v0.4.0

Added

• runtime/engine — checkpoint/restore via an optional
  CheckpointRuntime sub-interface plus a new Podman backend that
  implements it. Docker's checkpoint/restore is broken on current
  engines (the netns bind-mount on restore — upstream containerd#12141 /
  moby#37344), so Podman does the full round trip (checkpoint --export
  / restore --import: process + memory + writable rootfs in a portable,
  node-independent archive). Adds runtime.CheckpointRuntime,
  CheckpointSpec/RestoreSpec/CheckpointRef, Capabilities.Checkpoint,
  typed errors (ErrCheckpointUnsupported, CheckpointFailedError,
  RestoreFailedError), Engine.Checkpoint/Engine.Restore (Restore
  returns a fully reattached *Workspace), and
  Engine.CheckpointProject/RestoreProject for multi-service compose
  projects (enumerated by the com.docker.compose.project label). (#98)

Fixed

• compose — Dev Container Feature security metadata (privileged,
  init, capAdd, securityOpt) and entrypoint scripts are now
  applied to docker-compose services, matching the reference
  devcontainers/cli. Previously the metadata was merged into
  ResolvedConfig but never carried onto the service, so features like
  docker-in-docker silently failed on compose-source devcontainers:
  the daemon came up unprivileged and its docker-init.sh entrypoint
  never ran. Feature entrypoints are now chained ahead of the service
  command via a generated wrapper (native and shellout paths), and
  ContainerDetails surfaces Privileged/CapAdd/SecurityOpt from
  inspect. A failed image inspect in the entrypoint-preservation fallback
  now emits a WarnEvent instead of silently dropping the image
  ENTRYPOINT. Image-source (non-compose) entrypoint chaining and
  overrideCommand gating remain follow-ups (#104). (#103)
• compose/podman — orchestrator-driven health probing on Podman.
  Podman runs a container's HEALTHCHECK as root and fires the first
  probe immediately at start (ignoring start_period), which breaks
  privilege-dropping images — e.g. RabbitMQ's rabbitmq-diagnostics
  probe creates a root-owned .erlang.cookie the gosu-dropped uid-999
  server can't read. The compose orchestrator now probes health itself on
  backends that opt in (Podman returns true; Docker and Apple unchanged),
  deferring the first probe until after the service initializes, matching
  Docker. Also fixes multi-service checkpoint/restore. See
  design/compose-native-health.md. (#102)

Changed

• deps — bump github.com/google/go-containerregistry 0.21.6 →
  0.21.7. (#101)
• dev environment / CI — prebuild-based dev environment + CI (#88);
  pin prebuild base to bookworm (#89); use Compose v2 in
  docker-in-docker (#90); skip legacy docker-compose in
  docker-in-docker (#91); pin docker-in-docker to 2.x (#92); add :sha
  image tag and prune stale build intermediates (#93).

Full changelog: v0.3.0...v0.4.0