Most teams building a web + mobile product end up with two auth integrations that slowly drift apart. You don't need that. Here's how to run a single Supabase auth layer across a Next.js web app and an Expo mobile app in a monorepo — including the gotchas nobody warns you about. 1. Keep the Supabase client framework-agnostic Depend only on @supabase/supabase-js . Expose a factory that takes the storage adapter as an argument: export function createSupabaseClient({ url, ano...