Replaced v-brake pads too late - how to check if rim is damaged? I've just noticed that replacing the brake pads was overdue. The metal of the brake shoe started scratching the rim already some time probably (sorry, I know it hurts to read that...).

How to decide if the rim has been damaged permanently?

Edit: Judging with naked eye, I'd say rims are clearly concave. But not only for the rear wheel, also on the front wheel. That means I have to replace them?
One way to check is placing a straight edge, for example a ruler, against the braking surface. If the surface is worn enough to be concave, there will be a visible gap in the middle. 

Small scratches are not a problem, as already mentioned in a comment, many rims have pre-machined grooves to serve as wear indicators and even these do not cause any structural problems.