My winter project is rebuilding a Boxster alternator...
https://986forum.com/forums/performance-technical-chat/87604-rebuilding-alternator.html
As mentioned my alternator pulley was frozen solid, it should turn in one direction and free-wheel in the other. I think it is worth verifying this from time to time as a jammed pulley will cause wear and tear on the alternator and the serpentine belt, I would image. My friend Newart, who recently bought a Cayman to replace his Boxster, had his serpentine belt come off and discovered that the pulley was coming apart, so pulley problem is not rare.