Node WebSocket consumer drops events when subscribing to analytics/notification streams

Building a Node.js service to stream analytics notification events into Kafka. The WebSocket connection to the Genesys Cloud endpoint stabilizes, but the event stream cuts out after roughly 15 minutes. No explicit disconnect errors. Here’s the subscription logic:

socket.send(JSON.stringify({
 action: 'subscribe',
 query: 'analytics/notifications',
 data: { 'filter': 'type:conversation' }
}));

The onmessage handler stops firing. Have others seen this behavior with long-running analytics subscriptions?