Tanvi Tiwari worked on the facebookresearch/xformers repository, focusing on restoring the BlockDiagonalMask import within the attention mechanism codebase. Using Python, she identified and resolved a missing import in xformers/ops/fmha/__init__.py, which had caused runtime errors and potential API breakage for downstream models. Her approach involved targeted bug fixing and careful code refactoring to re-enable BlockDiagonalMask functionality while preserving compatibility for existing users. Although her contributions during the month were limited to this single bug fix, the work demonstrated attention to detail and a clear understanding of dependency management in large-scale machine learning libraries and collaborative open-source environments.