// ==UserScript==
// @name         短视频去水印下载 Pro (稳定提取版)
// @name:zh-CN   短视频去水印下载 Pro (稳定提取版)
// @version      2.5.2
// @license      MIT
// @description  抖音去水印下载 Pro — 采用稳定DOM提取+网络缓存双重保障，修复视频错乱与提取失败问题
// @author       LightDownload (Merged & Fixed)
// @match        *://*.douyin.com/*
// @grant        GM_xmlhttpRequest
// @grant        GM_download
// @grant        GM_setValue
// @grant        GM_getValue
// @grant        GM_addStyle
// @grant        unsafeWindow
// @connect      *
// @run-at       document-start
// @namespace    https://greasyfork.org/
// ==/UserScript==

(function () {
    'use strict';

    /* ══════════════════════════════════════════════════════════
       STATE
    ══════════════════════════════════════════════════════════ */
    var dirHandle     = null;
    var videoInfo     = null;
    var isDownloading = false;
    var lastNavUrl    = '';

    // 网络捕获缓存（用于封面和视频回退）
    var capturedVideos = [];
    var capturedCovers = [];

    var _itemObserver = null;
    var _currentItemKey = null;
    function getItemKey(el) {
        return el.getAttribute('data-aweme-id') || el.getAttribute('data-id') ||
               el.dataset.awemeid || el.dataset.id ||
               (el.parentElement ? Array.prototype.indexOf.call(el.parentElement.children, el) : 0) + '_i';
    }
    function setupItemObserver() {
        if (_itemObserver) { _itemObserver.disconnect(); _itemObserver = null; }
        var items = document.querySelectorAll('.page-recommend-container,.dySwiperSlide[data-e2e="feed-item"]');
        if (!items.length) return;
        _itemObserver = new IntersectionObserver(function(entries) {
            entries.forEach(function(entry) {
                if (entry.intersectionRatio >= 0.65) {
                    var key = getItemKey(entry.target);
                    if (key && key !== _currentItemKey) {
                        _currentItemKey = key;
                        capturedVideos = []; capturedCovers = [];
                    }
                }
            });
        }, { threshold: [0.65] });
        Array.prototype.forEach.call(items, function(item) { _itemObserver.observe(item); });
    }
    var _domWatcher = null;
    function watchForNewItems() {
        if (_domWatcher) return;
        _domWatcher = new MutationObserver(function(m) {
            for (var i=0;i<m.length;i++) { if(m[i].addedNodes.length){ setTimeout(setupItemObserver,200); break; } }
        });
        _domWatcher.observe(document.body, { childList:true, subtree:true });
    }

    /* ══════════════════════════════════════════════════════════
       ① 网络拦截器（用于封面捕获及视频回退）
    ══════════════════════════════════════════════════════════ */
    function scoreVideoUrl(url) {
        if (!url) return -99;
        var s = 0;
        if (/douyinvod\.com/.test(url))   s += 10;
        if (/v\d+-web\./.test(url))        s += 8;
        if (/amemv\.com/.test(url))        s += 7;
        if (/aweme\/v1\/play/.test(url))   s += 6;
        if (/\.mp4/.test(url))             s += 5;
        if (/mime_type=video/.test(url))   s += 4;
        if (/\.m3u8|\.ts\b|\.m4s|\/seg\/|fragment|chunk|segment/i.test(url)) s -= 20;
        if (url.length < 80) s -= 5;
        return s;
    }

    function isVideoUrl(url) { return scoreVideoUrl(url) > 0; }

    function isCoverUrl(url) {
        return /byteimg\.com\/img\/|douyinstatic\.com|pstatp\.com/.test(url) &&
               /\.(jpe?g|webp|png)/.test(url) &&
               !/avatar/.test(url);
    }

    function captureUrl(rawUrl) {
        if (!rawUrl || typeof rawUrl !== 'string') return;
        if (/^(blob:|data:)/.test(rawUrl)) return;
        var url; try { url = decodeURIComponent(rawUrl); } catch(e) { url = rawUrl; }
        if (isVideoUrl(url)) {
            pushCapture(capturedVideos, url, scoreVideoUrl(url));
        } else if (isCoverUrl(url)) {
            pushCapture(capturedCovers, url, 0);
        }
    }

    function pushCapture(list, url, score) {
        var base = url.split('?')[0];
        for (var i = 0; i < list.length; i++) {
            if (list[i].url.split('?')[0] === base) { list[i].ts = Date.now(); return; }
        }
        list.push({ url: url, score: score, ts: Date.now() });
        list.sort(function(a, b) { return b.score !== a.score ? b.score - a.score : b.ts - a.ts; });
        if (list.length > 40) list.pop();
    }

    function bestVideo() {
        if (!capturedVideos.length) return null;
        var now = Date.now();
        var fresh = capturedVideos.filter(function(c){ return now - c.ts < 90000; });
        var pool  = fresh.length ? fresh : capturedVideos;
        return pool[0].url;
    }

    function bestCover() {
        if (!capturedCovers.length) return null;
        var now = Date.now();
        var fresh = capturedCovers.filter(function(c){ return now - c.ts < 90000; });
        return (fresh.length ? fresh[0] : capturedCovers[0]).url;
    }

    (function setupInterceptors() {
        try {
            var oF = unsafeWindow.fetch.bind(unsafeWindow);
            unsafeWindow.fetch = function() {
                var a = Array.prototype.slice.call(arguments);
                captureUrl(typeof a[0] === 'string' ? a[0] : (a[0] && a[0].url) || '');
                return oF.apply(unsafeWindow, a);
            };
        } catch(e) {}
        try {
            var oO = unsafeWindow.XMLHttpRequest.prototype.open;
            unsafeWindow.XMLHttpRequest.prototype.open = function(m, url) {
                captureUrl(typeof url === 'string' ? url : '');
                return oO.apply(this, arguments);
            };
        } catch(e) {}
    })();

