Yes, that one I want immutable.
I wouldn't have an icon for both types. I was thinking that going forward the title links one would only get via copying the address bar while visiting the wiki page. In any case I don't want to break any existing title links.
That's an idea too. But a part of my annoyance with the title links is that many users don't think of the title in terms of it being used for access. So they make long ones, with punctuation and whatnot. In addition to changing them without thinking.
Maybe instead of a serial number for the permalink, allow the page creator to assign a Page Name (which becomes its permalink) with a short text, required to be group-unique; explicitly distinct from the page Title. I try to treat them that way anyway. That text could have URL-compatible character rules so that you don't subsequently have to deal with encoding them (and we don't have to deal with the ugliness of URL-encoded punctuation in the URL). A little like the distinction between a Group Name (aka email address) and a Group Title.