ultracite

ultracite is a cursor rule for Cursor from damien-schneider/agent-skills-library. It costs 1,084 tokens per session, scanned A, original, MIT.

Project rules for Ultracite, a preset that automatically formats code and checks it for common quality problems.

In plain words
What is it for?
Use them when writing JavaScript or TypeScript to guide formatting, types, naming, loops, and other style choices.
Why use it?
They give the project consistent coding standards and provide commands for fixing, checking, or diagnosing code-quality issues.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Use them when writing JavaScript or TypeScript to guide formatting, types, naming, loops, and other style choices.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/damien-schneider/agent-skills-library/ultracite
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/damien-schneider/agent-skills-library

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 ultracite

README.md
[![agentmods](https://agentmods.dev/badge/rules/damien-schneider/agent-skills-library/ultracite/github.svg)](https://agentmods.dev/rules/damien-schneider/agent-skills-library/ultracite)
Your own site
<a href="https://agentmods.dev/rules/damien-schneider/agent-skills-library/ultracite"><img src="https://agentmods.dev/badge/rules/damien-schneider/agent-skills-library/ultracite/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 ultracite

Your own site · 80×15
<a href="https://agentmods.dev/rules/damien-schneider/agent-skills-library/ultracite"><img src="https://agentmods.dev/badge/rules/damien-schneider/agent-skills-library/ultracite.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 1,084 This file is loaded in full into every session.
When invoked 1,084 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 $0.01084 $0.01084
Opus 5 $0.00542 $0.00542
Sonnet 5 $0.00217 $0.00217
Haiku 4.5 $0.00108 $0.00108

Measured 10d ago against content hash e14e13147efb, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

ultracite 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 10d 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.

.cursor/rules/ultracite.mdc · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ultracite Code Standards

This project uses Ultracite, a zero-config preset that enforces strict code quality standards through automated formatting and linting.

Quick Reference

  • Format code: bun x ultracite fix
  • Check for issues: bun x ultracite check
  • Diagnose setup: bun x ultracite doctor

Biome (the underlying engine) provides robust linting and formatting. Most issues are automatically fixable.


Core Principles

Write code that is accessible, performant, type-safe, and maintainable. Focus on clarity and explicit intent over brevity.

Type Safety & Explicitness

  • Use explicit types for function parameters and return values when they enhance clarity
  • Prefer unknown over any when the type is genuinely unknown
  • Use const assertions (as const) for immutable values and literal types
  • Leverage TypeScript's type narrowing instead of type assertions
  • Use meaningful variable names instead of magic numbers - extract constants with descriptive names

Modern JavaScript/TypeScript

  • Use arrow functions for callbacks and short functions
  • Prefer for...of loops over .forEach() and indexed for loops
  • Use optional chaining (?.) and nullish coalescing (??) for safer property access
  • Prefer template literals over string concatenation
  • Use destructuring for object and array assignments
  • Use const by default, let only when reassignment is needed, never var

Async & Promises

  • Always await promises in async functions - don't forget to use the return value
  • Use async/await syntax instead of promise chains for better readability
  • Handle errors appropriately in async code with try-catch blocks
  • Don't use async functions as Promise executors

React & JSX

  • Use function components over class components
  • Call hooks at the top level only, never conditionally
  • Specify all dependencies in hook dependency arrays correctly
  • Use the key prop for elements in iterables (prefer unique IDs over array indices)
  • Nest children between opening and closing tags instead of passing as props
  • Don't define components inside other components
  • Use semantic HTML and ARIA attributes for accessibility:
    • Provide meaningful alt text for images
    • Use proper heading hierarchy
    • Add labels for form inputs
    • Include keyboard event handlers alongside mouse events
    • Use semantic elements (<button>, <nav>, etc.) instead of divs with roles

Read the full file on GitHub · 124 lines

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. 10d ago First seen · 124 lines · 1,084 tokens per session scan A e14e13147efb

Subscribe to this mod's changes

ultracite is a cursor rule published in the GitHub repository damien-schneider/agent-skills-library (7 stars, last pushed 16d ago), licensed MIT. It adds 1,084 tokens to every session, about $0.0054 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.