(Lemmy) ghost nodes break cross-node interaction (do they not?)

The problem:

1. !cashless_society@nano.garden is created
2. node A users subscribe and post
3. node B users subscribe and post
4. nano.garden disappears forever
5. users on node A and B have no idea; they carry on posting to their local mirror of cashless_society.
6. node C never federated with nano.garden before it was unplugged

So there are actually 3 bugs AFAICT:

1. Transparency: users on nodes A and B get no indication that they are interacting with a ghost community.
2. Broken comms: posts to the ghost community from node A are never sync’d, thus never seen by node B users; and vice-versa.
3. Users on node C have no way to join the conversation because the search function only finds non-ghost communities.

The fix for ① is probably as simple as adding a field to the sidebar showing the timestamp of the last sync operation.

w.r.t. ②, presumably, A and B do not connect directly because they are each federated to the ghost node. So there is no way for node A posts to reach node B. Correct? Lemmy should be designed to accommodate a node disappearing at any time with no disruption to other nodes. Node A and B should directly sychronize.

w.r.t. ③ node C should still be able to join the conversation between A and B w.r.t the ghost community.

(original thread)