Remove the supervise flag; supervise every bottle

Issue #249: in practice the per-bottle `supervise` flag was never
turned off — all bottles should be supervised. Remove the manifest
flag and make the supervise sidecar unconditional, mirroring egress.

- Reject `supervise:` as a removed bottle key with a migration hint.
- Drop the `supervise` field from ManifestBottle and the extends merge.
- prepare_supervise always returns a SupervisePlan; the plan type is
  now non-optional and the per-backend `is None` guards are gone, so
  the supervise daemon, current-config mount, aliases, and MCP
  registration always render.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YcU7nerbg8cVj9R4EkpfLJ

tests/unit/test_macos_container_launch.py

@@ -15,6 +15,7 @@ from bot_bottle.backend.macos_container import launch
 from bot_bottle.backend.macos_container.bottle_plan import MacosContainerBottlePlan
 from bot_bottle.egress import EgressPlan
 from bot_bottle.git_gate import GitGatePlan
+from bot_bottle.supervise import SupervisePlan
 from bot_bottle.manifest import ManifestIndex
 
 _MANIFEST = ManifestIndex.from_json_obj({
@@ -27,7 +28,6 @@ def _plan(
     *,
     stage_dir: Path,
     git: bool = False,
-    supervise: bool = False,
     agent_git_gate_url: str = "",
     agent_supervise_url: str = "",
 ) -> MacosContainerBottlePlan:
@@ -67,10 +67,8 @@ def _plan(
         )
     else:
         git_gate_plan = SimpleNamespace(upstreams=())
-    supervise_plan = (
-        SimpleNamespace(queue_dir=Path("/state/supervise/queue"))
-        if supervise else None
-    )
+    # Every bottle is supervised (issue #249).
+    supervise_plan = SimpleNamespace(queue_dir=Path("/state/supervise/queue"))
     agent_provision = SimpleNamespace(
         guest_env={"LITERAL": "value"},
         provisioned_env={"CODEX_HOME": "/run/codex-home"},
@@ -101,7 +99,7 @@ class TestMacosContainerLaunchArgv(unittest.TestCase):
         self._tmp.cleanup()
 
     def test_sidecar_argv_uses_egress_network_first_and_explicit_dns(self):
-        plan = _plan(stage_dir=self.stage_dir, supervise=True)
+        plan = _plan(stage_dir=self.stage_dir)
         with patch.object(launch.os, "environ", {
             "BOT_BOTTLE_MACOS_CONTAINER_DNS": "9.9.9.9",
         }):
@@ -172,7 +170,7 @@ class TestMacosContainerLaunchArgv(unittest.TestCase):
     def test_git_gate_daemons_are_ready_gated(self):
         plan = _plan(stage_dir=self.stage_dir, git=True)
         self.assertEqual(
-            ("egress", "git-gate", "git-http"),
+            ("egress", "supervise", "git-gate", "git-http"),
             launch._sidecar_daemons(plan),
         )
         self.assertIn(
@@ -181,7 +179,7 @@ class TestMacosContainerLaunchArgv(unittest.TestCase):
         )
 
     def test_stamp_agent_urls_includes_git_http_when_git_gate_exists(self):
-        plan = _plan(stage_dir=self.stage_dir, git=True, supervise=True)
+        plan = _plan(stage_dir=self.stage_dir, git=True)
         with patch.object(launch.dataclasses, "replace") as replace:
             launch._stamp_agent_urls(plan, "192.168.128.2")
         replace.assert_called_once_with(
@@ -272,7 +270,10 @@ def _build_plan(stage_dir: Path) -> MacosContainerBottlePlan:
         stage_dir=stage_dir,
         git_gate_plan=cast(GitGatePlan, SimpleNamespace(upstreams=())),
         egress_plan=cast(EgressPlan, SimpleNamespace()),
-        supervise_plan=None,
+        supervise_plan=cast(
+            SupervisePlan,
+            SimpleNamespace(queue_dir=Path("/state/supervise/queue")),
+        ),
         agent_provision=AgentProvisionPlan(
             template="claude",
             command="claude",