fix: preserve real cancellation in MCP paths

tests/agent/test_task_cancel.py

@@ -111,6 +111,34 @@ class TestHandleStop:
 
 
 class TestDispatch:
+    @pytest.mark.asyncio
+    async def test_run_logs_and_continues_after_leaked_cancelled_error(self, monkeypatch):
+        loop, bus = _make_loop()
+        loop._connect_mcp = AsyncMock()
+        loop.close_mcp = AsyncMock()
+        loop.auto_compact.check_expired = MagicMock()
+        warnings: list[str] = []
+        calls = 0
+
+        async def consume_once_then_stop():
+            nonlocal calls
+            calls += 1
+            if calls == 1:
+                raise asyncio.CancelledError()
+            loop.stop()
+            raise asyncio.TimeoutError()
+
+        monkeypatch.setattr(bus, "consume_inbound", consume_once_then_stop)
+        monkeypatch.setattr(
+            "nanobot.agent.loop.logger.warning",
+            lambda message, *args, **kwargs: warnings.append(message),
+        )
+
+        await loop.run()
+
+        assert calls == 2
+        assert any("Ignoring leaked CancelledError" in warning for warning in warnings)
+
     def test_exec_tool_not_registered_when_disabled(self):
         from nanobot.agent.tools.shell import ExecToolConfig
         from nanobot.config.schema import ToolsConfig

tests/tools/test_mcp_tool.py

@@ -144,6 +144,35 @@ def _make_wrapper(session: object, *, timeout: float = 0.1) -> MCPToolWrapper:
     return MCPToolWrapper(session, "test", tool_def, tool_timeout=timeout)
 
 
+@pytest.mark.asyncio
+async def test_connect_missing_servers_propagates_external_cancellation(monkeypatch) -> None:
+    started = asyncio.Event()
+
+    async def connect_mcp_servers(_servers: dict, _registry: ToolRegistry) -> dict:
+        started.set()
+        await asyncio.sleep(60)
+        return {}
+
+    class State:
+        pass
+
+    state = State()
+    state._mcp_closing = False
+    state._mcp_servers = {"test": MCPServerConfig(command="fake")}
+    state._mcp_stacks = {}
+    state._mcp_connecting = False
+    monkeypatch.setattr(mcp_mod, "connect_mcp_servers", connect_mcp_servers)
+
+    task = asyncio.create_task(mcp_mod.connect_missing_servers(state, ToolRegistry()))
+    await asyncio.wait_for(started.wait(), timeout=1.0)
+    task.cancel()
+
+    with pytest.raises(asyncio.CancelledError):
+        await task
+
+    assert state._mcp_connecting is False
+
+
 def test_wrapper_preserves_non_nullable_unions() -> None:
     tool_def = SimpleNamespace(
         name="demo",