How to determine device state?

[turboboost55]

Hi, I'm modifying the sandbox web app to create a simple wallet for my keepkey. I'm trying to come up with a definitive way to determine what state a device is in. In other words, when can I know for sure the device has been paired and is ready for use? Does the reception of the CONNECT event imply a paired device, or is it possible to receive that event from an unpaired device? If a device is present in keyring.wallets, is that a definitive indicator? Sorry if these are all very elementary questions.