Mikhail Terekhov contributed to the UKGovernmentBEIS/control-arena repository by focusing on backend development and code maintainability using Python. He addressed a security-sensitive bug in the Attack Tool Call conversion logic, ensuring that warnings are triggered for improper conversions and refining tool name handling to maintain correct function mapping. Additionally, he performed a targeted data model cleanup by removing the unused resampled_monitor_responses field from DTRMetadata, reducing complexity while preserving existing behavior. His work combined bug fixing, code cleanup, and refactoring, resulting in a safer and more maintainable codebase. The changes demonstrated careful attention to correctness and long-term risk reduction.