diff --git a/apps/worker/video_processing/unified_render_service.py b/apps/worker/video_processing/unified_render_service.py
index 66c9e4c72..b63392f0e 100755
--- a/apps/worker/video_processing/unified_render_service.py
+++ b/apps/worker/video_processing/unified_render_service.py
@@ -1372,9 +1372,7 @@ class UnifiedRenderService:
                 if all_cut:
                     # 全硬切：用 concat filter，性能远优于 xfade
                     concat_inputs = "".join(f"[{label}]" for label in layer_labels)
-                    filter_parts.append(
-                        f"{concat_inputs}concat=n={len(layer_labels)}:v=1:a=0[{out_label}]"
-                    )
+                    filter_parts.append(f"{concat_inputs}concat=n={len(layer_labels)}:v=1:a=0[{out_label}]")
                     logger.info(
                         "[unified-render] layer=%s clips=%d using concat (all hard-cut)",
                         layer.role,