bundle_size.yml

name: Check bundle size

on:
  pull_request:

jobs:
  size:
    if: ${{ github.repository == 'primer/brand' }}
    name: Report bundle size
    runs-on: ubuntu-latest
    steps:
      - name: Checkout PR branch
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Create main branch worktree
        run: git worktree add /tmp/main ${{ github.event.pull_request.base.sha }}

      - name: Set up Node
        uses: actions/setup-node@v4
        with:
          node-version: 24

      - name: Caching dependencies
        uses: actions/cache@v4
        with:
          path: ~/.npm
          key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
          restore-keys: |
            ${{ runner.os }}-node-

      - name: Install and build (PR)
        run: |
          npm ci
          npm run build:lib

      - name: Measure bundle size (PR)
        run: npx size-limit --json > /tmp/pr-sizes.json

      - name: Install and build (main branch)
        working-directory: /tmp/main
        run: |
          npm ci
          cp ${{ github.workspace }}/.size-limit.js .size-limit.js
          npm run build:lib || true

      - name: Measure bundle size (main branch)
        working-directory: /tmp/main
        run: npx size-limit --json > /tmp/main-sizes.json 2>/dev/null || echo "[]" > /tmp/main-sizes.json

      - name: Generate size report
        id: size-report
        run: |
          REPORT=$(node packages/repo-configs/scripts/bundle-size-report.js /tmp/pr-sizes.json /tmp/main-sizes.json)
          echo "comment-body<<EOF" >> "$GITHUB_OUTPUT"
          echo "$REPORT" >> "$GITHUB_OUTPUT"
          echo "EOF" >> "$GITHUB_OUTPUT"

      - name: Add or update bundle size comment
        uses: phulsechinmay/rewritable-pr-comment@v0.3.0
        with:
          message: ${{ steps.size-report.outputs.comment-body }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          COMMENT_IDENTIFIER: 'bundle-size-report'