name: Backport PR to branch
on:
  issue_comment:
    types: [created]
  schedule:
    # once a day at 13:00 UTC to cleanup old runs
    - cron: '0 13 * * *'

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

# Avoid interrupting an in-flight backport: a cancelled `git am` mid-apply would
# leave a half-created branch/PR. Serialize per source PR (comment triggers) and
# per ref (schedule) without cancelling running work.
concurrency:
  group: backport-${{ github.event.issue.number || github.ref }}
  cancel-in-progress: false

jobs:
  backport:
    if: ${{ contains(github.event.comment.body, '/backport to') || github.event_name == 'schedule' }}
    # Reference the reusable workflow by local path so it always resolves to the
    # same commit as this caller, pinning backport behavior to the triggering
    # commit without an expression. An expression in `uses:` (e.g.
    # `backport-base.yml@${{ github.sha }}`) is not a valid reusable-workflow
    # reference and makes GitHub emit a failed "workflow file issue" run on every
    # push, regardless of this workflow's declared triggers.
    uses: ./.github/workflows/backport-base.yml
    with:
      pr_description_template: |
        Backport of #%source_pr_number% to %target_branch%

        /cc %cc_users%
    secrets: inherit