so this part isn't entirely true

"once a toot is federated it is on the remote instances forever;"

it seemed true for direct toots i sent to my other account, which never deleted remotely. but i just successfully deleted a public toot and it disappeared on the other acct.

someone just confirmed my observation that remote direct toots don't seem to disappear when deleted

so
public delete
direct don't?

just now sent unlisted and private test toots:
- unlisted was only visible remotely if i directly viewed my timeline in 4th column. did NOT show up in my follower tootstream. had expected it to.
- private was not visible on remote instance, as expected