During their work on the tc39/ecma262 repository, Dox Jin focused on upgrading the documentation build tooling by integrating ecmarkup version 21.4.0. This update streamlined the documentation process, improved rendering performance, and enhanced the reliability of documentation outputs. Dox applied skills in JavaScript, build automation, and dependency management to ensure the build system remained aligned with current tooling standards. By managing the upgrade through Git-based workflows, Dox reduced future maintenance overhead and enabled the project to benefit from recent bug fixes and performance improvements, demonstrating a methodical approach to keeping technical documentation infrastructure robust and up to date.