fix(mcp): defer stale stack cleanup during reconnect

tests/agent/test_mcp_connection.py

@@ -74,6 +74,15 @@ class _FakeMcpTool(Tool):
         return "ok"
 
 
+class _CancelScopeStack:
+    def __init__(self) -> None:
+        self.closed = False
+
+    async def aclose(self) -> None:
+        self.closed = True
+        raise asyncio.CancelledError("Cancelled via cancel scope test")
+
+
 def _make_loop(tmp_path, *, mcp_servers: dict | None = None) -> AgentLoop:
     bus = MessageBus()
     provider = MagicMock()
@@ -115,6 +124,18 @@ async def test_mcp_read_filter_drops_progress_notifications_without_progress_tok
     assert forwarded == [tool_change, valid_progress]
 
 
+@pytest.mark.asyncio
+async def test_close_mcp_swallows_sdk_cancel_scope_cleanup(tmp_path):
+    loop = _make_loop(tmp_path)
+    stack = _CancelScopeStack()
+    loop._mcp_stacks["remote"] = stack  # type: ignore[assignment]
+
+    await loop.close_mcp()
+
+    assert stack.closed is True
+    assert loop._mcp_stacks == {}
+
+
 @pytest.mark.asyncio
 async def test_connect_mcp_retries_when_no_servers_connect(tmp_path, monkeypatch: pytest.MonkeyPatch):
     loop = _make_loop(tmp_path)
@@ -220,6 +241,9 @@ async def test_reload_mcp_servers_adds_and_removes_tools_without_restart(
     assert removed["removed"] == ["browserbase"]
     assert not loop.tools.has("mcp_browserbase_navigate")
     assert "browserbase" not in loop._mcp_stacks
+
+    assert closed == []
+    await loop.close_mcp()
     assert closed == ["browserbase"]
 
 
@@ -281,6 +305,9 @@ async def test_request_mcp_reload_reaches_runtime_control_without_restart(
     assert result["removed"] == ["browserbase"]
     assert result["requires_restart"] is False
     assert not loop.tools.has("mcp_browserbase_navigate")
+
+    assert closed == []
+    await loop.close_mcp()
     assert closed == ["browserbase"]
 
 
@@ -376,12 +403,15 @@ async def test_mcp_tool_reconnects_after_session_terminated(
 
     assert output == "recovered"
     assert connect_count == 2
-    assert closed == ["remote"]
+    assert closed == []
     assert sessions[0].call_count == 1
     assert sessions[1].call_count == 1
     assert "remote" in loop._mcp_stacks
     assert loop.tools.get("mcp_remote_quote") is not old_tool
 
+    await loop.close_mcp()
+    assert closed == ["remote", "remote"]
+
 
 @pytest.mark.asyncio
 async def test_mcp_reconnect_handler_uses_sanitized_server_prefix(
@@ -491,4 +521,7 @@ async def test_concurrent_mcp_reconnect_reuses_fresh_session(
 
     assert outputs == ["fresh:alpha", "fresh:beta"]
     assert connect_count == 2
-    assert closed == ["remote"]
+    assert closed == []
+
+    await loop.close_mcp()
+    assert closed == ["remote", "remote"]