feat(backend): default to smolmachines

tests/integration/test_sandbox_escape.py

@@ -11,8 +11,9 @@ asserts each one is blocked:
   5. Secret exfil via README link pushed through git-gate
 
 The suite is backend-agnostic — it goes through `get_bottle_backend()`
-so a future smolmachines backend can be tested by setting
-`BOT_BOTTLE_BACKEND=smolmachines` without touching this file.
+so smolmachines can be tested by setting `BOT_BOTTLE_BACKEND=smolmachines`.
+When unset, this integration test pins Docker explicitly to preserve
+the Docker-backed CI path.
 
 PRD 0022 chunk 1 (this commit): fixture + setUpClass +
 tearDownClass + preflight tool check. Attack tests land in
@@ -146,7 +147,7 @@ class TestSandboxEscape(unittest.TestCase):
 
         cls._stage_dir = Path(tempfile.mkdtemp(prefix="sandbox-escape-stage."))
         try:
-            backend = get_bottle_backend()
+            backend = get_bottle_backend(backend_name)
             plan = backend.prepare(spec, stage_dir=cls._stage_dir)
             cls._identity = plan.slug
 

tests/integration/test_sidecar_bundle_compose.py

@@ -56,7 +56,7 @@ class TestSidecarBundleCompose(unittest.TestCase):
         stage_dir = Path(tempfile.mkdtemp(prefix="cb-bundle-smoke."))
         try:
             with patch.dict(os.environ, {"BOT_BOTTLE_SIDECAR_BUNDLE": "1"}):
-                backend = get_bottle_backend()
+                backend = get_bottle_backend("docker")
                 spec = BottleSpec(
                     manifest=_manifest(),
                     agent_name="demo",

tests/unit/test_backend_selection.py

@@ -32,10 +32,10 @@ class TestGetBottleBackend(unittest.TestCase):
             b = get_bottle_backend()
         self.assertEqual("smolmachines", b.name)
 
-    def test_default_docker(self):
+    def test_default_smolmachines(self):
         with patch.dict(os.environ, {}, clear=True):
             b = get_bottle_backend()
-        self.assertEqual("docker", b.name)
+        self.assertEqual("smolmachines", b.name)
 
     def test_unknown_dies(self):
         with patch.object(backend_mod, "die", side_effect=SystemExit("die")):

tests/unit/test_cli_start_backend_flag.py

@@ -39,7 +39,7 @@ class TestStartBackendFlag(unittest.TestCase):
         self.assertEqual("smolmachines", args.backend)
         self.assertEqual("researcher", args.name)
 
-    def test_flag_default_none_means_env_or_docker(self):
+    def test_flag_default_none_means_env_or_default_backend(self):
         args = self._build_parser().parse_args(["researcher"])
         self.assertIsNone(args.backend)
 

tests/unit/test_smolmachines_util.py

@@ -85,6 +85,7 @@ class TestPreflight(unittest.TestCase):
             msg = captured.getvalue()
             self.assertIn("smolvm", msg)
             self.assertIn("smolmachines.com/install.sh", msg)
+            self.assertIn("BOT_BOTTLE_BACKEND=docker", msg)
 
 
 if __name__ == "__main__":