apps/web/src/pages/generate/GeneratePage.tsx

@@ -9,7 +9,7 @@
  * - 标题样式通过 CSS 层实时叠加，所见即所得
  * - 最终成片仍走后端 FFmpeg 渲染（Step7 确认生成）
  */
-import React, { useMemo } from "react"
+import React, { useMemo, useEffect } from "react"
 import { Modal, message } from "antd"
 import { useNavigate } from "react-router-dom"
 import type { VoiceClone } from "@/api/voice-clone"
@@ -101,6 +101,11 @@ const GeneratePage: React.FC = () => {
     () => (materialMode === "auto" ? smartSelectedIds : selectedMaterials),
     [materialMode, smartSelectedIds, selectedMaterials],
   )
+  // 素材或模板变化时，清除旧的 previewTaskId，防止 Step7 复用过期预览产物
+  useEffect(() => {
+    setPreviewTaskId(null)
+  }, [previewAssetIds, selectedTemplate, setPreviewTaskId])
+
   const previewAssetsEnabled = currentStep >= 4 && previewAssetIds.length > 0
   const {
     assets: previewAssets,