branch-cleanup.yml

name: Branch Cleanup

# Only runs after CI passes on a push to develop or main.
# Deletes the source branch of the merged PR — but ONLY if post-merge CI succeeded.
# If CI fails after merge, the branch stays so you can fix and re-merge.

on:
  workflow_run:
    workflows: ["CI"]
    types: [completed]
    branches: [develop, main]

permissions:
  contents: write
  pull-requests: read

jobs:
  cleanup:
    name: Delete merged branch
    runs-on: ubuntu-latest
    if: >-
      github.event.workflow_run.conclusion == 'success' &&
      github.event.workflow_run.event == 'push'
    steps:
      - name: Find merged PR and delete source branch
        uses: actions/github-script@v7
        with:
          script: |
            const sha = context.payload.workflow_run.head_sha;
            const repo = context.repo;

            // Find PRs that were merged with this commit
            const { data: prs } = await github.rest.pulls.list({
              ...repo,
              state: 'closed',
              sort: 'updated',
              direction: 'desc',
              per_page: 10
            });

            const merged = prs.filter(pr =>
              pr.merged_at && pr.merge_commit_sha === sha
            );

            if (merged.length === 0) {
              console.log('No merged PR found for this push — nothing to clean up.');
              return;
            }

            for (const pr of merged) {
              const branch = pr.head.ref;
              const base = pr.base.ref;

              // Never delete develop or main
              if (['develop', 'main', 'master'].includes(branch)) {
                console.log(`Skipping protected branch: ${branch}`);
                continue;
              }

              // Only delete if the branch is in this repo (not a fork)
              if (pr.head.repo.full_name !== repo.owner + '/' + repo.repo) {
                console.log(`Skipping fork branch: ${pr.head.repo.full_name}/${branch}`);
                continue;
              }

              try {
                await github.rest.git.deleteRef({
                  ...repo,
                  ref: `heads/${branch}`
                });
                console.log(`Deleted branch ${branch} (PR #${pr.number} merged to ${base}, post-merge CI passed)`);
              } catch (e) {
                if (e.status === 422) {
                  console.log(`Branch ${branch} already deleted`);
                } else {
                  throw e;
                }
              }
            }

      - name: Report if CI failed (branch preserved)
        if: github.event.workflow_run.conclusion == 'failure'
        run: |
          echo "⚠️ Post-merge CI FAILED — source branch NOT deleted."
          echo "Fix the issue, then the branch will be cleaned up on the next successful run."