In September 2025, Sergey Lavrov focused on enhancing the robustness of the tsort component in the uutils/coreutils repository. He addressed stack overflow risks in large dependency graphs by converting the depth-first search algorithm from a recursive to an iterative approach using Rust. This change improved the scalability and reliability of tsort, particularly for complex inputs with cycles. Sergey also expanded the test suite to cover edge cases and verify correct cycle handling, ensuring no regressions were introduced. His work demonstrated strong skills in Rust programming, algorithm design, and testing, delivering measurable improvements to the stability of build and ecosystem tooling.