A METR study found experienced developers are 19% slower with AI tools on mature codebases, yet perceive themselves as 20% faster — a 39-point gap. This post introduces the 'vibe ceiling' concept and a practical decision framework for when to trust, carefully review, or rewrite AI-generated code. The framework centers on three questions (blast radius, reversibility, and junior-PR test), a green/yellow/red code-type classification system, and four hard-stop signals that indicate you should stop relying on AI output. Green code (UI, boilerplate, docs) can ship with a light scan; yellow code (data transforms, async logic, external state) needs careful review; red code (auth, payments, crypto, security) requires line-by-line reading or manual rewriting. The framework is positioned as a complement to spec-driven development and context engineering.
Table of contents
Why Experienced Developers Get Hit HardestThe Three Questions That MatterThe Code-Type Classification SystemThe Hard Signals That Tell You to Stop VibingConnecting the Framework to Spec-Driven DevelopmentRecalibrating Your ConfidenceThe Honest VersionSort: