A setup skill for the `cn()` utility used to combine Tailwind CSS class names. Tailwind CSS is a styling system where classes are written in markup; this utility also provides a standard Korean currency formatter.

Use it to place or update `lib/utils.ts`, install its class-name packages, and optionally document the usage rules in `CLAUDE.md`.

It prevents slightly different utility implementations from spreading across projects and handles conflicting or conditional class names consistently.

tailwind-cn — Skill for Claude Code by rungchan2

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.

Any agent

npx skills add rungchan2/frontend-skills --skill tailwind-cn

Clone the repo

git clone --depth 1 https://github.com/rungchan2/frontend-skills

Made for: Claude Code.

Or install project-packages, the plugin that ships this one along with the rest of its 8 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/rungchan2/frontend-skills/tailwind-cn/github.svg)](https://agentmods.dev/skills/rungchan2/frontend-skills/tailwind-cn)

Your own site

<a href="https://agentmods.dev/skills/rungchan2/frontend-skills/tailwind-cn"><img src="https://agentmods.dev/badge/skills/rungchan2/frontend-skills/tailwind-cn/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/rungchan2/frontend-skills/tailwind-cn"><img src="https://agentmods.dev/badge/skills/rungchan2/frontend-skills/tailwind-cn.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 140 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 757 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 original No closer match found 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.

Model	Per session	Once invoked
Fable 5.1	$0.00140	$0.00757
Opus 5	$0.00070	$0.00378
Sonnet 5	$0.00028	$0.00151
Haiku 4.5	$0.00014	$0.00076

Measured 12d ago against content hash c6f6787c5cec, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

tailwind-cn 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 12d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (assets/utils.ts), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/project-packages/skills/tailwind-cn/SKILL.md · 69 lines

What it actually says

Tailwind cn() 유틸 표준 세팅

shadcn/ui 기반 프로젝트의 lib/utils.ts를 표준 형태로 한 번에 세팅한다.

왜 필요한가

모든 프로젝트에서 cn()은 사실상 동일하게 쓰인다. 매번 다시 짜거나 조금씩 다른 변형이 생기는 걸 막는다.
formatCurrency 같은 한국 환경 표준 포맷도 같이 박아두면, 컴포넌트에서 Intl.NumberFormat 직접 호출이 사라진다.

워크플로우

1. 위치 결정

프로젝트 루트의 tsconfig.json 또는 components.json을 확인해 alias 경로를 본다.

프로젝트 구조	파일 위치
`src/` 구조 (Next.js 표준 신규)	`src/lib/utils.ts`
루트 직접 (`app/`, `lib/`가 루트에 있음)	`lib/utils.ts`

components.json이 이미 있다면 그 안의 aliases.utils 값을 우선한다.

2. 패키지 설치

pnpm add clsx tailwind-merge
# 또는 npm install / yarn add / bun add

(이미 설치되어 있으면 건너뛴다.)

3. 파일 생성

assets/utils.ts를 결정한 위치에 그대로 복사한다.

기존 파일이 있다면:

shadcn CLI가 만든 기본 cn()만 있는 경우 → 통째로 덮어쓴다.
다른 export가 추가되어 있는 경우 → cn과 formatCurrency만 표준 버전으로 교체하고 나머지는 보존한다. 사용자에게 어떤 export가 있는지 알려주고 확인받는다.

4. 사용 패턴 안내 (CLAUDE.md 추가)

선택적으로 프로젝트 CLAUDE.md에 다음 블록을 추가:

## 스타일 유틸 사용 규칙

- 모든 className 결합은 `cn()` 사용. 직접 문자열 결합 금지.
  ```tsx
  // ✅
  <div className={cn("p-4", isActive && "bg-blue-500")} />
  // ❌
  <div className={`p-4 ${isActive ? "bg-blue-500" : ""}`} />

통화 표시는 formatCurrency 사용. 컴포넌트에서 Intl.NumberFormat 직접 호출하지 않음.


CLAUDE.md 갱신 여부는 사용자에게 물어본 뒤 진행한다 (강제하지 않음).

## 산출물

- `lib/utils.ts` (또는 `src/lib/utils.ts`)
- `package.json`에 `clsx`, `tailwind-merge` 추가
- (선택) CLAUDE.md에 사용 규칙 블록 추가

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.

12d ago First seen · 69 lines · 140 tokens per session scan A c6f6787c5cec

Subscribe to this mod's changes

tailwind-cn is a skill published in the GitHub repository rungchan2/frontend-skills (2 stars, last pushed 4mo ago), licensed Apache-2.0. It adds 140 tokens to every session and 757 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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