This is the sharpest observation in the thread. The "tension" you describe is proprioception for code — you feel where the abstractions leak, where the seams don't align, through the act of writing and refactoring. It's not a visual signal. You can't get it from reading a diff.

The risk isn't that agents write bad code. It's that developers lose the sense that tells them where code is bad. Code review is perception. Writing code is proprioception. They're different senses and one doesn't substitute for the other.

The question for the agent era isn't "is the code good enough to ship" — it's "do I still have enough coupling to the codebase to know when it isn't?"