delete-stale-branches.yml

# Runs daily and deletes branches with no associated PR that haven't had a
# commit in over 60 days — these are abandoned branches that were never
# turned into a PR.
#
# Respects protected branches and skips fork branches.
# Deletes all matching branches per run, oldest first.

name: Delete stale branches

on:
  schedule:
    - cron: "0 4 * * *"
  workflow_dispatch:

permissions:
  contents: write
  pull-requests: read

jobs:
  delete-stale-branches:
    runs-on: ubuntu-latest
    steps:
      - name: Delete unassociated branches older than 60 days
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          deleted=0

          protected=$(gh api "repos/$GITHUB_REPOSITORY/branches?protected=true&per_page=100" \
            | jq -r '.[].name')

          is_protected() {
            echo "$protected" | grep -qx "$1"
          }

          delete_branch() {
            local branch="$1"
            local reason="$2"

            if is_protected "$branch"; then
              echo "Skipped (protected): $branch"
              return
            fi

            gh api "repos/$GITHUB_REPOSITORY/git/refs/heads/$branch" \
              -X DELETE 2>/dev/null \
              && { echo "Deleted ($reason): $branch"; deleted=$((deleted + 1)); } \
              || echo "Skipped (already gone): $branch"
          }

          echo "--- Unassociated branches older than 60 days (oldest first) ---"

          pr_branches=$(gh pr list \
            --repo "$GITHUB_REPOSITORY" \
            --state open \
            --limit 1000 \
            --json headRefName \
            | jq -r '.[].headRefName' \
            | sort -u)

          cutoff=$(date -d '60 days ago' --utc +%Y-%m-%dT%H:%M:%SZ 2>/dev/null \
            || date -u -v-60d +%Y-%m-%dT%H:%M:%SZ)

          echo "Cutoff date: $cutoff"

          candidates=$(mktemp)

          owner="${GITHUB_REPOSITORY%%/*}"
          repo="${GITHUB_REPOSITORY##*/}"
          cursor="null"

          while true; do
            response=$(gh api graphql -f query="
              query(\$owner: String!, \$repo: String!, \$cursor: String) {
                repository(owner: \$owner, name: \$repo) {
                  refs(refPrefix: \"refs/heads/\", first: 100, after: \$cursor) {
                    pageInfo { hasNextPage endCursor }
                    nodes {
                      name
                      target {
                        ... on Commit {
                          committedDate
                        }
                      }
                    }
                  }
                }
              }
            " -f owner="$owner" -f repo="$repo" -f cursor="$cursor")

            has_next=$(echo "$response" | jq -r '.data.repository.refs.pageInfo.hasNextPage')
            cursor=$(echo "$response" | jq -r '.data.repository.refs.pageInfo.endCursor')

            while IFS=$'\t' read -r branch last_commit; do
              if echo "$pr_branches" | grep -qx "$branch"; then
                continue
              fi

              if [[ "$last_commit" < "$cutoff" ]]; then
                printf '%s\t%s\n' "$last_commit" "$branch" >> "$candidates"
              fi
            done < <(echo "$response" | jq -r '.data.repository.refs.nodes[] | [.name, .target.committedDate] | @tsv')

            [ "$has_next" = "true" ] || break
          done

          while IFS=$'\t' read -r last_commit branch; do
            delete_branch "$branch" "no PR, last commit $last_commit"
          done < <(sort "$candidates")

          rm -f "$candidates"

          echo "--- Done: $deleted branch(es) deleted ---"