Opt-in [compat] tests ok ? augment ver list;

From just a package developer point of view, I agree that the only thing that sounds effectively different from existing CompatHelper workflow is the automatic merge, which seems somewhat risky. CompatHelper opens a PR on a new branch with the right commit and tests will run as long as your CI is set to run on PRs. So the only step of the process that you are eliminating is the button click at the end. To have a fully automatic workflow, you’d need to automatically call Registrator as well for a new release.