Isolation, file ownership and cleanup: the boring half of running coding agents in parallel on Windows

Someone left a comment on my last post that was a better outline than the post was:

Parallel agents are only practical when the workspace boundaries are boring and explicit. On Windows especially, I would care less about the launch trick and more about isolation, logs, file ownership, and cleanup after failed runs.

That is Alex Shev, and he is right. Four agents in a pane grid is the screenshot. The four things he listed are what decide whether you are still using the setup in a month.

I work on NestMux, so I have a stake in this. Most of what is below is plain Windows and plain git, and the commands run the same whether or not you use it. Where I describe a decision we made, I say so, and I say where it still falls short.

Isolation is not one HOME variable