See also bug 59811 ("AbuseFilter "Tag the edit for further review" doesn't work") which is regarding adding the Editfilter/Abusefilter "Tags" into edit-summaries.

Are any of these applicable to Flow posts/topics? I can't imagine too many real-world situations where anyone would blank or replace a post (especially when editing is restricted to post authors and admins), and in the rare cases they did, it doesn't seem like it would be as important to call out with an automated message as when it happens at the page level. We already use the "created page with $1" message, in the sense that we show a snippet preview of new comments. And redirect doesn't make sense at all in the Flow use-case... is there something I'm missing? :)

Hmm, good points! I guess the only use-case that makes sense would be Board-header edits, which should already be covered when Bug 57894 is fixed ("Flow: Editing the page header should give the editor a dialog requesting an edit-summary"). I guess this bug could be closed as a duplicate of that one?

That makes sense. We can keep this bug open to remind us of the "... and add an automated summary when there isn't one" part.