[Refactor][Diffusion] Complete generic backend plan consumption (#7313)

Signed-off-by: specture724 <specture724@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

tests/diffusion/models/flux2/test_flux2_transformer_tp.py

@@ -1,3 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
+
 import pytest
 import torch
 from pytest_mock import MockerFixture
@@ -265,7 +268,7 @@ class TestFlux2TransformerLayerwiseOffload:
         ]
 
     def test_get_blocks_from_dit(self):
-        from vllm_omni.diffusion.offloader.layerwise_backend import LayerWiseOffloadBackend
+        from vllm_omni.diffusion.offloader.block_discovery import get_blocks_from_dit
 
         # Block discovery only needs the ModuleList structure, not production dims.
         model = Flux2Transformer2DModel(
@@ -275,6 +278,6 @@ class TestFlux2TransformerLayerwiseOffload:
             attention_head_dim=4,
             joint_attention_dim=16,
         )
-        attr_names, blocks = LayerWiseOffloadBackend.get_blocks_from_dit(model)
+        attr_names, blocks = get_blocks_from_dit(model)
         assert attr_names == ["transformer_blocks", "single_transformer_blocks"]
         assert len(blocks) == 4