A monorepo workflow should run only when files under 'backend/**' change on push. Which trigger configuration implements that path filter?

GitHub Actions supports paths and paths-ignore under push and pull_request to limit workflow runs based on changed files. on.push.paths: ['backend/**'] runs the workflow when at least one changed file matches the glob. This saves minutes in monorepos. directories and only are not valid keys for this filter. A top-level on.path event does not exist. Related filters include branches, tags, and types for activity events. Caution: path filters interact with scheduled or manual workflows differently because those events may not have the same changed-file semantics — path filters apply to push and pull_request change sets. Also consider paths-ignore when you want to exclude docs or generated files from triggering CI.