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fix(auth): signup no longer falsely says "already registered" #12

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Merged
ralyodio merged 1 commit into from
Jun 12, 2026
Merged

fix(auth): signup no longer falsely says "already registered" #12

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22 changes: 7 additions & 15 deletions apps/web/src/app/api/auth/signup/route.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,22 +15,14 @@ export async function POST(req: NextRequest) {

if (error) return Response.json({ error: error.message }, { status: 400 });

// Supabase obfuscates an already-registered email when confirmations are on:
// it returns no error, no session, and either a null user or a user with
// empty identities. (A real new signup that returns a session is fine.)
const alreadyRegistered = !data.session && (!data.user || (data.user.identities?.length ?? 0) === 0);
if (alreadyRegistered) {
console.warn(`[auth] signup obfuscated/no-user for ${email} — likely already registered (session=${!!data.session})`);
return Response.json(
{ error: 'This email is already registered. Sign in instead, or use “forgot password”. If you never confirmed your email, request a new confirmation link.' },
{ status: 409 },
);
}

if (!data.user) return Response.json({ error: 'no user returned' }, { status: 500 });

// With email confirmation enabled, Supabase deliberately returns an IDENTICAL
// response for a brand-new email and an already-registered one — no error, no
// session, and (via supabase-js) a null user — to prevent email enumeration.
// We therefore can't (and must not) tell the user "already registered"; we
// just report that a confirmation email is on its way. If a session IS present
// (confirmation disabled), the user is signed in immediately.
const payload = {
user: { id: data.user.id, email: data.user.email },
user: data.user ? { id: data.user.id, email: data.user.email } : null,
session: data.session && {
access_token: data.session.access_token,
refresh_token: data.session.refresh_token,
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