[Model] Support Nemotron 3 Super NVFP4 (#20407)

python/sglang/srt/configs/model_config.py

@@ -793,6 +793,11 @@ class ModelConfig:
         quant_algo = json_quant_configs.get("quant_algo", None)
 
         if quant_algo == "MIXED_PRECISION":
+            architectures = getattr(self.hf_config, "architectures", []) or []
+            if getattr(self.hf_config, "model_type", None) == "nemotron_h" or any(
+                arch.startswith("NemotronH") for arch in architectures
+            ):
+                return {"quant_method": "modelopt_mixed", "quant_algo": quant_algo}
             return {"quant_method": "w4afp8", "quant_algo": quant_algo}
         elif quant_algo and ("FP4" in quant_algo or "NVFP4" in quant_algo):
             return {"quant_method": "modelopt_fp4", "quant_algo": quant_algo}
@@ -842,6 +847,10 @@ class ModelConfig:
             return "fp8"
         elif self.quantization == "modelopt_fp4":
             return "nvfp4"
+        elif self.quantization == "modelopt_mixed":
+            raise ValueError(
+                "modelopt_mixed is only supported for pre-quantized checkpoints."
+            )
         elif self.quantization == "modelopt":
             # Auto-detect from model config
             quant_cfg = self._parse_quant_hf_config()
@@ -872,6 +881,7 @@ class ModelConfig:
             "modelopt",
             "modelopt_fp8",
             "modelopt_fp4",
+            "modelopt_mixed",
         ]
         modelopt_quantization_specified = (
             self.quantization in _MODELOPT_QUANTIZATION_METHODS
@@ -913,6 +923,7 @@ class ModelConfig:
             "marlin",
             "modelopt_fp8",
             "modelopt_fp4",
+            "modelopt_mixed",
             "gptq_marlin_24",
             "gptq_marlin",
             "awq_marlin",
@@ -932,6 +943,7 @@ class ModelConfig:
         compatible_quantization_methods = {
             "modelopt_fp8": ["modelopt"],
             "modelopt_fp4": ["modelopt"],
+            "modelopt_mixed": ["modelopt"],
             "petit_nvfp4": ["modelopt"],
             "w8a8_int8": ["compressed-tensors", "compressed_tensors"],
             "w8a8_fp8": ["compressed-tensors", "compressed_tensors"],