Here's another quick sketch of the top view of the wire to demonstrate the Z. The first shows the gate partially open. The lower one shows the gate closed. The Z shaped wire is attached to the gate from the front, is bent around the gate itself then folded to reach the other post when closed.
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It doesn't provide that much "real" security except for very small animals. What it does do is create the appearance of closure, so predators aren't tempted to attack the weak spot.
Another way to approach the gate security could be to fasten (screw or bolt) a 1x4 or 1x6 (depending on the actual gap) to the gate post. That would form a true barrier on the back side of the opening but would allow the gate to open outward. That's how normal doors seal, with some sort of trim around the edges.
Here's what that would look like on the hinge side. The trim touches the gate but isn't fastened to it, only the gatepost around it. Another board on the back of the gatepost of the open side would work the same.
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