Sorry, I misread your question. There isn't in general, but some tools enable signatures for pages with the __NEWSECTIONLINK__ flag (which is usually used for village-pump-style pages).
@Pharos DiscussionTools has been installed since the opening of this task; does that resolve the issue?
I don't think there would be any disadvantage of using the stored state of the page, if that's any easier. Most users wouldn't understand anyway what the availability of the signature depends on, and probably wouldn't care as long as it's available on pages where they need it. Also it's very unlikely that someone would want to both change magic words and sign something in the same edit.