How I wired up auth in my vibe-coded app in 10 minutes

I kept putting off real authentication because it sounded hard. Turns out with the right prompt the agent wires it up almost by itself: 1) create the auth provider project, 2) describe exactly which sign-in methods you want, 3) test with a throwaway email. The only snag was the redirect URL — make sure you put your app's exact address in the provider settings.