Add SVDQuant W4A4 integration with comfy-kitchen (kitchen-native row-major)

quant_ops.py: register TensorCoreSVDQuantW4A4Layout when comfy-kitchen exposes
it; gate the kitchen CUDA backend on cuda >= 13 (the optimized kitchen CUDA
ops are validated against cu13+ runtimes; on older cu the backend falls back
to eager).

ops.py: handle svdquant_w4a4 quant_format by loading weight_scale / proj_down /
proj_up / smooth_factor into TensorCoreSVDQuantW4A4Layout.Params, with the
img_mlp.net.2 / txt_mlp.net.2 fallback for act_unsigned. Targets the row-major
kitchen-native kernels on feat/svdquant-w4a4-kitchen-native; the verbatim
zgemm path is a sibling branch.

comfy/ops.py

@@ -997,6 +997,35 @@ def mixed_precision_ops(quant_config={}, compute_dtype=torch.bfloat16, full_prec
                             orig_dtype=MixedPrecisionOps._compute_dtype,
                             orig_shape=(self.out_features, self.in_features),
                         )
+                    elif self.quant_format == "svdquant_w4a4":
+                        # SVDQuant W4A4: per-group weight scales + low-rank correction
+                        # (proj_down, proj_up) + activation smoothing (smooth_factor)
+                        wscales = self._load_scale_param(state_dict, prefix, "weight_scale", device, manually_loaded_keys)
+                        proj_down = self._load_scale_param(state_dict, prefix, "proj_down", device, manually_loaded_keys)
+                        proj_up = self._load_scale_param(state_dict, prefix, "proj_up", device, manually_loaded_keys)
+                        smooth_factor = self._load_scale_param(state_dict, prefix, "smooth_factor", device, manually_loaded_keys)
+                        act_unsigned = bool(layer_conf.get("act_unsigned", False))
+
+                        # Early Qwen-Image conversion artifacts did not persist the
+                        # fused GELU -> fc2 unsigned-activation flag. Those layers
+                        # are the second linear in the feed-forward block.
+                        if not act_unsigned and (
+                            layer_name.endswith(".img_mlp.net.2") or layer_name.endswith(".txt_mlp.net.2")
+                        ):
+                            act_unsigned = True
+
+                        if any(t is None for t in (wscales, proj_down, proj_up, smooth_factor)):
+                            raise ValueError(f"Missing SVDQuant W4A4 parameters for layer {layer_name}")
+
+                        params = layout_cls.Params(
+                            scale=wscales,
+                            orig_dtype=MixedPrecisionOps._compute_dtype,
+                            orig_shape=(self.out_features, self.in_features),
+                            proj_down=proj_down,
+                            proj_up=proj_up,
+                            smooth_factor=smooth_factor,
+                            act_unsigned=act_unsigned,
+                        )
                     else:
                         raise ValueError(f"Unsupported quantization format: {self.quant_format}")
 
@@ -1046,6 +1075,8 @@ def mixed_precision_ops(quant_config={}, compute_dtype=torch.bfloat16, full_prec
                     quant_conf = {"format": self.quant_format}
                     if self._full_precision_mm_config:
                         quant_conf["full_precision_matrix_mult"] = True
+                    if bool(getattr(getattr(self.weight, "_params", None), "act_unsigned", False)):
+                        quant_conf["act_unsigned"] = True
                     sd["{}comfy_quant".format(prefix)] = torch.tensor(list(json.dumps(quant_conf).encode('utf-8')), dtype=torch.uint8)
 
                     input_scale = getattr(self, 'input_scale', None)
@@ -1103,18 +1134,24 @@ def mixed_precision_ops(quant_config={}, compute_dtype=torch.bfloat16, full_prec
 
                 # Inference path (unchanged)
                 if _use_quantized:
+                    # Some layouts (e.g. SVDQuant W4A4) do activation quantization
+                    # inside their fused kernel and cannot pre-quantize a float
+                    # tensor up-front. Skip the input wrapping for those.
+                    layout_cls = get_layout_class(self.layout_type)
+                    layout_quantizes_input = getattr(layout_cls, "QUANTIZES_INPUT", True)
 
-                    # Reshape 3D tensors to 2D for quantization (needed for NVFP4 and others)
-                    input_reshaped = input.reshape(-1, input_shape[2]) if input.ndim == 3 else input
+                    if layout_quantizes_input:
+                        # Reshape 3D tensors to 2D for quantization (needed for NVFP4 and others)
+                        input_reshaped = input.reshape(-1, input_shape[2]) if input.ndim == 3 else input
 
