prototype

prototype is a skill for Claude Code, Codex from toBzh30/Claude-Project-Bootstrap. It costs 90 tokens per session (721 once invoked), scanned A, a copy of prototype, MIT.

Throwaway code built to answer a design question before the real implementation is chosen. It can test application logic in a small terminal program or compare several user-interface ideas on one page.

In plain words
What is it for?
Checking a data model or state machine, or comparing different UI directions for a page or component.
Why use it?
It makes uncertain behavior or layout easier to try and evaluate before committing production code.

Skill for Claude CodeCodex

Part of the engineering-craft plugin — 9 skills shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/tobzh30/claude-project-bootstrap/prototype
Any agent
npx skills add toBzh30/Claude-Project-Bootstrap --skill prototype
Clone the repo
git clone --depth 1 https://github.com/toBzh30/Claude-Project-Bootstrap

Made for: Claude Code, Codex.

Or install engineering-craft, the plugin that ships this one along with the rest of its 9 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for prototype

README.md
[![agentmods](https://agentmods.dev/badge/skills/tobzh30/claude-project-bootstrap/prototype.svg)](https://agentmods.dev/skills/tobzh30/claude-project-bootstrap/prototype)
Your own site
<a href="https://agentmods.dev/skills/tobzh30/claude-project-bootstrap/prototype"><img src="https://agentmods.dev/badge/skills/tobzh30/claude-project-bootstrap/prototype.svg" alt="Measured on agentmods" height="20"></a>
Per session 90 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 721 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 81% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00090 $0.00721
Opus 5 $0.00045 $0.00360
Sonnet 5 $0.00018 $0.00144
Haiku 4.5 $0.00009 $0.00072

Measured 4d ago against content hash 2d6533f9484f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

prototype scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

81% identical to prototype — 13 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/engineering-craft/skills/prototype/SKILL.md · 31 lines

How it starts

The opening of the file, as written. The whole thing — 31 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Prototype

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

Pick a branch

Identify which question is being answered — from the user's prompt, the surrounding code, or by asking the user:

  • "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. If the question is genuinely ambiguous: ask the user when working interactively; inside an explicitly-initiated AFK sweep, 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. One command to run. Whatever the project's existing task runner supports — pnpm <name>, python <path>, bun <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 and then delete it.
  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. Delete or absorb when done. When the prototype has answered its question, either delete it or fold the validated decision into the real code — don't leave it rotting in the repo.

Read the full file on GitHub · 31 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 31 lines · 90 tokens per session scan A 2d6533f9484f

Subscribe to this mod's changes

prototype is a skill published in the GitHub repository toBzh30/Claude-Project-Bootstrap (3 stars, last pushed 1mo ago), licensed MIT. It adds 90 tokens to every session and 721 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 81% identical to prototype, differing in 13 lines, and is treated as a copy.

Related

Other skills, from other repositories

reverse-ui

Reverse-engineer any web application into a complete pixel-perfect reproduction kit. Extracts design tokens, DOM structure, text content, assets, and responsive screenshots across multiple pages. Use when the user asks to "reverse-engineer a UI", "extract a design system", "analyze the design of a website", or wants…

big-emotion/agent-atelier · 74 tokens

blueprint

Extract a complete specs/ directory from any frontend codebase. Covers all 12 axes needed to rebuild or migrate a frontend app. Produces 80% quality on first pass, refined to 95% through guided iteration.

big-emotion/agent-atelier · 4 tokens

validate-fidelity

Validate specs and implementations against the reverse-UI oracle. Catches drift before it ships. Use when checking if a spec accurately describes the original UI or if an implementation matches the original.

big-emotion/agent-atelier · 41 tokens

designlang-tokens

Use when styling UI for cal.com — references the extracted design system tokens instead of inventing colors, spacing, or typography.

Manavarya09/design-extract · 30 tokens

critical-code-reviewer

Rigorously review code or pull requests for correctness, security, accessibility, maintainability, tests, and edge cases. Use when users request a critical code review, want a guided walkthrough of findings, need implementer-facing feedback, or want to prepare, create, or submit a GitHub pull request review.

posit-dev/skills · 67 tokens

token-audit

Audit a design system's token definitions for naming violations, missing semantic tiers, and structural debt. This audits how tokens are defined and organised, NOT how they are consumed in code. Trigger when someone says: audit my tokens, token naming review, are my tokens consistent, token health check, review my…

murphytrueman/design-system-ops · 93 tokens