fix: 自由创作分类入库区分视频与图片展示

core/backend/apps/ai/free_video.py

@@ -695,7 +695,8 @@ def serialize_free_video_task(task: AITask) -> dict:
                 return ""
         return ""
 
-    for asset in task.generated_assets.all():
+    generated_assets = list(task.generated_assets.all())
+    for asset in generated_assets:
         if asset.is_deleted:
             continue
         for f in asset.files.all():
@@ -706,7 +707,7 @@ def serialize_free_video_task(task: AITask) -> dict:
                 video_url = url
             elif not f.is_primary and "image" in (f.content_type or "") and not thumbnail_url:
                 thumbnail_url = url
-    if not video_url:
+    if not video_url and not generated_assets:
         video_url = payload.get("fallback_video_url") or ""
 
     return {