(() => {
    const socket = window.io && window.io();
    if (!socket) return;

    const listMatch = window.location.pathname.match(/^\/lists\/(\d+)$/);
    if (listMatch) socket.emit("list:join", listMatch[1]);

    socket.on("list:updated", ({ listId }) => {
        if (window.location.pathname === `/lists/${listId}`) window.location.reload();
    });
})();