I don't aggree 100% with the OP on this suggestion. I use an agent to build a feature, then if it's significantly important enough I will have it open a PR that I can review traditionally after testing.
Copying and pasting code may work but when the agent is right there and can go read a file on its own I don't see the point in copying and pasting this way.
Really though, like another comment said, I'm probably working on different problems than antirez, so your mileage may vary.
Is there any good tooling for making this part easier and less error prone, short of going to a full-fledged agent system?