    /* ══════════════════════════════════════════════════════════
       ② 查找当前Feed Item（增强版）
    ══════════════════════════════════════════════════════════ */
    function findCurrentFeedItem() {
        // 优先从正在播放的视频向上找
        var vids = Array.prototype.slice.call(document.querySelectorAll('video'));
        var playing = null;
        for (var i = 0; i < vids.length; i++) {
            if (!vids[i].paused && vids[i].readyState >= 2 && vids[i].currentTime > 0) {
                playing = vids[i]; break;
            }
        }
        if (!playing && vids.length) {
            var bestV = -1;
            for (var j = 0; j < vids.length; j++) {
                var r = vids[j].getBoundingClientRect();
                var v = Math.min(r.bottom, window.innerHeight) - Math.max(r.top, 0);
                if (v > bestV) { bestV = v; playing = vids[j]; }
            }
        }
        if (playing) {
            var el = playing.parentElement;
            while (el && el !== document.body) {
                if (el.classList.contains('page-recommend-container') || el.dataset.e2e === 'feed-item') return el;
                if (el.id === 'slideMode') return el;               // 详情页浮层
                if (el.classList.contains('playerControlHeight')) return el; // 详情页
                el = el.parentElement;
            }
        }
        // 降级：取可视区域最大的 feed 容器
        var items = Array.prototype.slice.call(
            document.querySelectorAll('.page-recommend-container,.dySwiperSlide[data-e2e="feed-item"],#slideMode,.playerControlHeight')
        );
        var best = null, bestVis = -1;
        for (var k = 0; k < items.length; k++) {
            var rr = items[k].getBoundingClientRect();
            var vv = Math.min(rr.bottom, window.innerHeight) - Math.max(rr.top, 0);
            if (vv > bestVis) { bestVis = vv; best = items[k]; }
        }
        return best;
    }

    /* ══════════════════════════════════════════════════════════
       ③ 图文检测（保留）
    ══════════════════════════════════════════════════════════ */
    function hasImageTextBadge(container) {
        var all = container.querySelectorAll('span,div,a,em,i,button');
        for (var i = 0; i < all.length; i++) {
            var t = all[i].textContent.trim();
            if (t === '图文') return true;
        }
        return !!(
            container.querySelector('.xgplayer-progress-outer.picture') ||
            container.querySelector('[class*="pictureMode"]') ||
            container.querySelector('[class*="PicTextTag"]') ||
            container.querySelector('[class*="picTextTag"]') ||
            container.querySelector('[class*="imageTextTag"]') ||
            container.querySelector('[class*="ImageTextTag"]') ||
            container.querySelector('[class*="img-text-tag"]') ||
            container.getAttribute('data-type') === 'image'
        );
    }

    function detectImagePost(container) {
        if (!container) return { isImage: false, images: [] };
        var isPic = hasImageTextBadge(container);
        if (!isPic) return { isImage: false, images: [] };
        var images = extractSlideImages(container);
        return { isImage: true, images: images };
    }

    function extractSlideImages(container) {
        var images = [];
        var seen = {};
        var slideSelectors = [
            '[class*="swiper-slide"]',
            '[class*="SwiperSlide"]',
            '[class*="slide-item"]',
            '[class*="ImageItem"]',
            '[class*="imageItem"]',
            '[class*="pic-item"]'
        ].join(',');
        var slides = container.querySelectorAll(slideSelectors);
        if (slides.length >= 2) {
            for (var i = 0; i < slides.length; i++) {
                var img = bestImgInSlide(slides[i]);
                if (img && !seen[img]) { seen[img] = true; images.push(img); }
            }
            if (images.length >= 2) return images;
        }
        var wrappers = container.querySelectorAll(
            '[class*="swiper-wrapper"],[class*="SwiperWrapper"],[class*="carousel"],[class*="Carousel"]'
        );
        if (wrappers.length) {
            var wrapper = wrappers[0];
            var imgs = wrapper.querySelectorAll('img');
            for (var j = 0; j < imgs.length; j++) {
                if (isContentImg(imgs[j])) {
                    var src = imgs[j].src || imgs[j].getAttribute('data-src') || '';
                    if (src && !seen[src]) { seen[src] = true; images.push(src); }
                }
            }
            if (images.length >= 2) return images;
        }
        return images;
    }

    function bestImgInSlide(slide) {
        var imgs = slide.querySelectorAll('img');
        for (var i = 0; i < imgs.length; i++) {
            if (isContentImg(imgs[i])) return imgs[i].src || imgs[i].getAttribute('data-src') || '';
        }
        return null;
    }

    function isContentImg(img) {
        if (!img) return false;
        var src = img.src || img.getAttribute('data-src') || '';
        if (!src || /^(blob:|data:)/.test(src) || src.length < 20) return false;
        if (/avatar|emoji|icon|logo|dot|indicator/i.test(src)) return false;
        if (/avatar|emoji|icon|logo|dot|indicator/i.test(img.className || '')) return false;
        var w = img.naturalWidth || img.width || (img.getBoundingClientRect && img.getBoundingClientRect().width) || 0;
        var h = img.naturalHeight || img.height || (img.getBoundingClientRect && img.getBoundingClientRect().height) || 0;
        if (w > 0 && w < 50) return false;
        if (h > 0 && h < 50) return false;
        var par = img.parentElement;
        for (var i = 0; i < 3 && par; i++) {
            if (/avatar|Avatar|userPhoto/i.test(par.className || '')) return false;
            par = par.parentElement;
        }
        return true;
    }

    /* ══════════════════════════════════════════════════════════
       ④ 封面提取（保留）
    ══════════════════════════════════════════════════════════ */
    function extractCover(container) {
        if (!container) return bestCover() || '';
        var xgPoster = container.querySelector(
            '.xgplayer-poster,.xg-poster,[class*="xgplayer-poster"],[class*="xg-poster"]'
        );
        if (xgPoster) {
            var bgStyle = xgPoster.getAttribute('style') || '';
            var bgMatch = bgStyle.match(/background(?:-image)?\s*:\s*url\(["']?(https?:[^"')]+)["']?\)/);
            if (!bgMatch) {
                var computedBg = window.getComputedStyle(xgPoster).backgroundImage;
                bgMatch = computedBg.match(/url\(["']?(https?:[^"')]+)["']?\)/);
            }
            if (bgMatch) return bgMatch[1];
            var xgImg = xgPoster.querySelector('img');
            if (xgImg && xgImg.src && !/^(blob:|data:)/.test(xgImg.src)) return xgImg.src;
        }
        var coverSels = ['img[class*="cover"]','img[class*="Cover"]','img[class*="poster"]','img[class*="Poster"]','img[class*="thumb"]','img[class*="Thumb"]'];
        for (var s = 0; s < coverSels.length; s++) {
            var ci = container.querySelector(coverSels[s]);
            if (ci && isContentImg(ci)) return ci.src;
        }
        var imgs = container.querySelectorAll('img');
        for (var i = 0; i < imgs.length; i++) {
            var src = imgs[i].src || imgs[i].getAttribute('data-src') || '';
            if (isContentImg(imgs[i]) && src) return src;
        }
        var bgEls = container.querySelectorAll('[class*="cover"],[class*="poster"],[class*="mask"]');
        for (var b = 0; b < bgEls.length; b++) {
            var bg = window.getComputedStyle(bgEls[b]).backgroundImage;
            var m = bg.match(/url\(["']?(https?:[^"')]+)["']?\)/);
            if (m) return m[1];
        }
        return bestCover() || '';
    }

