Worked on the optuna/optuna repository over a two-month period, focusing on targeted improvements to code quality and developer experience. Enhanced code readability and performance by refactoring string formatting from .format to f-strings, standardizing the approach across the codebase and reducing runtime overhead in string-heavy paths. In the plotting internals, introduced postponed evaluation of type annotations using __future__.annotations, which improved static typing and IDE support while maintaining API compatibility. Leveraged Python, Matplotlib, and data visualization skills to deliver these features, emphasizing maintainability and type safety without introducing breaking changes or altering existing public interfaces. No bugs were reported.