Since this is just a link decorator, it seems like something that would be more appropriate as a browser plugin which Inventaire.io subscribers could use on any site with Wikidata links.

If OpenLibrary is going to start privileging certain sites with publicity via links, I think it would be useful to have a set of public criteria which are used to determine whether or not a site qualifies. Otherwise it seems totally random when Better World Books or Inventaire.io get included and other sites don't.

Here's what's in the the inventaire.io database as of their last dump:
936960 wd:Q3331189 (edition)
818646 wd:Q47461344 (work)
636765 wd:Q5 (human)

That's a tiny fraction of Wikidata.

@tfmorris I see these no different as adding identifiers. Identifiers let us link to other parts of the internet and make our data more useful by allowing folks to use us as a 'normalizing' layer between many disparate services. We're generally not super picky ; if the link provides value we tend to include it.

This specific case is interesting because we aren't storing the inventaire IDs in open library, but just linking to them.

@davidscotson Does inventaire have its own set of identifiers under the hood? Or does it just use Wikidata? I'm noticing @tfmorris example seems to include another identifier space.

Inventaire has it's own identifiers for things that are not in Wikidata. I assume they 'upgrade' to wikidata over time when possible.

Not every book belongs in Wikidata since they have their own inclusion criteria:

For an item to be notable by Wikidata's policies, it must meet at least one of three criteria: Having a presence in any Wikimedia project (Wikipedia, Wikimedia Commons, Wikiquote, etc.) Making reference to a concept or object that is clearly identifiable. Validating statements made in other existing items.

Inventaire appear to have a wikidata passthrough, you can search for almost anything and it shows up, with some mild intelligence e.g.:

https://inventaire.io/entity/wd:Q152088

detects that it's not a book or author and redirects to a subject page for "French Fries":

https://inventaire.io/entity/wdt:P921-wd:Q152088

But I think that they'll show something sensible for anything that has book related data (authors, works, editions, series) in wikidata, which I assume applies to almost everything that has a wikidata link in Open Library.