    /* ══════════════════════════════════════════════════════════
       ⑤ 【修正】视频URL提取 —— 多重策略，确保能获取到链接
    ══════════════════════════════════════════════════════════ */
    function extractVideoUrl(container) {
        if (!container) {
            container = findCurrentFeedItem();
        }
        if (!container) return null;

        var videoEl = container.querySelector('video');
        if (!videoEl) return null;

        // 策略1：从 <source> 标签获取
        var sources = videoEl.querySelectorAll('source');
        for (var i = 0; i < sources.length; i++) {
            var s = sources[i].getAttribute('src') || '';
            if (!s || /^blob:/.test(s)) continue;
            try { s = decodeURI(s); } catch(e) {}
            if (s.indexOf('douyin') > -1 || s.indexOf('douyinvod') > -1 || s.indexOf('.mp4') > -1) {
                return s;
            }
        }

        // 策略2：获取 video.currentSrc（播放器当前使用的源）
        if (videoEl.currentSrc && !/^blob:/.test(videoEl.currentSrc)) {
            var cur = videoEl.currentSrc;
            try { cur = decodeURI(cur); } catch(e) {}
            if (cur.indexOf('douyin') > -1 || cur.indexOf('.mp4') > -1) {
                return cur;
            }
        }

        // 策略3：获取 video.src 属性
        var attrSrc = videoEl.getAttribute('src');
        if (attrSrc && !/^blob:/.test(attrSrc)) {
            try { attrSrc = decodeURI(attrSrc); } catch(e) {}
            if (attrSrc.indexOf('douyin') > -1 || attrSrc.indexOf('.mp4') > -1) {
                return attrSrc;
            }
        }

        // 策略4：如果以上都失败，回退到网络捕获缓存（防止提取不到）
        var fallback = bestVideo();
        if (fallback) {
            console.log('[SVD] DOM提取失败，使用网络捕获缓存:', fallback);
            return fallback;
        }

        return null;
    }

    // 处理302跳转，获取最终无水印直链
    function resolveVideoUrl(rawUrl, callback) {
        if (!rawUrl) {
            callback(null);
            return;
        }
        var method = navigator.userAgent.indexOf('Firefox') !== -1 ? 'GET' : 'HEAD';
        var headers = {
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36',
            'Origin': 'https://www.douyin.com',
            'Referer': 'https://www.douyin.com/'
        };
        GM_xmlhttpRequest({
            method: method,
            url: rawUrl,
            headers: headers,
            timeout: 20000,
            onload: function(res) {
                if (res.status === 200 || res.status === 401) {
                    callback(rawUrl);
                } else if (res.status === 302) {
                    var locationMatch = (res.responseHeaders || '').match(/[Ll]ocation:\s*(.+)/);
                    if (locationMatch) {
                        callback(locationMatch[1].trim());
                    } else {
                        callback(rawUrl);
                    }
                } else {
                    callback(rawUrl); // 降级
                }
            },
            onerror: function() {
                callback(rawUrl);
            }
        });
    }

    /* ══════════════════════════════════════════════════════════
       ⑥ RENDER_DATA 提取（保留，视频URL用实时提取）
    ══════════════════════════════════════════════════════════ */
    function extractFromRenderData() {
        try {
            var el = document.getElementById('RENDER_DATA');
            if (!el) return null;
            var raw = JSON.parse(decodeURIComponent(el.textContent));
            var detail = null;
            for (var key in raw) {
                if (key === '_location' || key === 'app' || key === '11') continue;
                if (raw[key] && raw[key].videoDetail) { detail = raw[key].videoDetail; break; }
            }
            if (!detail) return null;

            var author    = detail.authorInfo || detail.author || {};
            var video     = detail.video || {};
            var textExtra = detail.textExtra || [];

            var coverList = ((video.cover||{}).urlList) || ((video.dynamicCover||{}).urlList) || ((video.originCover||{}).urlList) || [];
            var coverUrl  = coverList[0] || bestCover() || '';
            var avList    = ((author.avatarThumb||{}).urlList) || ((author.avatarMedium||{}).urlList) || [];
            var avatarUrl = avList[0] || '';
            var topics    = textExtra.filter(function(t){ return t.hashtagName; }).map(function(t){ return '#'+t.hashtagName; });
            var createTime= detail.createTime ? new Date(detail.createTime*1000).toLocaleString('zh-CN',{hour12:false}) : '未知';
            var hasImages = !!(detail.imageAlbumMusicInfo || (detail.images && detail.images.length));
            // 实时判断是否为图文
            var container = findCurrentFeedItem();
            var isImagePost = hasImages || (container && hasImageTextBadge(container));
            var images = isImagePost ? (detail.images||[]).map(function(img){ return ((img.urlList||[])[0])||''; }).filter(Boolean) : [];

            return {
                platform:'抖音', author:author.nickname||author.uniqueId||'未知作者',
                authorId:author.uniqueId||'', avatarUrl:avatarUrl, createTime:createTime,
                desc:detail.desc||detail.title||'无文案', topics:topics,
                coverUrl:coverUrl, videoUrl: null, // 后续实时获取
                isImagePost: isImagePost, images: images
            };
        } catch(e) { console.warn('[SVD] RENDER_DATA:', e); return null; }
    }

    function extractVideoInfo() {
        var rd = extractFromRenderData();
        if (rd) {
            var container = findCurrentFeedItem() || document.querySelector('.playerControlHeight') || document.getElementById('slideMode');
            rd.videoUrl = extractVideoUrl(container);
            return rd;
        }
        var sm = document.getElementById('slideMode');
        if (sm) return extractFromContainer(sm, false);
        var pc = document.querySelector('.playerControlHeight');
        if (pc) return extractFromContainer(pc, true);
        var fi = findCurrentFeedItem();
        if (fi) return extractFromFeedItem(fi);
        return null;
    }

    function extractFromFeedItem(item) {
        var author  = ((item.querySelector('.account-name')||{textContent:''}).textContent||'').trim() || '未知作者';
        var avEl    = item.querySelector('[class*="avatar"] img,.avatar img,img[class*="Avatar"]');
        var avatarUrl = avEl ? avEl.src : '';
        var desc = '无文案';
        var te = item.querySelector('.title');
        if (te) { var sp=te.querySelector('span'); desc=((sp&&sp.textContent)||te.textContent||'').replace('展开','').trim(); }
        var topics = [];
        var tags = item.querySelectorAll('a[href*="hashtag"],[class*="Tag"],[class*="tag"]');
        for (var i=0;i<tags.length;i++){ var tt=tags[i].textContent.trim(); if(tt&&tt[0]==='#'&&topics.indexOf(tt)===-1) topics.push(tt); }
        var imgPost = detectImagePost(item);
        var coverUrl = extractCover(item);
        var videoUrl = imgPost.isImage ? null : extractVideoUrl(item);
        return {
            platform:'抖音', author:author, authorId:'', avatarUrl:avatarUrl,
            createTime:'未知（首页不提供时间）', desc:desc, topics:topics,
            coverUrl:coverUrl, videoUrl:videoUrl, isImagePost:imgPost.isImage, images:imgPost.images
        };
    }

