[Model][Feat] Support Minimax-H3 quality grading requests through dynamic loading/unloading with Cache-DiT (#5853)

Signed-off-by: mglyn <1203789601@qq.com>

vllm_omni/diffusion/models/interface.py

@@ -17,6 +17,7 @@ if TYPE_CHECKING:
 
     import torch
 
+    from vllm_omni.diffusion.cache.cachedit import CacheDiTBackend
     from vllm_omni.diffusion.data import DiffusionOutput
     from vllm_omni.diffusion.worker.input_batch import InputBatch
     from vllm_omni.diffusion.worker.utils import StepRequestState
@@ -131,3 +132,31 @@ def supports_prompt_update(pipeline: object) -> bool:
     """Return whether ``pipeline`` implements :class:`SupportsPromptUpdate`."""
 
     return isinstance(pipeline, SupportsPromptUpdate)
+
+
+@runtime_checkable
+class SupportsRequestScopedCacheDiT(Protocol):
+    """Optional protocol for pipelines that own Cache-DiT hook transitions."""
+
+    def adopt_cache_dit_backend(self, backend: CacheDiTBackend) -> None:
+        """Assume ownership of an enabled Cache-DiT backend."""
+        ...
+
+    def is_cache_dit_enabled(self) -> bool:
+        """Return whether this pipeline currently has Cache-DiT installed."""
+        ...
+
+
+def adopt_request_scoped_cache_dit(pipeline: object, backend: CacheDiTBackend) -> bool:
+    """Transfer an enabled Cache-DiT backend to an opted-in pipeline."""
+
+    if not isinstance(pipeline, SupportsRequestScopedCacheDiT):
+        return False
+    pipeline.adopt_cache_dit_backend(backend)
+    return True
+
+
+def is_request_scoped_cache_dit_enabled(pipeline: object) -> bool:
+    """Read Cache-DiT state from a pipeline that owns its lifecycle."""
+
+    return isinstance(pipeline, SupportsRequestScopedCacheDiT) and pipeline.is_cache_dit_enabled()