diff --git a/tests/diffusion/cache/test_cache_dit.py b/tests/diffusion/cache/test_cache_dit.py
index 68545fe27..22f9b8611 100644
--- a/tests/diffusion/cache/test_cache_dit.py
+++ b/tests/diffusion/cache/test_cache_dit.py
@@ -13,7 +13,7 @@ import torch
 from cache_dit.caching.cache_blocks.pattern_0_1_2 import CachedBlocks_Pattern_0_1_2
 
 import vllm_omni.diffusion.cache.cache_dit_backend as cd_backend
-from vllm_omni.diffusion.cache.cache_dit_backend import CacheDiTAdapterConfig, CacheDiTBackend
+from vllm_omni.diffusion.cache.cache_dit_backend import CacheDiTAdapterConfig, CacheDiTBackend, cache_summary
 from vllm_omni.diffusion.data import DiffusionCacheConfig
 from vllm_omni.diffusion.models.cosmos3.transformer_cosmos3 import Cosmos3VFMTransformer
 from vllm_omni.diffusion.models.helios.helios_transformer import HeliosTransformer3DModel
@@ -193,3 +193,12 @@ def test_ltx2_cache_dit_receives_audio_as_encoder(init_fake_tp_group):
     # Pattern_0 maps (hidden_states, encoder_hidden_states) to (video, audio)
     assert torch.equal(captured["hidden_states"], video_in)
     assert torch.equal(captured["encoder_hidden_states"], audio_in)
+
+
+def test_summary_with_no_transformer_is_nonfatal():
+    """Regression test for https://github.com/vllm-project/vllm-omni/issues/4325."""
+
+    class FakePipeline:
+        pass
+
+    cache_summary(pipeline=FakePipeline())
diff --git a/vllm_omni/diffusion/cache/cache_dit_backend.py b/vllm_omni/diffusion/cache/cache_dit_backend.py
index c1f194ee8..e3d07bfcd 100644
--- a/vllm_omni/diffusion/cache/cache_dit_backend.py
+++ b/vllm_omni/diffusion/cache/cache_dit_backend.py
@@ -59,9 +59,12 @@ CUSTOM_DIT_ENABLERS: dict[str, Callable] = {}
 
 # Small helper to centralize cache-dit summaries.
 def cache_summary(pipeline: Any, details: bool = True) -> None:
-    cache_dit.summary(pipeline.transformer, details=details)
+    if hasattr(pipeline, "transformer"):
+        cache_dit.summary(pipeline.transformer, details=details)
     if hasattr(pipeline, "transformer_2"):
         cache_dit.summary(pipeline.transformer_2, details=details)
+    if not hasattr(pipeline, "transformer") and not hasattr(pipeline, "transformer_2"):
+        logger.warning("CacheDiT summary failed; this pipeline has no defined transformer attribute")
 
 
 def default_get_pipeline_transformer(pipeline: Any) -> Any: