Worked on the TheGiraffe3/endless-sky repository to enhance code quality and maintainability through a focused refactoring effort. Applied C++ development skills to enforce const correctness across the codebase, systematically marking parameters and member functions as const where appropriate. This approach reduced the risk of unintended mutations, improved code safety, and made future refactoring more straightforward. By prioritizing const correctness, the work supported more predictable engine behavior and enabled compiler optimizations. The changes laid a foundation for robust, maintainable code, ensuring that future development in C++ would benefit from increased reliability and easier adaptation to evolving project requirements.