Worked on enhancing real-time authentication reliability in the supabase/supabase-js repository by implementing persistent custom JWT token handling across channel resubscriptions. Addressed issues where authentication tokens could be lost during reconnections, which previously disrupted session continuity for applications with multiple real-time subscriptions. Utilized TypeScript and full stack development skills to modify the RealtimeClient and RealtimeChannel components, ensuring tokens are preserved and authentication remains consistent. Focused on improving user experience for real-time communication scenarios by validating changes with targeted tests and preparing the feature for release. The work delivered smoother authentication flows and reduced session interruptions for real-time applications.