    function extractFromContainer(container, isDetail) {
        var an = container.querySelector('.account-name,[class*="nickname"] span,[class*="accountName"] span');
        var author = (an&&an.textContent.trim())||'未知作者';
        var avEl = container.querySelector('[class*="avatar"] img,.avatar img');
        var avatarUrl = avEl ? avEl.src : '';
        var desc = '无文案';
        if (isDetail) { var h1=container.querySelector('h1'); if(h1) desc=h1.textContent.trim(); }
        else { var tn=container.querySelector('.title'); if(tn) desc=tn.textContent.replace('展开','').trim(); }
        var imgPost = detectImagePost(container);
        return {
            platform:'抖音', author:author, authorId:'', avatarUrl:avatarUrl, createTime:'未知', desc:desc, topics:[],
            coverUrl:extractCover(container), videoUrl:imgPost.isImage?null:extractVideoUrl(container),
            isImagePost:imgPost.isImage, images:imgPost.images
        };
    }

    /* ══════════════════════════════════════════════════════════
       ⑦ 下载引擎（修正下载逻辑）
    ══════════════════════════════════════════════════════════ */
    var HEADERS = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36',
        'Origin': 'https://www.douyin.com',
        'Referer': 'https://www.douyin.com/'
    };

    function sanitize(s){ return (s||'').replace(/[\\/:*?"<>|\r\n]/g,'_').trim().substring(0,80); }
    function getFilename(info, type, idx) {
        var a=sanitize(info.author), d=sanitize((info.desc||'').substring(0,25));
        if (type==='video')  return a+'-'+d+'.mp4';
        if (type==='cover')  return a+'-封面.jpg';
        if (type==='image')  return a+'-图文第'+(idx+1)+'张.jpg';
        return a+'-文件.bin';
    }

    function saveFile(blob, filename) {
        if (dirHandle) {
            return dirHandle.getFileHandle(filename,{create:true})
                .then(function(fh){ return fh.createWritable(); })
                .then(function(wr){ return wr.write(blob).then(function(){ return wr.close(); }); })
                .then(function(){ return {ok:true,method:'fs'}; })
                .catch(function(){ return saveViaGM(blob,filename); });
        }
        return saveViaGM(blob, filename);
    }

    function saveViaGM(blob, filename) {
        return new Promise(function(res) {
            var bu=URL.createObjectURL(blob);
            GM_download({url:bu,name:filename,
                onload:  function(){ URL.revokeObjectURL(bu); res({ok:true,method:'gm'}); },
                onerror: function(e){ URL.revokeObjectURL(bu); res({ok:false,error:e.error||'失败'}); }
            });
        });
    }

    // 【修正】视频下载：优先实时提取，若失败则提示
    function doDownloadVideo() {
        if (isDownloading){ setStatus('下载进行中...','info'); return; }

        // 实时获取当前视频URL
        var container = findCurrentFeedItem() || document.querySelector('.playerControlHeight') || document.getElementById('slideMode');
        var rawUrl = extractVideoUrl(container);

        if (!rawUrl) {
            setStatus('❌ 未找到视频链接，请确保视频正在播放', 'err');
            return;
        }

        if (videoInfo) videoInfo.videoUrl = rawUrl;

        isDownloading = true; setBtnsEnabled(false);
        setStatus('正在解析视频地址...','info'); setProgress(0.02);

        resolveVideoUrl(rawUrl, function(finalUrl) {
            if (!finalUrl) {
                finishDL(false, '无法解析视频地址');
                return;
            }
            var filename = getFilename(videoInfo || {author:'未知',desc:'视频'}, 'video');
            fetchBlob(finalUrl, filename, '视频');
        });
    }

    function doDownloadCover() {
        var url = (videoInfo && videoInfo.coverUrl) || bestCover();
        if (!url) { setStatus('未找到封面','err'); return; }
        doDownload(url, getFilename(videoInfo||{author:'未知',desc:'封面'},'cover'), '封面');
    }

    function doDownload(url, filename, label) {
        if (isDownloading){ setStatus('下载进行中...','info'); return; }
        isDownloading=true; setBtnsEnabled(false);
        setStatus('正在验证 '+label+' ...','info'); setProgress(0.02);
        var method=navigator.userAgent.indexOf('Firefox')!==-1?'GET':'HEAD';
        GM_xmlhttpRequest({
            method:method, url:url, headers:HEADERS, timeout:20000,
            onload:function(r){
                var fu=url;
                if(r.status===302){ var m=(r.responseHeaders||'').match(/[Ll]ocation:\s*(.+)/); if(m)fu=m[1].trim(); }
                else if(r.status===403){ finishDL(false,'链接已失效，请等视频重新加载后下载'); return; }
                fetchBlob(fu, filename, label);
            },
            onerror:function(){ fetchBlob(url,filename,label); }
        });
    }

    function doDownloadImage(url, filename) {
        setStatus('正在下载图片: '+filename,'info');
        GM_xmlhttpRequest({
            method:'GET', url:url, headers:HEADERS, responseType:'blob', timeout:60000,
            onload:function(res){
                if(res.status===200){
                    saveFile(res.response, filename).then(function(r){
                        setStatus((r.ok?'✅ 已保存: ':'❌ ')+filename, r.ok?'ok':'err');
                    });
                } else { setStatus('❌ 图片下载失败 HTTP '+res.status,'err'); }
            },
            onerror:function(){ setStatus('❌ 图片下载出错','err'); }
        });
    }

    function fetchBlob(url, filename, label) {
        setStatus('正在下载 '+label+'...','info');
        GM_xmlhttpRequest({
            method:'GET', url:url, headers:HEADERS, responseType:'blob', timeout:3600000,
            onprogress:function(e){
                if(e.lengthComputable){
                    setProgress(e.loaded/e.total);
                    setStatus('⬇ '+(e.loaded/1048576).toFixed(1)+' / '+(e.total/1048576).toFixed(1)+' MB','info');
                }
            },
            onload:function(res){
                if(res.status===200){
                    setStatus('正在保存...','info');
                    saveFile(res.response, filename).then(function(r){
                        finishDL(r.ok, r.ok?(r.method==='fs'?'已存入目录: '+filename:'已触发下载: '+filename):r.error);
                    });
                } else finishDL(false,'HTTP '+res.status);
            },
            onerror:function(e){ finishDL(false,e.error||'网络错误'); }
        });
    }

    function finishDL(ok,msg){ isDownloading=false; setProgress(0); setBtnsEnabled(true); setStatus((ok?'✅ ':'❌ ')+msg,ok?'ok':'err'); }

