/**
 * Writes the in-app navigation trail that funnel attribution reads.
 *
 * Renders nothing. It exists because document.referrer cannot answer "which
 * page did they come from" in an App Router app: a soft navigation creates no
 * document, so the browser never updates it. See the trail comment in
 * lib/analytics.ts.
 *
 * Mounted once in the root layout, so every route is recorded — including the
 * ones that fire no event of their own, which are still somebody else's
 * previous page.
 */
'use client';

import { useEffect } from 'react';
import { usePathname } from 'next/navigation';
import { recordVisitedPath } from '@/lib/analytics';

export function RouteTrail() {
  const pathname = usePathname();

  useEffect(() => {
    recordVisitedPath(pathname);
  }, [pathname]);

  return null;
}