Whoa baby!
I think I understand the concept of this. Ok, so if the heat and gases come up from the far end of the fire box, into the cooking chamber, would the heat and gasses go out the oven door before going up the flue? I can see if it is bricked up for kiln firing, you can control the smoke path easier. Your design may be quite different than what I am trying to look at in the picture possibly.
During heating, the door(s) would be bricked or blocked (kaowool backed plates?). There's a chimney right above the entrance to the firebox- the exhaust gases go through corresponding slots (that's your "exit flue") on the opposite side of the chamber from where they entered and go up the chimney- there's no gas exchange through the doors. Throw in a pizza, dough, a roast, whatever- replace the door plate.
Heat can be added without opening the door at all. Maybe I'll add a port to spritz in some water. Plus- if I really want to, I could probably get it to 2300F for disposal of my enemies.
In that kiln pic above- the door would be bricked up when it was being fired.