Vercel + Supabase Debugger

Systematic diagnosis of issues in the Vercel + Supabase stack. Decision tree: symptom -> possible causes -> diagnostics -> fix.

When to Use

• Something is broken: "500 error", "not loading", "timeout", "blank page"
• Deploy failed on Vercel
• Auth not working: "can't log in", "session expired", "redirect loop"
• Data not returning from database: "empty list", "undefined", "null"
• CORS errors in console
• On demand: "debug", "diagnose", "why isn't it working"

When NOT to Use

• Problem is in a different stack (not Vercel + Supabase)
• Styling/CSS issue (that's design, not a bug)
• Feature request (wants new functionality, not a fix)