When Fast AI Code Meets Production Reality: Why Specs Matter More Than Speed

This article examines the gap between rapid AI-assisted code generation and production-ready software through a refund feature case study. While vibe coding delivers working features in minutes, it systematically misses critical architectural patterns—idempotency, transaction isolation, and state machines—that prevent subtle bugs from multiplying in production. The author's two-week debugging effort reveals that the real cost of skipping specification isn't lost time, but accumulated technical debt that demands far more engineering effort to remediate.