I have a wiki that is anonymously editable, but I would like to disable using the 'Restore Revision' sidebar action unless you are logged in. I would like to still allow anonymous users to view the Revisions page, just not actually click the Restore button.
I've tried many different plugins like denyaction, but it seems that 'revert' is not a valid action that can be denied? Or those plugins no longer work correctly.
How can I accomplish this? The reasoning is that I have a captcha installed on the edit page, but not for restoring revisions. I've found many crawlers will happily visit the Restore sidebar link during crawling, and start randomly restoring pages to older versions. For now I've added a robots.txt line, but that obviously only helps with bots that follow robots.txt rules.