/**
 * Thrown by a {@link Runtime}'s `deliver` when no in-flight session
 * matches the continuation token. Callers using the resume-or-start
 * pattern (e.g. {@link createSendFn}) treat this as the signal to start
 * a fresh session.
 */
export declare class RuntimeNoActiveSessionError extends Error {
    readonly code: "NO_ACTIVE_SESSION";
    readonly continuationToken: string;
    constructor(continuationToken: string);
}
/** Type guard for {@link RuntimeNoActiveSessionError}. */
export declare function isRuntimeNoActiveSessionError(error: unknown): error is RuntimeNoActiveSessionError;