Worked on the facebookresearch/fairseq2 repository to deliver a targeted stability improvement by addressing a bug in checkpoint management. Focused on the delete_stale_checkpoints function, the developer modified its logic to correctly handle scenarios where the trainer_dir is missing in FileCheckpointManager. Using Python, they ensured checkpoint step numbers are always appended to the step_numbers list, preventing the deletion process from skipping necessary cleanup. This fix reduces the risk of stale checkpoint accumulation and enhances experiment reliability across diverse environments. The work demonstrates attention to detail in bug fixing and a solid understanding of checkpoint management within machine learning infrastructure.