Haha, I actually just finished skimming through that exact blog post because it was one of the first things that came up when I searched for "postgresql changefeed" to see if there was some other functionality for doing it that I didn't know about.
I'll definitely need to go back and read it more thoroughly later and take a look through your code, thanks for the links.
I've continued working on this codebase, even pushing commits this week like this one: https://github.com/sagemathinc/cocalc/commit/c20a62446b6e43c...