test: add unit tests to pass diff-coverage gate (91%)

Cover the new production lines added on this branch:

- cli/__init__: MissingEnvVarError maps to return 1
- cli/start: no-agents-defined path, prepare_with_preflight calls
  render_preflight, _text_render_preflight backend name output
- env: resolve_env raises MissingEnvVarError for missing interpolated var
- smolmachines/launch: _proxy_host Linux/non-Linux branches,
  _discover_urls git-gate host and supervise URL stamping

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_cli_dispatch.py

@@ -64,6 +64,15 @@ class TestMainDispatch(unittest.TestCase):
             main(["x", "a", "b"])
         self.assertEqual([["a", "b"]], seen)
 
+    def test_missing_env_var_error_maps_to_1(self) -> None:
+        from bot_bottle.errors import MissingEnvVarError
+
+        def boom(_rest: list[str]) -> int:
+            raise MissingEnvVarError("MY_VAR", "MY_VAR is not set")
+
+        with patch.dict(climod.COMMANDS, {"x": boom}), patch("sys.stderr", io.StringIO()):
+            self.assertEqual(1, main(["x"]))
+
     def test_manifest_error_maps_to_1(self) -> None:
         def boom(_rest: list[str]) -> int:
             raise ManifestError("bad manifest")

tests/unit/test_cli_start_headless.py

@@ -9,6 +9,7 @@ is created.
 
 from __future__ import annotations
 
+import io
 import os
 import unittest
 from unittest.mock import MagicMock, patch
@@ -184,5 +185,55 @@ class TestCmdStartHeadless(unittest.TestCase):
         self.assertEqual("docker", self._launch_mock.call_args[1]["backend_name"])
 
 
+class TestPrepareWithPreflight(unittest.TestCase):
+    """prepare_with_preflight calls render_preflight with the plan and backend name."""
+
+    def test_render_preflight_called(self):
+        from pathlib import Path
+        mock_backend = MagicMock()
+        mock_plan = MagicMock()
+        mock_backend.prepare.return_value = mock_plan
+        mock_backend.name = "test-backend"
+        render = MagicMock()
+
+        with patch("bot_bottle.cli.start.get_bottle_backend", return_value=mock_backend), \
+             patch("bot_bottle.cli.start._identity_from_plan", return_value="id"), \
+             patch("bot_bottle.cli.start.info"):
+            start_mod.prepare_with_preflight(
+                MagicMock(),
+                stage_dir=Path("/tmp"),
+                render_preflight=render,
+                prompt_yes=MagicMock(),
+                dry_run=True,
+            )
+
+        render.assert_called_once_with(mock_plan, "test-backend")
+
+
+class TestNoAgentsDefined(unittest.TestCase):
+    """cmd_start prints an error and returns 1 when the manifest has no agents."""
+
+    def test_no_agents_defined_returns_1(self):
+        manifest = _make_manifest([], [])
+        with patch(
+            "bot_bottle.cli.start.ManifestIndex.resolve", return_value=manifest
+        ), patch("sys.stderr", io.StringIO()) as err:
+            rc = start_mod.cmd_start([])
+        self.assertEqual(1, rc)
+        self.assertIn("no agents defined", err.getvalue())
+
+
+class TestTextRenderPreflight(unittest.TestCase):
+    """_text_render_preflight returns a renderer that prints the backend name."""
+
+    def test_backend_name_in_output(self):
+        render = start_mod._text_render_preflight()
+        plan = MagicMock()
+        with patch("bot_bottle.cli.start._manifest_to_yaml", return_value=""), \
+             patch("sys.stderr", io.StringIO()) as err:
+            render(plan, "my-backend")
+        self.assertIn("my-backend", err.getvalue())
+
+
 if __name__ == "__main__":
     unittest.main()

tests/unit/test_manifest_validation.py

@@ -9,7 +9,11 @@ from __future__ import annotations
 
 import unittest
 
-from bot_bottle.manifest import ManifestBottle, ManifestIndex
+from unittest.mock import patch
+
+from bot_bottle.env import resolve_env
+from bot_bottle.errors import MissingEnvVarError
+from bot_bottle.manifest import Manifest, ManifestBottle, ManifestIndex
 from bot_bottle.manifest_agent import (
     ManifestAgent,
     ManifestAgentProvider,
@@ -238,5 +242,26 @@ class TestEagerIndexLookups(unittest.TestCase):
         self.assertIsNone(m.git_identity_summary())
 
