Build the leading event the transport sends when it opens a
subscriptions/listen stream: a notifications/subscriptions/acknowledged
notification carrying the agreed-upon subset of change-notification types the
server will deliver on the stream (draft basic/utilities/subscriptions). The
subset is what McpServer.acknowledgedSubsetFor reported for that one
stream's filter (each subscription is independent — §Multiple Concurrent
Subscriptions).
Per the draft spec the agreed subset is nested under params.notifications
(mirroring the notifications filter the client sent in the listen request);
the matching io.modelcontextprotocol/subscriptionId is stamped into
params._meta by the push channel when the event is delivered to the stream.
Build the leading event the transport sends when it opens a subscriptions/listen stream: a notifications/subscriptions/acknowledged notification carrying the agreed-upon subset of change-notification types the server will deliver on the stream (draft basic/utilities/subscriptions). The subset is what McpServer.acknowledgedSubsetFor reported for that one stream's filter (each subscription is independent — §Multiple Concurrent Subscriptions).
Per the draft spec the agreed subset is nested under params.notifications (mirroring the notifications filter the client sent in the listen request); the matching io.modelcontextprotocol/subscriptionId is stamped into params._meta by the push channel when the event is delivered to the stream.