diff --git a/docker-compose.yml b/docker-compose.yml
index 04b5fca..a6da150 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -8,6 +8,7 @@ services:
       - "3001:3001"
     volumes:
       - ./downloads:/app/server/downloads
+      - ./server/cache:/app/server/cache
     restart: unless-stopped
     # Login credentials for basic auth
     environment:
diff --git a/server/cache/.gitkeep b/server/cache/.gitkeep
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/server/cache/.gitkeep
@@ -0,0 +1 @@
+
diff --git a/server/server.js b/server/server.js
index 1cc1b73..df8f3d8 100644
--- a/server/server.js
+++ b/server/server.js
@@ -17,6 +17,7 @@ const app = express();
 const upload = multer({ dest: path.join(__dirname, "uploads") });
 const client = new WebTorrent();
 const torrents = new Map();
+let wss;
 const PORT = process.env.PORT || 3001;
 
 // --- İndirilen dosyalar için klasör oluştur ---
@@ -24,6 +25,20 @@ const DOWNLOAD_DIR = path.join(__dirname, "downloads");
 if (!fs.existsSync(DOWNLOAD_DIR))
   fs.mkdirSync(DOWNLOAD_DIR, { recursive: true });
 
+// --- Thumbnail cache klasörü ---
+const CACHE_DIR = path.join(__dirname, "cache");
+const THUMBNAIL_DIR = path.join(CACHE_DIR, "thumbnails");
+const VIDEO_THUMB_ROOT = path.join(THUMBNAIL_DIR, "videos");
+const IMAGE_THUMB_ROOT = path.join(THUMBNAIL_DIR, "images");
+
+for (const dir of [THUMBNAIL_DIR, VIDEO_THUMB_ROOT, IMAGE_THUMB_ROOT]) {
+  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
+}
+
+const VIDEO_THUMBNAIL_TIME = process.env.VIDEO_THUMBNAIL_TIME || "00:00:05";
+const VIDEO_EXTS = [".mp4", ".webm", ".mkv", ".mov", ".m4v"];
+const generatingThumbnails = new Set();
+
 app.use(cors());
 app.use(express.json());
 app.use(express.urlencoded({ extended: true }));
@@ -31,21 +46,186 @@ app.use("/downloads", express.static(DOWNLOAD_DIR));
 
 // --- En uygun video dosyasını seç ---
 function pickBestVideoFile(torrent) {
-  const videoExts = [".mp4", ".webm", ".mkv", ".mov", ".m4v"];
   const videos = torrent.files
     .map((f, i) => ({ i, f }))
-    .filter(({ f }) => videoExts.includes(path.extname(f.name).toLowerCase()));
+    .filter(({ f }) => VIDEO_EXTS.includes(path.extname(f.name).toLowerCase()));
   if (!videos.length) return 0;
   videos.sort((a, b) => b.f.length - a.f.length);
   return videos[0].i;
 }
 