    /* ══════════════════════════════════════════════════════════
       ⑧ UI样式与构建（完全保留）
    ══════════════════════════════════════════════════════════ */
    var THEME = {
        bg:       '#ffffff',
        bg2:      '#f7f8fa',
        bg3:      '#f0f2f5',
        border:   '#e4e6ea',
        border2:  '#ced0d4',
        text:     '#1c1e21',
        text2:    '#65676b',
        text3:    '#a8aaad',
        accent:   '#fe2c55',
        accentBg: 'rgba(254,44,85,0.08)',
        purple:   '#6366f1',
        green:    '#16a34a',
        red:      '#dc2626',
        blue:     '#2563eb',
        shadow:   '0 4px 24px rgba(0,0,0,0.10), 0 1px 4px rgba(0,0,0,0.06)'
    };

    function injectStyles() {
        if (document.getElementById('svd-styles')) return;
        var s = document.createElement('style');
        s.id = 'svd-styles';
        var rules = [
'#svd-win{',
'  position:fixed;top:58px;right:18px;width:410px;max-height:92vh;',
'  overflow-y:auto;overflow-x:hidden;',
'  background:'+THEME.bg+';',
'  border:1px solid '+THEME.border+';border-radius:16px;',
'  box-shadow:'+THEME.shadow+';',
'  z-index:2147483647;',
'  font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;',
'  font-size:13px;color:'+THEME.text+';',
'  scrollbar-width:thin;scrollbar-color:'+THEME.border+' transparent;',
'  transition:max-height .3s cubic-bezier(.4,0,.2,1);',
'}',
'#svd-win::-webkit-scrollbar{width:5px}',
'#svd-win::-webkit-scrollbar-thumb{background:'+THEME.border2+';border-radius:3px}',
'#svd-win.svd-mini{max-height:52px;overflow:hidden}',
'#svd-hdr{',
'  position:sticky;top:0;z-index:5;',
'  display:flex;align-items:center;gap:10px;',
'  padding:14px 16px;',
'  background:'+THEME.bg+';',
'  border-bottom:1px solid '+THEME.border+';',
'  border-radius:16px 16px 0 0;cursor:move;',
'}',
'.svd-badge{',
'  width:28px;height:28px;border-radius:9px;',
'  background:'+THEME.accent+';',
'  display:flex;align-items:center;justify-content:center;flex-shrink:0;',
'  box-shadow:0 2px 6px rgba(254,44,85,.35);',
'}',
'.svd-badge svg{width:15px;height:15px;fill:#fff}',
'.svd-title{flex:1;font-weight:700;font-size:14px;color:'+THEME.text+';letter-spacing:-.2px}',
'.svd-title em{color:'+THEME.accent+';font-style:normal}',
'.svd-wbtns{display:flex;gap:6px}',
'.svd-wbtn{',
'  width:22px;height:22px;border-radius:50%;border:none;cursor:pointer;',
'  font-size:11px;font-weight:700;line-height:1;',
'  display:flex;align-items:center;justify-content:center;',
'  transition:transform .15s,filter .15s;',
'}',
'.svd-wbtn:hover{transform:scale(1.15)}',
'.svd-wbtn-min{background:#fdbc40;color:#5a3900}',
'.svd-wbtn-x{background:#fd5f57;color:#5a0000}',
'.svd-sec{padding:12px 16px;border-bottom:1px solid '+THEME.border+';background:'+THEME.bg+'}',
'.svd-sec-lbl{font-size:10px;font-weight:700;letter-spacing:1.2px;text-transform:uppercase;color:'+THEME.text3+';margin-bottom:8px}',
'#svd-path-row{display:flex;align-items:center;gap:8px}',
'#svd-path-txt{',
'  flex:1;padding:7px 10px;',
'  background:'+THEME.bg2+';border:1px solid '+THEME.border+';border-radius:8px;',
'  color:'+THEME.text3+';font-size:11.5px;',
'  overflow:hidden;text-overflow:ellipsis;white-space:nowrap;',
'}',
'#svd-path-txt.set{color:'+THEME.green+';border-color:rgba(22,163,74,.3);background:rgba(22,163,74,.06)}',
'#svd-path-btn{',
'  padding:7px 13px;',
'  background:'+THEME.purple+';',
'  border:none;border-radius:8px;',
'  color:#fff;font-size:11.5px;font-weight:600;',
'  cursor:pointer;white-space:nowrap;',
'  box-shadow:0 2px 8px rgba(99,102,241,.3);',
'  transition:opacity .15s,transform .15s;',
'}',
'#svd-path-btn:hover{opacity:.88;transform:translateY(-1px)}',
'#svd-capbar{',
'  display:flex;align-items:center;gap:7px;',
'  padding:7px 16px;',
'  background:'+THEME.bg2+';',
'  border-bottom:1px solid '+THEME.border+';',
'  font-size:11px;',
'}',
'.svd-dot{width:7px;height:7px;border-radius:50%;background:'+THEME.text3+';flex-shrink:0;transition:background .3s}',
'.svd-dot.on{background:#16a34a;box-shadow:0 0 5px rgba(22,163,74,.6);animation:svd-pulse 1.5s infinite}',
'@keyframes svd-pulse{0%,100%{opacity:1}50%{opacity:.45}}',
'#svd-captxt{color:'+THEME.text3+'}',
'#svd-captxt.on{color:'+THEME.green+'}',
'#svd-refresh{',
'  width:100%;padding:8px;',
'  background:'+THEME.bg2+';border:1px solid '+THEME.border+';border-radius:8px;',
'  color:'+THEME.text2+';font-size:12px;font-weight:500;',
'  cursor:pointer;display:flex;align-items:center;justify-content:center;gap:6px;',
'  transition:background .15s,border-color .15s;',
'}',
'#svd-refresh:hover{background:'+THEME.bg3+';border-color:'+THEME.border2+'}',
'#svd-tbl{padding:4px 16px 12px;background:'+THEME.bg+';border-bottom:1px solid '+THEME.border+'}',
'.svd-row{display:grid;grid-template-columns:64px 1fr;gap:10px;padding:8px 0;border-bottom:1px solid '+THEME.bg3+';align-items:start}',
'.svd-row:last-child{border-bottom:none}',
'.svd-lbl{font-size:11.5px;font-weight:600;color:'+THEME.text3+';padding-top:1px}',
'.svd-val{font-size:12.5px;color:'+THEME.text+';line-height:1.5}',
'.svd-ac{display:flex;align-items:center;gap:9px}',
'.svd-av{width:34px;height:34px;border-radius:50%;object-fit:cover;flex-shrink:0;border:2px solid '+THEME.accentBg+'}',
'.svd-avph{width:34px;height:34px;border-radius:50%;background:'+THEME.bg3+';display:flex;align-items:center;justify-content:center;font-size:16px;flex-shrink:0}',
'.svd-aname{font-size:13px;font-weight:600;color:'+THEME.text+'}',
'.svd-aid{font-size:11px;color:'+THEME.text3+';margin-top:1px}',
'.svd-desc{max-height:60px;overflow-y:auto;font-size:12.5px;color:'+THEME.text2+';line-height:1.6;word-break:break-word;scrollbar-width:thin}',
'.svd-tags{display:flex;flex-wrap:wrap;gap:4px}',
'.svd-tag{padding:2px 8px;background:'+THEME.accentBg+';border:1px solid rgba(254,44,85,.2);border-radius:100px;color:'+THEME.accent+';font-size:11px;font-weight:500}',
'.svd-cimg{width:100%;max-height:130px;object-fit:cover;border-radius:10px;display:block;cursor:pointer;transition:opacity .2s}',
'.svd-cimg:hover{opacity:.85}',
'.svd-cph{width:100%;height:70px;background:'+THEME.bg2+';border:1.5px dashed '+THEME.border+';border-radius:10px;display:flex;align-items:center;justify-content:center;color:'+THEME.text3+';font-size:12px}',
'.svd-vid{width:100%;max-height:180px;border-radius:10px;background:#000;display:block;object-fit:contain}',
'.svd-imgrid{display:grid;grid-template-columns:repeat(3,1fr);gap:6px}',
'.svd-ig-item{position:relative;border-radius:8px;overflow:hidden;cursor:pointer;background:'+THEME.bg2+'}',
'.svd-igthumb{width:100%;aspect-ratio:1;object-fit:cover;display:block;transition:transform .2s}',
'.svd-ig-item:hover .svd-igthumb{transform:scale(1.04)}',
'.svd-ig-dl{',
'  position:absolute;bottom:5px;right:5px;',
'  background:rgba(255,255,255,.9);backdrop-filter:blur(4px);',
'  border:none;border-radius:6px;',
'  width:26px;height:26px;',
'  display:flex;align-items:center;justify-content:center;',
'  cursor:pointer;font-size:13px;',
'  opacity:0;transform:translateY(4px);',
'  transition:opacity .18s,transform .18s;',
'  box-shadow:0 1px 4px rgba(0,0,0,.15);',
'}',
'.svd-ig-item:hover .svd-ig-dl{opacity:1;transform:translateY(0)}',
'.svd-ig-idx{',
'  position:absolute;top:5px;left:6px;',
'  background:rgba(0,0,0,.45);',
'  color:#fff;font-size:10px;font-weight:600;',
'  padding:1px 5px;border-radius:4px;',
'}',
'.svd-imgdl-all{',
'  margin-top:7px;width:100%;padding:7px;',
'  background:'+THEME.bg2+';border:1px solid '+THEME.border+';border-radius:8px;',
'  color:'+THEME.text2+';font-size:11.5px;font-weight:500;',
'  cursor:pointer;display:flex;align-items:center;justify-content:center;gap:5px;',
'  transition:background .15s;',
'}',
'.svd-imgdl-all:hover{background:'+THEME.bg3+'}',
'.svd-url{font-size:10.5px;color:'+THEME.text3+';word-break:break-all;background:'+THEME.bg2+';border-radius:6px;padding:5px 8px;max-height:36px;overflow:hidden}',
'.svd-url.found{color:'+THEME.green+';background:rgba(22,163,74,.07)}',
'.svd-na{color:'+THEME.text3+';font-style:italic;font-size:11.5px}',
'#svd-actions{display:flex;gap:8px;padding:12px 16px;background:'+THEME.bg+';border-bottom:1px solid '+THEME.border+'}',
'.svd-abtn{',
'  flex:1;padding:10px 8px;border:none;border-radius:10px;',
'  font-size:12.5px;font-weight:700;cursor:pointer;',
'  display:flex;align-items:center;justify-content:center;gap:5px;',
'  transition:transform .15s,box-shadow .15s,opacity .15s;',
'}',
'.svd-abtn:hover{transform:translateY(-1px);box-shadow:0 4px 14px rgba(0,0,0,.12)}',
'.svd-abtn:disabled{opacity:.38;cursor:not-allowed;transform:none;box-shadow:none}',
'.svd-dlv{background:'+THEME.accent+';color:#fff}',
'.svd-dlc{background:'+THEME.bg2+';color:'+THEME.text2+';border:1.5px solid '+THEME.border+'}',
'#svd-statarea{padding:9px 16px 13px;background:'+THEME.bg+'}',
'#svd-prog{height:3px;background:'+THEME.bg3+';border-radius:2px;margin-bottom:7px;overflow:hidden;display:none}',
'#svd-progfill{height:100%;width:0%;background:'+THEME.accent+';border-radius:2px;transition:width .2s}',
'#svd-stattxt{font-size:11px;color:'+THEME.text3+';text-align:center;min-height:16px}',
'#svd-stattxt.ok{color:'+THEME.green+'}',
'#svd-stattxt.err{color:'+THEME.red+'}',
'#svd-stattxt.info{color:'+THEME.blue+'}',
'#svd-trig{position:fixed;bottom:108px;right:18px;width:46px;height:46px;border-radius:50%;',
'  background:'+THEME.accent+';border:none;cursor:pointer;z-index:2147483646;',
'  display:none;align-items:center;justify-content:center;',
'  box-shadow:0 4px 16px rgba(254,44,85,.4);transition:transform .2s;}',
'#svd-trig:hover{transform:scale(1.1)}',
'#svd-trig svg{width:22px;height:22px;fill:#fff}'
        ];
        s.textContent = rules.join('');
        document.head.appendChild(s);
    }

