feat(cli): add commit command to snapshot running bottle state

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>

bot_bottle/backend/docker/launch.py

@@ -47,6 +47,7 @@ from ...bottle_state import (
     bottle_state_dir,
     egress_state_dir,
     git_gate_state_dir,
+    read_committed_image,
 )
 from .compose import (
     bottle_plan_to_compose,
@@ -91,12 +92,22 @@ def launch(
         )
 
     try:
-        # Step 1: agent image build. Sidecar images get built lazily by
-        # `docker compose up` via the renderer's `build:` directives.
-        docker_mod.build_image(
-            plan.image, _REPO_DIR,
-            dockerfile=plan.dockerfile_path,
-        )
+        # Step 1: agent image. Use a committed snapshot when one exists
+        # and is present in the local daemon; otherwise build from the
+        # Dockerfile. Sidecar images get built lazily by `docker compose
+        # up` via the renderer's `build:` directives.
+        committed = read_committed_image(plan.slug)
+        if committed and docker_mod.image_exists(committed):
+            info(f"using committed image {committed!r}")
+            plan = dataclasses.replace(
+                plan,
+                agent_provision=dataclasses.replace(plan.agent_provision, image=committed),
+            )
+        else:
+            docker_mod.build_image(
+                plan.image, _REPO_DIR,
+                dockerfile=plan.dockerfile_path,
+            )
 
         internal_network = network_mod.network_name_for_slug(plan.slug)
         egress_network = network_mod.network_egress_name_for_slug(plan.slug)

bot_bottle/backend/docker/util.py

@@ -152,6 +152,21 @@ def build_image(ref: str, context: str, *, dockerfile: str = "") -> None:
 #         )
 
 
+def commit_container(container_name: str, image_tag: str) -> None:
+    """Run `docker commit <container_name> <image_tag>` to snapshot the
+    running container's filesystem state as a local Docker image."""
+    result = subprocess.run(
+        ["docker", "commit", container_name, image_tag],
+        capture_output=True, text=True, check=False,
+    )
+    if result.returncode != 0:
+        die(
+            f"docker commit {container_name!r} → {image_tag!r} failed: "
+            f"{(result.stderr or '').strip() or '<no stderr>'}"
+        )
+    info(f"committed {container_name!r} → {image_tag!r}")
+
+
 def image_id(ref: str) -> str:
     """Return the content-addressed image ID (e.g.
     `sha256:abcd...`) for `ref`. The smolmachines backend keys its

bot_bottle/bottle_state.py

@@ -43,6 +43,7 @@ from . import supervise as _supervise
 # Directory layout: ~/.bot-bottle/state/<identity>/...
 _STATE_SUBDIR = "state"
 _PER_BOTTLE_DOCKERFILE_NAME = "Dockerfile"
+_COMMITTED_IMAGE_NAME = "committed-image"
 _TRANSCRIPT_SUBDIR = "transcript"
 # Per-sidecar scratch subdirs. PRD 0018 chunk 2: bind-mount sources
 # live here so chunk 3's `docker compose up` can find them at stable
@@ -179,6 +180,32 @@ def write_per_bottle_dockerfile(identity: str, content: str) -> Path:
     return p
 
 
+def committed_image_path(identity: str) -> Path:
+    return bottle_state_dir(identity) / _COMMITTED_IMAGE_NAME
+
+
+def write_committed_image(identity: str, image_tag: str) -> Path:
+    """Persist the committed image tag for `identity`. The next
+    `cli.py resume <identity>` will boot from this image instead of
+    rebuilding from the Dockerfile."""
+    path = committed_image_path(identity)
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(image_tag.strip() + "\n")
+    path.chmod(0o644)
+    return path
+
+
+def read_committed_image(identity: str) -> str | None:
+    """Return the committed image tag for `identity`, or None if no
+    commit has been recorded. Used by the Docker launch step to skip
+    the Dockerfile build when a committed snapshot exists."""
+    path = committed_image_path(identity)
+    if not path.is_file():
+        return None
+    tag = path.read_text().strip()
+    return tag or None
+
+
 def per_bottle_image_tag(identity: str) -> str:
     """Image tag for a rebuilt bottle. Distinct from the base
     bot-bottle-claude:latest so per-bottle rebuilds don't collide in
@@ -314,6 +341,7 @@ __all__ = [
     "bottle_state_dir",
     "cleanup_state",
     "clear_preserve_marker",
+    "committed_image_path",
     "egress_state_dir",
     "git_gate_state_dir",
     "is_preserved",
@@ -323,9 +351,11 @@ __all__ = [
     "per_bottle_dockerfile_path",
     "per_bottle_image_tag",
     "preserve_marker_path",
+    "read_committed_image",
     "read_metadata",
     "supervise_state_dir",
     "transcript_snapshot_dir",
+    "write_committed_image",
     "write_metadata",
     "write_per_bottle_dockerfile",
 ]

bot_bottle/cli/__init__.py

@@ -1,6 +1,6 @@
 """Main CLI dispatcher.
 
