Jerome Simeon developed JsAst 2.0 for the coq/opam repository, delivering a minimal JavaScript abstract syntax tree that introduced let bindings and native float support. His work focused on creating a compact and stable AST representation, enabling the Rocq Prover to model JavaScript semantics with greater accuracy. By emphasizing forward-compatible API design and reducing integration friction, Jerome improved verification workflows and facilitated interoperability with downstream tooling. He applied his expertise in JavaScript development and compiler design to coordinate repository changes, enhancing traceability and build reproducibility. The project demonstrated depth in language modeling and careful attention to maintainable, extensible architecture.