WC laws are state specific in nature, the case law will control here. "Across the street" is certainly OUTSIDE what is known as the "Zone of Employment".
If they pay into the state fund, it is more feasible than if they are "self insured", that is, if your state permits some employers to be.
"Zone of employment" can also include OFF site injuries. Say our employer requests you drive a bag of invoices to X location and you are hurt while en route or on the other non company site.
Let's assume there is NO controlling case law, one can argue in the advent of non smoking laws and off premises smoking laws/policies, any minimal venture off property to smoke would be covered??
Then again "across the street" is outside the ZOE? This may take a detailed examination by a WC specialist in your state.
Q: Did she report the injury? Did she file a WC claim with them? You say in your first post, it was just one day of work missed.

