front-end-rule

front-end-rule is a cursor rule for Cursor from vinhnx/vtchat. It costs 528 tokens per session, scanned A, original, MIT.

A frontend setup rule for serving HTML, React, JavaScript, TypeScript, CSS, and Tailwind through Bun. Bun is a JavaScript runtime and toolchain; the rule specifically uses its built-in server and HTML imports instead of Vite.

In plain words
What is it for?
Use it when wiring a Bun-served frontend, importing React or styles from HTML, adding API routes, or enabling development features such as hot reloading.
Why use it?
It prevents different build and server approaches from being mixed in the same project.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Use it when wiring a Bun-served frontend, importing React or styles from HTML, adding API routes, or enabling development features such as hot reloading.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/vinhnx/vtchat/front-end-rule
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.

Clone the repo
git clone --depth 1 https://github.com/vinhnx/vtchat

Made for: Cursor.

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 front-end-rule

README.md
[![agentmods](https://agentmods.dev/badge/rules/vinhnx/vtchat/front-end-rule/github.svg)](https://agentmods.dev/rules/vinhnx/vtchat/front-end-rule)
Your own site
<a href="https://agentmods.dev/rules/vinhnx/vtchat/front-end-rule"><img src="https://agentmods.dev/badge/rules/vinhnx/vtchat/front-end-rule/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 front-end-rule

Your own site · 80×15
<a href="https://agentmods.dev/rules/vinhnx/vtchat/front-end-rule"><img src="https://agentmods.dev/badge/rules/vinhnx/vtchat/front-end-rule.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 528 This file is loaded in full into every session.
When invoked 528 The same file — it is already loaded in full.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00528 $0.00528
Opus 5.5 $0.00211 $0.00211
Sonnet 5.5 $0.00106 $0.00106
Haiku 4.5 $0.00053 $0.00053

Measured today against content hash 410f7603086a, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

front-end-rule 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 today.

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.

.cursor/rules/front-end-rule.mdc · 92 lines

What it actually says

Frontend

Use HTML imports with Bun.serve(). Don't use vite. HTML imports fully support React, CSS, Tailwind.

Server:

import index from "./index.html"

Bun.serve({
  routes: {
    "/": index,
    "/api/users/:id": {
      GET: (req) => {
        return new Response(JSON.stringify({ id: req.params.id }));
      },
    },
  },
  // optional websocket support
  websocket: {
    open: (ws) => {
      ws.send("Hello, world!");
    },
    message: (ws, message) => {
      ws.send(message);
    },
    close: (ws) => {
      // handle close
    }
  },
  development: {
    hmr: true,
    console: true,
  }
})

HTML files can import .tsx, .jsx or .js files directly and Bun's bundler will transpile & bundle automatically. <link> tags can point to stylesheets and Bun's CSS bundler will bundle.

<html>
  <body>
    <h1>Hello, world!</h1>
    <script type="module" src="./frontend.tsx"></script>
  </body>
</html>

With the following frontend.tsx:

import React from "react";

// import .css files directly and it works
import './index.css';

import { createRoot } from "react-dom/client";

const root = createRoot(document.body);

export default function Frontend() {
  return <h1>Hello, world!</h1>;
}

root.render(<Frontend />);

Then, run index.ts

bun --hot ./index.ts

For more information, read the Bun API docs in node_modules/bun-types/docs/**.md.

UI components

  • when try to install components, navigatete to ~/Developer/learn-by-doing/vtchat/packages/ui first, then use bunx
  • To install shadcn components, check example command: npx shadcn@latest add label
  • Use shadcn/ui components for UI elements
  • Use @repo/ui for shared UI components
  • Use lucide icons from lucide-react
  • Use Tailwind CSS for styling
  • Use clsx for conditional class names
  • Use tailwind-merge for merging Tailwind classes
  • Use framer-motion for animations
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. today First seen · 92 lines · 528 tokens per session scan A 410f7603086a

Subscribe to this mod's changes

front-end-rule is a cursor rule published in the GitHub repository vinhnx/vtchat (59 stars, last pushed 1mo ago), licensed MIT. It adds 528 tokens to every session, about $0.0021 per session on Opus 5.5. 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 2026-10-15.