Supabase + Next.js on Vercel Debugger

Critical: Verification Protocol

NEVER claim a fix is complete without these checks:

1. npx tsc --noEmit (zero errors)
2. npx vitest run (all pass)
3. npx next build (successful)
4. curl test against production URL (full API flow → 200)
5. Vercel runtime logs check (zero 404/500 after deploy)
6. Ask user to test in browser (curl success != browser success)

When a Supabase + Next.js app fails on Vercel, check these in order:

1. Environment Variables (Most Common)