Cursor + Claude: stop shipping broken env vars

I stopped guessing why builds break. I lint env vars. I generate .env.example from code. Not docs. I validate at runtime with Zod. One error message. I run a tiny Node script in CI. Fails fast. Context I ship small SaaS apps. Usually solo. Usually fast. And I kept losing time to env vars. The worst kind of bug. Works on my machine. Fails in CI. Or only fails after deploy. Or fails only in preview. Real examples from the last month: NEXT_PUBLIC_APP_URL was missing in Vercel pre...