nice! I initially stayed away from lua due so I could support earlier redises, but these days I would totally take that dependency on to simplify the code.

regarding that implementation, one diff I am spotting is that I also have a concept of global message id / global channel, this allows us to subscribe to a single spot and distribute from there (which keeps thread counts down and is particularly useful for server -> server comms.)

A lot of parity with our projects :)

Regarding web sockets, I decided against supporting them (initial implementations did) the issue is that web sockets are 100% flaky on HTTP and just add tons of unneeded complexity, in advent of HTTP/2 in NGINX they would be a net loss imo cause you would be wasting a connection.