backmerge.yml

# This workflow automatically merges `master` into `develop` whenever a
# new version release with a tag is published. It can also be triggered
# manually via workflow_dispatch for cases where an automatic backmerge
# is needed outside of the standard release process.
# If a merge conflict occurs, the workflow creates an issue to notify
# maintainers for manual resolution.

name: Backmerge (master → develop)

on:
  release:
    types: [published, prereleased]
  workflow_dispatch:

permissions:
  contents: write
  issues: write

concurrency:
  group: backmerge-master-into-develop
  cancel-in-progress: false

jobs:
  backmerge:
    runs-on: ubuntu-latest
    timeout-minutes: 10

    steps:
      - name: Checkout repository (for local actions)
        uses: actions/checkout@v6

      - name: Setup easyscience[bot]
        id: bot
        uses: ./.github/actions/setup-easyscience-bot
        with:
          app-id: ${{ vars.EASYSCIENCE_APP_ID }}
          private-key: ${{ secrets.EASYSCIENCE_APP_KEY }}
          repositories: ${{ github.event.repository.name }}

      - name: Checkout repository (with bot token)
        uses: actions/checkout@v6
        with:
          fetch-depth: 0
          token: ${{ steps.bot.outputs.token }}

      - name: Configure git identity
        run: |
          git config user.name "easyscience[bot]"
          git config user.email "${{ vars.EASYSCIENCE_APP_ID }}+easyscience[bot]@users.noreply.github.com"

      - name: Set merge message
        run: |
          if [[ "${{ github.event_name }}" == "workflow_dispatch" ]]; then
            MESSAGE="Backmerge: master into develop (manual) [skip ci]"
          else
            TAG="${{ github.event.release.tag_name }}"
            MESSAGE="Backmerge: master (${TAG}) into develop [skip ci]"
          fi

          echo "MESSAGE=$MESSAGE" >> "$GITHUB_ENV"
          echo "message=$MESSAGE" >> "$GITHUB_OUTPUT"
          echo "📝 Merge message: $MESSAGE" | tee -a "$GITHUB_STEP_SUMMARY"

      - name: Prepare branches
        run: |
          git fetch origin master develop
          git checkout -B develop origin/develop

      - name: Check if develop is already up-to-date
        id: up_to_date
        run: |
          if git merge-base --is-ancestor origin/master develop; then
            echo "value=true" >> "$GITHUB_OUTPUT"
            echo "ℹ️ Develop is already up-to-date with master" | tee -a "$GITHUB_STEP_SUMMARY"
          else
            echo "value=false" >> "$GITHUB_OUTPUT"
          fi

      - name: Try merge master into develop
        id: merge
        if: steps.up_to_date.outputs.value == 'false'
        continue-on-error: true
        run: |
          if ! git merge origin/master --no-ff -m "${MESSAGE}"; then
            echo "conflict=true" >> "$GITHUB_OUTPUT"
            echo "❌ Backmerge conflict detected." | tee -a "$GITHUB_STEP_SUMMARY"
            git status --porcelain || true
            exit 0
          fi

          echo "conflict=false" >> "$GITHUB_OUTPUT"
          echo "✅ Merge commit created." | tee -a "$GITHUB_STEP_SUMMARY"

      - name: Push to develop (if merge succeeded)
        if:
          steps.up_to_date.outputs.value == 'false' && steps.merge.outputs.conflict ==
          'false'
        run: |
          git push origin develop
          echo "🚀 Backmerge successful: master → develop" | tee -a "$GITHUB_STEP_SUMMARY"

      - name: Create issue (if merge failed with conflicts)
        if: steps.merge.outputs.conflict == 'true'
        uses: ./.github/actions/github-script
        with:
          github-token: ${{ steps.bot.outputs.token }}
          script: |
            const run = require('./.github/scripts/backmerge-conflict-issue.js')
            await run({ github, context, core })