Adds a Freezer ABC (backend/freeze.py) that encapsulates the
stop-commit-mark-preserved flow for all backends, following the same
pattern as BottleBackend. Each backend gets its own Freezer subclass:
DockerFreezer — docker commit
MacosContainerFreezer — container export + image rebuild; prompts
to stop if the container is running
SmolmachinesFreezer — smolvm pack create --from-vm
The base class owns write_committed_image, mark_preserved, and the
resume hint. Subclasses implement _freeze() and optionally override
_export_hint() for migration instructions.
Freezer.commit(agent, bottle) is the primary entry point for use
within a live launch context. Freezer.commit_slug(slug) is a
convenience wrapper for cmd_commit, which no longer branches on
backend names itself.
get_freezer(backend_name) is the factory, analogous to
get_bottle_backend(). CommitCancelled is raised by MacosContainerFreezer
when the user declines the stop prompt; cmd_commit catches it and
returns 0.
`container export` requires the container to be stopped first. When a
running bottle is detected, prompt the user to confirm, stop the
container, then commit. Adds `container_is_running` and
`stop_container` helpers to the macos-container util.
Addresses #240 (comment)
Adds `./cli.py commit [<slug>]` which runs `docker commit` on the
active agent container and stores the resulting image tag in per-bottle
state. The next `./cli.py resume <slug>` automatically boots from the
committed snapshot instead of rebuilding from the Dockerfile, preserving
all in-container state across restarts and migrations.
- bottle_state: add write_committed_image / read_committed_image helpers
- docker/util: add commit_container wrapper around `docker commit`
- docker/launch: check for a committed image before the Dockerfile build
step; fall back to normal build if the image is absent from the daemon
- cli/commit: new command with interactive slug picker; errors clearly on
non-Docker backends
- 50 new unit tests covering all paths
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>