How to count rows in SwiftData?

I'm currently writing an app that loads URLs from the HackerNews API. I have implemented Bookmarks by persisting any bookmarked data to SwiftData.

I am currently trying to implemented "viewed links" — i.e. if you click a link, it gets marked as viewed — I was able to do so by persisting the link ID to SwiftData and in each link view, it queries for itself against the existing "viewed" links, like so:

static func viewedPredicate(_ id: Int) -> Predicate<Viewed> {
    return #Predicate<Viewed> { $0.id == id }
}

var viewed: [Viewed] {
    return (try? modelContext.fetch(
        FetchDescriptor(
            predicate: ItemView.viewedPredicate(id)
        ))) ?? []
}

But now, I want to provide stats to the user, so I need to count how many viewed links exist. I don't want to return ALL objects from SwiftData, I want a simple Int that tells me how many there are. To do so, I implemented it as follows:

private var viewedCount: Int {
    return (try? modelContext.fetchCount(FetchDescriptor<Viewed>())) ?? 0
}

But when I delete the stats, the number does not get updated.

I get that the current approach is "unaware" of the link between the data and the view, but that's precisely my question.

How can I make the query update when the underlying model gets updated too?

I've searched far and wide and the best result I found was to simply use the @Query over Viewed and count after, this could be done purely on the SQLite side so I'm looking for a better solution.