Indexes are subcase -> supercase, it doesn't necessarily mean "child/parent", though, it just means "indexing case -> indexed case".  It's important that the cases rely on having that index around otherwise I think we're going to end up having lots of problems with the cases pointing to other cases that don't exist.

It's OK to have a raw selector from a case (we don't, for instance, even need to be guaranteeing that they're selecting a _case_ here, long term, they're just selecting a value. Could be used to filter a case list, or index into a fixture, for instance), but if we're explicitly loading a case, I think we should try to think of that use case as being from an index.