/**
 * Message sender identity (security model): a structured, server-stamped
 * record of who sent a message into a session. Attached to the durable
 * message queue payload and the `user.message` CMS event; surfaced to the
 * agent only in multi-writer sessions.
 *
 * Identity fields (`provider`, `subject`, `display`, `relation`) are stamped
 * at the API edge from the validated auth context — never trusted from the
 * client body. `origin` is client-declared display metadata only.
 *
 * This is attribution and prioritization metadata, NOT an authorization
 * mechanism — a message only reaches the queue because the dispatcher
 * already authorized it.
 */
export interface MessageSender {
    kind: "user" | "agent" | "system";
    /** Identity key of a user sender ((provider, subject) from the users catalog). */
    provider?: string;
    subject?: string;
    /** Human-readable name for rendering and prompt attribution. */
    display?: string;
    /** Relation to the session's tree at send time. */
    relation?: "owner" | "collaborator" | "admin";
    /** kind=agent: the sending session id. */
    sessionId?: string;
    /** Which surface sent it (display metadata, client-declared). */
    origin?: "portal" | "tui" | "mcp" | "api";
}
/**
 * Validate and normalize a sender record. Returns undefined for anything
 * that isn't a well-formed sender, so junk never rides the durable payload.
 */
export declare function normalizeMessageSender(sender: unknown): MessageSender | undefined;
/** Stable identity key for distinct-writer tracking. */
export declare function messageSenderKey(sender: MessageSender | null | undefined): string | null;
/** The `[FROM: …]` attribution line shown to the agent in multi-writer sessions. */
export declare function formatSenderAttribution(sender: MessageSender): string;
//# sourceMappingURL=message-sender.d.ts.map