Why a Spec, Not Just Vibes
Vibe coding doesn't mean skipping planning. It means doing planning fast and lightly, then directing the AI to execute. A spec is the steering wheel. Without it, the AI guesses at your intent on every , and small misunderstandings compound into a mess.
A spec gives you three things:
- Shared context — you can paste it into any AI and instantly re-establish what you're building.
- A scope boundary — a written line between "in" and "out" that stops feature creep.
- A task list — buildable chunks the AI can complete one at a time.
A spec works like a funnel: it takes a wide, fuzzy idea and narrows it, step by step, into small chunks the AI can actually build.
┌─────────────────────────┐
│ IDEA │ fuzzy, one line
└───────────┬─────────────┘
▼
┌───────────────────┐
│ SPEC │ problem · scope · stories
└─────────┬─────────┘
▼
┌───────────────┐
│ TASKS │ small, ordered steps
└───────┬───────┘
▼
┌───────────┐
│ BUILD │ one chunk at a time
└───────────┘
It doesn't need to be long. One page is plenty for most projects. In fact, a spec that grows past two pages is usually a warning sign: you're either planning too far ahead or quietly expanding scope. When in doubt, cut. The parts you delete are rarely missed, and the parts you keep get sharper.