The server->client push channel for *unsolicited* traffic — the messages
a server sends on the standalone SSE stream a client opens with an HTTP
GET to the MCP endpoint (basic/transports §Listening for Messages from the
Server), outside any in-flight POST. The Streamable HTTP transport creates
it (sharing the supplied StreamCoordinator) when the mount is set up;
it is created lazily on first access so callers can hold a reference
before mounting. Use notify (or the returned channel's emit) to deliver
notifications/requests to every connected GET listener.
The server->client push channel for *unsolicited* traffic — the messages a server sends on the standalone SSE stream a client opens with an HTTP GET to the MCP endpoint (basic/transports §Listening for Messages from the Server), outside any in-flight POST. The Streamable HTTP transport creates it (sharing the supplied StreamCoordinator) when the mount is set up; it is created lazily on first access so callers can hold a reference before mounting. Use notify (or the returned channel's emit) to deliver notifications/requests to every connected GET listener.