fix: 修复图片创作删除与垃圾桶预览

core/backend/apps/ai/serializers.py

@@ -38,6 +38,19 @@ class ImageConversationSerializer(serializers.ModelSerializer):
         return cached if cached is not None else obj.tasks.count()
 
 
+class ImageConversationTrashSerializer(ImageConversationSerializer):
+    """垃圾桶专用对话契约：只额外暴露一张展示封面，不影响普通对话列表查询。"""
+
+    cover_preview_url = serializers.SerializerMethodField()
+
+    class Meta(ImageConversationSerializer.Meta):
+        fields = [*ImageConversationSerializer.Meta.fields, "cover_preview_url"]
+        read_only_fields = [*ImageConversationSerializer.Meta.read_only_fields, "cover_preview_url"]
+
+    def get_cover_preview_url(self, obj) -> str:
+        return str(getattr(obj, "_trash_cover_preview_url", "") or "")
+
+
 class AITaskSerializer(serializers.ModelSerializer):
     model_config = ModelConfigSerializer(read_only=True)
     # 从 request_payload 抽出的分组/标签信息(由 AITaskViewSet annotate 提供;其它调用处无此注解则为 None)。