prototype: Answer Questions With Throwaway Code

Install this skill:

npx skills add mattpocock/skills skill=prototype -y -g

Source: mattpocock/skills/prototype

What it does

/prototype builds throwaway code to answer a question before you commit to a direction.

The important bit is that the question chooses the shape of the prototype.

If you need to understand logic or state, it builds a small runnable terminal app. If you need to understand UI, it creates a few visible variations you can switch between.

When to use it

Use /prototype when talking about the plan is not enough.

Good signs:

you cannot tell if an interaction will feel right
a state model is hard to reason about on paper
a prompt, flow, or UI needs to be seen before you can decide
the team is debating an abstract choice that a tiny demo could settle

The prototype is not the product. It is a flashlight.

The two branches

/prototype has two main branches:

Logic prototype: a tiny interactive terminal app for state machines, reducers, business rules, or data flow questions.
UI prototype: several visual variations on one route, usually switchable with a URL parameter or small control.

Picking the wrong branch wastes the exercise. The skill starts by identifying the question it is trying to answer.

Rules for good prototypes

A good prototype is:

clearly marked as throwaway
easy to run with one command
local and temporary by default
light on polish
explicit about state
deleted or absorbed once it has answered the question

Do not leave prototypes rotting in the repo. Keep the answer, not the scaffolding.

How it fits the workflow

/grill-with-docs -> /handoff to /prototype -> iterate -> /handoff back -> /to-prd -> /to-issues

Use /prototype after /grill-with-docs exposes a question that words cannot answer.

Once the prototype answers the question, capture the answer somewhere durable, then return to the planning thread.

Pairs well with

/grill-with-docs, to surface the question that needs a prototype
/handoff, to move context into and out of the prototype session
/to-prd, to capture the resolved direction after the prototype answers the question