.github/workflows/sync-branches.yml

name: Shadow Sync

on:
  push:
    branches:
      - "**"
      - "!shadow/**"
      - "!shadow"
      # If you do NOT want shadows for these, keep them excluded:
      # - "!main"
      # - "!master"
  delete:

jobs:
  sync-logic:
    runs-on: ubuntu-latest
    if: github.event_name == 'push'
    permissions:
      contents: write
    concurrency:
      group: shadow-sync-${{ github.ref_name }}
      cancel-in-progress: true
    steps:
      - name: Checkout Source
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Sync Shadow Branch
        run: |
          set -euo pipefail

          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

          SOURCE_BRANCH="${{ github.ref_name }}"
          SHADOW_BRANCH="shadow/${SOURCE_BRANCH}"

          # Create/reset shadow branch at the current source HEAD
          git checkout -B "$SHADOW_BRANCH"

          EXCLUDE_LIST=("packages/core/tests/fixtures")

          for item in "${EXCLUDE_LIST[@]}"; do
            if [ -e "$item" ]; then
              rm -rf "$item"
              git add -A "$item"
            fi
          done

          if ! git diff --cached --quiet; then
            git commit -m "chore(shadow): strip fixtures for $SOURCE_BRANCH"
          fi

          git push origin "$SHADOW_BRANCH" --force

  cleanup-logic:
    runs-on: ubuntu-latest
    if: github.event_name == 'delete' && github.event.ref_type == 'branch' && !startsWith(github.event.ref, 'shadow/')
    permissions:
      contents: write
    steps:
      - name: Delete Shadow Branch (via API)
        uses: actions/github-script@v7
        with:
          script: |
            const source = context.payload.ref;           // deleted branch name
            const shadow = `shadow/${source}`;
            const ref = `heads/${shadow}`;

            core.info(`Cleaning up shadow branch for ${source} -> ${shadow}`);

            try {
              await github.rest.git.deleteRef({
                owner: context.repo.owner,
                repo: context.repo.repo,
                ref,
              });
              core.info(`Deleted ${shadow}`);
            } catch (e) {
              if (e.status === 404 || e.status === 422) {
                core.info(`Shadow branch ${shadow} not found (already gone).`);
              } else {
                throw e;
              }
            }