/**
 * Tracks file content signatures (mtimeMs + size) so phantom fs.watch
 * events from macOS Spotlight, iCloud, Time Machine, and other background
 * daemons — which fire without actually modifying the file — can be filtered
 * out before triggering a rebuild.
 *
 * Why mtimeMs + size (not a content hash):
 *   - Microsecond-fast even on large markdown files.
 *   - Every editor and save tool bumps mtime on real writes.
 *   - Phantom readers (`getattrlist`, `stat`) on macOS do NOT bump mtime.
 *   - mtime resolution on APFS is nanosecond-precision, so collisions
 *     between two distinct real writes are not a concern.
 *   - File deletion and creation are correctly detected (signature flips
 *     between a real value and `null`).
 *
 * The tracker is a per-process singleton helper; instantiate once per
 * dev-server lifecycle and share across all watcher callbacks.
 */
export declare class FileSignatureTracker {
    private signatures;
    /**
     * Returns the current signature for the file, or `null` if the file
     * no longer exists, is unreadable, or is not a regular file.
     */
    getSignature(filePath: string): string | null;
    /**
     * Returns true only if the file's content signature differs from the
     * last recorded one. The first call for a given file returns true
     * (treat a new sighting as a change). The signature is recorded on
     * every call so that subsequent phantom events are filtered out.
     */
    hasChanged(filePath: string): boolean;
    /**
     * Drop the recorded signature for a file so the next event is treated
     * as new. Useful before a known mutation (e.g. just before a build
     * writes to a watched path).
     */
    forget(filePath: string): void;
    /** Drop everything (e.g. after closing/reopening watchers on config reload). */
    reset(): void;
}