Lock for front bi-folding door

[timbrass]

Is there any elegant solution to adding a lock to the front bifold door without replacing the door - I want to keep the original door. Clearly needs some form of latch so the bolt is not simply withdrawn when opening. A padlock would be ugly!

 

[lornaschinske]

Three point like what is used on a garage door? You would need to add a lever on the inside. They typically have a keyed locking handle.