Revit alternative: advice wanted on approach and strategy

We're a small co-op building Spare Kit, an open-source (MPL-2.0) geometry kernel in Rust, to power a Revit/CAD alternative that runs natively and in the browser (WASM). Much of the code is written by AI agents working through a mapped plan, with strict testing as the safeguard. The approach: Integer grid coordinates (±2^40 steps) with exact predicates (generated filters, exact integer fallback), so topology decisions never depend on float rounding. Flat geometry stays plane-based with implici...