diff --git a/apps/web/src/pages/generate/GeneratePage.tsx b/apps/web/src/pages/generate/GeneratePage.tsx
index 449b30174..2c822aa6d 100644
--- a/apps/web/src/pages/generate/GeneratePage.tsx
+++ b/apps/web/src/pages/generate/GeneratePage.tsx
@@ -72,6 +72,7 @@ const GeneratePage: React.FC = () => {
     autoSubtitles,
     bgm,
     editPlanId,
+    sourceEditPlanId,
     previewVideo,
     setPreviewVideo,
     previewModalOpen,
@@ -171,7 +172,7 @@ const GeneratePage: React.FC = () => {
     autoSubtitles,
     bgm,
     generateCount,
-    sourceEditPlanId: editPlanId,
+    sourceEditPlanId,
   })
 
   /* ================================================================
diff --git a/apps/web/src/pages/generate/hooks/useGenerateFormState/index.ts b/apps/web/src/pages/generate/hooks/useGenerateFormState/index.ts
index 2ae71dc77..e251cc25f 100755
--- a/apps/web/src/pages/generate/hooks/useGenerateFormState/index.ts
+++ b/apps/web/src/pages/generate/hooks/useGenerateFormState/index.ts
@@ -82,6 +82,13 @@ export interface GenerateFormState {
   editPlanId: string | null
   planConfigStr: string | null
 
+  /**
+   * 传给 Worker 的 source_edit_plan_id。
+   * 优先使用 URL 中的 edit_plan_id；URL 没有时回退为 selectedTemplate（模板 ID），
+   * 因为 Step2 的 clips 就是用 selectedTemplate 作为 plan_id 写入的。
+   */
+  sourceEditPlanId: string | null
+
   /* 预览弹窗 */
   previewVideo: GeneratedVideo | null
   setPreviewVideo: (v: GeneratedVideo | null) => void
@@ -100,6 +107,11 @@ export const useGenerateFormState = (): GenerateFormState => {
   /* ── 模板选择 ── */
   const { selectedTemplate, setSelectedTemplate, userTemplates } = useTemplateSelection()
 
+  /* ── source_edit_plan_id：URL 优先，否则回退到 selectedTemplate ── */
+  // selectedTemplate 是异步加载的（react-query），组件重新渲染时此值会自动更新，
+  // 因此最终传给 useGenerateVideo 的 sourceEditPlanId 能在模板就绪后拿到正确值。
+  const sourceEditPlanId = editPlanId || selectedTemplate || null
+
   /* ── 素材 ── */
   const [selectedMaterials, setSelectedMaterials] = useState<string[]>([])
   const [materialMode, setMaterialMode] = useState<"manual" | "auto">("manual")
@@ -189,6 +201,7 @@ export const useGenerateFormState = (): GenerateFormState => {
     autoSubtitles,
     bgm,
     editPlanId,
+    sourceEditPlanId,
     planConfigStr,
     previewVideo,
     setPreviewVideo,
diff --git a/apps/web/src/pages/generate/hooks/useStep6Cover.ts b/apps/web/src/pages/generate/hooks/useStep6Cover.ts
index f86141680..3786e499c 100644
--- a/apps/web/src/pages/generate/hooks/useStep6Cover.ts
+++ b/apps/web/src/pages/generate/hooks/useStep6Cover.ts
@@ -154,6 +154,7 @@ export function useStep6Cover({
           const previewResp = await createPreview({
             template_id: selectedTemplate,
             asset_ids: assetIds,
+            source_edit_plan_id: selectedTemplate,
             duration: duration || 30,
             ...(titleSettings?.title
               ? {
diff --git a/apps/web/src/pages/generate/utils/buildClipsFromAssets.ts b/apps/web/src/pages/generate/utils/buildClipsFromAssets.ts
index af3f2d718..320ec829f 100644
--- a/apps/web/src/pages/generate/utils/buildClipsFromAssets.ts
+++ b/apps/web/src/pages/generate/utils/buildClipsFromAssets.ts
@@ -6,7 +6,14 @@
  *   tplSeg = templateSegments[i] || lastSegment
  *   segDuration = clamp(assetDuration, tplSeg.duration_min, tplSeg.duration_max)
  *   start_time = 0
- *   duration = segDuration
+ *   // 关键：预览播放器中 endTime = min(startTime + segDuration, assetDuration)
+ *   // 因此 clips.duration 也必须用 min(segDuration, assetDuration) 截断，
+ *   // 避免素材实际时长比 clamp 后的 segDuration 短时，Worker 尝试读取不存在的片段
+ *   duration = min(segDuration, assetDuration)
+ *
+ * 预览播放器（Canvas 实时预览）直接在内存中构建 segments 播放，不读 edit_plan_clips；
+ * 本函数产出的 clips 写入 DB 后由 Worker 渲染。两边用完全相同的时长计算，
+ * 保证用户在编辑过程中看到的预览与最终生成视频一致。
  */
 import type { AssetItem } from "@/api/assets"
 import type { TemplateSegment } from "@/api/templates/types"
@@ -47,10 +54,15 @@ export function buildClipsFromAssets({
       ? Math.min(tplSeg.duration_max, Math.max(tplSeg.duration_min, assetDuration))
       : Math.min(assetDuration, 10)
 
+    // 与 FrontendPreviewPlayer.buildPlaybackSegments 中
+    //   endTime = Math.min(startTime + segDuration, assetDuration)
+    // 保持一致：duration 不能超过素材实际时长
+    const duration = Math.min(segDuration, assetDuration)
+
     return {
       asset_id: assetId,
       start_time: 0,
-      duration: segDuration,
+      duration,
       order: i,
     }
   })