Heartbeat

The feed supports an optional client-initiated application-level ping you can use to probe the connection.

Optional application-level ping

You can also probe the connection from the client with an application-level message. The server replies with a pong carrying its current server time in epoch milliseconds:

{ "type": "ping" }

{ "type": "pong", "timestamp": 1747741200000 }

It is an ordinary JSON message you can use as an end-to-end liveness check or to measure round-trip latency. It is optional.