The current content of source/ does not look to influence the build at all, its about the generator code itself. Therefore changing the content of the site should not trigger a build. That can be done with paths filter as docuemtned here https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onpushpull_requestpull_request_targetpathspaths-ignore and used in ORM for example.