Samuel Hatt focused on improving the stability of the puzzle streak feature in the lichess-org/mobile repository during December 2025. He identified and resolved a bug where the puzzle streak did not reset correctly after failing the first puzzle, ensuring the application’s logic now aligns with intended user experience. Using Dart and Flutter, Samuel implemented a targeted fix and paired it with a regression test to safeguard against future issues. His work emphasized thorough debugging, code review, and a streamlined release process, contributing to the reliability of mobile puzzle mode. This effort demonstrated depth in mobile development and rigorous testing practices.