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prototype

skill · 26 lines · MIT · skills/engineering/prototype/SKILL.md

The facts

Its description

Build a throwaway prototype to answer a design question. Use when the user wants to sanity-check whether a state model or logic feels right, or explore what a UI should look like.

The description the agent reads to decide when to use it.

From its settingsline 3

When it starts

The agent picks this skill when the user wants to quickly sanity-check a design idea with throwaway code — either to feel out whether a state model or piece of logic behaves right, or to see a few options for what a screen should look like. The description frames it as answering a design question, not building anything real.

Things a person might say (the model's guesses)

  • “I'm not sure this state machine handles the case where a booking gets cancelled and then rebooked — can I poke at it?”
  • “Can you mock up a few really different layouts for the settings page so I can pick one?”
  • “I want to feel out what this API should look like before we write it.”

A model's summary of when it is used.

A model's reading

Files it mentions

LOGIC.md, UI.md

Files the text names, such as ones to read or write. Found by matching words, so treat them as pointers.

Found by matching wordsline 14 line 15

What leads to it

Other skills that hand off to this one, call it, require it or offer it instead, as a model read them.

A model's reading

Licence

MIT, from LICENSE

The terms its author shares it under, which let it be shown here.

From the repositorylicence text
Other files in this skill (3) Close

The text

Open on GitHub

Most marks come from matching words in the file, so treat them as pointers.

1---
2name: prototype
3description: Build a throwaway prototype to answer a design question. Use when the user wants to sanity-check whether a state model or logic feels right, or explore what a UI should look like.
4---
5
6# Prototype
7
8A prototype is **throwaway code that answers a question**. The question decides the shape.
9

Prototype

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

Raw lines 1 to 9
10## Pick a branch
12Identify which question is being answered, using the user's prompt, the surrounding code, or by asking if the user is around:
14- **"Does this logic / state model feel right?"** → [LOGIC.md](LOGIC.md). Build a single shareable HTML file (free-play buttons plus tabbed guided walkthroughs) that pushes the state machine through cases that are hard to reason about on paper, and that a non-developer can drive.
15- **"What should this look like?"** → [UI.md](UI.md). Generate several radically different UI variations on a single route, switchable via a URL search param and a floating bottom bar.
17The two branches produce very different artifacts, so getting this wrong wastes the whole prototype. If the question is 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.

Pick a branch

Identify which question is being answered, using the user's prompt, the surrounding code, or by asking if the user is around:

  • "Does this logic / state model feel right?" → LOGIC.md. Build a single shareable HTML file (free-play buttons plus tabbed guided walkthroughs) that pushes the state machine through cases that are hard to reason about on paper, and that a non-developer can drive.
  • "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, so getting this wrong wastes the whole prototype. If the question is 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.

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Reads a file LOGIC.md :14
Reads a file UI.md :15
19## Rules that apply to both
211. **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.
222. **Trivial to run.** A UI prototype starts from one command in the project's task runner: `pnpm <name>`, `python <path>`, `bun <path>`, etc. A logic demo is a single HTML file the user double-clicks. Either way, no thinking required to start it.
233. **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.
244. **Skip the polish.** No tests, no error handling beyond what makes the prototype _runnable_, no abstractions. The point is to learn something fast.
255. **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.
266. **Capture it when done.** Fold any validated decision into the real code, then capture the prototype itself as a **primary source**: commit it to a throwaway branch, out of main, and leave a context pointer to that branch on the implementation issue. Capture the answer too (the verdict and the question it settled) in the issue or a commit. The main branch keeps only the validated decision.

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. Trivial to run. A UI prototype starts from one command in the project's task runner: pnpm <name>, python <path>, bun <path>, etc. A logic demo is a single HTML file the user double-clicks. Either way, no thinking required to start it.
  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. Fold any validated decision into the real code, then capture the prototype itself as a primary source: commit it to a throwaway branch, out of main, and leave a context pointer to that branch on the implementation issue. Capture the answer too (the verdict and the question it settled) in the issue or a commit. The main branch keeps only the validated decision.
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From mattpocock/skills at 4ae2317, 2026-10-31. Skills read by DeepSeek V4.1 Flash on 2026-11-04. Summary and techniques by Claude Opus 5.5 on 2026-11-06.