Hand pie
A hand pie is a fully sealed, single-portion pie built to be eaten from the hand, with pastry sturdy enough to survive a lunchbox.
The engineering constraint is the seal: a thick filling, a clean egg-washed border, a firm crimp, and a vent are what keep the filling inside where it belongs.
The form shows up everywhere workers needed lunch: the Cornish pasty, the Jamaican patty, the empanada, and the curry puff are all hand pies by different names.