// Experimental in-memory patch to one pinned module, not an upstream/product change.
export function routeEscape(source) {
  const start = source.indexOf('    const isHighestLayer = node ? index === layers.length - 1 : false;');
  const end = source.indexOf('    React.useEffect(() => {\n      if (!node) return;', start);
  if (start < 0 || end < 0) throw new Error('Pinned source locators changed');
  const helper = `
const fepDocuments = new WeakMap();
function fepRegister(doc, node, callback) {
  let state = fepDocuments.get(doc);
  if (!state) {
    state = { owners: new Map() };
    state.listener = event => {
      if (event.key !== 'Escape' || event.defaultPrevented) return;
      const entry = [...state.owners].filter(([element]) => element.isConnected).at(-1);
      if (!entry) return;
      window.routingObserved.trace.push({kind:'dispatch', owner:entry[0].getAttribute('aria-labelledby')});
      // Snapshot one owner. No fall-through to the parent after cancellation or teardown.
      entry[1](event);
    };
    doc.addEventListener('keydown', state.listener, {capture:true});
    fepDocuments.set(doc, state);
  }
  state.owners.set(node, callback);
  window.routingObserved.trace.push({kind:'register', owner:node.getAttribute('aria-labelledby'), count:state.owners.size});
  return () => {
    state.owners.delete(node);
    window.routingObserved.trace.push({kind:'unregister', owner:node.getAttribute('aria-labelledby'), count:state.owners.size});
    if (!state.owners.size) {
      doc.removeEventListener('keydown', state.listener, {capture:true});
      fepDocuments.delete(doc);
      window.routingObserved.trace.push({kind:'listener-removed'});
    }
  };
}
`;
  const replacement = `    const fepHandler = React.useRef(null);
    React.useLayoutEffect(() => {
      fepHandler.current = event => {
        onEscapeKeyDown?.(event);
        if (!event.defaultPrevented && onDismiss) {event.preventDefault();onDismiss();}
      };
    });
    React.useLayoutEffect(() => {
      if (!node) return;
      return fepRegister(ownerDocument, node, event => fepHandler.current?.(event));
    }, [node, ownerDocument]);
`;
  return helper + source.slice(0,start) + replacement + source.slice(end);
}