If I was negative and then suddenly developed antibodies, I would watch for inflammation, clotting, stroke, etc. symptoms very carefully for about a month. Those can happen even to people who had asymptomatic cases. After that month, you are really in the clear.

I think a positive antibody test actually does mean you are unlikely to catch it again. Even if your antibody level drops over time, your memory B cells will know how to crank out more antibody very quickly. It would be a good idea to avoid being exposed to heavy viral loads and mutated strains, but I would not hesitate to work in a normal job or go food shopping. Eating in restaurants, probably no. Takeout, probably yes.

One thing you might want to do is to donate plasma to help somebody else. I would still wear a mask in public, just to serve as a good example to others. If I was single, would I hook up with strangers? I think I would restrict that to people with positive antibody tests as well. Kind of like hook-ups in the age of AIDS without PReP.