+function ensureDirForFile(filePath) {
+  const dir = path.dirname(filePath);
+  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
+}
+
+function sanitizeRelative(relPath) {
+  return relPath.replace(/^[\\/]+/, "");
+}
+
+function relPathToSegments(relPath) {
+  return sanitizeRelative(relPath).split(/[\\/]/).filter(Boolean);
+}
+
+function rootFromRelPath(relPath) {
+  const segments = relPathToSegments(relPath);
+  return segments[0] || null;
+}
+
+function getVideoThumbnailPaths(relPath) {
+  const parsed = path.parse(relPath);
+  const relThumb = path.join("videos", parsed.dir, `${parsed.name}.jpg`);
+  const absThumb = path.join(THUMBNAIL_DIR, relThumb);
+  return { relThumb, absThumb };
+}
+
+function getImageThumbnailPaths(relPath) {
+  const parsed = path.parse(relPath);
+  const relThumb = path.join(
+    "images",
+    parsed.dir,
+    `${parsed.name}${parsed.ext || ".jpg"}`
+  );
+  const absThumb = path.join(THUMBNAIL_DIR, relThumb);
+  return { relThumb, absThumb };
+}
+
+function thumbnailUrl(relThumb) {
+  const safe = relThumb
+    .split(path.sep)
+    .filter(Boolean)
+    .map(encodeURIComponent)
+    .join("/");
+  return `/thumbnails/${safe}`;
+}
+
+function markGenerating(absThumb, add) {
+  if (add) generatingThumbnails.add(absThumb);
+  else generatingThumbnails.delete(absThumb);
+}
+
+function queueVideoThumbnail(fullPath, relPath) {
+  const { relThumb, absThumb } = getVideoThumbnailPaths(relPath);
+  if (fs.existsSync(absThumb) || generatingThumbnails.has(absThumb)) return;
+
+  ensureDirForFile(absThumb);
+  markGenerating(absThumb, true);
+
+  const cmd = `ffmpeg -y -ss ${VIDEO_THUMBNAIL_TIME} -i "${fullPath}" -frames:v 1 -vf "scale=320:-1" -q:v 2 "${absThumb}"`;
+  exec(cmd, (err) => {
+    markGenerating(absThumb, false);
+    if (err) {
+      console.warn(`⚠️ Video thumbnail oluşturulamadı (${fullPath}): ${err.message}`);
+      return;
+    }
+    console.log(`🎞️ Video thumbnail oluşturuldu: ${absThumb}`);
+    const root = rootFromRelPath(relPath);
+    if (root) broadcastFileUpdate(root);
+  });
+}
+
+function queueImageThumbnail(fullPath, relPath) {
+  const { relThumb, absThumb } = getImageThumbnailPaths(relPath);
+  if (fs.existsSync(absThumb) || generatingThumbnails.has(absThumb)) return;
+
+  ensureDirForFile(absThumb);
+  markGenerating(absThumb, true);
+
+  const outputExt = path.extname(absThumb).toLowerCase();
+  const needsQuality = outputExt === ".jpg" || outputExt === ".jpeg";
+  const qualityArgs = needsQuality ? ' -q:v 5' : "";
+
+  const cmd = `ffmpeg -y -i "${fullPath}" -vf "scale=320:-1"${qualityArgs} "${absThumb}"`;
+  exec(cmd, (err) => {
+    markGenerating(absThumb, false);
+    if (err) {
+      console.warn(`⚠️ Resim thumbnail oluşturulamadı (${fullPath}): ${err.message}`);
+      return;
+    }
+    console.log(`🖼️ Resim thumbnail oluşturuldu: ${absThumb}`);
+    const root = rootFromRelPath(relPath);
+    if (root) broadcastFileUpdate(root);
+  });
+}
+
+function removeThumbnailsForPath(relPath) {
+  const normalized = sanitizeRelative(relPath);
+  if (!normalized) return;
+
+  const directDirs = [
+    path.join(VIDEO_THUMB_ROOT, normalized),
+    path.join(IMAGE_THUMB_ROOT, normalized)
+  ];
+
+  for (const target of directDirs) {
+    try {
+      if (fs.existsSync(target) && fs.lstatSync(target).isDirectory()) {
+        fs.rmSync(target, { recursive: true, force: true });
+      }
+    } catch (err) {
+      console.warn(`⚠️ Thumbnail klasörü silinemedi (${target}): ${err.message}`);
+    }
+  }
+
+  const parsed = path.parse(normalized);
+  const candidates = [
+    path.join(VIDEO_THUMB_ROOT, parsed.dir, `${parsed.name}.jpg`),
+    path.join(IMAGE_THUMB_ROOT, parsed.dir, `${parsed.name}${parsed.ext}`)
+  ];
+
+  for (const candidate of candidates) {
+    try {
+      if (fs.existsSync(candidate)) fs.rmSync(candidate, { recursive: true, force: true });
+    } catch (err) {
+      console.warn(`⚠️ Thumbnail silinemedi (${candidate}): ${err.message}`);
+    }
+  }
+}
+
+function resolveThumbnailAbsolute(relThumbPath) {
+  const normalized = sanitizeRelative(relThumbPath);
+  const resolved = path.resolve(THUMBNAIL_DIR, normalized);
+  if (
+    resolved !== THUMBNAIL_DIR &&
+    !resolved.startsWith(THUMBNAIL_DIR + path.sep)
+  ) {
+    return null;
+  }
+  return resolved;
+}
+
+function broadcastFileUpdate(rootFolder) {
+  if (!wss) return;
+  const data = JSON.stringify({
+    type: "fileUpdate",
+    path: rootFolder
+  });
+  wss.clients.forEach((c) => c.readyState === 1 && c.send(data));
+}
+
+function broadcastSnapshot() {
+  if (!wss) return;
+  const data = JSON.stringify({ type: "progress", torrents: snapshot() });
+  wss.clients.forEach((c) => c.readyState === 1 && c.send(data));
+}
+
 // --- Snapshot (thumbnail dahil, tracker + tarih eklendi) ---
 function snapshot() {
   return Array.from(torrents.values()).map(
     ({ torrent, selectedIndex, savePath, added }) => {
-      const thumbPath = path.join(savePath, "thumbnail.jpg");
-      const hasThumb = fs.existsSync(thumbPath);
+      const rootFolder = path.basename(savePath);
+      const bestVideoIndex = pickBestVideoFile(torrent);
+      const bestVideo = torrent.files[bestVideoIndex];
+      let thumbnail = null;
+
+      if (bestVideo) {
+        const relPath = path.join(rootFolder, bestVideo.path);
+        const { relThumb, absThumb } = getVideoThumbnailPaths(relPath);
+        if (fs.existsSync(absThumb)) thumbnail = thumbnailUrl(relThumb);
+        else if (torrent.progress === 1)
+          queueVideoThumbnail(path.join(savePath, bestVideo.path), relPath);
+      }
+
       return {
         infoHash: torrent.infoHash,
         name: torrent.name,
@@ -63,31 +243,12 @@ function snapshot() {
           length: f.length
         })),
         selectedIndex,
-        thumbnail: hasThumb ? `/thumbnail/${torrent.infoHash}` : null
+        thumbnail
       };
     }
   );
 }
 
