Updating dependent branches when rebasing, automagically

I'm regularly rewriting my history, often with the lens of improving my commit messages. On the Renovate project, we use a Merge Queue with Squash Merge, which means that if I do want to have atomic commits, I need to split them across PRs, which adds a bit of noise to manage them. Alternatively, I could bypass branch protection requirements to do a rebase merge, but that's the only way to do a rebase merge with a Merge Queue. Now that GitHub has launched stacked PRs, it's now possible to get this behaviour as I wanted, but with the safety of the Merge Queue. But the issue is what happens when I've amended the commit message on one of the PRs, and now need to trigger a cascading rebase? As of ~5 minutes ago, I would have to do that all manually, like a chump. It turns out - thanks to a pointer from Claude Opus 5 - Git has had a capability to improve this for years! In Git 2.38 (2022-10-03), git rebase --update-refs was added, which allows doing exactly this, but without any of the…