Prototyping

Prototyping

A prototype answers one question and dies. Its only job is to turn an uncertainty into a fact cheaply — the code is disposable; the answer is what you keep.

When to use

• A specific question is uncertain and faster to build than to argue: does this algorithm work, does this layout read, does this library do what its docs claim.
• Reached from feasibility-check (a killer risk) or ui-ux-design (a layout choice).
• Skip when you already know the answer, or the question is vague — a prototype that answers the wrong question is pure waste.

Step 1: Pre-register

1. Write one question, the falsifiable pass/fail observation, the time-box and size-box, and what decision each result changes. Vague → do not build.
2. Name the workspace and artifacts this probe owns, its environment, the data class it touches. Prefer isolated synthetic data.
3. Bind disposal before building: allowed access and effects, evidence retention, exact cleanup targets and their recoverability, cleanup owner, current authority for creating and removing.
4. Production-like data, real services, live traffic, running systems, destructive cleanup → explicit authorization each, protections proportional to risk.

Step 2: Build and observe

1. Build the smallest disposable probe: driver, fixtures, instrumentation only. No reusable abstraction, production integration, or generality.
2. Logic → a tiny driver or executable assertion on the uncertain behavior. UI → only the structurally different populated variants the registered question needs.
3. Stop at the declared boundary. Record raw observations, environment, limitations, and passed / failed / inconclusive against the predeclared criterion. Never move the threshold after seeing the result.

Step 3: Retain the result, dispose of the code

1. Store question, evidence, and decision durably. Load-bearing choice settled → invoke architecture-decisions.
2. Rebuild accepted behavior in the real code under its normal tests, review, and verification gates. Never lift prototype code.
3. Remove only pre-registered scratch artifacts inside the disposable boundary, under current authority for those exact targets. Repository branch, worktree, ref, or workspace disposal → finishing-a-branch. External or destructive cleanup → its own current scoped choice. Otherwise preserve and report cleanup pending.
4. Never delete pre-existing, shared, user-owned, or ownership-uncertain state.

Common mistakes

• No written question — you can't tell when you're done, and the code becomes "real" by accident.
• Building production-grade tests or generality instead of the smallest executable observation.
• Variants that differ only in colour — that's a tweak, not an answer.
• Quietly probing a real service or sensitive data because “it is only a spike.”
• Keeping or copying the prototype “as a base” — rebuild the learned behavior under the product's real gates.