-function createImageThumbnail(filePath, outputDir) {
-  const fileName = path.basename(filePath);
-  const thumbDir = path.join(outputDir, "thumbnail");
-  const thumbPath = path.join(thumbDir, fileName);
-
-  if (!fs.existsSync(thumbDir)) fs.mkdirSync(thumbDir, { recursive: true });
-
-  // 320px genişlikte orantılı thumbnail oluştur
-  const cmd = `ffmpeg -y -i "${filePath}" -vf "scale=320:-1" -q:v 5 "${thumbPath}"`;
-
-  exec(cmd, (err) => {
-    if (err) {
-      console.warn(`❌ Thumbnail oluşturulamadı: ${fileName}`, err.message);
-    } else {
-      console.log(`🖼️ Thumbnail oluşturuldu: ${thumbPath}`);
-    }
-  });
-}
-
 // --- Basit kimlik doğrulama sistemi ---
 const USERNAME = process.env.USERNAME;
 const PASSWORD = process.env.PASSWORD;
@@ -156,11 +317,7 @@ app.post("/api/transfer", requireAuth, upload.single("torrent"), (req, res) => {
           length: f.length
         }))
       });
-      const data = JSON.stringify({
-        type: "progress",
-        torrents: snapshot()
-      });
-      wss.clients.forEach((c) => c.readyState === 1 && c.send(data));
+      broadcastSnapshot();
     });
 
     // --- İndirme tamamlandığında thumbnail oluştur ---
@@ -170,49 +327,32 @@ app.post("/api/transfer", requireAuth, upload.single("torrent"), (req, res) => {
 
       console.log(`✅ Torrent tamamlandı: ${torrent.name}`);
 
-      // --- 1️⃣ Video için thumbnail oluştur ---
-      const videoFile = torrent.files[entry.selectedIndex];
-      const videoPath = path.join(entry.savePath, videoFile.path);
-      const thumbnailPath = path.join(entry.savePath, "thumbnail.jpg");
-
-      const cmd = `ffmpeg -ss 00:00:30 -i "${videoPath}" -frames:v 1 -q:v 2 "${thumbnailPath}"`;
-      exec(cmd, (err) => {
-        if (err)
-          console.warn(`⚠️ Video thumbnail oluşturulamadı: ${err.message}`);
-        else {
-          console.log(`🎞️ Video thumbnail oluşturuldu: ${thumbnailPath}`);
-          const data = JSON.stringify({
-            type: "fileUpdate",
-            path: path.relative(DOWNLOAD_DIR, entry.savePath)
-          });
-          wss.clients.forEach((c) => c.readyState === 1 && c.send(data));
-        }
-      });
-
-      // --- 2️⃣ Resimler için thumbnail oluştur ---
-      // Tüm resimleri tara, küçük hallerini kök klasör altındaki /thumbnail klasörüne oluştur
-      const rootThumbDir = path.join(entry.savePath, "thumbnail");
-      if (!fs.existsSync(rootThumbDir))
-        fs.mkdirSync(rootThumbDir, { recursive: true });
+      const rootFolder = path.basename(entry.savePath);
 
       torrent.files.forEach((file) => {
-        const filePath = path.join(entry.savePath, file.path);
-        const mimeType = mime.lookup(filePath) || "";
+        const fullPath = path.join(entry.savePath, file.path);
+        const relPath = path.join(rootFolder, file.path);
+        const mimeType = mime.lookup(fullPath) || "";
 
