Vibe Coding vs Spec Coding: Same Refund Feature, Built Twice

Short summary

Vibe coding—prompting AI without specifications—produced a refund feature with 4 production bugs requiring 2 weeks of emergency patching. Spec coding—writing comprehensive specifications upfront—prevented all bugs by enforcing concurrency control, idempotency, state machines, and retry logic. Code quality depends on input specification quality, not the AI tool itself.

• •Vibe coding appears fast (10 min) but creates technical debt: one real refund feature needed 4 production patches over 2 weeks
• •Spec coding requires upfront investment (90 min) but pre-handles concurrency, state management, and idempotency—eliminating entire bug categories
• •AI output quality is driven by input constraints and specification detail, not tool capability

Generated with AI, which can make mistakes.