Gaurav Singh Rajput contributed to the Rocket.Chat/Rocket.Chat repository by focusing on the reliability and maintainability of the calendar-related user interface. He addressed a bug in the Outlook Calendar Join button, preventing event bubbling so that event details open correctly, which reduced user confusion and improved feature reliability. Additionally, he refactored frontend CSS hover effects by moving hover styles outside the OutlookEventItem component, streamlining code organization for easier future maintenance. His work utilized React, JavaScript, and TypeScript, demonstrating a methodical approach to front end development and ensuring that both user experience and developer workflows were enhanced within the project.