♻️ 重构MCPClient会话管理，增加会话所有权控制的测试用例

tests/test_mcpclient.py

@@ -0,0 +1,44 @@
+import asyncio
+from contextlib import asynccontextmanager
+from types import SimpleNamespace
+from unittest import IsolatedAsyncioTestCase
+
+from anyio import CancelScope
+
+from nonebot_plugin_llmchat.mcpclient import MCPClient
+
+
+class TestMCPClientSessionOwnership(IsolatedAsyncioTestCase):
+    async def test_session_context_is_closed_by_its_owner_task(self):
+        entered_by = None
+        exited_by = None
+
+        @asynccontextmanager
+        async def task_bound_context():
+            nonlocal entered_by, exited_by
+            entered_by = asyncio.current_task()
+            with CancelScope():
+                try:
+                    yield SimpleNamespace()
+                finally:
+                    exited_by = asyncio.current_task()
+
+        client = object.__new__(MCPClient)
+        client.operation_timeout = 1
+
+        async def initialize(server_name, session_stack):
+            session = await session_stack.enter_async_context(task_bound_context())
+            return session, session_stack
+
+        client._initialize_server_session = initialize
+
+        session, handle = await client._create_server_session("test")
+        client.sessions = {"test": session}
+        client._session_handles = {"test": handle}
+        client._session_last_used = {"test": 0.0}
+
+        await client._close_server_session("test")
+
+        assert entered_by is handle.owner_task
+        assert exited_by is handle.owner_task
+        assert handle.owner_task.done()