mythos: Skill for Claude Code

.agents/skills/shadcn-ui/SKILL.md

shadcn-ui is a skill for Claude Code, Codex from forbiddenlink/mythos. It costs 73 tokens per session (9,880 once invoked), scanned A, a copy of shadcn-ui, MIT.

A guide to shadcn/ui, a collection of React interface components that developers add and customize in their own project. It covers controls such as buttons, forms, dialogs, menus, tables, and notifications, with accessibility and Tailwind CSS styling.

In plain words
What is it for?
Use it when setting up shadcn/ui, adding components, building validated forms, customizing themes, or creating layouts and data displays in React or Next.js projects.
Why use it?
It gives developers established patterns for building consistent user interfaces without designing every common control from scratch.

Skill for Claude CodeCodex

Written for Claude Code: allowed-tools in frontmatter. Also seen: installed under .agents/ (shared by several agents).

This is forbiddenlink/mythos's own configuration. It tells Claude Code and Codex how to work on mythos itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mythos configures →

Reuse

Borrowing it

Nothing to install: this file belongs to forbiddenlink/mythos. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/forbiddenlink/mythos/main/.agents/skills/shadcn-ui/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/forbiddenlink/mythos

Made for: Claude Code, Codex.

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 shadcn-ui

README.md
[![agentmods](https://agentmods.dev/badge/skills/forbiddenlink/mythos/shadcn-ui/github.svg)](https://agentmods.dev/skills/forbiddenlink/mythos/shadcn-ui)
Your own site
<a href="https://agentmods.dev/skills/forbiddenlink/mythos/shadcn-ui"><img src="https://agentmods.dev/badge/skills/forbiddenlink/mythos/shadcn-ui/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for shadcn-ui

Your own site · 80×15
<a href="https://agentmods.dev/skills/forbiddenlink/mythos/shadcn-ui"><img src="https://agentmods.dev/badge/skills/forbiddenlink/mythos/shadcn-ui.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 9,880 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 86% 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 5.1 $0.00073 $0.09880
Opus 5 $0.00036 $0.04940
Sonnet 5 $0.00015 $0.01976
Haiku 4.5 $0.00007 $0.00988

Measured 8d ago against content hash f73889c829b6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

shadcn-ui 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 8d 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

86% identical to shadcn-ui — 491 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.

.agents/skills/shadcn-ui/SKILL.md · 1,617 lines

How it starts

The opening of the file, as written. The whole thing — 1,617 lines — stays where its author put it; the contents beside it link to each section on GitHub.

shadcn/ui Component Patterns

Expert guide for building accessible, customizable UI components with shadcn/ui, Radix UI, and Tailwind CSS.

Table of Contents

When to Use

  • Setting up a new project with shadcn/ui
  • Installing or configuring individual components
  • Building forms with React Hook Form and Zod validation
  • Creating accessible UI components (buttons, dialogs, dropdowns, sheets)
  • Customizing component styling with Tailwind CSS
  • Implementing design systems with shadcn/ui
  • Building Next.js applications with TypeScript
  • Creating complex layouts and data displays

Quick Start

For new projects, use the automated setup:

# Create Next.js project with shadcn/ui
npx create-next-app@latest my-app --typescript --tailwind --eslint --app
cd my-app
npx shadcn@latest init

# Install essential components
npx shadcn@latest add button input form card dialog select

For existing projects:

# Install dependencies
npm install tailwindcss-animate class-variance-authority clsx tailwind-merge lucide-react

# Initialize shadcn/ui
npx shadcn@latest init

What is shadcn/ui?

shadcn/ui is not a traditional component library or npm package. Instead:

Read the full file on GitHub · 1,617 lines

Files

What ships with it

4 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. 8d ago First seen · 1,617 lines · 73 tokens per session scan A f73889c829b6

Subscribe to this mod's changes

shadcn-ui is a skill published in the GitHub repository forbiddenlink/mythos (2 stars, last pushed today), licensed MIT. It adds 73 tokens to every session and 9,880 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 86% identical to shadcn-ui, differing in 491 lines, and is treated as a copy.

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