[Bugfix] Fix image num check error (#5838)

Signed-off-by: dengyunyang <584797741@qq.com>

tests/diffusion/test_diffusion_config_propagation.py

@@ -15,7 +15,10 @@ from vllm_omni.diffusion.data import (
     DiffusionParallelConfig,
     OmniDiffusionConfig,
 )
-from vllm_omni.diffusion.model_metadata import QWEN_IMAGE_EDIT_PLUS_MAX_INPUT_IMAGES
+from vllm_omni.diffusion.model_metadata import (
+    HUNYUAN_IMAGE3_MAX_INPUT_IMAGES,
+    QWEN_IMAGE_EDIT_PLUS_MAX_INPUT_IMAGES,
+)
 
 pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
 
@@ -136,6 +139,30 @@ def test_task_type_roundtrip():
     assert od.task_type == "model-defined-task"
 
 
+def test_architecture_name_resolves_via_pipeline_class_fallback():
+    # Direct hit: the architecture name itself is the metadata table key.
+    qwen_od_config = OmniDiffusionConfig(
+        model="Qwen/Qwen-Image-Edit-2511",
+        model_class_name="QwenImageEditPlusPipeline",
+    )
+    qwen_od_config.update_multimodal_support()
+
+    assert qwen_od_config.supports_multimodal_inputs is True
+    assert qwen_od_config.max_multimodal_image_inputs == QWEN_IMAGE_EDIT_PLUS_MAX_INPUT_IMAGES
+
+    # Fallback: the HF architecture name differs from the internal pipeline class
+    # name, so ``get_diffusion_model_metadata`` must consult ``_DIFFUSION_MODELS``
+    # and resolve the metadata via the pipeline class name.
+    hunyuan_od_config = OmniDiffusionConfig(
+        model="tencent/HunyuanImage-3.0-Instruct",
+        model_class_name="HunyuanImage3ForCausalMM",
+    )
+    hunyuan_od_config.update_multimodal_support()
+
+    assert hunyuan_od_config.supports_multimodal_inputs is True
+    assert hunyuan_od_config.max_multimodal_image_inputs == HUNYUAN_IMAGE3_MAX_INPUT_IMAGES
+
+
 def test_additional_config_roundtrip():
     additional_config = {"torchair_graph_config": {"enabled": True}}
     od = _roundtrip_diffusion_config(model="x", additional_config=additional_config)