Level 1: docker-compatible CLI (verbs, flags, loud refusal of isolation
flags the filesystem-only contract cannot honor) — built in session B.
Level 2: OCI image pull, flattened to a rootfs — deferred, stdlib-doable.
Level 3: a daemon speaking the Docker Engine API subset Testcontainers
actually uses (Testcontainers never calls the CLI) — deferred, but the
CLI is built as a thin frontend over the same internal service from the
start. Records the port-mapping crux of host networking and the
unprivileged-netns escape hatch as a future RFC.
Step 21 session B and the werkdock README follow the docker-shaped
semantics: run takes an image, instances correspond to containers.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>