diff --git a/tests/unit/test_pr312_security_debt.py b/tests/unit/test_pr312_security_debt.py
index 0c9a3c2e1..4e82ea757 100755
--- a/tests/unit/test_pr312_security_debt.py
+++ b/tests/unit/test_pr312_security_debt.py
@@ -14,10 +14,8 @@ sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "apps" / "worker"))
 sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "apps" / "api"))
 
 import pytest
-
 from video_processing.path_security import PathSecurityError
 
-
 # ── Fixtures ──────────────────────────────────────────────────────────────────
 
 
@@ -103,20 +101,22 @@ class TestMultiTrackSecurity:
 
         from video_processing.multi_track_mixer import (
             MAX_AUDIO_TRACKS,
-            MultiTrackMixConfig,
             AudioTrack,
+            MultiTrackMixConfig,
             mix_multi_track,
         )
 
         # 创建超过上限的轨道数
         tracks = []
         for i in range(MAX_AUDIO_TRACKS + 5):
-            tracks.append(AudioTrack(
-                track_id=f"track_{i}",
-                track_type="sfx",
-                audio_path=str(sample_audio),
-                volume=0.5,
-            ))
+            tracks.append(
+                AudioTrack(
+                    track_id=f"track_{i}",
+                    track_type="sfx",
+                    audio_path=str(sample_audio),
+                    volume=0.5,
+                )
+            )
 
         config = MultiTrackMixConfig(tracks=tracks)
 
@@ -128,6 +128,7 @@ class TestMultiTrackSecurity:
         with patch("video_processing.multi_track_mixer._prepare_single_track", return_value=True):
             with patch("video_processing.multi_track_mixer.run_ffmpeg"):
                 import shutil
+
                 with patch("shutil.copy2"):
                     result = mix_multi_track(ctx, sample_audio, config, 10.0)
 
@@ -141,19 +142,21 @@ class TestMultiTrackSecurity:
 
         from video_processing.multi_track_mixer import (
             MAX_AUDIO_TRACKS,
-            MultiTrackMixConfig,
             AudioTrack,
+            MultiTrackMixConfig,
             mix_multi_track,
         )
 
         tracks = []
         for i in range(3):
-            tracks.append(AudioTrack(
-                track_id=f"track_{i}",
-                track_type="sfx",
-                audio_path=str(sample_audio),
-                volume=0.5,
-            ))
+            tracks.append(
+                AudioTrack(
+                    track_id=f"track_{i}",
+                    track_type="sfx",
+                    audio_path=str(sample_audio),
+                    volume=0.5,
+                )
+            )
 
         config = MultiTrackMixConfig(tracks=tracks)
 
@@ -231,8 +234,8 @@ class TestConcatSecurity:
         from video_processing.concat_engine import (
             MAX_CONCAT_SEGMENTS,
             ConcatConfig,
-            ConcatSegment,
             ConcatEngine,
+            ConcatSegment,
         )
 
         # 创建超过上限的段数
@@ -254,8 +257,8 @@ class TestConcatSecurity:
         from video_processing.concat_engine import (
             MAX_CONCAT_SEGMENTS,
             ConcatConfig,
-            ConcatSegment,
             ConcatEngine,
+            ConcatSegment,
         )
 
         segments = [
@@ -324,8 +327,8 @@ class TestConcatSecurity:
 
         from video_processing.concat_engine import (
             ConcatConfig,
-            ConcatSegment,
             ConcatEngine,
+            ConcatSegment,
         )
 
         segments = [