Thanks to all for your input. I did witness the rebar installation and the gunite application, and all was done to spec. The only thing that differs from the drawing is that the bottom corner radii going from wall to floor, was supposed to be something like 18" radius (huge), and it was not troweled with that large of a radius. And, the cracking is at the topside of the pool, not the bottom. There was no overexcavation and refill with gravel, AB, etc., as none was called for in the engineering work.
I am pretty sure that the issue was caused by absolutely no rain for seven months (Feb thru Aug) this year, and then a 2" deluge a week before the crack occurred. Aside from the pool, in the past 3 weeks, we have 1/4" gaps open up in our travertine pavers near the pool (expansion), and artificial turf next to the pavers develop 3 large wrinkles (contraction).
I have filled the pool cracks with a white marine polyurethane sealant (ugly) which cures underwater, and this has stopped the leak according to food dye tests after application.