TabAtkins: (or any others here with insight into this area) Is there any mechanism I can use with either CSS and/or HTML attributes to programatically toggle a node’s “relevant to the user” state? And a way to use that in combination with its content-visibility state to toggle making it visible?

On the face of it, it seems like what the HTML inert attribute means is the same as what CSS means by “not relevant to the user” — and so, the combination of inert + content-visibility: auto could/should cause a node to be non-visible.

But the CSS doesn’t actually say that, nor do implementations do that.

The context is: I want to implement closing/opening of details elements using content-visibility internally but also make the contents searchable with find-in-page. The relevant part of the current HTML spec requirements say to use hidden:

The details element's second slot is expected to have its style attribute set to "display: block; content-visibility: hidden;" when the details element does not have an open attribute.

…however, the relevant part of the current CSS Containment spec about hidden says this:

The element skips its contents. The skipped contents must not be accessible to user-agent features, such as find-in-page, tab-order navigation, etc., nor be selectable or focusable.

…while the relevant part about auto says this:

If the element is not relevant to the user, it also skips its contents. Unlike hidden, the skipped contents must still be available as normal to user-agent features such as find-in-page, tab order navigation, etc., and must be focusable and selectable as normal.

So, to conform to the current CSS spec requirements, to allow find-in-page on closed details elements, it seems I actually should not use hidden to make them closed (despite what the HTML spec currently says), but should instead use auto.

However, just using content-visibility: auto for closed details will not on its own make their contents non-visible — instead it seems I need to somehow also make the contents not “relevant to the user”. And to me at least, it seems like inert could/should be the way to do that, and the CSS and/or HTML specs could/should say that.

But if not with inert, is there some other way to make a node not “relevant to the user”?