But if I want to jump ahead and read the last page of a book first, is it reasonable for an author to tell me I can't do that?

From an artistic point of view, yes it is. It's a bit like doing a crossword with the answers in big letters next to it... It destroys the point.

	▲	DennisP 3 days ago \| parent [-]
		I agree but for some reason, there are people who enjoy doing that. I think they should be allowed to do as they like. In any case, Amazon claims this feature is spoiler-free and that would be easy to implement. It likely works by feeding the book into an LLM context, and they could simply feed in the portion you've already read.