Add size-limit for small libraries with GitHub Actions

[yamcodes]

📋 Summary

Add size-limit to track and enforce bundle size limits for the arkenv package. This will help prevent bundle size regressions and maintain the library's small footprint.

📊 Current Bundle Sizes

Based on gzipped sizes of the current build:

• ESM (dist/index.js): 2,015 bytes (1.97 KB)
• CJS (dist/index.cjs): 2,446 bytes (2.39 KB)

🎯 Proposed Limits

Set limits to current size + 1KB:

• ESM (dist/index.js): 3,039 bytes (≈ 3.0 KB)
• CJS (dist/index.cjs): 3,470 bytes (≈ 3.4 KB)

🔧 Implementation Steps

1. Install Dependencies

Add size-limit and the preset for small libraries:

pnpm add -D size-limit @size-limit/preset-small-lib --filter=arkenv

2. Configure size-limit

Add size-limit configuration to packages/arkenv/package.json:

{
  "size-limit": [
    {
      "path": "dist/index.js",
      "limit": "3.0 KB"
    },
    {
      "path": "dist/index.cjs",
      "limit": "3.4 KB"
    }
  ]
}

3. Add size Script

Add the size script to packages/arkenv/package.json:

{
  "scripts": {
    "size": "size-limit"
  }
}

4. Create GitHub Actions Workflow

Create .github/workflows/size-limit.yml:

name: size-limit

on:
  pull_request:
    branches: [main]

jobs:
  size:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - uses: pnpm/action-setup@v4
      - uses: actions/setup-node@v6
        with:
          node-version: lts/*
          cache: pnpm
      - run: pnpm install
      - run: pnpm run build --filter=arkenv
      - uses: andresz1/size-limit-action@v1
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}
          skip_step: build
          build_script: build
          package_manager: pnpm
          directory: packages/arkenv

5. Update Test Suite (Optional)

Consider adding size check to the test suite:

{
  "scripts": {
    "test": "vitest && pnpm run size"
  }
}

📚 References

• size-limit documentation
• @size-limit/preset-small-lib
• size-limit GitHub Action

✅ Acceptance Criteria

• size-limit installed and configured
• Size limits set to current size + 1KB for both ESM and CJS builds
• GitHub Actions workflow created and working
• Size check runs on pull requests
• Size limit comments appear on PRs when limits are exceeded
• Documentation updated (if needed)

🎨 Additional Notes

• The preset @size-limit/preset-small-lib uses esbuild and file plugins, which is perfect for small libraries
• Size-limit will use Brotli compression by default (which matches our current gzipped measurements)
• The GitHub Action will automatically comment on PRs with size information and reject if limits are exceeded