Long Yingchi contributed to the hmemcpy/nixpkgs repository by developing and stabilizing Nix tooling, focusing on both feature delivery and compatibility improvements. They built the nixf-diagnose CLI tool, a wrapper for nixf-tidy, which enhances diagnostic output for developers working with Nix-based projects. To ensure ongoing compatibility with the latest Nix features, Long addressed build issues in the NixD language server by adjusting CXXFLAGS include paths, supporting Nix 2.28. Their work demonstrated practical application of build systems, package management, and the Nix language, providing targeted solutions that improved both developer experience and toolchain reliability within the project.