Where agents will potentially become extremely useful/dystopian is when they just silently watch your entire screen at all times. Isolated, encrypted and local preferably.
Imagine it just watching you coding for months, planning stuff, researching things, it could potentially give you personal and professional advice from deep knowledge about you. "I noticed you code this way, may i recommend this pattern" or "i noticed you have signs of this diagnosis from the way you move your mouse and consume content, may i recommend this lifestyle change".
I wonder how long before something like that is feasible, ie a model you install that is constantly updated, but also constantly merged with world data so it becomes more intelligent on two fronts, and can follow as hardware and software advances over the years.
Such a model would be dangerously valuable to corporations / bad actors as it would mirror your psyche and remember so much about you - so it would have to be running with a degree of safety i can't even imagine, or you'd be cloneable or loose all privacy.