[diffusion][bugfix] Separate Diffusers hooks from model metadata (#6749)

Signed-off-by: david6666666 <530634352@qq.com>
Signed-off-by: Gao Han <hgaoaf@connect.ust.hk>
Co-authored-by: Gao Han <hgaoaf@connect.ust.hk>

tests/diffusion/test_diffusion_output_formatter.py

@@ -328,6 +328,25 @@ def test_formatter_preserves_audio_model_video_audio_and_actions(
     }
 
 
+def test_formatter_uses_native_model_identity_for_diffusers_video_frames(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(output_formatter, "supports_audio_output", lambda _: False)
+    frames = [["frame-0", "frame-1"]]
+    postprocess_output = normalize_diffusion_postprocess_output(frames)
+
+    [result] = format_diffusion_outputs(
+        request=_request("make a video"),
+        od_config=_config("WanImageToVideoPipeline"),
+        diffusion_output=DiffusionOutput(output=frames),
+        output_data=frames,
+        postprocess_output=postprocess_output,
+    )
+
+    assert result.images == frames
+    assert result.final_output_type == "video"
+
+
 def test_formatter_preserves_audio_only_postprocess_dict(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None: