It’s all Docker images under the covers, so our devs also have the option of downloading and running that image locally instead of in a Codespaces VM. That was always possible before, of course, but Codespaces gave us the impetus to invest the effort in Dockerizing the dev environment more rigorously.

Oh, that is cool. Sounds like a nice mix actually. Local vim, browsers, known system. And container with mount-bind to actually compile and run stuff in.