 
+class TestResolveEnv(unittest.TestCase):
+    """resolve_env raises MissingEnvVarError when an interpolated entry's
+    host var is unset."""
+
+    def _manifest(self, env_dict: dict[str, str]) -> Manifest:
+        idx = ManifestIndex.from_json_obj({
+            "bottles": {"dev": {"env": env_dict}},
+            "agents": {"demo": {"bottle": "dev"}},
+        })
+        return idx.load_for_agent("demo")
+
+    def test_missing_interpolated_host_var_raises(self):
+        manifest = self._manifest({"API_KEY": "${HOST_API_KEY}"})
+        with patch.dict("os.environ", {}, clear=False):
+            import os
+            os.environ.pop("HOST_API_KEY", None)
+            with self.assertRaises(MissingEnvVarError) as cm:
+                resolve_env(manifest)
+        self.assertIn("HOST_API_KEY", str(cm.exception))
+
+
 if __name__ == "__main__":
     unittest.main()

tests/unit/test_smolmachines_provision.py

@@ -506,5 +506,54 @@ class TestProvisionGitUser(unittest.TestCase):
         self.assertIn("bot@example.com", calls[0][0])
 
 
+class TestProxyHost(unittest.TestCase):
+    """_proxy_host returns the bridge gateway on Linux and the loopback
+    alias on other platforms."""
+
+    def test_linux_returns_bundle_gateway(self):
+        plan = _plan()
+        with patch("bot_bottle.backend.smolmachines.launch.platform.system",
+                   return_value="Linux"):
+            result = _launch._proxy_host(plan, "127.0.0.16")
+        self.assertEqual(plan.bundle_gateway, result)
+
+    def test_non_linux_returns_loopback(self):
+        plan = _plan()
+        with patch("bot_bottle.backend.smolmachines.launch.platform.system",
+                   return_value="Darwin"):
+            result = _launch._proxy_host(plan, "127.0.0.16")
+        self.assertEqual("127.0.0.16", result)
+
+
+class TestDiscoverUrls(unittest.TestCase):
+    """_discover_urls stamps git-gate host + supervise URL into the plan."""
+
+    def test_git_gate_host_set_when_upstreams_present(self):
+        plan = _plan()
+        plan = replace(
+            plan,
+            git_gate_plan=replace(
+                plan.git_gate_plan,
+                upstreams=(GitGateUpstream(
+                    name="bot-bottle",
+                    upstream_url="ssh://git@host/repo.git",
+                    upstream_host="host",
+                    upstream_port="22",
+                    identity_file="/tmp/key",
+                    known_host_key="",
+                ),),
+            ),
+        )
+        with patch.object(_launch._bundle, "bundle_host_port", return_value="9420"):
+            stamped = _launch._discover_urls(plan, "127.0.0.16")
+        self.assertEqual("127.0.0.16:9420", stamped.agent_git_gate_host)
+
+    def test_supervise_url_set_when_supervise_present(self):
+        plan = _plan(supervise=True)
+        with patch.object(_launch._bundle, "bundle_host_port", return_value="55556"):
+            stamped = _launch._discover_urls(plan, "127.0.0.16")
+        self.assertEqual("http://127.0.0.16:55556/", stamped.agent_supervise_url)
+
+
 if __name__ == "__main__":
     unittest.main()