[Diffusion] Address DLO host cache review feedback

Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/config/test_omni_config.py

@@ -921,6 +921,18 @@ def test_structured_diffusion_config_restricts_host_weight_registration_to_no_al
         )
 
 
+@pytest.mark.parametrize(
+    "field_name",
+    [
+        "dlo_host_weight_cache_lock_timeout",
+        "dlo_host_weight_cache_pin_limit_gib",
+    ],
+)
+def test_structured_diffusion_config_rejects_non_finite_host_weight_cache_values(field_name):
+    with pytest.raises(ValueError, match=rf"{field_name} must be finite"):
+        omni_config_module._DiffusionConfigProjection(**{field_name: float("inf")})
+
+
 def test_from_pipeline_config_matches_stage_config_to_omegaconf_behavior_for_representative_stage():
     pipeline = _resolve_pipeline_or_skip("qwen3_tts")
     legacy_stage = merge_pipeline_deploy(pipeline, _load_default_deploy(pipeline))[0]