diff --git a/apps/web/src/pages/generate/components/PreviewVideoPanel.tsx b/apps/web/src/pages/generate/components/PreviewVideoPanel.tsx
index 723a44545..8de11fbf7 100644
--- a/apps/web/src/pages/generate/components/PreviewVideoPanel.tsx
+++ b/apps/web/src/pages/generate/components/PreviewVideoPanel.tsx
@@ -2,6 +2,9 @@
  * 右侧预览视频面板
  * Step3 生成预览后常驻显示预览视频
  * Step4+ 用 Canvas 绘制标题预览（替代 CSS overlay，与 ASS 渲染行为一致）
+ *
+ * 设计说明：标题预览仅在有视频时显示（叠加在视频画面上方）。
+ * 无视频状态（idle/loading/error）下不再单独显示标题预览，这是有意为之的设计简化。
  */
 import React, { useRef, useEffect, useCallback } from "react"
 import { PlayCircleOutlined, LoadingOutlined } from "@ant-design/icons"