Nice! We love hearing about personal setups to solve these same problems. One difference between boxes.dev and your setup is that we spawn an exact copy of the main box for each agent thread, so it's totally isolated. But doing parallel agents on one box can definitely work too, it's just more work to configure a project for it.

Our bet is that a lot of people will want something prebuilt, and that the last-mile UX for making a good coding workspace (including code review, etc) is actually nontrivial, especially at companies.