/**
 * On-demand README retrieval for the detail panel.
 *
 * READMEs are not published into the catalog. At roughly 8 KB apiece, 1984 of
 * them would add ~16 MB to a document the browser parses every time the
 * marketplace opens — and the text would be as stale as the last crawl. They
 * are fetched per entry instead, straight from the repository's default
 * branch.
 *
 * The target URL is always derived from `owner/repo` as it appears in the
 * host's own catalog. Nothing about the request comes from the browser except
 * an entry id, so this route cannot be pointed at an arbitrary host.
 */
/** What a lookup produced. */
export interface ReadmeResult {
    readonly markdown: string;
    readonly sourceUrl?: string;
    readonly message?: string;
}
/**
 * Whether `owner/repo` is shaped the way GitHub spells it.
 *
 * The value comes from the host's own catalog rather than the browser, but it
 * is interpolated into a URL, so it is checked anyway: a catalog is a file on
 * disk, and a file on disk can be edited.
 * @param repo - the `owner/repo` string.
 * @returns true when safe to interpolate.
 */
export declare function isSafeRepo(repo: string): boolean;
/** Fetches and caches repository READMEs. */
export declare class ReadmeStore {
    private readonly warn;
    private readonly cache;
    constructor(warn: (line: string) => void);
    /**
     * Get a repository's README, from cache when it is fresh.
     * @param repo - `owner/repo` as spelled by GitHub.
     * @returns the Markdown, or a message explaining why there is none.
     */
    get(repo: string): Promise<ReadmeResult>;
    /**
     * Try each candidate filename until one returns content.
     *
     * `HEAD` resolves to whatever the default branch is, so neither the branch
     * name nor a redirect needs to be discovered first.
     * @param repo - `owner/repo`.
     * @returns the first README found, or undefined.
     */
    private fetchFirst;
    /**
     * Store a README, evicting the oldest entry when full.
     * @param repo - the cache key.
     * @param row - the fetched content.
     */
    private remember;
}