Fix: handle MCP notifications/initialized without 400

mcp_summary_server.py

@@ -285,10 +285,10 @@ class MCPSummaryHandler(BaseHTTPRequestHandler):
                 })
                 return
 
+            # Some clients probe for OpenAPI spec; safe to return 404.
             self.send_error(404, "Not Found")
         except Exception as e:
             logger.error(f"GET error: {e}", exc_info=True)
-            # Ensure we still send something
             try:
                 self.send_error(500, "Internal Server Error")
             except Exception:
@@ -322,6 +322,22 @@ class MCPSummaryHandler(BaseHTTPRequestHandler):
 
             logger.info(f"MCP request: method={method}, id={req_id}")
 
+            # MCP: notifications (e.g. notifications/initialized)
+            # These are one-way; respond with 200 and no result, do not error.
+            if isinstance(method, str) and method.startswith("notifications/"):
+                # If there's an id, respond with empty result; otherwise just 200.
+                if req_id is not None:
+                    self._send_json(200, {
+                        "jsonrpc": "2.0",
+                        "id": req_id,
+                        "result": {}
+                    })
+                else:
+                    self.send_response(200)
+                    self.send_header("Content-Length", "0")
+                    self.end_headers()
+                return
+
             # MCP: initialize
             if method == "initialize":
                 self._send_json(200, {
@@ -376,12 +392,11 @@ class MCPSummaryHandler(BaseHTTPRequestHandler):
                     })
                 return
 
-            # Unknown method
+            # Unknown method (non-notification) -> 400
             self._send_json(400, {"error": "Unknown method: " + str(method)})
 
         except Exception as e:
             logger.error(f"POST error: {e}", exc_info=True)
-            # Fallback response to avoid silent drop
             try:
                 self.send_error(500, "Internal Server Error")
             except Exception: