Leon contributed to the MinaProtocol/mina and o1-labs/o1js repositories by delivering build system stability, cross-platform compatibility, and automated testing improvements. He enhanced OCaml/Dune and Rust build processes, resolving MacOS arm64 issues through custom dependency pinning and architecture-aware adjustments. In o1js, Leon reorganized changelog scripts, optimized linting with Oxlint, and introduced a cache regression testing framework to verify cache integrity. His work consolidated code quality measures, expanded CI/CD automation, and modularized build processes using TypeScript, JavaScript, and Nix. These efforts reduced maintenance overhead, improved developer feedback loops, and strengthened reliability across both backend and DevOps workflows.