diff --git a/apps/worker/video_processing/render_audio.py b/apps/worker/video_processing/render_audio.py
index f86deda78..d61a59325 100755
--- a/apps/worker/video_processing/render_audio.py
+++ b/apps/worker/video_processing/render_audio.py
@@ -16,14 +16,13 @@ import subprocess
 from dataclasses import dataclass, field
 from pathlib import Path
 
-from video_processing.speed_engine import SpeedEngine
-
 # 延迟导入避免循环依赖：unified_render_service 定义 ResolvedClip / RenderLayer，
 # 本模块提供音频函数供 unified_render_service 调用。
 # 使用 from __future__ import annotations + TYPE_CHECKING 解决类型引用。
 from typing import TYPE_CHECKING
 
 from video_processing.ffmpeg_utils import FFMPEG_BIN, probe_has_audio, run_ffmpeg
+from video_processing.speed_engine import SpeedEngine
 
 if TYPE_CHECKING:
     from video_processing.unified_render_service import RenderLayer, ResolvedClip
@@ -178,6 +177,7 @@ def concat_main_audio(
         else:
             # 有调速：用 filter_complex + atempo
             from video_processing.speed_engine import SpeedConfig
+
             speed_engine = SpeedEngine()
             config = SpeedConfig(speed=float(speed))
             config.clamp()
@@ -237,6 +237,7 @@ def concat_main_audio(
         # 音频调速 — atempo 多级串联
         if abs(speed - 1.0) >= 1e-6:
             from video_processing.speed_engine import SpeedConfig
+
             config = SpeedConfig(speed=float(speed))
             config.clamp()
             atempo_filter = speed_engine.build_audio_filter(config)
diff --git a/apps/worker/video_processing/speed_engine.py b/apps/worker/video_processing/speed_engine.py
index ea21f6616..1ab365b17 100755
--- a/apps/worker/video_processing/speed_engine.py
+++ b/apps/worker/video_processing/speed_engine.py
@@ -11,7 +11,6 @@
 from dataclasses import dataclass
 from typing import Optional
 
-
 # ─── 常量 ───────────────────────────────────────────────
 MIN_SPEED = 0.25
 MAX_SPEED = 4.0
diff --git a/apps/worker/video_processing/unified_render_service.py b/apps/worker/video_processing/unified_render_service.py
index 66ae7076f..cfe87ba50 100755
--- a/apps/worker/video_processing/unified_render_service.py
+++ b/apps/worker/video_processing/unified_render_service.py
@@ -1131,7 +1131,6 @@ class UnifiedRenderService:
             return min(clip.duration, clip.actual_duration) if clip.actual_duration > 0 else clip.duration
         return clip.actual_duration if clip.actual_duration > 0 else 0.0
 
-
     @staticmethod
     def _clip_speed(clip: ResolvedClip) -> float:
         """获取 clip 的播放速度，无效值回退到 1.0."""
@@ -1148,4 +1147,3 @@ class UnifiedRenderService:
         if abs(speed - 1.0) < 1e-6:
             return base
         return base / speed
-
diff --git a/tests/unit/test_speed_engine.py b/tests/unit/test_speed_engine.py
index cce4ff4cb..6da62ef06 100755
--- a/tests/unit/test_speed_engine.py
+++ b/tests/unit/test_speed_engine.py
@@ -8,7 +8,6 @@ from video_processing.speed_engine import (
     SpeedEngine,
 )
 
-
 # ─── SpeedConfig 解析与校验 ──────────────────────────────────