import type { Payload } from '../interfaces';
/**
 * Reference returned from {@link StorageDriver.store}. `claimData` is an
 * opaque key/value map the driver uses to retrieve the payload later.
 *
 * @internal
 * @experimental
 */
export declare class StorageDriverClaim {
    readonly claimData: Record<string, string>;
    constructor(claimData: Record<string, string>);
}
/**
 * Workflow identity information passed to a storage driver.
 *
 * @internal
 * @experimental
 */
export interface StorageDriverWorkflowInfo {
    readonly kind: 'workflow';
    /** The namespace of the workflow execution. */
    readonly namespace: string;
    /** The workflow ID. */
    readonly id?: string;
    /** The workflow run ID, if available. */
    readonly runId?: string;
    /** The workflow type name, if available. */
    readonly type?: string;
}
/**
 * Activity identity information passed to a storage driver.
 *
 * @internal
 * @experimental
 */
export interface StorageDriverActivityInfo {
    readonly kind: 'activity';
    /** The namespace of the activity execution. */
    readonly namespace: string;
    /** The activity ID. */
    readonly id?: string;
    /** The activity run ID (only for standalone activities). */
    readonly runId?: string;
    /** The activity type name, if available. */
    readonly type?: string;
}
/**
 * Identity of the workflow or activity that produced the payloads being stored.
 *
 * @internal
 * @experimental
 */
export type StorageDriverTargetInfo = StorageDriverWorkflowInfo | StorageDriverActivityInfo;
/**
 * Context handed to {@link StorageDriver.store} (and to the selector).
 *
 * @internal
 * @experimental
 */
export interface StorageDriverStoreContext {
    /** Aborts the in-flight operation; siblings are cancelled on first error. */
    abortSignal?: AbortSignal;
    /** Identity of the workflow / activity that produced the payloads. */
    target?: StorageDriverTargetInfo;
}
/**
 * Context handed to {@link StorageDriver.retrieve}.
 *
 * @internal
 * @experimental
 */
export interface StorageDriverRetrieveContext {
    abortSignal?: AbortSignal;
}
/**
 * External storage backend driver.
 *
 * `name` is the per-instance routing key written into the wire format.
 * `type` is a stable cross-language driver-implementation identifier
 * reported via worker heartbeat (e.g. `"aws.s3driver"`).
 *
 * @internal
 * @experimental
 */
export interface StorageDriver {
    readonly name: string;
    readonly type: string;
    store(context: StorageDriverStoreContext, payloads: Payload[]): Promise<StorageDriverClaim[]>;
    retrieve(context: StorageDriverRetrieveContext, claims: StorageDriverClaim[]): Promise<Payload[]>;
}
/**
 * User-supplied function that picks the destination driver for a given
 * payload, or returns `null` to keep the payload inline.
 *
 * @internal
 * @experimental
 */
export type StorageDriverSelector = (context: StorageDriverStoreContext, payload: Payload) => StorageDriver | null;
/**
 * Configuration for external storage. Holds the registered drivers, an
 * optional selector, and the size threshold above which payloads are
 * eligible for offloading to external storage. A selector function is
 * required when more than one driver is registered.
 *
 * @internal
 * @experimental
 */
export declare class ExternalStorage {
    readonly drivers: StorageDriver[];
    /**
     * Selects the destination driver for each payload, or returns `null` to keep
     * the payload inline.
     */
    readonly driverSelector: StorageDriverSelector;
    readonly payloadSizeThreshold: number;
    private readonly driversByName;
    constructor({ drivers, driverSelector, payloadSizeThreshold, }: {
        drivers: StorageDriver[];
        driverSelector?: StorageDriverSelector;
        /** Omit for default (256 KiB). Set `0` to consider all payloads regardless of size. */
        payloadSizeThreshold?: number;
    });
    /** Look up a registered driver by name. Returns `null` if no driver with that name is registered. */
    getDriver(name: string): StorageDriver | null;
}