Show HN: LemmaScript, a verification toolchain for TypeScript via Dafny (github.com)

I created LemmaScript to compile TypeScript to a verification backend (Dafny or Lean) and prove properties on the systematically derived model. I'll keep developing this, but I have a few case studies already, and it looks quite promising, with the caveat that each case study pushed the development of the core further. I can support both greenfield and brownfield projects, and in many cases, verification can be in-place: the TypeScript source is just annotated and verified independently but runs as is.