    function buildWindow() {
        if (document.getElementById('svd-win')) return;
        var w = document.createElement('div');
        w.id = 'svd-win';
        w.innerHTML = [
'<div id="svd-hdr">',
'  <div class="svd-badge"><svg viewBox="0 0 24 24"><path d="M5 20h14v-2H5v2zm0-10h4v6h6v-6h4l-7-7-7 7z"/></svg></div>',
'  <span class="svd-title">短视频下载 <em>Pro</em></span>',
'  <div class="svd-wbtns"><button class="svd-wbtn svd-wbtn-min" title="最小化">─</button><button class="svd-wbtn svd-wbtn-x" title="关闭">✕</button></div>',
'</div>',
'<div class="svd-sec">',
'  <div class="svd-sec-lbl">📁 保存路径</div>',
'  <div id="svd-path-row"><div id="svd-path-txt">未选择目录，将使用浏览器默认下载</div><button id="svd-path-btn">📂 选择目录</button></div>',
'</div>',
'<div id="svd-capbar"><div class="svd-dot" id="svd-capdot"></div><span id="svd-captxt">等待视频加载请求...</span></div>',
'<div class="svd-sec" style="padding-top:9px;padding-bottom:9px"><button id="svd-refresh">🔄&nbsp; 刷新 / 读取当前视频信息</button></div>',
'<div id="svd-tbl">',
'  <div class="svd-row"><span class="svd-lbl">平台</span><span class="svd-val" id="svd-f-plt"><span class="svd-na">—</span></span></div>',
'  <div class="svd-row"><span class="svd-lbl">作者</span><div class="svd-val" id="svd-f-aut"><span class="svd-na">—</span></div></div>',
'  <div class="svd-row"><span class="svd-lbl">发布时间</span><span class="svd-val" id="svd-f-time"><span class="svd-na">—</span></span></div>',
'  <div class="svd-row"><span class="svd-lbl">发布文案</span><div class="svd-desc" id="svd-f-desc"><span class="svd-na">—</span></div></div>',
'  <div class="svd-row"><span class="svd-lbl">话题</span><div class="svd-val" id="svd-f-tags"><span class="svd-na">—</span></div></div>',
'  <div class="svd-row"><span class="svd-lbl">封面</span><div class="svd-val" id="svd-f-cov"><span class="svd-na">—</span></div></div>',
'  <div class="svd-row" id="svd-row-content"><span class="svd-lbl" id="svd-content-lbl">视频</span><div class="svd-val" id="svd-f-vid"><span class="svd-na">—</span></div></div>',
'  <div class="svd-row"><span class="svd-lbl">链接</span><div class="svd-url" id="svd-f-url">等待捕获...</div></div>',
'</div>',
'<div id="svd-actions">',
'  <button class="svd-abtn svd-dlv" id="svd-btn-v" disabled>⬇ 下载视频</button>',
'  <button class="svd-abtn svd-dlc" id="svd-btn-c" disabled>🖼 下载封面</button>',
'</div>',
'<div id="svd-statarea"><div id="svd-prog"><div id="svd-progfill"></div></div><div id="svd-stattxt">点击「刷新」读取当前视频信息</div></div>'
        ].join('');
        document.body.appendChild(w);
        bindEvents(w);
        makeDraggable(w, w.querySelector('#svd-hdr'));
    }

