sync-master-to-develop.yml

name: Sync master to develop

on:
  pull_request_target:
    branches: [master]
    types: [closed]

permissions:
  contents: read
  pull-requests: write

concurrency:
  group: sync-master-to-develop
  cancel-in-progress: false

jobs:
  sync:
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-latest
    timeout-minutes: 5
    steps:
      - name: Open sync PR if needed
        env:
          GH_TOKEN: ${{ github.token }}
          GH_REPO: ${{ github.repository }}
        run: |
          set -euo pipefail

          existing_pr=$(gh pr list --base develop --head master --state open --json number --jq '.[0].number // empty')
          if [[ -n "$existing_pr" ]]; then
            echo "Sync PR #$existing_pr already exists."
            exit 0
          fi

          ahead=$(gh api "repos/$GH_REPO/compare/develop...master" --jq '.ahead_by')
          if [[ "$ahead" -eq 0 ]]; then
            echo "develop already contains master."
            exit 0
          fi

          gh pr create \
            --base develop \
            --head master \
            --title "Sync master into develop" \
            --body "Automatically sync changes merged into master back into develop. CI is skipped for this branch pair."