The check has to run at read time. Owner A adds a title she bought in Play Books as a notebook source and uses it next to her own documents [4]. Collaborator B opens the shared notebook, and Google says B must also own that Play Book to keep engaging with its content [6]. So the source list is not a property of the notebook. It is the intersection of the declared sources and the viewer's entitlements, resolved per viewer at request time [2]. Two people can put the same question to the same notebook and get differently grounded answers, because one of them has the receipt.
Provisioning follows from that. A twelve-person team standardising on one title needs twelve entitlements; standardise on five titles and the same team needs sixty [1]. The notebook amortises nothing. The dev.to write-up frames this as access management staying inside the workflow, and cautions that a manager cannot assume one purchase enables every colleague [11]. The licensing model underneath is the one public lending has run on for a century: one copy, one reader.
More than 100,000 books from major publishers is Google's figure for the initial catalog [2]. Read it the way you would read someone else's benchmark table. For it to describe your situation, the handful of titles your team actually cites has to be among the eligible ones [1], in the edition your people bought. It also has to stay eligible after the publisher revisits the arrangement. The account of the announcement names authors working on curated Featured Notebooks, including Steven Pinker, Michael Pollan and Jennifer Wallace [9], but it does not list eligible titles, name the participating publishers, or describe how a book's text reaches the retrieval step [12].
That retrieval path is the part I would want documented before building a training workflow on top of it. If the text sits in a server-side index and the entitlement is a permission check in front of it, then refunds and edition changes become events that quietly change what a notebook is grounded in. Google has described books in Gemini Notebook as the starting point for a wider initiative rather than its final scope [10]. Whatever content type arrives next arrives with the same check in front of it, which is why the revocation behaviour matters more to an operator than the catalog size does.
