import { Content, Part } from '../models/types';
import { InvocationContext } from './InvocationContext';
import { ReadonlyContext } from './ReadonlyContext';
import { EventActions } from '../events/EventActions';
import { State } from '../sessions/State';
/**
 * Callback context for agent invocations.
 * Provides mutable access to the agent's state and context.
 */
export declare class CallbackContext extends ReadonlyContext {
    private eventActions;
    private mutableState;
    constructor(invocationContext: InvocationContext, eventActions?: EventActions);
    /**
     * The delta-aware state of the current session.
     *
     * For any state change, you can mutate this object directly,
     * e.g. `ctx.state['foo'] = 'bar'`
     */
    get state(): State;
    /**
     * The user content that started this invocation. READONLY field.
     */
    get userContent(): Content | undefined;
    /**
     * Loads an artifact attached to the current session.
     *
     * @param filename The filename of the artifact.
     * @param version The version of the artifact. If undefined, the latest version will be returned.
     * @returns The artifact, or undefined if not found.
     */
    loadArtifact(filename: string, version?: number): Part | undefined | Promise<Part | undefined>;
    /**
     * Saves an artifact and records it as delta for the current session.
     *
     * @param filename The filename of the artifact.
     * @param artifact The artifact to save.
     * @returns The version of the artifact.
     */
    saveArtifact(filename: string, artifact: Part): number | Promise<number>;
}