Add modular pipeline for HunyuanVideo 1.5 (#13389)

* Add modular pipeline support for HunyuanVideo 1.5

* Fix I2V latent/cond spatial dimension mismatch

* Fix guidance_scale default to 7.5 matching ClassifierFreeGuidance

* Fix tokenizer type: use Qwen2TokenizerFast to match model

* Fix system message string formatting to match standard pipeline

* Rewrite HunyuanVideo 1.5 modular: use standard pipeline methods directly

* Remove I2V exports (T2V only for now)

* Fix encoder: use static methods directly instead of encode_prompt

* Inline all standard pipeline methods, remove runtime dependency

* Add HunyuanVideo 1.5 image-to-video modular blocks

* Fix missing FrozenDict import in before_denoise.py

* auto-generated docstrings via #auto_docstring

* Fix ruff lint and format issues

* use InputParam/OutputParam templates and fix ruff

* Address LTX review feedback here like add AutoBlocks, refactor I2V latents, lift encoders

* Add workflow map, workflow tests, auto docstrings, export only AutoBlocks

* Address Claude CI review

* Address claude CI review 2

---------

Co-authored-by: YiYi Xu <yixu310@gmail.com>

Author: akshan-main

src/diffusers/__init__.py

@@ -458,6 +458,8 @@
             "HeliosPyramidDistilledAutoBlocks",
             "HeliosPyramidDistilledModularPipeline",
             "HeliosPyramidModularPipeline",
+            "HunyuanVideo15AutoBlocks",
+            "HunyuanVideo15ModularPipeline",
             "LTXAutoBlocks",
             "LTXModularPipeline",
             "QwenImageAutoBlocks",
@@ -1244,6 +1246,8 @@
             HeliosPyramidDistilledAutoBlocks,
             HeliosPyramidDistilledModularPipeline,
             HeliosPyramidModularPipeline,
+            HunyuanVideo15AutoBlocks,
+            HunyuanVideo15ModularPipeline,
             LTXAutoBlocks,
             LTXModularPipeline,
             QwenImageAutoBlocks,

src/diffusers/modular_pipelines/__init__.py

@@ -88,6 +88,10 @@
         "QwenImageLayeredModularPipeline",
         "QwenImageLayeredAutoBlocks",
     ]
+    _import_structure["hunyuan_video1_5"] = [
+        "HunyuanVideo15AutoBlocks",
+        "HunyuanVideo15ModularPipeline",
+    ]
     _import_structure["ltx"] = [
         "LTXAutoBlocks",
         "LTXModularPipeline",
@@ -123,6 +127,10 @@
             HeliosPyramidDistilledModularPipeline,
             HeliosPyramidModularPipeline,
         )
+        from .hunyuan_video1_5 import (
+            HunyuanVideo15AutoBlocks,
+            HunyuanVideo15ModularPipeline,
+        )
         from .ltx import LTXAutoBlocks, LTXModularPipeline
         from .modular_pipeline import (
             AutoPipelineBlocks,

src/diffusers/modular_pipelines/hunyuan_video1_5/__init__.py

@@ -0,0 +1,49 @@
+from typing import TYPE_CHECKING
+
+from ...utils import (
+    DIFFUSERS_SLOW_IMPORT,
+    OptionalDependencyNotAvailable,
+    _LazyModule,
+    get_objects_from_module,
+    is_torch_available,
+    is_transformers_available,
+)
+
+
+_dummy_objects = {}
+_import_structure = {}
+
+try:
+    if not (is_transformers_available() and is_torch_available()):
+        raise OptionalDependencyNotAvailable()
+except OptionalDependencyNotAvailable:
+    from ...utils import dummy_torch_and_transformers_objects  # noqa F403
+
+    _dummy_objects.update(get_objects_from_module(dummy_torch_and_transformers_objects))
+else:
+    _import_structure["modular_blocks_hunyuan_video1_5"] = [
+        "HunyuanVideo15AutoBlocks",
+    ]
+    _import_structure["modular_pipeline"] = ["HunyuanVideo15ModularPipeline"]
+
+if TYPE_CHECKING or DIFFUSERS_SLOW_IMPORT:
+    try:
+        if not (is_transformers_available() and is_torch_available()):
+            raise OptionalDependencyNotAvailable()
+    except OptionalDependencyNotAvailable:
+        from ...utils.dummy_torch_and_transformers_objects import *  # noqa F403
+    else:
+        from .modular_blocks_hunyuan_video1_5 import HunyuanVideo15AutoBlocks
+        from .modular_pipeline import HunyuanVideo15ModularPipeline
+else:
+    import sys
+
+    sys.modules[__name__] = _LazyModule(
+        __name__,
+        globals()["__file__"],
+        _import_structure,
+        module_spec=__spec__,
+    )
+
+    for name, value in _dummy_objects.items():
+        setattr(sys.modules[__name__], name, value)