During March 2025, Caspar Kielwein focused on enhancing code quality and maintainability in the TheGiraffe3/endless-sky repository. He implemented a comprehensive refactor to enforce const correctness throughout the C++ codebase, ensuring that parameters and member functions not intended to be modified were explicitly marked as const. This approach reduced the risk of unintended mutations, improved code safety, and made future refactoring efforts more straightforward. By prioritizing const correctness and careful refactoring, Caspar laid the groundwork for more robust and predictable engine behavior, leveraging his expertise in C++ development to support safer changes and facilitate ongoing maintainability.