During February 2025, D14z focused on stabilizing Kotlin argument construction within the facebook/buck2-prelude repository. By reverting a previous change, D14z ensured that the get_language_version function directly contributed the correct arguments to kotlinc, removing the need for a separate get_language_version_arg function. This adjustment, implemented using Kotlin and Starlark, restored the expected inclusion of the language version in extra_kotlinc_arguments, preventing build and configuration errors. D14z’s work centered on build system configuration and compiler argument management, demonstrating careful rollback and refactoring practices to maintain system stability and developer velocity while improving downstream compatibility for Kotlin compilation workflows.