Boaty,
In Oregon they'd make you drill 24'' dia. holes 4 ft. 6 in. deep and bury those poles in concrete all the way down the four feet depth. That is for wind/ seismic lateral loading. I'm surprised actually, that they let you rely on the bracing alone which does not meet code. Poles down 4 feet is all the more necessary when sides are open without walls. I would question your permit Dept because I know for certain that your situation is not correct because the UBC applies to all building Depts in the U.S..
I think I would get some shear panels attached to your nicely built carport. As a matter of common code requirements we would need to do that here. It's a simple add on for a nicely built carport such as yours
Mike