I Vibe-Coded an Entire Pipeline. It Cost $14,000. AI Missed Everything.

Friday afternoon. New client. Tight deadline. I thought - let me vibe-code the whole thing. Describe what I need, let AI generate everything. Terraform modules. Kubernetes manifests. GitHub Actions. Monitoring dashboards. Tests passed. Code was clean. I deployed. Monday morning: $14,000 AWS bill. What the AI missed: The Terraform module used on-demand instances instead of spot. The auto-scaler had no maximum limit whatsoever. The monitoring stack had zero cost alerts configured. Every single thing an experienced engineer would catch in review, the AI generated incorrectly - the code worked fine - but AI optimizes for correctness, not cost. It does not know your traffic patterns. It does not know your budget. It does not know that your workload runs four hours a day and spot instances would cut the bill by 80%. The comparison is instructive. AI version: works perfectly, costs 10x. Senior engineer version: works perfectly, costs 1x. The gap is not code quality. It is judgment - knowing your on-call schedule, your compliance requirements, what is actually running in production. What changed in my workflow after this: cost constraints go in the prompt before anything else. Every…