Biome Code Quality Tools

# Biome Code Quality Tools for Google Antigravity

Configure fast code quality tooling with Biome in your Google Antigravity IDE projects. This comprehensive guide covers linting rules, formatting options, and import organization optimized for Gemini 3 agentic development.

## Biome Configuration

Set up Biome with comprehensive rules:

```json
// biome.json
{
  "$schema": "https://biomejs.dev/schemas/1.5.0/schema.json",
  "organizeImports": {
    "enabled": true
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true,
      "complexity": {
        "noBannedTypes": "error",
        "noExtraBooleanCast": "error",
        "noUselessCatch": "error",
        "noWith": "error"
      },
      "correctness": {
        "noConstAssign": "error",
        "noConstantCondition": "warn",
        "noUnreachable": "error",
        "noUnusedVariables": "warn",
        "useIsNan": "error"
      },
      "security": {
        "noDangerouslySetInnerHtml": "warn",
        "noGlobalEval": "error"
      },
      "style": {
        "noVar": "error",
        "useConst": "error",
        "useTemplate": "error"
      },
      "suspicious": {
        "noConsoleLog": "warn",
        "noDebugger": "error",
        "noDoubleEquals": "error",
        "noExplicitAny": "warn"
      },
      "a11y": {
        "useAltText": "error",
        "useButtonType": "error",
        "useValidAnchor": "error"
      }
    }
  },
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 100,
    "lineEnding": "lf"
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single",
      "jsxQuoteStyle": "double",
      "trailingComma": "es5",
      "semicolons": "always",
      "arrowParentheses": "always",
      "bracketSpacing": true
    }
  },
  "json": {
    "formatter": {
      "enabled": true,
      "indentWidth": 2
    }
  },
  "files": {
    "ignore": [
      "node_modules",
      ".next",
      "dist",
      "build",
      "coverage"
    ]
  }
}
```

## Package Scripts

Configure npm scripts for Biome:

```json
// package.json
{
  "scripts": {
    "lint": "biome lint .",
    "lint:fix": "biome lint --apply .",
    "format": "biome format --write .",
    "format:check": "biome format .",
    "check": "biome check .",
    "check:fix": "biome check --apply .",
    "ci": "biome ci ."
  }
}
```

## VS Code Integration

Configure VS Code for Biome:

```json
// .vscode/settings.json
{
  "editor.defaultFormatter": "biomejs.biome",
  "editor.formatOnSave": true,
  "editor.codeActionsOnSave": {
    "source.organizeImports.biome": "explicit",
    "quickfix.biome": "explicit"
  },
  "[javascript]": {
    "editor.defaultFormatter": "biomejs.biome"
  },
  "[typescript]": {
    "editor.defaultFormatter": "biomejs.biome"
  },
  "[typescriptreact]": {
    "editor.defaultFormatter": "biomejs.biome"
  },
  "[json]": {
    "editor.defaultFormatter": "biomejs.biome"
  }
}
```

## Git Hooks with Lefthook

Set up pre-commit hooks:

```yaml
# lefthook.yml
pre-commit:
  parallel: true
  commands:
    biome:
      glob: "*.{js,jsx,ts,tsx,json}"
      run: npx biome check --apply {staged_files}
      stage_fixed: true
    
    typecheck:
      glob: "*.{ts,tsx}"
      run: npx tsc --noEmit
```

## CI Integration

Add Biome to CI pipeline:

```yaml
# .github/workflows/ci.yml
name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      
      - uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: npm
      
      - run: npm ci
      
      - name: Biome CI
        run: npm run ci
      
      - name: Type Check
        run: npx tsc --noEmit
```

## Rule Customization

Override rules for specific files:

```json
{
  "overrides": [
    {
      "include": ["**/*.test.ts", "**/*.spec.ts"],
      "linter": {
        "rules": {
          "suspicious": {
            "noExplicitAny": "off"
          }
        }
      }
    },
    {
      "include": ["scripts/**"],
      "linter": {
        "rules": {
          "suspicious": {
            "noConsoleLog": "off"
          }
        }
      }
    }
  ]
}
```

## Best Practices

1. **Use recommended rules** as a baseline
2. **Configure per-project overrides** as needed
3. **Enable organize imports** for consistent ordering
4. **Set up editor integration** for real-time feedback
5. **Use git hooks** for pre-commit checks
6. **Run in CI** to catch issues early
7. **Migrate from ESLint/Prettier** gradually