diff --git a/viewer/src/main.rs b/viewer/src/main.rs
index 48873a0..8521538 100644
--- a/viewer/src/main.rs
+++ b/viewer/src/main.rs
@@ -253,6 +253,10 @@ 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;
+        let mut last_arr: Option<Instant> = None;
         tokio::spawn(async move {
             let mut size_logged = false;
             loop {
@@ -260,25 +264,55 @@ fn session(
                     Ok((hdr, payload)) => {
                         stats.bytes.fetch_add(payload.len() as u64, Ordering::Relaxed);
                         stats.frames.fetch_add(1, Ordering::Relaxed);
+                        // 与上一帧的到达间隔：≤100ms 才算"突发到达"。
+                        // 桌面静止时 agent 以 2Hz 空闲重发，帧龄天然 ≥500ms，
+                        // 不能按陈旧帧丢弃——否则静止桌面所有帧被跳过 →
+                        // 永久黑屏 + KeyFrameReq/IDR 死循环（v0.8 实测教训）
+                        let burst = matches!(last_arr, Some(t) if t.elapsed() <= Duration::from_millis(100));
+                        last_arr = Some(Instant::now());
                         // 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) {
-                                let old = stats.e2e.load(Ordering::Relaxed) as i64;
-                                let sm = if stats.e2e_valid.load(Ordering::Relaxed) {
-                                    (old * 4 + e) / 5
-                                } else {
-                                    e
-                                };
-                                stats.e2e.store(sm as u64, Ordering::Relaxed);
-                                stats.e2e_valid.store(true, Ordering::Relaxed);
-                                est = Some(sm);
+                                // 积压判定必须同时满足：突发到达（背靠背）+ 帧龄>250ms。
+                                // QUIC 可靠有序，积压须逐帧读出但可不解码——跳过解码
+                                // 让队列以网络速度排空
+                                stale = burst && e > 250;
+                                // 空闲重发帧的帧龄不代表显示延迟，不计入 EMA
+                                if burst || e < 250 {
+                                    let old = stats.e2e.load(Ordering::Relaxed) as i64;
+                                    let sm = if stats.e2e_valid.load(Ordering::Relaxed) {
+                                        (old * 4 + e) / 5
+                                    } else {
+                                        e
+                                    };
+                                    stats.e2e.store(sm as u64, Ordering::Relaxed);
+                                    stats.e2e_valid.store(true, Ordering::Relaxed);
+                                    est = Some(sm);
+                                }
                             }
                         }
                         stats.on_frame_arrival(est);
+                        if stale {
+                            skip_stale += 1;
+                            if skip_stale % 60 == 1 {
+                                eprintln!(
+                                    "[viewer] backlog: stale burst frame skipped (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 +324,12 @@ 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 +375,10 @@ 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 +402,7 @@ fn session(
     push(&msg_tx, ControlMsg::KeyFrameReq);
 
     let mut window = Window::new(
-        "mvp-remote v0.7-LowLatency (Esc 退出)",
+        "mvp-remote v0.8.1-CatchUp (Esc 退出)",
         w,
         h,
         WindowOptions {