v0 supabase builds the UI — you still need the backend

v0 supabase shipped a beautiful interface in minutes — then login failed, saves vanished, and the live site had no backend behind the facade.

v0 excels at components and flows. You described a dashboard or auth screen. It generated React, shadcn patterns, and Supabase client calls. Deploy to Vercel looked like launch day. Users sign up and data never appears. Console shows 401 or RLS errors. The UI is real. The backend contract — project, policies, URLs, env — is still your job.

What you see when v0 supabase stops at the frontend

Failures look like backend misconfig, not bad CSS.

• Forms submit, lists stay empty after reload. Inserts blocked by RLS or wrong project keys.
• Auth modal works once, session dies on refresh. Site URL still localhost.
• Console: Invalid API key or JWT. Env vars missing on Vercel Production.
• Anyone can read all rows. Tables created without ENABLE ROW LEVEL SECURITY.
• Preview in v0 fine, Vercel broken. Different origins, same missing dashboard updates.
• Two Supabase projects. v0 linked one; deploy env points at another empty project.

Auth-specific loops belong in supabase auth. The full publish checklist mirrors lovable deploy — v0 is another UI generator hitting the same last-mile wall.

Why v0 supabase does not finish the backend

v0 optimizes for visual output and plausible client code. It can reference Supabase SDK methods and even paste anon keys into examples. It does not log into your Supabase dashboard to enable RLS, add redirect URLs, or create production policies.

Generated code assumes a project exists with matching schema. If tables are missing, the AI may invent migration SQL you still must run in SQL Editor or CLI. Demo rows in prompts are not your users table.

Deploy platforms strip secrets. v0 → Vercel export ships components, not your Supabase dashboard state. Site URL defaults remain localhost until you change them.

OAuth providers need manual registration. Google Cloud does not learn your new Vercel URL from a v0 chat message.

Expecting v0 to “handle Supabase” end-to-end confuses UI generation with infrastructure setup. Both are required; only one is automated.

v0 iterations tempt you to polish animations while auth URLs stay wrong. Users notice empty tables, not hover states. Ship backend wiring first on a plain Vercel URL. Add custom domain and UI polish after insert and login survive reload.

Server Components and route handlers in Next exports need the same env discipline as Vite apps. v0 may generate API routes that read secrets — those names must exist in Vercel Production, not only in the v0 preview sandbox.

Wire v0 supabase to production step by step

1. Create or open Supabase project. One project for preview and production unless you deliberately split environments.
2. Run schema from v0 output. Execute SQL for tables and types in Supabase SQL Editor. Confirm tables exist in Table Editor.
3. Enable RLS on every user data table. Add select/insert/update policies tied to auth.uid().
4. Copy URL and anon key to Vercel Production env. Use exact names v0 generated: NEXT_PUBLIC_SUPABASE_URL, etc.
5. Set Site URL and Redirect URLs. Add Vercel production URL, preview URLs, localhost. Match paths your callback route uses.
6. Configure auth providers. Google/GitHub OAuth clients must list Supabase callback URI.
7. Deploy and test in private window. Sign up, insert row, reload page. Row must persist.
8. Add custom domain last. Update Supabase URLs again when domain goes live.

Do not ship service role keys in client bundles v0 generated. Move privileged operations to server routes with secrets only on the host.

Storage buckets and realtime channels follow the same gap as tables. v0 may generate upload UI without storage policies. Create buckets in Supabase, restrict public access, and test file upload on the Vercel URL before you call storage done.

Edge functions and server actions still need CORS and auth aligned with your live origin. A component that called Supabase directly in preview may need a server wrapper in production to hide secrets.

Seed data in v0 prompts is not production data. Delete demo rows before launch. Run migrations in order: extensions, tables, RLS, then policies. Skipping order produces tables that exist but reject every client call.

Match Supabase project region to your Vercel region when latency matters. v0 does not choose for you. Cross-region adds round trips that feel like “Supabase broken” on first load.

Checklist before you call v0 supabase live

• Supabase project has all tables v0 code references
• RLS enabled with policies tested via anon key
• Production env vars set on Vercel or host
• Site URL matches live origin
• Redirect URLs include deploy and preview hosts
• OAuth providers updated if used
• Sign-up and one insert survive page reload on live URL
• No service role key in client-side code

FAQ

Does v0 supabase include a working database?

v0 generates UI and client code that calls Supabase APIs. You must create or link a Supabase project, run migrations, enable RLS, and set URL configuration. The chat does not provision production backend for you.

Why does v0 supabase work in preview but not on Vercel?

Preview may use embedded or example keys. Vercel production needs every VITE_ or NEXT_PUBLIC_ var plus server secrets. Site URL and Redirect URLs must list your live domain.

What should I set up first for v0 supabase?

Create the Supabase project, copy URL and anon key into host env, enable RLS on user tables, set Site URL to your deploy origin, then redeploy. Test insert and login before sharing the URL.