Wow, this could be really useful for my team. We've built a ton of customized workflows on top of github. We use a modified git-flow process, and have bespoke solutions for automatically tagging branches when branches w/ name "hotfix" get into master, when long-living releases get merged, tons of logic for getting commits on a "release-*" branch into dev and other branches.

We ended up building a custom github worker that listens to all of this, but it's opaque and our Bus factor is 1 for that tool. Putting it on Github where anyone can change the rules and see them cleanly is fantastic!