Refine cache clean action

.github/workflows/cleanup-caches.yml

@@ -1,27 +1,27 @@
 # Mostly for DeterminateSystems/magic-nix-cache-action
-name: 👋 caches in a branch
+name: 👋 caches in merged PRs
 on:
   pull_request:
     types:
       - closed
+  schedule:
+    # Every 12:42 JST
+    # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule
+    - cron: '42 3 * * *'
+  workflow_dispatch:
 
 jobs:
   cleanup:
     runs-on: ubuntu-24.04
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      # Intentionally cover all merged PRs to keep simple logics. See https://github.com/kachick/times_kachick/issues/311
       - name: Cleanup
         run: |
-          echo "Fetching list of cache key"
-          cacheKeysForPR=$(gh cache list --ref $BRANCH --limit 100 --json id --jq '.[].id')
-
-          ## Setting this to not fail the workflow while deleting cache keys.
-          set +e
-          echo "Deleting caches..."
-          for cacheKey in $cacheKeysForPR
-          do
-              gh cache delete $cacheKey
-          done
-          echo "Done"
+          gh pr list --state merged --json number --jq '.[].number' --limit 2000 | \
+            xargs --no-run-if-empty -I '{}' gh cache list --sort size_in_bytes --order desc --json id --jq '.[].id' --limit 100 --ref 'refs/pull/{}/merge' | \
+            xargs --no-run-if-empty --max-lines=1 gh cache delete
         env:
           GH_TOKEN: ${{ github.token }}
-          BRANCH: refs/pull/${{ github.event.pull_request.number }}/merge