During March 2026, Diogo Cruz focused on backend robustness for the UKGovernmentBEIS/inspect_ai repository, addressing a critical issue in JSON patching logic. He implemented a targeted bug fix in Python that introduced type checks to ensure fast-path list operations were only applied to list containers, preventing runtime crashes when dictionaries contained numeric string keys. This change improved the stability and maintainability of the json_changes module, especially under benchmark workloads in ControlArena and Shade Arena contexts. By isolating dictionary and list handling and adding regression coverage, Diogo reduced production risk and technical debt, supporting more reliable backend performance and future development.