I'm not sure I agree with the idea of a locked instance returning not found. I think it delivers an idea inconsistent with the intent of the locking mechanism. I would say HTTP 405 (MethodNotAllowed) or something like that instead, as a 404 wouldn't let the end user know that it needs to be unlocked. Also, I don't think we want to lock the show action, as the lock is supposed to represent immutability, not visibility.
I'm not sure I agree with the idea of a locked instance returning not found. I think it delivers an idea inconsistent with the intent of the locking mechanism. I would say HTTP 405 (MethodNotAllowed) or something like that instead, as a 404 wouldn't let the end user know that it needs to be unlocked. Also, I don't think we want to lock the show action, as the lock is supposed to represent immutability, not visibility.