interesting!

it does need checkout if you externalize the filter

This reverts commit 6bedbe0.

.github/workflows/ci.yml

@@ -10,8 +10,7 @@ jobs:
     runs-on:     ubuntu-latest
     permissions: { pull-requests: read }
     steps:
-      - if:   github.event_name != 'pull_request'
-        uses: actions/checkout@v4
+      - uses: actions/checkout@v4
       - id:   filter
         uses: dorny/paths-filter@v3
         with: { filters: .github/filters.yml }