-        if (mimeType.startsWith("image/")) {
-          const thumbPath = path.join(rootThumbDir, path.basename(filePath));
-
-          // 320px genişlikte, orantılı küçük versiyon oluştur
-          const imgCmd = `ffmpeg -y -i "${filePath}" -vf "scale=320:-1" -q:v 5 "${thumbPath}"`;
-          exec(imgCmd, (err) => {
-            if (err)
-              console.warn(
-                `⚠️ Resim thumbnail oluşturulamadı (${file.name}): ${err.message}`
-              );
-            else console.log(`🖼️ Resim thumbnail oluşturuldu: ${thumbPath}`);
-          });
+        if (mimeType.startsWith("video/")) {
+          queueVideoThumbnail(fullPath, relPath);
+        } else if (mimeType.startsWith("image/")) {
+          queueImageThumbnail(fullPath, relPath);
         }
       });
+
+      // Eski thumbnail yapısını temizle
+      try {
+        const legacyThumb = path.join(entry.savePath, "thumbnail.jpg");
+        if (fs.existsSync(legacyThumb)) fs.rmSync(legacyThumb, { force: true });
+        const legacyDir = path.join(entry.savePath, "thumbnail");
+        if (fs.existsSync(legacyDir))
+          fs.rmSync(legacyDir, { recursive: true, force: true });
+      } catch (err) {
+        console.warn("⚠️ Eski thumbnail klasörü temizlenemedi:", err.message);
+      }
+
+      broadcastSnapshot();
     });
   } catch (err) {
     res.status(500).json({ error: err.message });
@@ -220,15 +360,12 @@ app.post("/api/transfer", requireAuth, upload.single("torrent"), (req, res) => {
 });
 
 // --- Thumbnail endpoint ---
-app.get("/thumbnail/:hash", (req, res) => {
-  const entry = torrents.get(req.params.hash);
-  if (!entry) return res.status(404).end();
-
-  const thumbnailPath = path.join(entry.savePath, "thumbnail.jpg");
-  if (!fs.existsSync(thumbnailPath))
-    return res.status(404).send("Thumbnail yok");
-
-  res.sendFile(thumbnailPath);
+app.get("/thumbnails/:path(*)", requireAuth, (req, res) => {
+  const relThumb = req.params.path || "";
+  const fullPath = resolveThumbnailAbsolute(relThumb);
+  if (!fullPath) return res.status(400).send("Geçersiz thumbnail yolu");
+  if (!fs.existsSync(fullPath)) return res.status(404).send("Thumbnail yok");
+  res.sendFile(fullPath);
 });
 
 // --- Torrentleri listele ---
@@ -252,6 +389,7 @@ app.delete("/api/torrents/:hash", requireAuth, (req, res) => {
   const { torrent, savePath } = entry;
   torrent.destroy(() => {
     torrents.delete(req.params.hash);
+    const rootFolder = savePath ? path.basename(savePath) : null;
     if (savePath && fs.existsSync(savePath)) {
       try {
         fs.rmSync(savePath, { recursive: true, force: true });
@@ -260,6 +398,11 @@ app.delete("/api/torrents/:hash", requireAuth, (req, res) => {
         console.warn(`⚠️ ${savePath} silinemedi:`, err.message);
       }
     }
+    if (rootFolder) {
+      removeThumbnailsForPath(rootFolder);
+      broadcastFileUpdate(rootFolder);
+    }
+    broadcastSnapshot();
     res.json({ ok: true });
   });
 });
@@ -314,6 +457,7 @@ app.delete("/api/file", requireAuth, (req, res) => {
     // 1) Dosya/klasörü sil
     fs.rmSync(fullPath, { recursive: true, force: true });
     console.log(`🗑️ Dosya/klasör silindi: ${fullPath}`);
+    removeThumbnailsForPath(filePath);
 
