fix(runtime): harden connector lifecycle

tests/unit_tests/box/test_box_connector.py

@@ -1,11 +1,13 @@
 from __future__ import annotations
 
+import asyncio
 from types import SimpleNamespace
 from unittest.mock import AsyncMock, Mock
 
 import pytest
 
 from langbot_plugin.box.client import ActionRPCBoxClient
+from langbot.pkg.box import connector as connector_module
 from langbot.pkg.box.connector import BoxRuntimeConnector
 
 
@@ -122,3 +124,95 @@ async def test_box_runtime_connector_cleans_partial_transport_on_connect_failure
 
     assert connector._stop_transport.await_count == 2
     connector._close_managed_subprocess.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+async def test_box_stdio_connection_does_not_capture_unconsumed_stderr(
+    monkeypatch: pytest.MonkeyPatch,
+):
+    monkeypatch.setattr('langbot.pkg.utils.platform.get_platform', lambda: 'linux')
+    monkeypatch.setattr('langbot.pkg.utils.platform.standalone_box', False)
+    created = {}
+
+    class FakeHandler:
+        def __init__(self, connection):
+            self.release = asyncio.Event()
+
+        async def call_action(self, action, data):
+            return None
+
+        async def run(self):
+            await self.release.wait()
+
+        async def close(self):
+            self.release.set()
+
+    class FakeController:
+        def __init__(self, **kwargs):
+            created.update(kwargs)
+            self.process = SimpleNamespace(returncode=0)
+
+        async def run(self, callback):
+            await callback(object())
+
+        async def close(self):
+            return None
+
+    monkeypatch.setattr(connector_module, 'Handler', FakeHandler)
+    monkeypatch.setattr(
+        'langbot_plugin.runtime.io.controllers.stdio.client.StdioClientController',
+        FakeController,
+    )
+    connector = BoxRuntimeConnector(make_app(Mock()))
+
+    await connector.initialize()
+
+    assert created['capture_stderr'] is False
+    assert connector._handler is not None
+    await connector.aclose()
+
+
+@pytest.mark.asyncio
+async def test_box_disconnect_notifies_once_and_clears_handler(
+    monkeypatch: pytest.MonkeyPatch,
+):
+    monkeypatch.setattr('langbot.pkg.utils.platform.get_platform', lambda: 'linux')
+    monkeypatch.setattr('langbot.pkg.utils.platform.standalone_box', False)
+    disconnect = AsyncMock()
+
+    class FakeHandler:
+        def __init__(self, connection):
+            pass
+
+        async def call_action(self, action, data):
+            return None
+
+        async def run(self):
+            return None
+
+        async def close(self):
+            return None
+
+    class FakeController:
+        def __init__(self, **kwargs):
+            self.process = SimpleNamespace(returncode=0)
+
+        async def run(self, callback):
+            await callback(object())
+
+        async def close(self):
+            return None
+
+    monkeypatch.setattr(connector_module, 'Handler', FakeHandler)
+    monkeypatch.setattr(
+        'langbot_plugin.runtime.io.controllers.stdio.client.StdioClientController',
+        FakeController,
+    )
+    connector = BoxRuntimeConnector(make_app(Mock()), runtime_disconnect_callback=disconnect)
+
+    await connector.initialize()
+    await asyncio.sleep(0)
+
+    disconnect.assert_awaited_once_with(connector)
+    assert connector._handler is None
+    await connector.aclose()