Branching EPUB story of futures never happened

Write an original branching short story as an EPUB 3 ebook. A night archivist opens a cabinet containing objects from futures that never happened. Exactly sixteen story scenes total, including exactly three distinct terminal endings. Choices change discoveries and accessible endings. Use EPUB internal hyperlinks, no JavaScript. Deliver the actual EPUB, editable sources, a JSON scene graph and a small offline validator. Check package structure, every internal link, all scene reachability and ending count; graph must agree with the book. Include an original simple cover and a navigation explanation outside the sixteen story scenes. Write evocative short scenes with continuity, not placeholder graph labels. Deliver English materials, original content and offline reproducible checks. The artifact is the product; no web application or external service. Make reasonable reversible design choices independently.