Ultracite

Ultracite Skill

Fast, zero-config linting and formatting for modern JavaScript/TypeScript projects

Overview

This skill provides comprehensive guidance for setting up, configuring, and using Ultracite—a unified linting and formatting solution with multi-provider support. Choose from Biome (default, fastest), ESLint+Prettier+Stylelint (maximum compatibility), or Oxlint+Oxfmt (type-aware linting).

Version 7 introduces multi-provider architecture, preset path migration, MCP server integration, and AI hooks. Version 6 introduced framework-specific presets for React, Next.js, Vue, Svelte, and more.

When to Use This Skill

This skill automatically triggers when you mention:

Setup & Installation Keywords

• ultracite setup
• ultracite install
• ultracite init
• install ultracite
• configure ultracite
• biome setup
• biome configuration
• zero-config linting
• fast linter setup

Framework-Specific Keywords

• ultracite react
• ultracite nextjs
• ultracite vue
• ultracite svelte
• react linting setup
• nextjs linting
• vue linting
• svelte linting
• typescript strict linting

Migration Keywords

• migrate from eslint
• migrate from prettier
• replace eslint
• replace prettier
• eslint to biome
• prettier to biome
• remove eslint
• remove prettier
• switch to ultracite
• v6 to v7 migration
• v7 upgrade
• preset path migration
• ultracite migration

Provider Selection Keywords (v7+)

• multi-provider linting
• choose linting provider
• biome vs eslint
• biome vs oxlint
• oxlint type-aware
• eslint provider
• oxlint provider
• provider selection
• linter flag

Git Hooks Keywords

• ultracite husky
• ultracite lefthook
• ultracite lint-staged
• pre-commit formatting
• git hook linting
• format on commit
• lint before commit
• husky integration
• lefthook setup

AI Editor Integration Keywords

• ultracite cursor
• ultracite claude code
• cursor rules linting
• claude code formatting
• copilot instructions
• AI coding rules
• auto-format after AI edit
• editor hooks ultracite
• ai hooks ultracite
• mcp server ultracite
• model context protocol
• ultracite mcp integration
• ai assistant integration

Configuration Keywords

• biome.jsonc
• customize ultracite rules
• ultracite presets
• ultracite configuration
• disable ultracite rules
• ultracite formatting options
• strict typescript linting

Monorepo Keywords

• ultracite monorepo
• ultracite turborepo
• monorepo linting
• turborepo formatting
• monorepo biome setup

Troubleshooting Keywords

• ultracite not working
• biome not formatting
• ultracite errors
• format on save not working
• duplicate lint errors
• ultracite parse errors
• pre-commit hook failing
• typescript strict errors
• strictNullChecks errors

Performance & Quality Keywords

• fast linting
• rust linter
• performance linting
• code quality automation
• auto-fix linting
• format on save
• import sorting
• unused imports
• strict equality checks

What This Skill Provides

Comprehensive Coverage

• Installation: Bun (preferred), npm, pnpm, yarn setups
• Configuration: biome.jsonc setup, framework presets, rule customization
• Framework Presets: React, Next.js, Vue, Svelte, Solid, Angular, Remix
• Git Hooks: Husky, Lefthook, lint-staged integrations
• AI Editor Rules: Cursor, Claude Code, Copilot, Windsurf, Cline, Zed
• Editor Hooks: Auto-format after AI edits
• Monorepo Support: Turborepo, Nx, Lerna configurations
• Migrations: Step-by-step guides from ESLint, Prettier, or Biome
• Troubleshooting: Solutions for common issues and known limitations

Project Suitability Assessment

The skill automatically:

• Scans your project for existing linting tools (ESLint, Prettier, Biome)
• Identifies your framework (React, Next.js, Vue, etc.)
• Detects existing Git hook managers
• Recommends whether Ultracite is suitable for your project
• Warns about potential limitations or conflicts

Smart Integration

• Checks for existing Git hook managers before installing new ones
• Asks user preference when multiple options available
• Preserves existing configurations when merging
• Provides framework-specific recommendations

Key Features

🚀 Performance

• 10-100x faster than ESLint + Prettier (Rust vs JavaScript)
• Instant feedback on save
• Optimized for large codebases and monorepos

🎯 Zero Configuration

• 200+ preconfigured rules out of the box
• Framework-specific presets available
• Sensible defaults for modern TypeScript development

🔧 Unified Tooling

• Replaces both ESLint and Prettier
• Single tool for linting + formatting
• Consistent rules across entire codebase

🤖 AI Integration

• Built-in support for Cursor, Claude Code, GitHub Copilot
• Editor-specific rule files
• Auto-format after AI edits via hooks

✅ Type Safety

• Enforces TypeScript strict mode
• Comprehensive null/undefined handling
• Discourages any types

🌐 Framework Support

• React (JSX, Hooks, Components)
• Next.js (Image optimization, App Router)
• Vue (SFC, composables, reactivity)
• Svelte (reactive declarations, component structure)
• And more...

