/**
 * Configurable crawl traversal strategy — matches crawl4AI's BFS/DFS/
 * Best-First deep-crawl strategies (ZeTa previously had a single hardcoded
 * FIFO queue, i.e. always BFS).
 *
 * Array-like on purpose (`length`, `shift()`, `push()`, `filter()`) so it
 * drops into crawler.ts's existing queue call sites with a rename, not a
 * rewrite — BFS's `shift()` behavior is byte-for-byte the same as the plain
 * array it replaces, so BFS (the default) has zero behavior change.
 */
export type TraversalStrategy = 'BFS' | 'DFS' | 'BEST_FIRST';
export declare class CrawlFrontier {
    private items;
    private readonly strategy;
    private readonly keywords;
    private readonly urlFilter;
    constructor(strategy: TraversalStrategy, seedUrls: string[], keywords?: string[], urlFilter?: string);
    get length(): number;
    /**
     * P3b: sparse-parent boost — if the parent page had fewer than 5 interactive
     * elements (thin/canvas page), its child URLs score +1 in BEST_FIRST mode so
     * the frontier revisits sparse branches before deep-linked content.
     */
    push(url: string, pushOpts?: {
        parentElements?: number;
    }): void;
    /** Dequeues the next URL per this frontier's strategy. undefined if empty. */
    shift(): string | undefined;
    filter(predicate: (url: string) => boolean): string[];
    /** Remove queued URLs not matching the regex pattern. Returns count removed. */
    filterByPattern(pattern: string): number;
}