Fix FP8 Z-Image quality gate

Signed-off-by: WeiQing Chen <david6666666@users.noreply.github.com>

tests/diffusion/quantization/test_fp8_config.py

@@ -213,6 +213,35 @@ def test_integration_per_component():
     assert config.quantization_config.component_configs["vae"] is None
 
 
+def test_recursive_replace_linear_resolves_component_quantization(monkeypatch):
+    from vllm_omni.diffusion.data import OmniDiffusionConfig
+    from vllm_omni.diffusion.models import utils
+
+    model = nn.Module()
+    model.text_encoder = nn.Sequential(nn.Linear(2, 2))
+    model.transformer = nn.Sequential(nn.Linear(2, 2))
+    config = OmniDiffusionConfig(
+        model="test",
+        quantization_config={
+            "transformer": {"method": "fp8"},
+            "default": None,
+        },
+    )
+
+    calls = {}
+
+    def fake_replace(linear, style, quant_config, *, prefix):
+        calls[prefix] = quant_config
+        return nn.Identity()
+
+    monkeypatch.setattr(utils, "replace_linear_class", fake_replace)
+
+    utils.recursive_replace_linear(model, config)
+
+    assert calls["text_encoder.0"] is None
+    assert calls["transformer.0"].get_name() == "fp8"
+
+
 def test_transformer_config_auto_detects_modelopt_fp8():
     from vllm.model_executor.layers.quantization.modelopt import ModelOptFp8Config