Our approach, which is behind a feature flag right now, is to allow users to attach "assets" to jj change IDs (these are sort of like stable git commit SHAs). This is how we will power inline comments, and it's how we'll power Notion-style SQLite-based databases. We already have, checked in, an implementation of IVM built on top of SQLite, specifically for this purpose. I don't see how we could be a Notion competitor without them.