If you're on a Mac working on a linux docker containers, your Docker engine is already running a VM (and a linux VM doesn't need one). So you're still only "one VM away" from the real environment. Most IDEs support directly working in the VM via SSH if you need to inspect the code.

You then run --dangerously-skip-permissions and do all changes via PRs. I have been running this combined with workmux [0] for a couple of months and highly recommend it. You can one-shot several whole PRs concurrently with this setup.

The reason it beats a cloud VM is because when you're running multiple concurrent copies of all containers in a project, it quickly eats up memory. Running a cloud VM 24/7 with high enough memory is expensive.

0. https://github.com/raine/workmux

I see the power and am considering Max but 5x cost is difficult to swallow. Just doing this for a lark, not professionally.

  > So now you need Docker-in-Docker, which means --privileged mode, which defeats the entire purpose of sandboxing.
  > That means trading “Claude might mess up my filesystem” for “Claude has root-level access to my container runtime.”

On both Linux and MacOS, use this:

  # Build 'claude' VM and Docker context
  
  $ colima start --profile claude --vm-type=qemu
  $ docker context create claude --docker "host=unix://$HOME/.colima/claude/docker.sock"
  $ docker context use claude
  
  # Start DinD, pass through ports 8080 and 8443, and mount one host directory (for a Git repo)
  
  $ docker run -d --name dind-lab --privileged -e DOCKER_TLS_CERTDIR= -v dind-lab-data:/var/lib/docker \
    -p 8080:8080 -p 8443:8443 -v /home/MYUSER/GITDIR:/mnt/host/home/MYUSER/GITDIR \
    docker:27-dind
  $ docker run --rm -it -e DOCKER_HOST=tcp://127.0.0.1:2375 \
    -p 8080:8080 -p 8443:8443 -v /mnt/host/home/MYUSER/GITDIR:/home/MYUSER/GITDIR \
    ubuntu:24.04 bash

  # Or if you don't want to pass-through ports w/ DinD twice, use its network namespace directly
  #  ( docker run --rm -it -e DOCKER_HOST=tcp://127.0.0.1:2375 --network container:dind-lab .... )

You could do rootless Docker/Podman, but there's a lot of broken stuff to deal with that will just distract the AI.

[1]: https://github.com/nikvdp/cco [2]: https://code.claude.com/docs/en/sandboxing

IMO, if you are not running in the dangerous mode then you are really missing out on one of the best aspects of claude code- its ability to iterate. If you have to confirm each iteration then it's just not practical.