Worked on the optuna/optuna repository to enhance codebase quality by removing dead and unused code, focusing on maintainability and reducing technical debt. Leveraged Python and static analysis tools, including Skylos and LLM-assisted verification, to safely identify and eliminate obsolete functions and variables without altering existing behavior. Applied ruff format for consistent code style, further improving readability and future maintainability. The approach emphasized careful validation to prevent regressions, ensuring that internal changes supported a stable foundation for future development. This work streamlined the codebase, making onboarding easier for new contributors and enabling more efficient feature implementation moving forward.