const updateDots = () => {
                dotsContainer.querySelectorAll('.photo-lightbox-dot').forEach((d, i) => {
                    d.classList.toggle('is-active', i === current);
                });
            };

            const updateNav = () => {
                const multi = images.length > 1;
                prevBtn.classList.toggle('is-hidden', !multi);
                nextBtn.classList.toggle('is-hidden', !multi);
                updateDots();
            };

            const buildDots = () => {
                dotsContainer.innerHTML = images.length > 1
                    ? images.map((_, i) => `<span class="photo-lightbox-dot${i === 0 ? ' is-active' : ''}"></span>`).join('')
                    : '';
            };

            const renderCurrentImage = () => {
                lightboxImg.src = images[current].url;
                lightboxImg.alt = images[current].alt || '';
                preloadNearby(current);
            };

            const open = (index) => {
                current = index || 0;
                renderCurrentImage();
                buildDots();
                updateNav();
                overlay.classList.add('is-open');
                document.body.style.overflow = 'hidden';
            };

            const close = () => {
                overlay.classList.remove('is-open');
                document.body.style.overflow = '';
            };

            const navigate = async (dir) => {
                if (isNavigating) {
                    return;
                }

                const nextIndex = (current + dir + images.length) % images.length;

                if (nextIndex === current) {
                    return;
                }

                isNavigating = true;
                lightboxImg.style.opacity = '0.35';

                try {
                    await preloadImage(images[nextIndex].url);
                    current = nextIndex;
                    renderCurrentImage();
                    updateNav();
                } finally {
                    lightboxImg.style.opacity = '1';
                    isNavigating = false;
                }
            };