refactor: move MCP lifecycle out of AgentLoop (#5343)

tests/test_openai_api.py

@@ -34,8 +34,7 @@ AUTH_HEADERS = {"Authorization": f"Bearer {API_KEY}"}
 def _make_mock_agent(response_text: str = "mock response") -> MagicMock:
     agent = MagicMock()
     agent.process_direct = AsyncMock(return_value=response_text)
-    agent._connect_mcp = AsyncMock()
-    agent.close_mcp = AsyncMock()
+    agent.aclose = AsyncMock()
     agent._last_usage = {"prompt_tokens": 100, "completion_tokens": 50}
     return agent
 
@@ -149,6 +148,59 @@ async def test_api_routes_allow_requests_without_configured_api_key(aiohttp_clie
     mock_agent.process_direct.assert_called_once()
 
 
+@pytest.mark.skipif(not HAS_AIOHTTP, reason="aiohttp not installed")
+@pytest.mark.asyncio
+async def test_api_prepares_application_resources_before_each_turn(aiohttp_client) -> None:
+    events: list[str] = []
+    agent = _make_mock_agent()
+
+    async def prepare_agent() -> None:
+        events.append("prepare")
+
+    async def process_direct(**_kwargs):
+        events.append("process")
+        return "ready"
+
+    agent.process_direct = process_direct
+    app = create_app(agent, prepare_agent=prepare_agent)
+    client = await aiohttp_client(app)
+
+    response = await client.post(
+        "/v1/chat/completions",
+        json={"messages": [{"role": "user", "content": "hello"}]},
+    )
+
+    assert response.status == 200
+    assert events == ["prepare", "process"]
+
+
+@pytest.mark.skipif(not HAS_AIOHTTP, reason="aiohttp not installed")
+@pytest.mark.asyncio
+async def test_api_preparation_is_bounded_by_request_timeout(aiohttp_client) -> None:
+    agent = _make_mock_agent()
+    started = asyncio.Event()
+
+    async def prepare_agent() -> None:
+        started.set()
+        await asyncio.Event().wait()
+
+    app = create_app(
+        agent,
+        request_timeout=0.01,
+        prepare_agent=prepare_agent,
+    )
+    client = await aiohttp_client(app)
+
+    response = await client.post(
+        "/v1/chat/completions",
+        json={"messages": [{"role": "user", "content": "hello"}]},
+    )
+
+    assert started.is_set()
+    assert response.status == 504
+    agent.process_direct.assert_not_awaited()
+
+
 @pytest.mark.skipif(not HAS_AIOHTTP, reason="aiohttp not installed")
 @pytest.mark.asyncio
 async def test_no_user_message_returns_400(aiohttp_client, app) -> None:
@@ -275,8 +327,7 @@ async def test_followup_requests_share_same_session_key(aiohttp_client) -> None:
 
     agent = MagicMock()
     agent.process_direct = fake_process
-    agent._connect_mcp = AsyncMock()
-    agent.close_mcp = AsyncMock()
+    agent.aclose = AsyncMock()
     agent._last_usage = {}
 
     app = create_app(agent, model_name="m", api_key=API_KEY)
@@ -315,8 +366,7 @@ async def test_fixed_session_requests_are_serialized(aiohttp_client) -> None:
 
     agent = MagicMock()
     agent.process_direct = slow_process
-    agent._connect_mcp = AsyncMock()
-    agent.close_mcp = AsyncMock()
+    agent.aclose = AsyncMock()
     agent._last_usage = {}
 
     app = create_app(agent, model_name="m", api_key=API_KEY)
@@ -433,8 +483,7 @@ async def test_empty_response_falls_back_without_retry(aiohttp_client) -> None:
 
     agent = MagicMock()
     agent.process_direct = always_empty
-    agent._connect_mcp = AsyncMock()
-    agent.close_mcp = AsyncMock()
+    agent.aclose = AsyncMock()
     agent._last_usage = {}
 
     app = create_app(agent, model_name="m", api_key=API_KEY)
@@ -457,7 +506,6 @@ async def test_process_direct_accepts_media() -> None:
     from nanobot.bus.runtime_events import RuntimeEventPublisher
 
     loop = AgentLoop.__new__(AgentLoop)
-    loop._connect_mcp = AsyncMock()
     loop._session_locks = {}
     loop.runtime_event_publisher = RuntimeEventPublisher()