/**
 * The crtrd broker `error` control frame — `{ code, message, id? }`. `id` is a
 * correlation token echoed only from the request that failed (a read-op /
 * `dequeue`); absent on uncorrelated errors. There is NO `retryable` field.
 */
export interface BrokerErrorFrame {
    type: 'error';
    code: string;
    message: string;
    /** Correlation token, echoed from the failed request; absent on uncorrelated errors. */
    id?: string;
}
/**
 * The `welcome` frame's history/state snapshot, narrowed to what a relay consumer
 * replays: the message history and the streaming flag. `M` is the message shape
 * (pi's `AgentMessage` in a pi consumer; `unknown` by default).
 */
export interface BrokerWelcomeSnapshot<M = unknown> {
    messages: M[];
    state?: {
        isStreaming?: boolean;
    };
}
/**
 * The crtrd broker `welcome` control frame — the history/resume catch-up snapshot
 * delivered on (re)attach.
 */
export interface BrokerWelcomeFrame<M = unknown> {
    type: 'welcome';
    snapshot?: BrokerWelcomeSnapshot<M>;
}
/**
 * The broker-control frames a relay consumer reads: `welcome` (catch-up snapshot)
 * and `error`. The broker interleaves others (display_*, control_changed, ack, …)
 * under non-colliding `type` discriminants; a relay mapper drops those through its
 * `default` arm untyped, so they are not enumerated here.
 */
export type BrokerControlFrame<M = unknown> = BrokerWelcomeFrame<M> | BrokerErrorFrame;
/**
 * What the crtrd broker attach delivers to a relay consumer: the live engine
 * event stream (`E` — pi's `AgentSessionEvent`, relayed verbatim) unioned with the
 * broker's own control frames. Discriminants never collide: an `AgentSessionEvent`
 * owns no `welcome` / `error` `type`.
 */
export type BrokerAttachFrame<E, M = unknown> = E | BrokerControlFrame<M>;