Worked on the facebook/folly repository to address a bug in the Span class’s reverse iterator implementation. Focused on stabilizing reverse-iterator semantics by correcting issues with reverse traversal, element access, and iterator comparison, ensuring that downstream consumers receive consistent and reliable behavior. Developed and integrated a regression test to verify the fix and prevent future regressions, emphasizing robust testing practices. Utilized C++ and applied knowledge of data structures and iterators to deliver a targeted solution within a complex codebase. The work prioritized code stability and correctness, contributing to the maintainability and reliability of the folly library’s core components.