fix(smolmachines): build sidecar image before launch

bot_bottle/backend/smolmachines/launch.py

@@ -142,6 +142,7 @@ def launch(
         # daemons the agent needs to reach from the smolvm guest.
         bundle_spec = _bundle_launch_spec(plan, network, loopback_ip)
         token_env = _resolve_token_env(plan, os.environ)
+        _bundle.ensure_bundle_image(bundle_spec.image)
         _bundle.start_bundle(bundle_spec, env={**os.environ, **token_env})
         stack.callback(_bundle.stop_bundle, plan.slug)
 

bot_bottle/backend/smolmachines/sidecar_bundle.py

@@ -29,7 +29,14 @@ from pathlib import Path
 from typing import Sequence
 
 from ...log import die, warn
-from ..docker.sidecar_bundle import SIDECAR_BUNDLE_IMAGE
+from ..docker import util as docker_mod
+from ..docker.sidecar_bundle import (
+    SIDECAR_BUNDLE_DOCKERFILE,
+    SIDECAR_BUNDLE_IMAGE,
+)
+
+
+_REPO_DIR = str(Path(__file__).resolve().parent.parent.parent.parent)
 
 
 def bundle_network_name(slug: str) -> str:
@@ -85,6 +92,21 @@ class BundleLaunchSpec:
     publish_host_ip: str = "127.0.0.1"
 
 
+def ensure_bundle_image(image: str = SIDECAR_BUNDLE_IMAGE) -> None:
+    """Build the sidecar bundle image before `docker run`.
+
+    The Docker backend gets this for free from compose's `build:`
+    stanza. smolmachines starts the bundle with plain `docker run`,
+    so without an explicit build a first launch tries to pull the
+    local-only `bot-bottle-sidecars:latest` tag from a registry.
+    """
+    docker_mod.build_image(
+        image,
+        _REPO_DIR,
+        dockerfile=SIDECAR_BUNDLE_DOCKERFILE,
+    )
+
+
 def create_bundle_network(network_name: str, subnet: str, gateway: str) -> None:
     """`docker network create` with an explicit subnet + gateway
     so the bundle's `--ip` lands on the address the Smolfile's