What is the "Working title" field in the New Book wizard? (from v1.6.3)

It separates your book's title from the AI prompt. The topic box is purely the prompt — write it as long and detailed as you like. The working title, when set, is what appears in your library and on disk, and the AI will NOT replace it with its own proposal (title suggestions stay available on the book page). Leave it blank and BookyAI proposes a title from the outline, as before.