This is basically the same stuff I've already tried in the sandbox. But this might be a more suitable place. (And it's more likely that somebody experienced notices it here and has some additional suggestion.)
Still, I am not used to AMScd syntax and I am much more familiar with xypic syntax.
So for me probably a more natural way is to use presheaf website and include picture in chat. (And I would probably do the same in posts on the main site.)
This is obtained after using this code on presheaf website:
Presheaf also generates this link: presheaf.com/?d=d436d21r6r3h1w5p565g6o2i5m5l2c1v (We'll see to which extent this link is stable. I mean whether the image and the code is still available at the same link after some time.)
Still, if I want to display image as oneboxed, it has to be the only thing in the message. So if I want to share both the diagram and the source, I have to post two separate messages.
