import type { Session, WorkingMemory } from '../types/index.js';
import type { ModelMessage } from 'ai';
/**
 * Manages session lifecycle: load, save, delete, message append, turn counting.
 * Shared by Runtime and VoiceEngine.
 */
export interface ConversationState {
    /** Load an existing session or create a new one. */
    load(sessionId: string, userId?: string): Promise<Session>;
    /** Persist session to the backing store. */
    save(session: Session): Promise<void>;
    /** Delete a session from the backing store. */
    delete(sessionId: string): Promise<void>;
    /** Get a WorkingMemory wrapper for the session. */
    workingMemory(session: Session): WorkingMemory;
    /** Append a user message to the session history. */
    appendUserMessage(session: Session, text: string): void;
    /** Append an assistant message to the session history. */
    appendAssistantMessage(session: Session, text: string): void;
    /** Append a raw ModelMessage to the session history. */
    appendMessage(session: Session, message: ModelMessage): void;
    /** Get the current turn number for the session. */
    getSessionTurn(session: Session): number;
    /** Increment and return the new turn number. */
    bumpSessionTurn(session: Session): number;
    /** Update the session's updatedAt timestamp. */
    touchSession(session: Session): void;
    /** Create a fresh session with defaults. */
    createSession(id: string, defaultAgentId: string, userId?: string): Session;
}