Diana Amfreitas refactored the fromFullPaths function in the adzerk/apso repository to improve stack safety and scalability when processing large path lists. She applied functional programming techniques in Scala, introducing a tail-recursive approach with an accumulator to prevent StackOverflow errors while maintaining the existing API. Diana centralized the core logic in an internal helper, optimizing recursion and ensuring maintainability. She expanded the test suite to validate correctness, scalability, and the last-wins behavior for duplicate paths, emphasizing robust, test-driven development. Her work demonstrated depth in recursion optimization, JSON manipulation, and testing, resulting in a more reliable and maintainable codebase.