/**
 * [WHO]: SessionMessageQueue owns pending UI text and next-turn custom context
 * [FROM]: CustomMessage type only; no runtime host dependency
 * [TO]: AgentSession delivery, cancellation and lifecycle adapters
 * [HERE]: core/runtime/session-message-queue.ts - session input queue state
 */
import type { CustomMessage } from "../messages.js";
export declare class SessionMessageQueue {
    private steeringTexts;
    private followUpTexts;
    private nextTurnMessages;
    get steering(): readonly string[];
    get followUp(): readonly string[];
    get pendingCount(): number;
    enqueue(mode: "steer" | "followUp", text: string): void;
    delivered(text: string): void;
    clear(): {
        steering: string[];
        followUp: string[];
    };
    clearFollowUp(matches?: (text: string) => boolean): void;
    nextTurn(message: CustomMessage): void;
    drainNextTurn(): CustomMessage[];
}