During September 2025, Dung Bui Huu focused on stabilizing the end-to-end testing infrastructure for the nccasia/mezon-fe repository. He addressed a critical bug by reverting previously added end-to-end test markers in the pin message flow, which involved removing e2e identifiers from the channel top bar, context menu, delete message modal, and pin message modal. Working primarily with JavaScript and TypeScript, Dung updated the relevant testing identifier constants to ensure UI behavior remained consistent and test flakiness was minimized. His efforts centered on frontend development and component maintenance, prioritizing test reliability and infrastructure hygiene over new feature delivery during this period.