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.
git clone --depth 1 https://github.com/TheSethRose/DevRulesWrote 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.
[](https://agentmods.dev/rules/thesethrose/devrules/shadcnui)<a href="https://agentmods.dev/rules/thesethrose/devrules/shadcnui"><img src="https://agentmods.dev/badge/rules/thesethrose/devrules/shadcnui/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.
<a href="https://agentmods.dev/rules/thesethrose/devrules/shadcnui"><img src="https://agentmods.dev/badge/rules/thesethrose/devrules/shadcnui.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00000 | $0.01768 |
| Opus 5.5 | $0.00000 | $0.00707 |
| Sonnet 5.5 | $0.00000 | $0.00354 |
| Haiku 4.5 | $0.00000 | $0.00177 |
Grade A, and why
ShadcnUI 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.
shadcn/ui Best Practices
Core Philosophy
- Component Ownership / Open Code: Understand that shadcn/ui components are copied into your project (typically
components/ui/) via the CLI, not installed as an opaque dependency. You own this code and are encouraged to customize it. - Composition: Components are designed to be composable, often built upon lower-level primitives (like Radix UI).
- Tailwind CSS Based: Styling relies heavily on Tailwind CSS utility classes.
- Accessibility: Built with accessibility primitives.
- CLI Driven: Interaction (initialization, adding components, building registries) is primarily done via the
shadcn-uiCLI.
CLI Usage
Use a package runner like npx, pnpm dlx, yarn dlx, or bunx.
init
Initializes dependencies and configuration (components.json, cn util, CSS variables) for a project.
Command:
# Example using npx
npx shadcn-ui@latest init [components...]
Usage: shadcn init [options] [components...]
Initialize your project and install dependencies.
Arguments:
components: Optional. The components to add or a URL to the component upon initialization.
Options:
-y, --yes: Skip confirmation prompt. (default: true)-d, --defaults: Use default configuration. (default: false)-f, --force: Force overwrite of existing configuration. (default: false)-c, --cwd <cwd>: The working directory. Defaults to the current directory.-s, --silent: Mute output. (default: false)--src-dir: Use the src directory when creating a new project. (default: false)--no-src-dir: Do not use the src directory when creating a new project.--css-variables: Use CSS variables for theming. (default: true)--no-css-variables: Do not use CSS variables for theming.-h, --help: Display help for command.
add
Adds components and their dependencies to your project.
Command:
# Example using npx
npx shadcn-ui@latest add <component> [component...]
Usage: shadcn add [options] [components...]
Add a component to your project.
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.
- 1mo ago First seen · 138 lines · 0 tokens per session scan A 5968acc06855
ShadcnUI is a cursor rule published in the GitHub repository TheSethRose/DevRules (26 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,768 tokens. 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 2026-08-30.
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