[Model] Support SenseNova-U1.5-8B-MoT and its distilled 8-step LoRA (#6516)

Signed-off-by: MrlixiangWE <mrdanaer@gmail.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/diffusion/test_diffusion_model_runner.py

@@ -179,6 +179,30 @@ def test_request_scoped_cache_dit_lifecycle_is_pipeline_opt_in():
     assert events == [backend]
 
 
+def test_release_captured_graphs_clears_runners_and_delegates_to_the_pipeline():
+    """Both halves in one place, so a pipeline that keeps captures is collected
+    without the caller knowing which pipelines have one."""
+    released = []
+    runner = object.__new__(DiffusionModelRunner)
+    runner.graph_runners = {"decode": object()}
+    runner.pipeline = SimpleNamespace(release_captured_graphs=lambda: released.append(True))
+
+    runner.release_captured_graphs()
+
+    assert runner.graph_runners == {}
+    assert released == [True]
+
+
+def test_release_captured_graphs_tolerates_a_pipeline_without_captures():
+    """Most pipelines keep none, and the runner may not carry `graph_runners`."""
+    runner = object.__new__(DiffusionModelRunner)
+    runner.pipeline = object()
+
+    runner.release_captured_graphs()
+
+    assert not hasattr(runner, "graph_runners")
+
+
 def _make_runner(cache_backend, cache_backend_name: str, enable_cache_dit_summary: bool = True):
     runner = object.__new__(DiffusionModelRunner)
     runner.vllm_config = object()