What happens if you clear the upgrade or standby list but aren't at the gate to pick up a new boarding pass when the agent calls your name:

1. Does your seat automatically change in the AA app, so you get the new seat and don't need to do anything more (i.e., if you're hoping to go standby or clear the upgrade list, it doesn't matter if you're at the gate or not),

OR

2. Do you get a new seat only if you come to the podium when the gate agent calls your name (i.e., if you're not at the gate, you'll lose your upgrade or standby seat)?

I'm not new; I've been flying AA and US for 20+ years. However, I can't tell what happens in this situation. Sometimes I go standby on an earlier flight, and as I'm in flight on the earlier flight, I check the AA app and see that I've cleared the upgrade list on my original flight and my seat has changed--even though I'm no longer on that flight.

Thanks.