So I was adding an addendum to the previous post, and then I tried to publish the update. WordPress gave the very annoying “Are you sure you want to do this” error, which is about as useful as an error message as not having an error message at all. Clicking on the “Please try again” link just brought me back to the post editing page with all my edits gone.
Then I noticed that it said that there was an autosave that was more recent than the post, so I restored that and then hit the update button immediately.
Then in the split second where the page was loading, I noticed that now the editing page said that there was a browser autosave that differed from the server autosave. And of course it was too late to do anything about it. The page loaded, and the earlier edits were live (mostly TeX fixes because I’m bad at TeX), but a whole paragraph at the end got nuked.