sync-fork.yml

name: Sync fork from upstream

on:
  schedule:
    # Run once a day without competing with the top-of-hour Actions load.
    - cron: "17 2 * * *"
  workflow_dispatch:

permissions:
  actions: write
  contents: write

concurrency:
  group: fork-sync-${{ github.repository }}
  cancel-in-progress: false

jobs:
  sync:
    name: Merge upstream into fork
    # This workflow is copied into forks with the upstream source. Never run
    # the write step in FileMintApp/FileMint itself.
    if: ${{ github.event.repository.fork == true }}
    runs-on: ubuntu-latest
    timeout-minutes: 10
    steps:
      - name: Check out the fork default branch
        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
        with:
          ref: ${{ github.event.repository.default_branch }}
          fetch-depth: 0
          persist-credentials: true

      - name: Merge upstream changes
        id: sync
        env:
          UPSTREAM_REPOSITORY: FileMintApp/FileMint
          UPSTREAM_BRANCH: main
          TARGET_BRANCH: ${{ github.event.repository.default_branch }}
        run: |
          set -euo pipefail
          echo "changed=false" >> "$GITHUB_OUTPUT"

          if [[ "$GITHUB_REPOSITORY" == "$UPSTREAM_REPOSITORY" ]]; then
            echo "The upstream repository is not a sync destination."
            exit 0
          fi

          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git remote add upstream "https://github.com/${UPSTREAM_REPOSITORY}.git"
          git fetch --no-tags upstream "$UPSTREAM_BRANCH"

          # A normal merge preserves commits made in the fork. A conflict
          # stops the job before push so a maintainer can resolve it manually.
          before_sync=$(git rev-parse HEAD)
          git merge --no-edit "upstream/${UPSTREAM_BRANCH}"
          after_sync=$(git rev-parse HEAD)

          if [[ "$before_sync" == "$after_sync" ]]; then
            echo "Fork is already up to date."
            exit 0
          fi

          git push origin "HEAD:${TARGET_BRANCH}"
          echo "changed=true" >> "$GITHUB_OUTPUT"

      - name: Dispatch fork CI after sync
        # A manual run can retry CI dispatch after a previous post-push
        # dispatch failure, even when the fork is already current.
        if: ${{ steps.sync.outputs.changed == 'true' || github.event_name == 'workflow_dispatch' }}
        env:
          GH_TOKEN: ${{ github.token }}
          CI_WORKFLOW: ci.yml
          TARGET_BRANCH: ${{ github.event.repository.default_branch }}
        run: |
          set -euo pipefail
          gh workflow run "$CI_WORKFLOW" \
            --repo "$GITHUB_REPOSITORY" \
            --ref "$TARGET_BRANCH"