I'm writing my final thesis and there's a lot of material I would like to reuse from my proposal -- introductions, motivations, etc. -- and it would be nice to just copy-paste (and update a bit) entire chapters from the proposal.
But then I started to wonder what the technical status of a proposal really is. It's not archived anywhere, it's not "published" in any traditional sense. Is it a sort of first draft of the final thesis? Is it possible/legal/acceptable to reuse portions of it in the final thesis? Or is that plagiarism?