Ivan Zolotukhin focused on improving the reliability of leadership transitions in the tarantool/tarantool repository by addressing a critical issue in the Raft-based state machine. He delivered a targeted fix to box.ctl.promote(), ensuring the function waits for the instance to become writable after assuming Raft leadership, which prevents errors caused by premature promotion. This change eliminated the need for manual operator intervention and reduced the risk of runtime failures in production clusters. Ivan applied his expertise in concurrent and system programming, using C and Lua, and demonstrated careful debugging and testing to enhance cluster stability and streamline the promotion workflow.