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Well YMMV (I've seen them fail a few different ways) but personally, my progression was as follows.

-a few months ago (when it was still colder - harder starts, less amperage from battery, heated seats and windshield, more air compressor use, higher loads on alternator) the alternator started to whine after starting.

-whine after start got louder, and more recently I noticed that if you waited for the air compressor to shut off, you could hear most of the whine go away (ie it's load based and it's definitely struggling)

-maybe a month ago I made that thread about the volume lowering and enabling "low power mode" 20 minutes AFTER I started my car, while idling in traffic. That was the big red flag for me.

-about a week after that, while playing with a new scanner at work - I noticed that my charging voltage at idle was 14.4-14.8 - so that is NOT always a sure-fire way to check. These alternators vary their CURRENT output via PWM signal as you know, but the key is that it's current-related. You can have an open voltage of 14.4 with minimal loads and the alternator isn't working very hard. It's possible that when loads are applied AND the unit gets hotter, that's when voltage falls dramatically.

- Monday when I left work in evening it was 85 degrees for the first time in a while, I cranked the front and rear AC blowers to full and was listening to music in stop-go idling traffic (in hindsight, a LOT of load at a low RPM) - about 10 minutes later as the rpms dropped each time I stopped in traffic, I noticed a LOUD whine on rpm decel. Sounded like front right engine bay area.. as I left my windows down I smelled burning electronics smell (from the stories on here of people reconnecting new batteries after they die, everyone mentioned smoke/smell) so I connected the dots and turned everything off. As I said in other thread - pulled into indy lot about 45 min in (on same road I commute on) and decided to make the remaining 20 min run home.

That's when I checked and saw (engine off) 12.5, and 12.4 engine on.. 12 flat with engine on and all HVAC on.

***ENTIRE TIME the vehicle gave me no warnings, errors, codes, dash lights, whatever.. even when idling at 12.05v after I got home. Perhaps there's a time limit before it triggers, or I wasn't at the threshold yet? I'm shocked the OP's vehicle even ran at 10-something volts!

I think the heat and the high loads with low RPM was too much for it. If you're curious, you can get your car warm and throw on front/rear AC on max, front/rear heated windshield glass, and front/rear heated seats. Sit by your front passenger wheel well and listen - maybe with safety glasses.

Also FWIW I had a brand new H9 MTP interstate in my car, so that probably buffered a lot of the loads actually, and prevented major issues - if you've got an older or weaker battery I'd imagine things would be more dramatic.

edit: the delco/remy unit is fine so far, I did notice a slight bearing squeak down there (laying under car while running with that cover off) but I think it was coming from the larger fan belt tensioner pulley located next to it, hard to tell with your face a few inches from that huge fan.

edit2: i read a few people complaining of erratic fan behavior before alternator failures - probably some degree of AC voltage getting into the vehicle past battery and messing with PWM fan signals. I did notice a more defined fan sequence on startup. If you're having issues w/ fan maybe add that to the list above as well.