prototype

name	prototype
description	Build a throwaway prototype in the real codebase to answer one design question before production code — does this state model hold up, what should this screen look like. Trigger on "prototype this", "spike this", "quick prototype", "throwaway version", "let me try a few variants first". Not `dev-ui-design` (a standalone HTML mockup) or `dev-research` (verifying an approach).

Prototype

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

First, name the question

Write the question down in one sentence before writing any code. If you can't — or if the honest answer is "we already know, we just haven't typed it yet" — this isn't a prototype task. Building one anyway produces code with no verdict attached, which is the expensive kind of waste: it looks like progress and settles nothing.

Skip straight past this skill when:

• The answer is already known and the work is just writing it properly → build the real thing.
• The question is "which library / API / approach should we use" and it's answered by reading docs and running a small spike → dev-research.
• The question is "what should this look like" but there's no app to host it — no route, no running frontend, and the point is a shareable static mockup → dev-ui-design, which writes one self-contained docs/<feature>/prototype.html.

Pick a branch

With the question written down, it — not the file type — picks the branch:

• "Does this logic / state model feel right?" → LOGIC.md. 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?" → UI.md. Generate several radically different UI variations on a single route, switchable via a URL search param and a floating bottom bar.

The two branches produce very different artifacts — getting this wrong wastes the whole prototype. A question about what happens is logic even when it lives in a component; a question about what the user sees is UI even when the hard part is on the server.

If it's genuinely ambiguous and the user isn't reachable, default to whichever branch better matches the surrounding code (a backend module → logic; a page or component → UI) and state the assumption at the top of the prototype so the first reader can correct it cheaply.

Rules that apply to both

1. Throwaway from day one, and clearly marked as such. Locate the prototype code close to where it will actually be used (next to the module or page it's prototyping for) so context is obvious — but name it so a casual reader can see it's a prototype, not production. For throwaway UI routes, obey whatever routing convention the project already uses; don't invent a new top-level structure.
2. One command to run. Whatever the project's existing task runner supports — pnpm <name>, python <path>, go run <path>, etc. The user must be able to start it without thinking.
3. No persistence by default. State lives in memory. Persistence is the thing the prototype is checking, not something it should depend on. If the question explicitly involves a database, hit a scratch DB or a local file with a clear "PROTOTYPE — wipe me" name.
4. Skip the polish. No tests, no error handling beyond what makes the prototype runnable, no abstractions. The point is to learn something fast.
5. Surface the state. After every action (logic) or on every variant switch (UI), print or render the full relevant state so the user can see what changed.
6. Capture it when done. A prototype that ends without a written verdict was a spike the team will re-run in six months. Two separate things get captured:
   • The answer — the question and what it settled, in one short paragraph. It belongs wherever the follow-up work is tracked (the issue, the PR description, or the commit that folds the decision in). If a docs/<feature-name>/ directory already exists for this work, that's the natural home.
   • The prototype — as a primary source, on a throwaway branch out of main (prototype/<question-slug>), with a pointer to it next to the answer. Main keeps the validated decision and none of the scaffolding; the switcher, the TUI shell, and the losing variants rot fast and confuse the next reader.

Commit hygiene and message style: see the git-safe skill (no Co-authored-by:, git add -u not -A, imperative why-focused subject).