-                    # Fall back to non-quantized for non-2D tensors
-                    if input_reshaped.ndim == 2:
-                        reshaped_3d = input.ndim == 3
-                        # dtype is now implicit in the layout class
-                        scale = getattr(self, 'input_scale', None)
-                        if scale is not None:
-                            scale = comfy.model_management.cast_to_device(scale, input.device, None)
-                        input = QuantizedTensor.from_float(input_reshaped, self.layout_type, scale=scale)
+                        # Fall back to non-quantized for non-2D tensors
+                        if input_reshaped.ndim == 2:
+                            reshaped_3d = input.ndim == 3
+                            # dtype is now implicit in the layout class
+                            scale = getattr(self, 'input_scale', None)
+                            if scale is not None:
+                                scale = comfy.model_management.cast_to_device(scale, input.device, None)
+                            input = QuantizedTensor.from_float(input_reshaped, self.layout_type, scale=scale)
 
                 output = self.forward_comfy_cast_weights(input, compute_dtype, want_requant=isinstance(input, QuantizedTensor))
 

comfy/quant_ops.py

@@ -37,6 +37,9 @@ except ImportError as e:
     class _CKNvfp4Layout:
         pass
 
+    class _CKSVDQuantW4A4Layout:
+        pass
+
     def register_layout_class(name, cls):
         pass
 
@@ -55,6 +58,16 @@ if not _CK_MXFP8_AVAILABLE:
     class _CKMxfp8Layout:
         pass
 
+_CK_SVDQUANT_W4A4_AVAILABLE = False
+if _CK_AVAILABLE:
+    try:
+        from comfy_kitchen.tensor import TensorCoreSVDQuantW4A4Layout as _CKSVDQuantW4A4Layout
+        _CK_SVDQUANT_W4A4_AVAILABLE = True
+    except ImportError:
+        logging.info("comfy_kitchen does not expose SVDQuant W4A4 layout; int4 SVDQuant checkpoints will not be supported.")
+        class _CKSVDQuantW4A4Layout:
+            pass
+
 import comfy.float
 
 # ==============================================================================
@@ -162,6 +175,13 @@ class TensorCoreFP8E5M2Layout(_TensorCoreFP8LayoutBase):
     FP8_DTYPE = torch.float8_e5m2
 
 
+# SVDQuant W4A4 — pre-quantized offline (no runtime quantize), pass through the
+# kitchen-registered layout class unchanged. Comfy-side extension reserved in
+# case per-layer input scales or other Comfy-specific metadata are added later.
+class TensorCoreSVDQuantW4A4Layout(_CKSVDQuantW4A4Layout):
+    pass
+
+
 # Backward compatibility alias - default to E4M3
 TensorCoreFP8Layout = TensorCoreFP8E4M3Layout
 
@@ -176,6 +196,8 @@ register_layout_class("TensorCoreFP8E5M2Layout", TensorCoreFP8E5M2Layout)
 register_layout_class("TensorCoreNVFP4Layout", TensorCoreNVFP4Layout)
 if _CK_MXFP8_AVAILABLE:
     register_layout_class("TensorCoreMXFP8Layout", TensorCoreMXFP8Layout)
+if _CK_SVDQUANT_W4A4_AVAILABLE:
+    register_layout_class("TensorCoreSVDQuantW4A4Layout", TensorCoreSVDQuantW4A4Layout)
 
 QUANT_ALGOS = {
     "float8_e4m3fn": {
@@ -204,6 +226,14 @@ if _CK_MXFP8_AVAILABLE:
         "group_size": 32,
     }
 
+if _CK_SVDQUANT_W4A4_AVAILABLE:
+    QUANT_ALGOS["svdquant_w4a4"] = {
+        "storage_t": torch.int8,
+        "parameters": {"weight_scale", "proj_down", "proj_up", "smooth_factor"},
+        "comfy_tensor_layout": "TensorCoreSVDQuantW4A4Layout",
+        "group_size": 64,
+    }
+
 
 # ==============================================================================
 # Re-exports for backward compatibility
@@ -216,6 +246,7 @@ __all__ = [
     "TensorCoreFP8E4M3Layout",
     "TensorCoreFP8E5M2Layout",
     "TensorCoreNVFP4Layout",
+    "TensorCoreSVDQuantW4A4Layout",
     "QUANT_ALGOS",
     "register_layout_op",
 ]