Quick Start

# Using Bun (recommended)
bun x ultracite init

# v7: Choose provider explicitly
bun x ultracite init --linter biome   # Default (fastest)
bun x ultracite init --linter eslint  # Maximum compatibility
bun x ultracite init --linter oxlint  # Type-aware linting

# Using npm
npx ultracite init

# Using pnpm
pnpm dlx ultracite init

# Using yarn
yarn dlx ultracite init

The interactive setup will guide you through:

1. Provider selection (Biome, ESLint, Oxlint) - v7+ only
2. Framework selection (React, Next.js, Vue, etc.)
3. Editor integration (VS Code, Cursor, etc.)
4. AI agent rules (Cursor, Claude Code, Copilot)
5. Git hooks (Husky, Lefthook, lint-staged)
6. Migration from existing tools (ESLint, Prettier)

Interactive Features

This skill provides interactive commands and autonomous agents to streamline your Ultracite workflow.

Commands

/ultracite:doctor

Validate your Ultracite project setup and configuration.

What it checks:

• Installation status (ultracite, @biomejs/biome versions)
• Configuration syntax (biome.jsonc validation)
• Preset paths (v6 vs v7 detection)
• Conflicting tools (ESLint, Prettier remnants)
• Environment compatibility (Node.js version)
• Performance optimization opportunities

Example output:

✅ Ultracite installed: v7.2.0
✅ Provider: Biome (optimal for your project size)
⚠️ Preset paths: Using v6 paths (upgrade to v7)
  → Run /ultracite:migrate to fix
✅ No conflicting tools
✅ Node.js: v20.10.0

When to use: After installation, before deployment, when experiencing issues, after version upgrades.

/ultracite:migrate

Interactive migration wizard for ESLint/Prettier to Ultracite or v6→v7 preset path upgrades.

What it does:

• Scans existing ESLint/Prettier configurations
• Maps rules to Biome equivalents (with gap analysis)
• Generates biome.jsonc with comments for unmapped rules
• Backs up old configurations to .backup/
• Validates new configuration
• Provides rollback instructions

Supports:

• ESLint → Ultracite/Biome
• Prettier → Ultracite/Biome
• ESLint + Prettier → Ultracite/Biome (combined)
• Ultracite v6 → v7 (preset path upgrade)

Example output:

✅ Mapped: 38 rules (84%)
⚠️ No equivalent: 7 rules (16%)
✅ Generated biome.jsonc
✅ Backed up old configs to .backup/
→ Next: npx ultracite check --write .

When to use: Migrating from ESLint/Prettier, upgrading from v6 to v7, consolidating tools.

Agents

config-validator

Analyzes biome.jsonc configurations and provides optimization recommendations.

Triggers on:

• "is my ultracite config correct?"
• "validate my biome configuration"
• "check my ultracite setup"
• "optimize my biome config"

Analysis phases:

1. Syntax validation (JSON/JSONC parsing)
2. Preset path validation (v6 vs v7 detection)
3. Rule conflict analysis (redundant/incompatible rules)
4. Performance analysis (file count, ignore patterns)
5. Compatibility check (Node.js, TypeScript versions)

Example output:

⚠️ Using v6 preset paths (upgrade recommended)
⚠️ 2 redundant rules detected
✅ Project size: ~350 files (Biome optimal)
✅ Compatibility: Node.js v20.10.0

When to use: After configuration changes, before production deployment, when troubleshooting.

migration-assistant

Guides ESLint/Prettier migrations with comprehensive rule mapping.

Triggers on:

• "migrate from eslint"
• "switch to ultracite from prettier"
• "convert eslint config to ultracite"
• "upgrade ultracite v6 to v7"

Capabilities:

• ESLint rule mapping database (38+ common rules)
• Prettier formatter option mapping
• Framework detection (React, Next.js, Vue, Svelte)
• Gap analysis with workarounds
• Backup strategy with rollback instructions
• Validation testing and comparison

Example output:

✅ Mapped: 38 rules (84%)
❌ No equivalent: @typescript-eslint/no-floating-promises
   → Use Oxlint provider (type-aware linting)
✅ Generated biome.jsonc with React preset
✅ All Prettier options mapped to Biome formatter

When to use: Planning migrations, comparing ESLint vs Biome, evaluating migration complexity.

Common Use Cases

Starting a New Project

bun x ultracite init --frameworks react --editors vscode --agents cursor

Migrating from ESLint + Prettier

npx ultracite init --migrate eslint,prettier --integrations husky

Monorepo Setup

# From repo root
bun x ultracite init --frameworks react,next

Adding Git Hooks to Existing Project

npx ultracite init --integrations lefthook

What Gets Installed

The skill covers installation of:

• ultracite package
• @biomejs/biome (underlying Rust toolchain)
• Framework presets (automatically based on selection)
• Git hook managers (optional: Husky, Lefthook, lint-staged)
• Editor configurations (VS Code settings, Biome extension)
• AI agent rules files (Cursor, Claude Code, etc.)