    function bindEvents(w) {
        w.querySelector('.svd-wbtn-min').addEventListener('click', function(){ w.classList.toggle('svd-mini'); });
        w.querySelector('.svd-wbtn-x').addEventListener('click', function(){
            w.style.display='none';
            var t=q('svd-trig'); if(t) t.style.display='flex';
        });
        w.querySelector('#svd-path-btn').addEventListener('click', function(){
            if (!window.showDirectoryPicker){ setStatus('浏览器不支持目录选择','err'); return; }
            window.showDirectoryPicker({mode:'readwrite'}).then(function(dh){
                dirHandle=dh;
                var d=q('svd-path-txt'); d.textContent='📁 '+dh.name; d.classList.add('set');
                setStatus('下载目录: '+dh.name,'ok');
            }).catch(function(e){ if(e.name!=='AbortError') setStatus('目录选择失败: '+e.message,'err'); });
        });
        w.querySelector('#svd-refresh').addEventListener('click', function(){ doRefresh(); });
        w.querySelector('#svd-btn-v').addEventListener('click', function(){ doDownloadVideo(); });
        w.querySelector('#svd-btn-c').addEventListener('click', function(){ doDownloadCover(); });
    }

    function renderInfo(info) {
        videoInfo=info;
        if (!info){ setStatus('❌ 未能解析视频信息，请等视频播放后刷新','err'); return; }

        q('svd-f-plt').textContent = info.platform;

        var ae=q('svd-f-aut'); ae.innerHTML='';
        var ac=document.createElement('div'); ac.className='svd-ac';
        if (info.avatarUrl){ var ai=new Image(); ai.className='svd-av'; ai.src=info.avatarUrl; ai.onerror=function(){ ai.replaceWith(avPh()); }; ac.appendChild(ai); }
        else ac.appendChild(avPh());
        var nw=document.createElement('div');
        nw.innerHTML='<div class="svd-aname">'+esc(info.author)+'</div>'+(info.authorId?'<div class="svd-aid">@'+esc(info.authorId)+'</div>':'');
        ac.appendChild(nw); ae.appendChild(ac);

        q('svd-f-time').textContent = info.createTime;
        q('svd-f-desc').textContent = info.desc||'无文案';

        var te=q('svd-f-tags'); te.innerHTML='';
        if (info.topics&&info.topics.length){
            var tw=document.createElement('div'); tw.className='svd-tags';
            info.topics.forEach(function(t){ var sp=document.createElement('span'); sp.className='svd-tag'; sp.textContent=t; tw.appendChild(sp); });
            te.appendChild(tw);
        } else te.innerHTML='<span class="svd-na">无话题标签</span>';

        var ce=q('svd-f-cov'); ce.innerHTML='';
        if (info.coverUrl){
            var ci=new Image(); ci.className='svd-cimg'; ci.src=info.coverUrl; ci.title='点击查看原图';
            ci.addEventListener('click',function(){ window.open(info.coverUrl,'_blank'); });
            ci.onerror=function(){ ce.innerHTML='<div class="svd-cph">封面加载失败</div>'; };
            ce.appendChild(ci);
        } else ce.innerHTML='<div class="svd-cph">封面加载中...</div>';

        var lbl=q('svd-content-lbl'); if(lbl) lbl.textContent=info.isImagePost?'图片':'视频';

        var ve=q('svd-f-vid'); ve.innerHTML='';
        if (info.isImagePost) {
            if (info.images&&info.images.length) {
                buildImageGrid(ve, info);
            } else ve.innerHTML='<span class="svd-na">图文笔记（含背景音乐，无独立视频）</span>';
            var vbtn=q('svd-btn-v'); if(vbtn) vbtn.disabled=true;
        } else if (info.videoUrl) {
            var vd=document.createElement('video'); vd.className='svd-vid'; vd.controls=true; vd.preload='metadata';
            if (info.coverUrl) vd.poster=info.coverUrl; vd.src=info.videoUrl;
            ve.appendChild(vd);
        } else ve.innerHTML='<span class="svd-na">流媒体视频，等待链接捕获中...</span>';

        var ue=q('svd-f-url');
        if (ue){
            var u2=info.videoUrl;
            if(u2){ ue.textContent=u2.substring(0,90)+(u2.length>90?'…':''); ue.className='svd-url found'; }
            else { ue.textContent='未捕获到链接，请稍候'; ue.className='svd-url'; }
        }

        q('svd-btn-v').disabled = !!(info.isImagePost);
        q('svd-btn-c').disabled = !info.coverUrl;
        setStatus('✅ 视频信息加载完成','ok');
    }

