prototype

prototype is a skill for Claude Code, Codex from rengwu/wayfinder-maps. It costs 39 tokens per session (666 once invoked), scanned A, a copy of prototype, MIT.

A skill for building temporary code that answers a specific design question. It can test how logic behaves or show different possible user interfaces.

In plain words
What is it for?
Use it to test state models and difficult cases in a small terminal program, or compare several UI ideas from one entry point.
Why use it?
It lets you explore uncertain behavior or layout before committing to production code.

Skill for Claude CodeCodex

Part of the wayfinder-maps plugin — 14 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/rengwu/wayfinder-maps/prototype
Any agent
npx skills add rengwu/wayfinder-maps --skill prototype
Clone the repo
git clone --depth 1 https://github.com/rengwu/wayfinder-maps

Made for: Claude Code, Codex.

Or install wayfinder-maps, the plugin that ships this one along with the rest of its 14 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/rengwu/wayfinder-maps/prototype.svg)](https://agentmods.dev/skills/rengwu/wayfinder-maps/prototype)
Your own site
<a href="https://agentmods.dev/skills/rengwu/wayfinder-maps/prototype"><img src="https://agentmods.dev/badge/skills/rengwu/wayfinder-maps/prototype.svg" alt="Measured on agentmods" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 666 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 83% 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 $0.00039 $0.00666
Opus 5 $0.00019 $0.00333
Sonnet 5 $0.00008 $0.00133
Haiku 4.5 $0.00004 $0.00067

Measured 5d ago against content hash 185dcce3fcb5, 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 5d 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

83% 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.

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 if the user is around:

  • "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 behind a single entry point, switchable at runtime.

The two branches produce very different artifacts — 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, screen, or view → 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 or screens, obey whatever structural 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 — make <name>, pnpm <name>, python <path>, cargo run --bin <name>, mix 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 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. 5d ago First seen · 31 lines · 39 tokens per session scan A 185dcce3fcb5

Subscribe to this mod's changes

prototype is a skill published in the GitHub repository rengwu/wayfinder-maps (115 stars, last pushed 1mo ago), licensed MIT. It adds 39 tokens to every session and 666 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 83% identical to prototype, differing in 13 lines, and is treated as a copy.

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