/**
 * Minimal href sanitizer for the built-in link popover.
 *
 * The v1 toolbar used the shared `@superdoc/url-validation` package, which is not
 * a resolvable runtime dependency of the published `superdoc` ES build. This
 * keeps the same fail-closed posture (only known-safe schemes pass) without
 * pulling in that package: dangerous schemes (`javascript:`, `data:`,
 * `vbscript:`) return `null`, mirroring the v1 contract that callers treat a
 * `null` result as an invalid URL.
 */
/**
 * Validate and normalize an href. Returns `{ href }` for safe values, or `null`.
 */
export declare function sanitizeHref(value: unknown): {
    href: string;
} | null;