How to track presence for absinthe subscriptions?

I need to track who’s subscribed to mutations or other events in absinthe. I want to log a list of subscribers when the event is triggered, either via trigger in absinthe schema or directly via Subscription.publish().
I tried Phoenix.Presence but it seems as though absinthe topics and Phoenix topics are not the same thing, although I thought Absinthe delegates to Phoenix for PubSub stuff.
Another way to do it may be via Phoenix.Tracker - but Tracker.track function takes topic name as an argument, and I don’t know where to intercept the subscription and unsubscription to add the topic to the tracker.