diff --git a/viewer/src/main.rs b/viewer/src/main.rs
index 48873a0..19eaac8 100644
--- a/viewer/src/main.rs
+++ b/viewer/src/main.rs
@@ -253,6 +253,9 @@ fn session(
         let latest = latest.clone();
         let mut decoder = openh264::decoder::Decoder::new()
             .map_err(|e| anyhow::anyhow!("decoder init failed: {e}"))?;
+        let mut rgb_buf: Vec<u8> = Vec::new();
+        let mut last_kfreq = Instant::now();
+        let mut skip_stale = 0u64;
         tokio::spawn(async move {
             let mut size_logged = false;
             loop {
@@ -262,11 +265,16 @@ fn session(
                         stats.frames.fetch_add(1, Ordering::Relaxed);
                         // 端到端延迟 = 接收时刻 - 时钟偏移 - 采集时刻（EMA 平滑）
                         let mut est = None;
+                        let mut stale = false;
                         if stats.offset_valid.load(Ordering::Relaxed) {
                             let e =
                                 now_ms() as i64 - stats.offset.load(Ordering::Relaxed)
                                     - hdr.ts_ms as i64;
                             if (0..5000).contains(&e) {
+                                // 积压保护：QUIC 视频流可靠有序，积压必须逐帧读出，
+                                // 但陈旧帧（>250ms）可以不解码——跳过解码让积压以
+                                // 网络速度排空，否则消化速率≈到达速率永远追不回来
+                                stale = e > 250;
                                 let old = stats.e2e.load(Ordering::Relaxed) as i64;
                                 let sm = if stats.e2e_valid.load(Ordering::Relaxed) {
                                     (old * 4 + e) / 5
@@ -279,6 +287,22 @@ fn session(
                             }
                         }
                         stats.on_frame_arrival(est);
+                        if stale {
+                            skip_stale += 1;
+                            if skip_stale % 120 == 1 {
+                                eprintln!(
+                                    "[viewer] backlog: stale frame skipped (e2e>250ms, total {skip_stale})"
+                                );
+                            }
+                            // 限频请求关键帧：积压排空后从 IDR 重新衔接画面
+                            if last_kfreq.elapsed() >= Duration::from_millis(200) {
+                                last_kfreq = Instant::now();
+                                if let Ok(mut slot) = latest.lock() {
+                                    *slot = Some((0, 0, Vec::new()));
+                                }
+                            }
+                            continue;
+                        }
                         match decoder.decode(&payload) {
                             Ok(Some(yuv)) => {
                                 let (dw, dh) = yuv.dimensions();
@@ -290,11 +314,12 @@ fn session(
                                         hdr.width, hdr.height
                                     );
                                 }
-                                let mut rgb = vec![0u8; dw as usize * dh as usize * 3];
-                                yuv.write_rgb8(&mut rgb);
+                                rgb_buf.clear();
+                                rgb_buf.resize(dw as usize * dh as usize * 3, 0);
+                                yuv.write_rgb8(&mut rgb_buf);
                                 // latest-wins：直接覆盖旧帧，无积压
                                 if let Ok(mut slot) = latest.lock() {
-                                    *slot = Some((dw, dh, rgb));
+                                    *slot = Some((dw, dh, rgb_buf.clone()));
                                 }
                             }
                             Ok(None) => {}
@@ -340,7 +365,10 @@ fn session(
                         stats.offset_valid.store(true, Ordering::Relaxed);
                     }
                     Ok(_) => {}
-                    Err(_) => break,
+                    Err(e) => {
+                        eprintln!("[viewer] control stream closed: {e} (RTT/LOSS 将停止更新)");
+                        break;
+                    }
                 }
             }
         });
@@ -364,7 +392,7 @@ fn session(
     push(&msg_tx, ControlMsg::KeyFrameReq);
 
     let mut window = Window::new(
-        "mvp-remote v0.7-LowLatency (Esc 退出)",
+        "mvp-remote v0.8-CatchUp (Esc 退出)",
         w,
         h,
         WindowOptions {