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christofferbergjchristofferbergj/agent-skills/skills/planning/design-prototype/SKILL.md

design-prototype

Skill1 starsChanged 23 days agoMITView on GitHub

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.

5 other projects use a version of this.

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The file

We split this skill into the rules it gives an agent

2 rules. 0 are common, 2 are distinctive, and 0 are very specific to this project.

  • 0

    Common

    Most of the 5 edited versions we read keep these.

  • 2

    Distinctive

    This author's own choices. Worth a look.

  • 0

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Skip the polish: No tests, no error handling beyond what makes the prototype _runnable_, no abstractions.

    line 26
  2. Distinctive:

    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 …

    line 27

“Common” is measured: kept by at least 6 in 10 of the 5 edited versions of this file we could read. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Invoke /domain-modeling to resolve and read the project's configured artifacts; persist accepted model changes through that owner only when this task authorizes edits. Use /swarm for any delegated work with the actual host schema, isolated writers, and disclosed fallback.

Prototype

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

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.

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. Record the question, observed answer, and remaining uncertainty. Reconcile accepted model changes through /domain-modeling. Keep the prototype as a labeled primary source in the project's chosen scratch location or an authorized throwaway branch, and link it from the implementation artifact. Fold a decision into production code only when implementation is in scope; publishing a branch or issue comment follows the existing grant. The main branch keeps only the validated decision.

Complete when the selected branch produces a runnable artifact, its relevant state is visible, and the design question has an observed answer or explicit uncertainty with a durable pointer.

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