Henry Mercer focused on improving archive handling reliability in the github/codeql-action repository by addressing a bug related to zstd archive extraction. He reverted a previous change that introduced conditional use of 'gtar', restoring consistent reliance on the standard 'tar' command for both extraction and version checks. This adjustment simplified the command selection logic and reduced maintenance complexity, particularly in continuous integration environments. Working primarily with JavaScript, Node.js, and Shell Scripting, Henry’s solution enhanced cross-platform compatibility and stabilized archive operations. The work demonstrated a targeted, in-depth approach to resolving CI flakiness and improving maintainability without introducing new features.