cleanup-branches.yml

name: Cleanup Merged PR Branches

on:
  # Auto-delete head branch whenever a PR is merged
  pull_request:
    types: [closed]
  # Manual trigger to bulk-delete all existing merged-PR branches
  workflow_dispatch:

permissions:
  contents: write

jobs:
  cleanup-on-merge:
    if: github.event_name == 'pull_request' && github.event.pull_request.merged == true
    name: Delete branch on PR merge
    runs-on: ubuntu-latest
    steps:
      - name: Delete head branch
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const branch = context.payload.pull_request.head.ref;
            const owner = context.repo.owner;
            const repo = context.repo.repo;

            // Never delete protected branches
            const protectedBranches = ['main', 'develop', 'master'];
            if (protectedBranches.includes(branch)) {
              console.log(`Skipping protected branch: ${branch}`);
              return;
            }

            try {
              await github.rest.git.deleteRef({
                owner,
                repo,
                ref: `heads/${branch}`,
              });
              console.log(`Deleted branch: ${branch}`);
            } catch (err) {
              if (err.status === 422) {
                console.log(`Branch already deleted: ${branch}`);
              } else {
                throw err;
              }
            }

  bulk-cleanup:
    if: github.event_name == 'workflow_dispatch'
    name: Bulk delete all merged-PR branches
    runs-on: ubuntu-latest
    steps:
      - name: Delete branches for merged PRs
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const owner = context.repo.owner;
            const repo = context.repo.repo;

            const protectedBranches = new Set(['main', 'develop', 'master']);

            // Collect all head branches from merged PRs (paginate through all pages)
            const mergedBranches = new Set();
            for await (const response of github.paginate.iterator(
              github.rest.pulls.list,
              { owner, repo, state: 'closed', per_page: 100 }
            )) {
              for (const pr of response.data) {
                if (pr.merged_at) {
                  mergedBranches.add(pr.head.ref);
                }
              }
            }

            // Fetch all current branches
            const existingBranches = new Set();
            for await (const response of github.paginate.iterator(
              github.rest.repos.listBranches,
              { owner, repo, per_page: 100 }
            )) {
              for (const branch of response.data) {
                existingBranches.add(branch.name);
              }
            }

            // Delete branches that are in merged PRs and still exist
            const toDelete = [...mergedBranches].filter(
              b => existingBranches.has(b) && !protectedBranches.has(b)
            );

            console.log(`Found ${toDelete.length} branches to delete.`);
            let deleted = 0;
            let failed = 0;

            for (const branch of toDelete) {
              try {
                await github.rest.git.deleteRef({
                  owner,
                  repo,
                  ref: `heads/${branch}`,
                });
                console.log(`Deleted: ${branch}`);
                deleted++;
              } catch (err) {
                if (err.status === 422) {
                  console.log(`Already gone: ${branch}`);
                } else {
                  console.error(`Failed to delete ${branch}: ${err.message}`);
                  failed++;
                }
              }
            }

            console.log(`Done. Deleted: ${deleted}, Failed: ${failed}`);
            if (failed > 0) {
              throw new Error(`Failed to delete ${failed} branch(es). See logs above.`);
            }