[diffusion] Default Hunyuan VAE to tiled decode (#36012)

python/sglang/multimodal_gen/configs/pipeline_configs/hunyuan.py

@@ -93,7 +93,9 @@ class HunyuanConfig(PipelineConfig):
     # DiT
     dit_config: DiTConfig = field(default_factory=HunyuanVideoConfig)
     # VAE
-    vae_config: VAEConfig = field(default_factory=HunyuanVAEConfig)
+    vae_config: VAEConfig = field(
+        default_factory=lambda: HunyuanVAEConfig(parallel_decode_mode="tiled")
+    )
     # Denoising stage
     embedded_cfg_scale: int = 6
     flow_shift: int = 7

python/sglang/multimodal_gen/test/unit/test_hunyuan_config.py

@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: Apache-2.0
+
+from sglang.multimodal_gen.configs.pipeline_configs.hunyuan import (
+    FastHunyuanConfig,
+    HunyuanConfig,
+)
+
+
+def test_hunyuan_configs_default_to_parallel_tiled_vae_decode():
+    for config_cls in (HunyuanConfig, FastHunyuanConfig):
+        assert config_cls().vae_config.parallel_decode_mode == "tiled"
+
+
+def test_hunyuan_parallel_decode_mode_can_be_overridden():
+    for config_cls in (HunyuanConfig, FastHunyuanConfig):
+        config = config_cls()
+
+        config.update_config_from_dict(
+            {"vae_config.parallel_decode_mode": "spatial_shard"}
+        )
+
+        assert config.vae_config.parallel_decode_mode == "spatial_shard"