clear-cache.yaml

name: Clear PR caches

on:
  pull_request:
    # triggers on close / merge of a PR
    types:
      - closed

jobs:
  cleanup:
    runs-on: ubuntu-latest
    permissions:
      actions: write
    steps:
      - name: Cleanup caches for closed PR
        # remove all cache entries for this PR
        # caches usability hierarchy : master → PR
        # other PRs / master cannot reuse them
        # so clear them when the PR is closed or merged
        run: |
          gh cache list --ref refs/pull/${{ github.event.pull_request.number }}/merge --json id \
            | jq -r '.[].id' \
            | xargs -I{} gh cache delete {}
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          GH_REPO: ${{ github.repository }}