fix(mcp): clean up failed HTTP connections

tests/tools/test_mcp_probe.py

@@ -5,10 +5,13 @@ import asyncio
 import socket
 from unittest.mock import MagicMock, patch
 
+import httpx
 import pytest
 
+from nanobot.agent.tools import mcp as mcp_mod
 from nanobot.agent.tools.mcp import _probe_http_url, connect_mcp_servers
 from nanobot.agent.tools.registry import ToolRegistry
+from nanobot.config.schema import MCPServerConfig
 from nanobot.security.network import configure_ssrf_whitelist
 
 _PROXY_ENV_VARS = ("HTTP_PROXY", "HTTPS_PROXY", "ALL_PROXY", "http_proxy", "https_proxy", "all_proxy")
@@ -171,6 +174,58 @@ async def test_connect_skips_unreachable_sse():
     assert len(registry._tools) == 0
 
 
+@pytest.mark.asyncio
+async def test_connect_isolates_streamable_http_status_failure(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """A reachable endpoint returning HTTP 530 must not poison the event loop."""
+    async def _reachable(_url: str) -> bool:
+        return True
+
+    def _return_http_530(request: httpx.Request) -> httpx.Response:
+        return httpx.Response(530, text="cloudflare error 1033", request=request)
+
+    monkeypatch.setattr(mcp_mod, "validate_url_target", lambda _url: (True, ""))
+    monkeypatch.setattr(mcp_mod, "_probe_http_url", _reachable)
+    monkeypatch.setattr(
+        mcp_mod,
+        "PinnedDNSAsyncTransport",
+        lambda: httpx.MockTransport(_return_http_530),
+    )
+
+    loop = asyncio.get_running_loop()
+    previous_exception_handler = loop.get_exception_handler()
+    unhandled: list[BaseException] = []
+
+    def _capture_unhandled(_loop: asyncio.AbstractEventLoop, context: dict) -> None:
+        if isinstance(context.get("exception"), BaseException):
+            unhandled.append(context["exception"])
+
+    loop.set_exception_handler(_capture_unhandled)
+    try:
+        registry = ToolRegistry()
+        stacks = await asyncio.wait_for(
+            connect_mcp_servers(
+                {
+                    "cloudflare": MCPServerConfig(
+                        type="streamableHttp",
+                        url="https://mcp.example.com/mcp",
+                    )
+                },
+                registry,
+            ),
+            timeout=5.0,
+        )
+        await asyncio.sleep(0)
+
+        assert stacks == {}
+        assert registry.tool_names == []
+        assert unhandled == []
+        assert not any(task.get_name() == "mcp:cloudflare" for task in asyncio.all_tasks())
+    finally:
+        loop.set_exception_handler(previous_exception_handler)
+
+
 @pytest.mark.asyncio
 async def test_probe_not_called_for_stdio():
     """stdio transport should not be probed — it spawns a local process."""