The person who owns the whole book
You hold the theme, the ladder, and the deadline calendar. You do not design every spread — you decide what the book is about and make sure every section is pulling toward it. When two sections fight over the same four pages, you settle it. When a deadline is going to be missed, you know before the plant does, because the ladder tells you.
What the platform grants: Full-book scope: you can open any section, read every spread's version history, and see the coverage report for the entire book. You are the one role that is not walled to a single section.