fix(mcp): preserve loop during probes

tests/tools/test_mcp_probe.py

@@ -162,14 +162,14 @@ class TestProbeMcpServerTools:
         assert result["github"][0] == ("my_tool", "")
 
     def test_cleanup_called_even_on_failure(self):
-        """_stop_mcp_loop is called even when probe fails."""
+        """Probe cleanup is attempted even when probe fails."""
         config = {"github": {"command": "npx", "connect_timeout": 5}}
 
         with patch("tools.mcp_tool._MCP_AVAILABLE", True), \
              patch("tools.mcp_tool._load_mcp_config", return_value=config), \
              patch("tools.mcp_tool._ensure_mcp_loop"), \
              patch("tools.mcp_tool._run_on_mcp_loop", side_effect=RuntimeError("boom")), \
-             patch("tools.mcp_tool._stop_mcp_loop") as mock_stop:
+             patch("tools.mcp_tool._stop_mcp_loop_if_idle") as mock_stop:
 
             from tools.mcp_tool import probe_mcp_server_tools
             result = probe_mcp_server_tools()

tests/tools/test_mcp_stability.py

@@ -57,6 +57,32 @@ class TestMCPLoopExceptionHandler:
         finally:
             mcp_mod._stop_mcp_loop()
 
+    def test_probe_cleanup_does_not_stop_loop_with_registered_servers(self):
+        """Probe cleanup must not kill the shared loop used by live MCP tools."""
+        import tools.mcp_tool as mcp_mod
+
+        with mcp_mod._lock:
+            mcp_mod._servers.clear()
+            mcp_mod._server_connecting.clear()
+        try:
+            mcp_mod._ensure_mcp_loop()
+            with mcp_mod._lock:
+                loop = mcp_mod._mcp_loop
+                mcp_mod._servers["live"] = MagicMock(session=object())
+
+            assert mcp_mod._stop_mcp_loop_if_idle() is False
+
+            with mcp_mod._lock:
+                assert mcp_mod._mcp_loop is loop
+                assert mcp_mod._mcp_thread is not None
+            assert loop is not None
+            assert loop.is_running()
+        finally:
+            with mcp_mod._lock:
+                mcp_mod._servers.clear()
+                mcp_mod._server_connecting.clear()
+            mcp_mod._stop_mcp_loop()
+
 
 # ---------------------------------------------------------------------------
 # Fix 2: stdio PID tracking