Implementing Public Watermark Delivery — Keep Original Promo Frames Private

Keep one immutable master private, generate a versioned watermarked derivative once, and let only that derivative cross the public cache boundary. For an edtech creator portfolio that turns prompts into short promo videos, the poster image shown in galleries is disposable and cacheable while the clean frame used to regenerate or re-edit the video is neither. The decision rule is blunt: if changing an object would require creative work again, it is a master; if it can be reproduced from a master plus a recipe, it is a derivative. TL;DR: Put masters and derivatives in separate storage namespaces