prototype

An agent skill by mattpocock, from mattpocock/skills. Tags: design, prototyping, ui-ux, validation, workflow.

What it does

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.

Install

With the skills CLI, which installs into Claude Code, Codex, Cursor and other agents:

npx skills add mattpocock/skills --skill prototype

Or copy the skill folder into Claude Code's skills directory by hand (~/.claude/skills for every project, or .claude/skills inside one):

git clone --depth 1 https://github.com/mattpocock/skills
cp -r skills/skills/engineering/prototype ~/.claude/skills/prototype

Safety box score

Grade A, minimal risk: 7 of 100 risk points, rated 2026-10-21. The grade rates what the skill and its scripts can reach on the machine of whoever installs it, across eight categories from shell execution to secrets access. How the score works.

This skill is a documentation-only prototyping guide: it tells the agent how to create throwaway logic or UI demos inside a repo, with no bundled scripts, downloads, or external services. The main risks are limited repo edits and accidental use of the wrong prototype shape (logic vs UI), not machine or account compromise.

Category levels, from 0 (none) to 3 (high)
Category	Level	Why
Code & shell execution	0 (none)	No scripts, shell commands, or code-evaluation tools are shipped; the files are plain Markdown guidance and a YAML descriptor.
Network access	0 (none)	There is no instruction to fetch remote content or send data off-machine; the skill is entirely local and file-based.
Filesystem reach	1 (low)	It directs the agent to create prototype files near the target code and to commit them to a throwaway branch, but only within the repository and without destructive paths.
Secrets & credentials	0 (none)	The skill does not ask for passwords, tokens, keychains, `.env` files, or other credentials.
Privilege & persistence	0 (none)	No sudo, global installs, services, shell startup changes, or OS-level settings are requested.
Instruction hijack surface	0 (none)	The text contains normal workflow guidance only; it does not instruct the agent to ignore higher-priority rules, hide behavior, or follow remote instructions.
Irreversible actions	1 (low)	It asks for repository actions like capturing the prototype on a throwaway branch and keeping main clean, but it does not push, deploy, message, pay, or delete external resources.
Transparency	0 (none)	All shipped content is readable Markdown/YAML; there are no binaries, generated blobs, or decoded-at-runtime payloads.

Before installing

Read `SKILL.md`, `LOGIC.md`, and `UI.md` to confirm you want throwaway prototype behavior, not production code.
Check that your project has an appropriate place for the prototype to live next to the target page/module.
If you plan to use the UI branch, verify there is an existing route or host page that can support a `?variant=` switcher.
Confirm your team is okay with no tests and no persistence for this prototype, per the skill rules.

Rated 2026-10-21 by an automated review of 4 files from the skill's repository.

Source

Repository: mattpocock/skills (all skills from this repository)
Path: skills/engineering/prototype/SKILL.md
Branch: main
Updated: 2026-10-05

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