Worked on enhancing YAML editing validation within the dart-lang/tools repository, focusing on improving the reliability of configuration workflows. Addressed a critical bug by implementing robust detection of both syntax and semantic errors in YAML files, ensuring that edits consistently produce valid structures and align with expected outcomes. Utilized Dart for backend development and leveraged YAML processing techniques to strengthen error detection after edits. This work reduced the likelihood of downstream configuration issues, streamlined debugging, and improved the overall developer experience when working with YAML-based configurations. The contribution centered on backend reliability and correctness rather than feature expansion during the period.