Here is another tricky door problem in the same spirit as this question:
All three images are the same door. Notice this is not a single leaf door, but actually has two swinging leaves. Instead of a rigid frame on the strike side, there is a short stub that can swing out to make the total opening width wider.
The stub is hollow wood veneer with locking points on the top and bottom (see middle picture). The installed door lever is a storeroom function lock, and this opening is used about 12 - 15 times per hour during business hours. It should be locked the rest of the time.
What kind of lock or hardware would you suggest for securing this opening?