Blocking over the entirety of /filter doesn't necessarily imply that the callbacks themselves are not async
Indeed
Perhaps we're arguing about terminology so I'll restate it: the callback is using a separate call chain, and rightly so, since it is a callback.
I don't think we are, it seems to me that you are speculating (and maybe you are right), you introduced that idea of callback, and now you say because it's a callback it's using a seperate call chain, but as far as an user can see, filter is just an alias (you would do it in the same call chain if you were to implement a /filter with scripting) that call multiple time another alias before returning, there's no reason to expect a seperate call chain imo.
Note that this same behaviour occurs with local event identifiers, so it's not just an issue with $v1.
Yeah, I just noticed that with $v1, sounds like you are right but it could still be a /filter -k related problem
