biome

Getting Started

1. Install the skill using the command above
2. Open your AI coding agent (Claude Code, Codex, Gemini CLI, or Cursor)
3. Reference the skill in your prompt
4. The AI will use the skill's capabilities automatically

Example Prompts

• "Review the open pull requests and summarize what needs attention"
• "Generate a changelog from the last 20 commits on the main branch"

Overview

Biome is a fast all-in-one formatter and linter for JavaScript, TypeScript, JSX, JSON, and CSS that replaces ESLint and Prettier with a single tool. It offers 300+ lint rules with auto-fix, formats 10K-file monorepos in under a second, and requires minimal configuration with sensible defaults.

Instructions

• When setting up Biome, run biome init to generate biome.json with recommended defaults, then configure indentStyle, lineWidth, and quoteStyle to match team preferences.
• When running checks, use biome check for combined lint and format verification, biome check --fix for auto-fixing, and biome ci in CI pipelines for strict validation without fixes.
• When migrating from ESLint, run biome migrate eslint to automatically map ESLint rules, and biome migrate prettier to carry over formatter settings.
• When customizing rules, start with "recommended": true and disable specific rules only with documented reasons, using per-directory overrides for different rules in tests versus source.
• When integrating with editors, install the Biome VS Code extension or IntelliJ plugin for format-on-save and inline diagnostics.
• When setting up pre-commit hooks, use biome check --fix via husky or lefthook to fix issues before they reach CI.

Examples

Example 1: Replace ESLint and Prettier with Biome

User request: "Migrate my project from ESLint + Prettier to Biome"

Actions:

1. Run biome migrate eslint and biome migrate prettier to generate biome.json
2. Remove ESLint and Prettier configs, dependencies, and scripts
3. Update CI pipeline to use biome ci for combined lint and format checks
4. Configure VS Code settings to use Biome as default formatter

Output: A project using Biome as the single code quality tool, with faster checks and simpler configuration.

Example 2: Set up Biome in a monorepo with pre-commit hooks

User request: "Configure Biome for a monorepo with different rules for apps and packages"

Actions:

1. Create root biome.json with "recommended": true and shared settings
2. Add per-directory overrides for test files (relaxed rules) and packages (strict rules)
3. Set up lefthook with biome check --fix on pre-commit
4. Add biome ci to the CI pipeline with files.ignore for generated code

Output: A monorepo with consistent code quality, auto-fix on commit, and strict CI validation.

Guidelines

• Use biome ci in CI pipelines since it checks formatting and linting in one pass and fails fast.
• Start with "recommended": true and disable specific rules only with documented justification.
• Run biome migrate eslint to transition from ESLint since Biome maps most rules automatically.
• Use biome check --fix in pre-commit hooks to fix issues before they reach CI.
• Keep biome.json minimal since the defaults are well-chosen; override only what the team genuinely disagrees with.
• Enable organize imports since Biome sorts imports faster than ESLint plugins.