Initiate a server->client ping on the GET SSE stream owned by the session
sessionId (its Mcp-Session-Id). On a stateful HTTP server every per-session
GET stream is registered under its session id as the listener's owner token, so
the probe must be scoped to that token to reach the right stream — an empty
token (the no-arg pingClient) matches no session-scoped listener and would
always fail. The waiter is likewise scoped to sessionId, so only a response
POSTed under the same session resolves it. Throws as the no-arg form does, plus
when no GET stream is connected for that session.
Initiate a server->client ping on the GET SSE stream owned by the session sessionId (its Mcp-Session-Id). On a stateful HTTP server every per-session GET stream is registered under its session id as the listener's owner token, so the probe must be scoped to that token to reach the right stream — an empty token (the no-arg pingClient) matches no session-scoped listener and would always fail. The waiter is likewise scoped to sessionId, so only a response POSTed under the same session resolves it. Throws as the no-arg form does, plus when no GET stream is connected for that session.