    function buildImageGrid(container, info) {
        var grid=document.createElement('div'); grid.className='svd-imgrid';
        info.images.forEach(function(url, idx){
            var item=document.createElement('div'); item.className='svd-ig-item';
            var numLabel=document.createElement('span'); numLabel.className='svd-ig-idx'; numLabel.textContent=idx+1;
            var img=new Image(); img.className='svd-igthumb'; img.src=url; img.loading='lazy';
            img.onerror=function(){ item.style.background='#f0f0f0'; img.style.opacity='.3'; };
            var dlBtn=document.createElement('button'); dlBtn.className='svd-ig-dl'; dlBtn.title='下载第'+(idx+1)+'张'; dlBtn.textContent='⬇';
            (function(u,i){ dlBtn.addEventListener('click',function(e){ e.stopPropagation(); doDownloadImage(u, getFilename(info,'image',i)); }); })(url,idx);
            item.appendChild(img); item.appendChild(numLabel); item.appendChild(dlBtn);
            grid.appendChild(item);
        });
        container.appendChild(grid);
        var allBtn=document.createElement('button'); allBtn.className='svd-imgdl-all';
        allBtn.innerHTML='⬇ 全部下载（'+info.images.length+'张）';
        allBtn.addEventListener('click',function(){
            info.images.forEach(function(url,i){
                setTimeout(function(){ doDownloadImage(url, getFilename(info,'image',i)); }, i*300);
            });
        });
        container.appendChild(allBtn);
    }

    function avPh(){ var d=document.createElement('div'); d.className='svd-avph'; d.textContent='👤'; return d; }
    function q(id){ return document.getElementById(id); }
    function esc(s){ return String(s||'').replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;'); }
    function setStatus(m,c){ var e=q('svd-stattxt'); if(!e)return; e.textContent=m; e.className=c||''; }
    function setProgress(r){ var b=q('svd-prog'),f=q('svd-progfill'); if(!b||!f)return; if(r<=0||r>=1){b.style.display='none';f.style.width='0%';}else{b.style.display='block';f.style.width=(r*100).toFixed(1)+'%';} }
    function setBtnsEnabled(on){ var vb=q('svd-btn-v'),cb=q('svd-btn-c'); if(!on){if(vb)vb.disabled=true;if(cb)cb.disabled=true;return;} if(vb) vb.disabled=!!(videoInfo&&videoInfo.isImagePost); if(cb) cb.disabled=!(videoInfo&&videoInfo.coverUrl); }

    function tickCapture() {
        var dot=q('svd-capdot'), txt=q('svd-captxt'); if(!dot||!txt) return;
        var cv=capturedVideos.length, now=Date.now();
        var fresh=cv&&(now-capturedVideos[0].ts<10000);
        if (cv){ dot.className='svd-dot on'; txt.className='on'; txt.textContent='已捕获 '+cv+' 条视频链接'+(fresh?' ✦':''); }
        else { dot.className='svd-dot'; txt.className=''; txt.textContent='等待视频加载请求...'; }
        if (videoInfo&&!videoInfo.isImagePost&&!videoInfo.videoUrl&&cv){
            videoInfo.videoUrl = extractVideoUrl(findCurrentFeedItem()) || bestVideo();
            patchVideoUI(videoInfo.videoUrl);
        }
        if (videoInfo&&!videoInfo.coverUrl&&capturedCovers.length){
            videoInfo.coverUrl=bestCover(); patchCoverUI(videoInfo.coverUrl);
        }
    }

    function patchVideoUI(url){
        var el=q('svd-f-vid'), ue=q('svd-f-url'); if(!el||!url) return;
        if (!el.querySelector('video')){
            var vd=document.createElement('video'); vd.className='svd-vid'; vd.controls=true; vd.preload='metadata';
            if(videoInfo&&videoInfo.coverUrl) vd.poster=videoInfo.coverUrl; vd.src=url;
            el.innerHTML=''; el.appendChild(vd);
        }
        if(ue){ ue.textContent=url.substring(0,90)+(url.length>90?'…':''); ue.className='svd-url found'; }
        var vb=q('svd-btn-v'); if(vb) vb.disabled=false;
    }

    function patchCoverUI(url){
        var el=q('svd-f-cov'); if(!el||!url) return;
        if (!el.querySelector('img')){
            var ci=new Image(); ci.className='svd-cimg'; ci.src=url;
            ci.addEventListener('click',function(){ window.open(url,'_blank'); });
            el.innerHTML=''; el.appendChild(ci);
        }
        var cb=q('svd-btn-c'); if(cb) cb.disabled=false;
    }

    function makeDraggable(el, handle) {
        var d=false,sx,sy,ox,oy;
        handle.addEventListener('mousedown',function(e){
            if(e.target.classList.contains('svd-wbtn')) return;
            d=true; sx=e.clientX; sy=e.clientY;
            var r=el.getBoundingClientRect(); ox=r.left; oy=r.top;
            document.addEventListener('mousemove',mv); document.addEventListener('mouseup',mu); e.preventDefault();
        });
        function mv(e){ if(!d)return; el.style.left=(ox+e.clientX-sx)+'px'; el.style.top=(oy+e.clientY-sy)+'px'; el.style.right='auto'; }
        function mu(){ d=false; document.removeEventListener('mousemove',mv); document.removeEventListener('mouseup',mu); }
    }

    function buildTrigger(){
        if (q('svd-trig')) return;
        var btn=document.createElement('button'); btn.id='svd-trig'; btn.title='打开下载助手';
        btn.innerHTML='<svg viewBox="0 0 24 24"><path d="M5 20h14v-2H5v2zm0-10h4v6h6v-6h4l-7-7-7 7z"/></svg>';
        btn.addEventListener('click',function(){ var w=q('svd-win'); if(w){w.style.display='';btn.style.display='none';} });
        document.body.appendChild(btn);
    }

    function doRefresh(){
        setStatus('正在读取视频信息...','info');
        setTimeout(function(){ renderInfo(extractVideoInfo()); }, 350);
    }

    function bootstrap(){ injectStyles(); buildWindow(); buildTrigger(); watchForNewItems(); setTimeout(function(){ setupItemObserver(); doRefresh(); },1800); }

    if (document.readyState==='loading') document.addEventListener('DOMContentLoaded',function(){ setTimeout(bootstrap,500); });
    else setTimeout(bootstrap,500);

    setInterval(function(){
        if (!q('svd-win'))    buildWindow();
        if (!q('svd-trig'))   buildTrigger();
        if (!q('svd-styles')) injectStyles();
        tickCapture();
        var cur=location.href;
        if (cur!==lastNavUrl){
            lastNavUrl=cur;
            capturedVideos=[]; capturedCovers=[];
            setTimeout(doRefresh,1800);
        }
    }, 800);
})();