That's pretty much the flow I formalized here: https://github.com/nvidia/rumpelpod

Instead of generating patches, this exposes the agent's checkout as a git remote though.

Most similar tools (and I believe your tooling as well?) bind-mount the repository checkout from the host into the container. This was always a source of user and permission errors for me, since you have to align the user ids inside and outside the container. Also, some build tools don't like it when the repo is on a different filesystem (bind mount vs container root) than the rest of the system. So I made rumpelpod just bake the repo checkout into the base image that the container is launched from, and since then I haven't had any issues like this.

For giving the agent access to a docker daemon I found sysbox to work very well. Usually the advice for nested containers is to pass in the host's docker socket into the container. But that would break the outer container isolation completely, since access to the docker daemon is equivalent to root access on the host. With sysbox it's trivial to run a nested docker instance inside the outer container. I haven't tried it with podman yet though. In theory sysbox is just another OCI runtime, but there's probably some tinkering required to get it to work.