A guide for using shadcn/ui, a collection of user-interface components added as source code to a project. It covers finding, adding, styling, fixing, and combining components.

Use it to add or search for components, inspect project settings and documentation, fix component issues, and compose interfaces such as dashboards or settings pages.

It helps developers reuse existing interface pieces and follow the project's component and design conventions instead of writing every control from scratch.

How Second-Inc/second configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to Second-Inc/second. 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/Second-Inc/second/main/.agents/skills/shadcn/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/Second-Inc/second

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/second-inc/second/shadcn/github.svg)](https://agentmods.dev/skills/second-inc/second/shadcn)

Your own site

<a href="https://agentmods.dev/skills/second-inc/second/shadcn"><img src="https://agentmods.dev/badge/skills/second-inc/second/shadcn/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/second-inc/second/shadcn"><img src="https://agentmods.dev/badge/skills/second-inc/second/shadcn.svg" alt="Reviewed on agentmods" width="80" 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 4,055 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 92% 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.

Model	Per session	Once invoked
Fable 5.1	$0.00090	$0.04055
Opus 5.5	$0.00036	$0.01622
Sonnet 5.5	$0.00018	$0.00811
Haiku 4.5	$0.00009	$0.00405

Measured 2mo ago against content hash 89ae3bdf17a0, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

shadcn 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 2mo 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

92% identical to shadcn — 76 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/SKILL.md · 243 lines

How it starts

The opening of the file, as written. The whole thing — 243 lines — stays where its author put it; the contents beside it link to each section on GitHub.

shadcn/ui

A framework for building ui, components and design systems. Components are added as source code to the user's project via the CLI.

IMPORTANT: Run all CLI commands using the project's package runner: npx shadcn@latest, pnpm dlx shadcn@latest, or bunx --bun shadcn@latest — based on the project's packageManager. Examples below use npx shadcn@latest but substitute the correct runner for the project.

Current Project Context

!`npx shadcn@latest info --json`

The JSON above contains the project config and installed components. Use npx shadcn@latest docs <component> to get documentation and example URLs for any component.

Principles

Use existing components first. Use npx shadcn@latest search to check registries before writing custom UI. Check community registries too.
Compose, don't reinvent. Settings page = Tabs + Card + form controls. Dashboard = Sidebar + Card + Chart + Table.
Use built-in variants before custom styles. variant="outline", size="sm", etc.
Use semantic colors. bg-primary, text-muted-foreground — never raw values like bg-blue-500.

Critical Rules

These rules are always enforced. Each links to a file with Incorrect/Correct code pairs.

Styling & Tailwind → styling.md

className for layout, not styling. Never override component colors or typography.
No space-x-* or space-y-*. Use flex with gap-*. For vertical stacks, flex flex-col gap-*.
Use size-* when width and height are equal. size-10 not w-10 h-10.
Use truncate shorthand. Not overflow-hidden text-ellipsis whitespace-nowrap.
No manual dark: color overrides. Use semantic tokens (bg-background, text-muted-foreground).
Use cn() for conditional classes. Don't write manual template literal ternaries.
No manual z-index on overlay components. Dialog, Sheet, Popover, etc. handle their own stacking.

Forms & Inputs → forms.md

Read the full file on GitHub · 243 lines

Files

What ships with it

12 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.

2mo ago First seen · 243 lines · 90 tokens per session scan A 89ae3bdf17a0

Subscribe to this mod's changes

shadcn is a skill published in the GitHub repository Second-Inc/second (79 stars, last pushed yesterday), licensed Apache-2.0. It adds 90 tokens to every session and 4,055 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 92% identical to shadcn, differing in 76 lines, and is treated as a copy.

Debugging Frontend TypeScript Writing and docs agent-management ai-agents on-prem self-hosted shadcn-ui

shadcn next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
shadcnSecond-Inc/second	Skill	79	yesterday	Apache-2.0	A	90	Claude Code, Codex
debugging-executionsn8n-io/n8n	Skill	210k	yesterday	none	A	86	Claude Code, Codex
n8n-docs-assistantn8n-io/n8n	Skill	210k	yesterday	none	A	71	Claude Code, Codex
coolify-incidentclezcoding/awesome-coolify	Skill	0	6d ago	MIT	A	32	Claude Code, Codex
coolify-diagnoseclezcoding/awesome-coolify	Skill	0	6d ago	MIT	A	32	Claude Code, Codex
systematic-debuggingThreat-Vector-Security/guardian-agent	Skill	13	1mo ago	Apache-2.0	A	25	Claude Code, Codex
system-operationsThreat-Vector-Security/guardian-agent	Skill	13	1mo ago	Apache-2.0	A	0	Claude Code, Codex

second: Skill for Claude Code