sync-dev-from-master.yml

name: Sync dev from master

on:
  push:
    branches:
      - master
  workflow_dispatch:

permissions:
  contents: write
  pull-requests: write
  issues: write

jobs:
  sync-dev:
    runs-on: ubuntu-latest

    steps:
      - name: Check out repository history
        uses: actions/checkout@v5
        with:
          fetch-depth: 0

      - name: Set Git identity
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"

      - name: Fetch master and dev
        run: |
          git fetch origin master dev

      - name: Fast-forward dev to master
        id: sync
        continue-on-error: true
        run: |
          set -euo pipefail

          # Start from the tracked remote branch so each run sees the real dev head.
          git checkout -B dev origin/dev

          # Release merges should already contain dev. If they do, keep dev as a
          # simple fast-forward of master instead of creating an extra merge commit.
          if ! git merge-base --is-ancestor origin/dev origin/master; then
            echo "origin/dev is not an ancestor of origin/master"
            exit 1
          fi

          git merge --ff-only origin/master

      - name: Push updated dev
        id: push
        if: steps.sync.outcome == 'success'
        continue-on-error: true
        run: |
          set -euo pipefail
          git push origin HEAD:dev

      - name: Mark successful sync in workflow summary
        if: steps.sync.outcome == 'success' && steps.push.outcome == 'success'
        run: |
          {
            echo "## dev sync"
            echo
            echo "dev was fast-forwarded to master and pushed successfully"
          } >> "$GITHUB_STEP_SUMMARY"

      - name: Open sync PR or issue when sync fails
        if: steps.sync.outcome != 'success' || steps.push.outcome != 'success'
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          SYNC_OUTCOME: ${{ steps.sync.outcome }}
          WORKFLOW_NAME: ${{ github.workflow }}
          RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
          MASTER_SHA: ${{ github.sha }}
          REPOSITORY: ${{ github.repository }}
        run: |
          set -euo pipefail

          # Keep the failure reason short so the fallback PR or issue is readable
          if [ "${SYNC_OUTCOME}" != "success" ]; then
            reason="automatic fast-forward from master into dev failed"
          else
            reason="automatic push of synced dev branch failed"
          fi

          body_file="$(mktemp)"
          {
            echo "## dev sync needs attention"
            echo
            echo "${reason}"
            echo
            echo "- workflow: ${WORKFLOW_NAME}"
            echo "- run: ${RUN_URL}"
            echo "- master sha: ${MASTER_SHA}"
            echo
            echo "This was triggered by a push to \`master\` and did not complete the expected fast-forward \`master -> dev\` sync"
          } > "${body_file}"

          existing_pr="$(gh pr list --base dev --head master --state open --json number --jq '.[0].number // empty')"
          if [ -n "${existing_pr}" ]; then
            gh pr comment "${existing_pr}" --body-file "${body_file}" || true
            echo "Opened work already exists as PR #${existing_pr}" >> "$GITHUB_STEP_SUMMARY"
            exit 1
          fi

          if gh pr create \
            --base dev \
            --head master \
            --title "Sync dev from master" \
            --body-file "${body_file}"
          then
            echo "Opened a sync PR from master into dev" >> "$GITHUB_STEP_SUMMARY"
            exit 1
          fi

          existing_issue="$(gh issue list --state open --search "in:title \"Sync dev from master\" repo:${REPOSITORY}" --json number --jq '.[0].number // empty')"
          if [ -n "${existing_issue}" ]; then
            gh issue comment "${existing_issue}" --body-file "${body_file}" || true
            echo "Opened work already exists as issue #${existing_issue}" >> "$GITHUB_STEP_SUMMARY"
            exit 1
          fi

          gh issue create \
            --title "Sync dev from master failed" \
            --body-file "${body_file}"

          echo "Opened a sync issue because the PR path was not available" >> "$GITHUB_STEP_SUMMARY"
          exit 1