I'll post something about it soon - while the changes were wide-ranging for us (because these post-action tasks were initially scattered throughout our app), the extra infrastructure required was really pretty minimal. Most of the actual time spent in this refactoring was writing new tests for code that we'd previously been unable to practically test.

In the meantime, the pub/sub setup we've got is pretty similar to the one presented a little way down the following article:

https://www.theagileplanner.com/blog/building-agile-planner/...

Our listeners sit completely separate from the controllers, though, and we're not using them for anything like handling controller response logic (I'm not sure how I feel about that, although the idea is certainly interesting).