Signup & Email Confirmation Handle pending confirmation explicitly and exchange the email token hash for a session
Phase 17 - Supabase Authentication Volume 05 - Authentication & Security
signUp
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verifyOtp
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Phase 17 implements cookie-based Supabase Auth in Next.js. NestJS token verification remains Phase 18.
Signup is not always immediate login With email confirmation enabled, signUp can create the user while returning no active session. The UI must represent this as a pending-confirmation state rather than assuming signup always means the user is already authenticated.
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signUp()
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Error? -> generic signup failure
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No session? -> ask user to check email
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Email confirmation is part of the authentication lifecycle, not an unrelated email feature.
const { data, error } = await supabase.auth.signUp({ email, password, })
if (error) { redirect('/login?error=Unable+to+create+account') }
if (!data.session) { redirect('/login?message=Check+your+email+to+confirm+your+account') }
redirect('/account')
Confirmation endpoint The /auth/confirm route reads token_hash and type, verifies the OTP/token hash with Supabase Auth, allows the server client to persist the session cookies, then redirects to the authenticated area. Keep public signup/sign-in failures generic because auth systems may deliberately avoid exposing whether an account exists.
const { error } = await supabase.auth.verifyOtp({ type, token_hash: tokenHash, })
if (!error) return NextResponse.redirect(accountUrl)
Authentication answers who the request represents. Treating decoded or client-supplied identity as trusted is a security boundary failure.
Restate the goal of “Signup and Email Confirmation” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: credentials/session → token → verification → trusted identity → protected operation. Mark the one boundary this lesson changes.
Inspect the current repository state and record the exact files, route, table, or runtime involved. Avoid creating an abstraction before you can name the existing owner.
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
Connect the slice to TaskFlow’s phase artifact: Working TaskFlow authentication UI/session integration whose server-side checks are explicit and ready to hand tokens to NestJS.. Verify behavior from the outside as a user or API client would.
Create one controlled failure that is safe to reproduce. Predict the symptom first, capture evidence, locate the earliest broken boundary, then fix only that cause.
Close the reference and rebuild or explain the core change from memory. Record what you would monitor or test before trusting the same change in production.
const token = readBearerToken(request);
const claims = await verifier.verify(token);
request.user = {
id: claims.sub,
email: claims.email,
};Do not copy this as a finished answer. Predict what each boundary does, type the smallest useful slice, run it, then compare the result with your prediction.
Inspect whether a token exists, whether it is expired, which issuer/audience signed it, and what the API verifier expects.
Trust only verified server claims; never repair identity by accepting a client-sent user id.
Without copying the final source, create a second small scenario that applies “Signup and Email Confirmation” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Implement sign-out and prove protected routes recover to unauthenticated state.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Using service-role key in browser code
Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.Why does this responsibility live here, what input does it trust, what output proves success, and what would go wrong if another layer owned it?
If your explanation is vague, repeat the boundary trace before moving on.Close the reference. Reproduce the core idea from memory or explain the exact request/data flow aloud. Then check your diff or notes for accidental shortcuts that bypass validation, authorization, error handling, or verification earned in earlier phases.