/**
 * A source the caller named explicitly (a platform, or `engines` of platforms) that cannot run right now: missing
 * dsh-browser, login / CLI / token, disabled in settings, cooling down. A structured error rather than an empty result, so
 * the caller can tell the user what is missing instead of reading "no results" as "nothing exists". The action layer maps it
 * to CAPABILITY_UNAVAILABLE and adds the catalog's setup text for `source`.
 * @module web-search-pro/providers/unavailable
 */
export declare class SourceUnavailableError extends Error {
    readonly code = "SOURCE_UNAVAILABLE";
    /** Route id of the provider (`zhihu`). */
    readonly source: string;
    /** What is missing or why it is unavailable, as the readiness probe reported it. */
    readonly missing: readonly string[];
    constructor(message: string, source: string, missing?: readonly string[]);
}