Igor Kamyshnikov contributed to the MHSanaei/3x-ui repository by delivering a targeted bug fix in the Subscription Service, addressing an issue with VLESS connection links. He modified the backend logic to ensure that subscription links now return the Inbound Listen address rather than the service IP, which aligns with VLESS protocol requirements and reduces user-facing errors. Working primarily with Go, Igor applied his skills in API development and networking to improve link consistency and reliability for end users. His work demonstrated a focused approach to debugging and protocol integration, resulting in a more robust and predictable subscription-driven connection experience.