How does Supabase support anonymous sign-ins, and how do you convert one to a permanent account?

Anonymous sign-in creates a real row in auth.users and issues a normal JWT, but without any email, password, or OAuth identity attached — useful for letting a first-time visitor use an app (add items to a cart, save a draft) before committing to creating an account.

const { data, error } = await supabase.auth.signInAnonymously();

Because the anonymous session already has a stable user ID, any data it creates (rows tied to auth.uid()) carries over automatically once the user later links an email, password, or OAuth provider to that same account — there's no separate migration step needed, since it's the same underlying user row gaining a real identity rather than a new one being created.

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