Thanks is a single revision action, so viewing a mulit diff with two or more edits between the left and the right side should not include a thanks link, because it will only thanks for the edit on the right side or add a better tooltip, but that maybe will not be read.
If you think, that this is not a issue, feel free to mark as INVALID
Version: master
Severity: normal
Is thanks for a revision or for the diff between two revisions? That is the question here, but when it is for a diff, what is with page creation, which does not have a diff?
It's for a revision. You'll notice, if you get the diff for a two-revision change, and then thank the user, when he views the notification, it'll give an opportunity to "View edit". When he clicks to do so, it'll only show him the most recent of the revisions in the diff for which he was thanked. This is consistent with the fact that only one revid is stored in event.event_extra. https://www.mediawiki.org/wiki/Extension:Echo/echo_event_table#event_extra
Change 105384 had a related patch set uploaded by Jackmcbarn:
Add oldRev parameter to DiffRevisionTools hook
Change 105387 had a related patch set uploaded by Jackmcbarn:
Remove misleading Thank button from some diffs