biome-linting

# Biome Linting

Fast, unified linting and formatting (10-25x faster than ESLint + Prettier).

## Why Biome in 2026

| Aspect | Biome | ESLint + Prettier |
|--------|-------|-------------------|
| Speed | ~200ms for 10k lines | 3-5s |
| Config files | 1 (biome.json) | 4+ |
| npm packages | 1 binary | 127+ |
| Rules | 421 | Varies by plugins |
| Type inference | Yes (v2.0+) | Requires tsconfig |

## Quick Start

```bash
# Install
npm install --save-dev --save-exact @biomejs/biome

# Initialize
npx @biomejs/biome init

# Check (lint + format)
npx @biomejs/biome check .

# Fix
npx @biomejs/biome check --write .

# CI mode (fails on errors)
npx @biomejs/biome ci .
```

## Biome 2.0 Features

**Type Inference**: Reads `.d.ts` from node_modules for type-aware rules:

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "noFloatingPromises": "error"  // Catches unhandled promises
      }
    }
  }
}
```

**Multi-file Analysis**: Cross-module analysis for better diagnostics.

## Basic Configuration

```json
{
  "$schema": "https://biomejs.dev/schemas/2.0.0/schema.json",
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 100
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true,
      "correctness": {
        "noUnusedVariables": "error",
        "noUnusedImports": "error"
      },
      "suspicious": {
        "noExplicitAny": "warn"
      }
    }
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single",
      "trailingCommas": "all"
    }
  }
}
```

## ESLint Migration

```bash
# Auto-migrate configuration
npx @biomejs/biome migrate eslint --write
```

**Common Rule Mappings:**
| ESLint | Biome |
|--------|-------|
| no-unused-vars | correctness/noUnusedVariables |
| no-console | suspicious/noConsole |
| @typescript-eslint/* | Most supported |
| eslint-plugin-react | Most supported |
| eslint-plugin-jsx-a11y | Most supported |

## CI Integration

```yaml
# .github/wo