Okay, I am going to make the call on this one.
I actually made a mistake on when the next combat triggered when I pushed the action forward from one room to the other. You solved the first riddle with complete success. The combat should have triggered when you crossed to the other room. At that point you would have been at full HPs.
So, given that a) I pushed the action forward
b) I missed the combat trigger
c) The following fight is a boss fight as Nemesis correctly says
You can gain the benefits of a short rest now if you so choose. This will happen in the time frame of 60 seconds. So anything you could do in 10 rounds inside that room you have time to prepare for now before combat triggers.