During October 2025, Andrey Silvestrov focused on enhancing the reliability of the Filestore POSIX test suite in the ydb-platform/nbs repository. He addressed a persistent issue by enabling bind syscall support and extending the misc.sh test harness with create_file and dirgen_max functions, ensuring that mknod-related tests execute consistently. Working primarily in C and Shell, Andrey improved POSIX compliance and reduced flaky test failures, which streamlined continuous integration workflows. His targeted bug fix resolved issue-4541, resulting in more deterministic test outcomes and supporting faster development cycles for features dependent on Filestore behavior. The work demonstrated depth in system programming and testing.