Worked on the ydb-platform/ydb repository to enhance progress tracking for index building by introducing a new calculation method that accounts for both levels and shard completion. Applied C++ and algorithm design skills to develop logic that provides more granular visibility into build progress, addressing previous limitations in tracking. Added comprehensive unit tests to ensure the reliability and correctness of the new progress calculation, supporting maintainable and robust code. Also resolved an issue related to progress tracking, improving the accuracy and transparency of build status reporting. The work focused on backend logic, emphasizing correctness and testability through careful implementation and validation.