/**
 * Soft-404 Detector
 *
 * Detects pages that return HTTP 200 but whose content is actually a
 * "page not found" placeholder. These are surprisingly common — many
 * CMS and wiki platforms prefer 200+template over a real 404:
 *
 *   - Wikipedia / Wikisource: "Wikipedia does not have an article with
 *     this exact name", "does not have a text with this exact name"
 *   - GitHub: "This is not the web page you are looking for"
 *   - Many CMSes: a themed "Page not found" template
 *   - E-commerce sites: "Product not available" with full site chrome
 *   - Custom 404 handlers that serve 200 for SEO-adjacent reasons
 *
 * A status-code-only check passes these pages, but their content is
 * worthless for the caller. This detector adds a second signal based
 * on a curated list of phrases that reliably indicate a soft-404.
 *
 * ## Design choices
 *
 * - **Phrase list, not regex**: phrases are faster to reason about,
 *   easier to extend, and less prone to catastrophic false-positives
 *   than regex patterns.
 * - **Case-insensitive substring match**: matches the convention used
 *   by the rest of the verification engine (`excludesText` behavior).
 * - **Title-aware**: the title often carries the strongest signal
 *   ("Page not found — Example.com") but isn't in the markdown body,
 *   so we scan both.
 * - **Conservative**: phrases are chosen to minimize false positives
 *   on legitimate content. A product description about "page not
 *   found errors" won't trip the detector because the phrase is
 *   embedded in other text and the phrase "Page not found" alone is
 *   intentionally NOT on the list — we require more specific markers.
 *
 * ## Not in scope
 *
 * This detector doesn't try to detect:
 *  - Paywalled or auth-gated content (use `containsText` for the
 *    specific paywall text, or check `excludesText: 'sign in'`)
 *  - Rate limits (handled by the standard `excludesText: 'rate limit
 *    exceeded'` built-in check)
 *  - JavaScript-rendered content that didn't load (handled by
 *    `minLength` built-in check)
 *  - Generic 404 text in documentation about HTTP (false-positive
 *    risk — we avoid matching the literal phrase "404 Not Found"
 *    unless it also appears in the page title)
 */
/**
 * Structured signal returned by `detectSoft404`. Callers that want
 * the full signal (which phrases matched, where) use this; callers
 * that only need a pass/fail use `isLikelySoft404`, which is a thin
 * wrapper around `.detected`.
 */
export interface Soft404Signal {
    /** True if at least one phrase matched in title or body. */
    detected: boolean;
    /** Phrases that matched in the page title, if any. */
    matchedTitlePhrases: string[];
    /** Phrases that matched in the page body, if any. */
    matchedBodyPhrases: string[];
}
/**
 * Detects whether a page is a soft-404 based on title and body
 * content, returning a structured signal with the specific phrases
 * that triggered the detection. This is the primary detection API;
 * use `isLikelySoft404` when you only need a boolean.
 *
 * Both arguments are optional — at least one should be provided for
 * a meaningful check. If both are empty/missing, returns a signal
 * with `detected: false` and empty phrase arrays.
 *
 * @param body    Page markdown or text content. Case is ignored.
 * @param title   Page title. Case is ignored. Only matched against
 *                TITLE_PHRASES, which is stricter than BODY_PHRASES.
 */
export declare function detectSoft404(body?: string | null, title?: string | null): Soft404Signal;
/**
 * Returns true if the page looks like a soft-404. Thin wrapper over
 * `detectSoft404` for callers that only need a boolean.
 *
 * @param body    Page markdown or text content. Case is ignored.
 * @param title   Page title. Case is ignored. Only matched against
 *                TITLE_PHRASES, which is stricter than BODY_PHRASES.
 */
export declare function isLikelySoft404(body?: string | null, title?: string | null): boolean;
/**
 * Exposed for tests and for callers that want to extend the detector
 * with their own phrases. Mutating these lists affects subsequent
 * `isLikelySoft404` calls — callers that need isolation should pass
 * their own phrase lists through a future extension point.
 */
export declare const _internalForTests: {
    BODY_PHRASES: readonly string[];
    TITLE_PHRASES: readonly string[];
};
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