In the wild we have 3 things: the mention marker in kind-1, the kind-6 with a content like "# [ 0 ]" and a tag with the mention marker, and a kind-6 with the json-encoded event in the body. I added support for that last one to gossip recently because it was less than 10 minutes of work. The first one was already supported. The middle one doesn't work on gossip right now, but I should fix that.