.github/workflows/stale-branches.yml

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name: stale-branches-report

on:
  schedule:
    - cron: '0 6 1 * *'   # monthly, on the 1st at 06:00 UTC
  workflow_dispatch:       # allows maintainers to run it on demand
                           # (Actions → stale-branches-report → Run workflow)
    inputs:
      months:
        description: 'Report branches with no commits newer than this many months'
        required: false
        default: '6'
      dry_run:
        description: 'Only show the report in the run log (do not post to the issue)'
        type: boolean
        required: false
        default: false

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

jobs:
  report:
    runs-on: ubuntu-latest
    env:
      MONTHS: ${{ inputs.months || '6' }}
      DRY_RUN: ${{ inputs.dry_run == true }}
    steps:
      - name: Report stale branches to #11858
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          REPO: ${{ github.repository }}
          ISSUE: '11858'
        run: |
          set -euo pipefail
          cutoff=$(date -d "$MONTHS months ago" +%s)
          echo "Branches with no commits since $(date -d "$MONTHS months ago" +%Y-%m-%d) and no open PR:"

          # collect all branch names
          : > branches.txt
          page=1
          while : ; do
            gh api "repos/$REPO/branches?per_page=100&page=$page" > page.json
            [ "$(jq length page.json)" -eq 0 ] && break
            jq -r '.[].name' page.json >> branches.txt
            page=$((page+1))
          done

          : > stale.txt
          while IFS= read -r branch; do
            # skip protected branches (release / maintenance lines)
            protected=$(gh api "repos/$REPO/branches/$branch" --jq '.protected' 2>/dev/null || echo true)
            [ "$protected" = "true" ] && continue
            # skip branches that are the head of an open PR
            open_prs=$(gh pr list --repo "$REPO" --state open --head "$branch" --json number --jq 'length')
            [ "$open_prs" -gt 0 ] && continue
            last=$(gh api "repos/$REPO/commits/$branch" --jq '.commit.committer.date' 2>/dev/null || true)
            [ -z "$last" ] && continue
            [ "$(date -d "$last" +%s)" -gt "$cutoff" ] && continue
            echo "- \`$branch\` — last commit \`${last:0:10}\`" >> stale.txt
          done < branches.txt

          {
            echo "### Monthly stale-branch report — $(date +%Y-%m-%d)"
            echo
            echo "<i>Threshold: branches with no commits in the last ${MONTHS} months and no open PR.</i>"
            echo
            if [ -s stale.txt ]; then
              echo "Branches with no commits in the last ${MONTHS} months **and** no open PR:"
              echo
              cat stale.txt
              echo
              echo "<details><summary>Tip: deleting a stale branch</summary>"
              echo
              echo '```'
              echo "gh api -X DELETE repos/$REPO/git/refs/heads/<branch-name>"
              echo '```'
              echo
              echo "</details>"
            else
              echo "No stale branches found. 🎉"
            fi
          } > report.md

          if [ "$DRY_RUN" = "true" ]; then
            echo "DRY RUN — report not posted to the issue. Output:"
            cat report.md
            exit 0
          fi

          # update the latest existing report comment if present, otherwise create a new one
          comment_id=$(gh api "repos/$REPO/issues/$ISSUE/comments?per_page=100" \
            --jq '.[] | select(.user.login == "github-actions[bot]") | select(.body | startswith("### Monthly stale-branch report")) | .id' \
            | tail -1 || true)
          if [ -n "${comment_id:-}" ]; then
            gh api -X PATCH "repos/$REPO/issues/comments/$comment_id" -F body=@report.md --jq '.html_url'
          else
            gh issue comment "$ISSUE" --repo "$REPO" --body-file report.md
          fi