Engineering

Prototype

Build a throwaway prototype to flesh out a design — a runnable terminal app for state/business-logic questions, or several radically different UI variations toggleable from one route.

by Matt PocockRepository →Source →

Prototype

A prototype is throwaway code that answers a question. The question decides the shape.

Pick a branch

Identify which question is being answered:

"Does this logic / state model feel right?" → Build a tiny interactive terminal app that pushes the state machine through cases that are hard to reason about on paper.
"What should this look like?" → Generate several radically different UI variations on a single route, switchable via a URL search param and a floating bottom bar.

Rules that apply to both

Throwaway from day one, and clearly marked as such. Locate the prototype code close to where it will actually be used.
One command to run. Whatever the project's existing task runner supports.
No persistence by default. State lives in memory.
Skip the polish. No tests, no error handling beyond what makes the prototype runnable, no abstractions.
Surface the state. After every action, print or render the full relevant state so the user can see what changed.
Delete or absorb when done. When the prototype has answered its question, either delete it or fold the validated decision into the real code.

When done

The answer is the only thing worth keeping from a prototype. Capture it somewhere durable (commit message, ADR, issue, or a NOTES.md next to the prototype) along with the question it was answering.