OptionalLastThe prior conversation this visit chains from (stamped on Conversation.LastConversationID).
OptionalLinkedResolved polymorphic identity entity id (stamped on the existing Conversation.LinkedEntityID when set; also on AIAgentSession.LinkedEntityID).
OptionalLinkedResolved polymorphic identity record id (stamped on the existing Conversation.LinkedRecordID when set; also on AIAgentSession.LinkedRecordID).
OptionalVisitorDurable, opaque returning-visitor anchor (stamped on Conversation.VisitorKey).
Returning-visitor context carried on UserInfo for a public web-widget guest session, sourced from the verified session token's claims. Lets a server-created conversation (the voice path, which mints its conversation server-side) stamp the same returning-visitor anchor + linked identity the text path stamps client-side, so cross-session memory works uniformly across modalities. Not a database/GraphQL field — an in-memory, per-session carrier.