     // 2) İlk segment (klasör adı) => folderId (örn: "1730048432921")
     const folderId = (filePath.split(/[\\/]/)[0] || "").trim();
@@ -334,27 +478,15 @@ app.delete("/api/file", requireAuth, (req, res) => {
       entry?.torrent?.destroy(() => {
         torrents.delete(matchedInfoHash);
         console.log(`🧹 Torrent kaydı da temizlendi: ${matchedInfoHash}`);
-        // anında WebSocket güncellemesi (broadcastSnapshot global fonksiyonunu kullanıyorsan onu çağır)
-        if (typeof broadcastSnapshot === "function") {
-          broadcastSnapshot();
-        } else if (wss) {
-          const data = JSON.stringify({
-            type: "progress",
-            torrents: snapshot()
-          });
-          wss.clients.forEach((c) => c.readyState === 1 && c.send(data));
-        }
+        broadcastSnapshot();
       });
     } else {
       // Torrent eşleşmediyse de listeyi tazele (ör. sade dosya silinmiştir)
-      if (typeof broadcastSnapshot === "function") {
-        broadcastSnapshot();
-      } else if (wss) {
-        const data = JSON.stringify({ type: "progress", torrents: snapshot() });
-        wss.clients.forEach((c) => c.readyState === 1 && c.send(data));
-      }
+      broadcastSnapshot();
     }
 
+    if (folderId) broadcastFileUpdate(folderId);
+
     res.json({ ok: true });
   } catch (err) {
     console.error("❌ Dosya silinemedi:", err.message);
@@ -402,29 +534,20 @@ app.get("/api/files", requireAuth, (req, res) => {
       const full = path.join(dir, entry.name);
       const rel = path.relative(DOWNLOAD_DIR, full);
 
-      if (rel.toLowerCase().includes("/thumbnail")) continue;
-
       // 🔥 Ignore kontrolü (hem dosya hem klasör için)
       if (isIgnored(entry.name) || isIgnored(rel)) continue;
 
       if (entry.isDirectory()) {
         result = result.concat(walk(full));
       } else {
-        if (entry.name.toLowerCase() === "thumbnail.jpg") continue;
-
         const size = fs.statSync(full).size;
         const type = mime.lookup(full) || "application/octet-stream";
 
-        const parts = rel.split(path.sep);
-        const rootHash = parts[0];
-        const videoThumbPath = path.join(
-          DOWNLOAD_DIR,
-          rootHash,
-          "thumbnail.jpg"
-        );
-        const hasVideoThumb = fs.existsSync(videoThumbPath);
-
-        const urlPath = encodeURIComponent(rel).replace(/%2F/g, "/");
+        const safeRel = sanitizeRelative(rel);
+        const urlPath = safeRel
+          .split(/[\\/]/)
+          .map(encodeURIComponent)
+          .join("/");
         const url = `/media/${urlPath}`;
 
         const isImage = String(type).startsWith("image/");
@@ -432,27 +555,20 @@ app.get("/api/files", requireAuth, (req, res) => {
 
         let thumb = null;
 
-        // 🎬 Video thumbnail
-        if (hasVideoThumb) {
-          thumb = `/downloads/${rootHash}/thumbnail.jpg`;
+        if (isVideo) {
+          const { relThumb, absThumb } = getVideoThumbnailPaths(safeRel);
+          if (fs.existsSync(absThumb)) thumb = thumbnailUrl(relThumb);
+          else queueVideoThumbnail(full, safeRel);
         }
 
-        // 🖼️ Resim thumbnail (thumbnail klasöründe varsa)
-        const imageThumbPath = path.join(
-          DOWNLOAD_DIR,
-          rootHash,
-          "thumbnail",
-          path.basename(rel)
-        );
-
-        if (isImage && fs.existsSync(imageThumbPath)) {
-          thumb = `/downloads/${rootHash}/thumbnail/${encodeURIComponent(
-            path.basename(rel)
-          )}`;
+        if (isImage) {
+          const { relThumb, absThumb } = getImageThumbnailPaths(safeRel);
+          if (fs.existsSync(absThumb)) thumb = thumbnailUrl(relThumb);
+          else queueImageThumbnail(full, safeRel);
         }
 
         result.push({
-          name: rel,
+          name: safeRel,
           size,
           type,
           url,
@@ -527,7 +643,7 @@ if (fs.existsSync(publicDir)) {
   });
 }
 
-const wss = new WebSocketServer({ server });
+wss = new WebSocketServer({ server });
 wss.on("connection", (ws) => {
   ws.send(JSON.stringify({ type: "progress", torrents: snapshot() }));
 });
@@ -535,8 +651,7 @@ wss.on("connection", (ws) => {
 // --- ⏱️ Her 2 saniyede bir aktif torrent durumu yayınla ---
 setInterval(() => {
   if (torrents.size > 0) {
-    const data = JSON.stringify({ type: "progress", torrents: snapshot() });
-    wss.clients.forEach((c) => c.readyState === 1 && c.send(data));
+    broadcastSnapshot();
   }
 }, 2000);