-Commands: cleanup, edit, info, init, list, resume, start, supervise
+Commands: cleanup, commit, edit, info, init, list, resume, start, supervise
 """
 
 from __future__ import annotations
@@ -12,6 +12,7 @@ from ..manifest import ManifestError
 from ._common import PROG
 from . import list as _list_mod
 from .cleanup import cmd_cleanup
+from .commit import cmd_commit
 from .edit import cmd_edit
 from .info import cmd_info
 from .init import cmd_init
@@ -23,6 +24,7 @@ cmd_list = _list_mod.cmd_list
 
 COMMANDS = {
     "cleanup": cmd_cleanup,
+    "commit": cmd_commit,
     "edit": cmd_edit,
     "info": cmd_info,
     "init": cmd_init,
@@ -37,6 +39,7 @@ def usage() -> None:
     sys.stderr.write(f"usage: {PROG} <command> [args...]\n\n")
     sys.stderr.write("Commands:\n")
     sys.stderr.write("  cleanup   stop and remove all active bot-bottle containers\n")
+    sys.stderr.write("  commit    snapshot a running bottle's container state to a Docker image\n")
     sys.stderr.write("  edit      open an agent in vim for editing\n")
     sys.stderr.write("  info      print env, skills, and prompt details for a named agent\n")
     sys.stderr.write("  init      interactively create a new agent and add it to bot-bottle.json\n")

bot_bottle/cli/commit.py

@@ -0,0 +1,75 @@
+"""commit: freeze a running Docker bottle's container state to a local image.
+
+Runs `docker commit <container> <image-tag>` on the active agent
+container and stores the image tag in per-bottle state so the next
+`./cli.py resume <slug>` boots from that snapshot instead of
+rebuilding from the Dockerfile.
+
+Only the Docker backend is supported. Smolmachines VMs have no
+container-level commit API in the current smolvm CLI surface.
+"""
+
+from __future__ import annotations
+
+import argparse
+
+from ..backend import enumerate_active_agents
+from ..backend.docker.util import commit_container
+from ..bottle_state import mark_preserved, read_metadata, write_committed_image
+from ..log import die, info
+from ._common import PROG
+from . import tui
+
+
+_COMMITTED_IMAGE_PREFIX = "bot-bottle-committed-"
+_DOCKER_BACKENDS = {"docker", ""}
+
+
+def _committed_image_tag(slug: str) -> str:
+    return f"{_COMMITTED_IMAGE_PREFIX}{slug}:latest"
+
+
+def _agent_container_name(slug: str) -> str:
+    return f"bot-bottle-{slug}"
+
+
+def cmd_commit(argv: list[str]) -> int:
+    parser = argparse.ArgumentParser(prog=f"{PROG} commit", add_help=True)
+    parser.add_argument(
+        "slug",
+        nargs="?",
+        default=None,
+        help=(
+            "bottle slug from `cli.py list active` "
+            "(omit to pick interactively)"
+        ),
+    )
+    args = parser.parse_args(argv)
+
+    slug = args.slug
+    if slug is None:
+        active = enumerate_active_agents()
+        if not active:
+            die("no active bottles; start one with `./cli.py start`")
+        choices = [a.slug for a in active]
+        slug = tui.filter_select(choices, title="Select bottle to commit")
+        if slug is None:
+            return 0
+
+    metadata = read_metadata(slug)
+    backend = metadata.backend if metadata else ""
+    if backend not in _DOCKER_BACKENDS:
+        die(
+            f"commit is only supported for the docker backend; "
+            f"bottle {slug!r} uses {backend!r}"
+        )
+
+    container = _agent_container_name(slug)
+    image_tag = _committed_image_tag(slug)
+
+    commit_container(container, image_tag)
+    write_committed_image(slug, image_tag)
+    mark_preserved(slug)
+    info(f"to resume from this snapshot: ./cli.py resume {slug}")
+    info(f"to export for migration:      docker save {image_tag} -o {slug}.tar")
+    return 0