Comparisons
Pairs that get conflated in real conversations. Neither column wins — what decides is the situation. Each record leads with the confusion, because the confusion is the reason the record exists.
Outcome vs outputFirst version vs prototypeDecision record vs one-pagerSuccess metric vs guardrailReversible vs irreversible decisionsFeature flag vs long-lived branchNumbers vs conversationsIncident vs bug
First version vs prototype
What people get wrong about this pair
A prototype that ships to production becomes a first version with none of the engineering a first version needs; a first version built to prototype standards is the thing on-call gets paged for at 3 a.m. Decide which one you are building before the sprint, not after.
First version
Use it when
When you need real users to use a real thing so a real number can move.
Prototype
Use it when
When the question is "would anyone want this" and a clickable mock or a manual process answers it.
| Aspect | First version | Prototype |
|---|---|---|
| Goes to real users | Yes, behind a flag or to a cohort | Rarely, and never unattended |
| Engineering bar | Small but production-grade: errors, auth, observability | Whatever gets the answer fastest |
| What it answers | Does the smallest real version move the number? | Do people react the way we hope? |
| After the answer | Iterate or remove | Throw away, always |