If a card is in closed view, and you open to edit it (or do anything on the other tabs), then when you go back to view mode (eg. by clicking on view or saving an edit), the card returns to closed view.
It should stay open :)
For now I just went back to fixing this in show.html.erb, which seems a bit sloppy. It does preserve "closed" as the original view, fwiw, but it's hacky.
I think we may have other partner relationships similar to open/closed (including other versions of open/closed) that would justify making this more generic.