Why was this question bumped to the top of the homepage?

Question

I refreshed the home page a few minutes ago and saw that the question about keeping banana ice cream soft was at the top of the list, 3 hours after it was asked (activity on the site has happened since it was asked, so I was expecting it to be 5th or 6th in the list).

It shows that calico-cat did something to the question 26 minutes ago, but when I click through to the page there are no answers and no edits, and the home page also reports 0 answers. Calico-cat's user page shows no activity on that question.

Did calico-cat answer and then delete their answer? Was an edit rolled back and thus doesn't show up? I'm just trying to get a better feel for what bumps things to the top of the homepage, when I saw no answers I was expecting a tag edit, but see no edit history.

If it was an answer that was then deleted, should the backend no longer treat that as an edit and sort it back to the proper place? My concern is, if that is what happened, anyone could bump a question by answering and then quickly deleting their answer. Not a big deal, as it does report that user's name on the homepage as the most recent activity on the question so bump-fraud should be minimal, but I'm still curious as to exactly what happened.

Answer 1

Yes, he/she answered and then deleted the answer. Moderators and 10k users can see it.

I believe that the last activity stats on the front page are cached, so there's no way to "un-bump" it or have the front page revert to a previous instance. Generally speaking, deleting a post simply has no effect whatsoever on the front page.

You'll notice if you move your cursor over the last activity date (from the front page, next to where calico-cat's name is) that the link is not actually clickable. As far as I know, that always means a deleted post.