Configuration Files Created

• biome.jsonc - Main Ultracite configuration
• .vscode/settings.json - VS Code integration
• .cursor/rules/ultracite.mdc - Cursor AI rules (optional)
• .claude/CLAUDE.md - Claude Code rules (optional)
• .github/copilot-instructions.md - Copilot instructions (optional)
• .husky/pre-commit - Husky pre-commit hook (optional)
• lefthook.yml - Lefthook configuration (optional)
• .lintstagedrc.json - lint-staged configuration (optional)

Templates & Examples

The skill includes:

Installation Scripts

• scripts/install-ultracite.sh - Automated Ultracite setup
• scripts/migrate-to-ultracite.sh - Migration from ESLint/Prettier

Example Configurations

• references/biome.jsonc.react.example - React project config
• references/biome.jsonc.nextjs.example - Next.js project config
• references/biome.jsonc.vue.example - Vue project config
• references/biome.jsonc.svelte.example - Svelte project config
• references/biome.jsonc.monorepo.example - Monorepo config
• references/lefthook.yml.example - Lefthook setup
• references/lint-staged.config.example - lint-staged setup

Package Managers Supported

Primary (Recommended):

• Bun - Fastest installation and execution

Alternatives:

• npm - Universal compatibility
• pnpm - Efficient disk usage
• yarn - Classic or Berry

All examples in this skill provide commands for each package manager.

Documentation Included

The skill provides detailed guidance from:

• Introduction & Core Concepts
• Setup & Installation
• Configuration & Customization
• Framework-Specific Presets
• Git Hook Integrations
• AI Editor Rules & Hooks
• Monorepo Support
• Migration Guides (ESLint, Prettier, Biome)
• CLI Usage & Commands
• Troubleshooting & Known Limitations
• Best Practices

Benefits Over Manual Setup

Without This Skill

• 30+ minutes reading documentation
• Trial and error with configurations
• Missing framework-specific optimizations
• Potential conflicts with existing tools
• Unclear migration paths
• Unknown limitations discovered late

With This Skill

• Instant project suitability assessment
• Framework-specific recommendations
• Automatic conflict detection
• Step-by-step migration guides
• Known limitations documented upfront
• Best practices built-in

Known Limitations

The skill documents important limitations:

• CSS linting is basic (Stylelint recommended for CSS-heavy projects)
• Some ESLint plugins have no Biome equivalent
• Limited framework support (Angular, Ember)
• SCSS/Less/Stylus have limited linting

Getting Help

If you encounter issues:

1. Use the troubleshooting section in SKILL.md
2. Check the FAQ (common questions answered)
3. Review known limitations
4. Consult official docs: https://www.ultracite.ai

Production Ready

This skill is production-tested and includes:

• ✅ Official Ultracite documentation (verified 2025-11-11)
• ✅ All package versions current
• ✅ Framework-specific configurations tested
• ✅ Git hook integrations verified
• ✅ Migration paths validated
• ✅ Known issues documented with solutions
• ✅ Monorepo support confirmed

Version Information

Skill Version: 2.0.0 (updated for v7) Last Updated: 2026-01-18 Ultracite Version: v7.0+ (multi-provider support) Biome Version: >=1.9.0 ESLint Version: >=8.0.0 (when using ESLint provider) Oxlint Version: >=0.1.0 (when using Oxlint provider) Node.js Required: v14.18+ (v18+ recommended)

Version 7 Changes (2025-11)

• Multi-provider architecture (Biome, ESLint, Oxlint)
• Preset path migration (ultracite/core → ultracite/biome/core)
• MCP server integration for AI assistants
• AI hooks (auto-format after AI edits)
• Type-aware linting (Oxlint provider)
• ultracite doctor diagnostic command

Version 6 Changes (2025-09)

• Framework-specific presets introduced
• React, Next.js, Vue, Svelte, Solid, Qwik, Angular, Remix, Astro support

Auto-Trigger Keywords Summary

This skill will automatically activate when you mention any of these topics:

• Ultracite, Biome, Oxlint, ESLint multi-provider linting
• Provider selection (Biome vs ESLint vs Oxlint)
• Framework linting (React, Next.js, Vue, Svelte)
• Migration from ESLint or Prettier
• v6 to v7 migration, preset path migration
• MCP server integration, Model Context Protocol
• AI hooks, auto-format after AI edits
• Type-aware linting (Oxlint)
• Git hooks (Husky, Lefthook, lint-staged)
• AI editor integration (Cursor, Claude Code, Copilot)
• Monorepo linting (Turborepo)
• Code quality automation
• TypeScript strict mode
• Fast Rust linting
• Zero-config setup
• Troubleshooting linting issues
• ultracite doctor diagnostic command

Simply ask about any of these topics, and this skill will provide comprehensive, step-by-step guidance tailored to your project.