Agora Realtime Messages

agora.data_source and agora.data_sink carry client commands and Agent events over the same shared RTC session as audio. They are C++ Nodes, not a new Core abstraction.

Node	Port	Schema
agora.data_source	message_out Byte output	application/vnd.muxiva.client-command+json, max 1 KiB
agora.data_sink	message_in Byte input	Application bytes, max 32 KiB; transport packets max 1 KiB

The data stream is reliable and ordered. Muxiva paces outbound packets below Agora's 6 KiB/s limit. The Voice Agent example's project-local voice_room.event_encoder maps EventFrame values to its muxiva.client-event/v1 application contract. agora.data_sink owns the transport concern: messages larger than one packet use muxiva.transport-fragment/v1 and are reassembled by the client.

This split is intentional. Client schemas and voice cancellation policy belong to an application Node, while RTC packet limits belong to the Agora transport Node. Neither is a Runtime Core builtin.

All Agora Nodes acquire one process-wide shared session with the configured Bot UID. In the first isolation model, only the configured Browser UID is accepted. Audio and data from other participants are ignored.

NotificationBus is not involved in this path. It remains local observability only.