orca/.github/workflows/ci-branch-cache-sweep.yml

name: Sweep idle branch caches

# Branch-scoped caches serve only their branch, and nothing else removes them before LRU eviction
# reaches main's shared entries. PR merge refs belong to ci-closed-pr-caches.yml; tag refs to releases.
on:
  schedule:
    - cron: '23 */3 * * *'
  workflow_dispatch:
    inputs:
      dry_run:
        description: List what would be deleted without deleting it.
        type: boolean
        default: true

permissions:
  actions: write

concurrency:
  group: ci-branch-cache-sweep
  cancel-in-progress: false

jobs:
  sweep:
    runs-on: ubuntu-24.04
    timeout-minutes: 10
    steps:
      # No checkout: only this script runs, with the cache-write token.
      - uses: actions/github-script@v8
        env:
          DRY_RUN: ${{ github.event_name == 'workflow_dispatch' && inputs.dry_run }}
        with:
          script: |
            const keep = new Set(['refs/heads/main'])
            const idleMs = 6 * 60 * 60 * 1000
            const dryRun = process.env.DRY_RUN === 'true'
            const now = Date.now()
            const caches = await github.paginate(github.rest.actions.getActionsCacheList, {
              ...context.repo, per_page: 100
            })
            let count = 0
            let bytes = 0
            for (const cache of caches) {
              if (typeof cache.ref !== 'string' || !cache.ref.startsWith('refs/heads/') ||
                  keep.has(cache.ref)) continue
              const idle = now - Date.parse(cache.last_accessed_at)
              // An unparseable access time compares false, so the cache is kept.
              if (!(idle > idleMs)) continue
              core.info(`${dryRun ? 'Would delete' : 'Deleting'} ${cache.ref} ${cache.key} ` +
                `(${cache.size_in_bytes} B, idle ${Math.round(idle / 3600000)} h)`)
              count += 1
              bytes += cache.size_in_bytes ?? 0
              if (dryRun) continue
              try {
                await github.rest.actions.deleteActionsCacheById({
                  ...context.repo, cache_id: cache.id
                })
              } catch (error) {
                if (error.status !== 404) throw error
              }
            }
            core.info(`${dryRun ? 'Would remove' : 'Removed'} ${count} idle branch caches ` +
              `(${(bytes / 1e9).toFixed(2)} GB)`)