Fix create and show commands for experimental models (#13741)

* x: make `ollama create --experimental` import from safetensors

This change allows pulling in safetensors models into the new experimental model format, and also
fixes the `ollama show` command to be able to correctly display the model information.

* gofumpt the linter

* gofumpt the linter again

* validate the model name

x/create/client/quantize.go

@@ -0,0 +1,127 @@
+//go:build mlx
+
+package client
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/ollama/ollama/x/imagegen/mlx"
+)
+
+// quantizeTensor loads a tensor from safetensors format, quantizes it,
+// and returns safetensors data for the quantized weights, scales, and biases.
+// Supported quantization types: "fp8" (affine 8-bit)
+// Uses MLX's native SaveSafetensors to ensure correct dtype handling (especially uint32 for quantized weights).
+func quantizeTensor(r io.Reader, name, dtype string, shape []int32, quantize string) (qweightData, scalesData, qbiasData []byte, qweightShape, scalesShape, qbiasShape []int32, err error) {
+	tmpDir := ensureTempDir()
+
+	// Read safetensors data to a temp file (LoadSafetensorsNative needs a path)
+	tmpFile, err := os.CreateTemp(tmpDir, "quant-input-*.safetensors")
+	if err != nil {
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to create temp file: %w", err)
+	}
+	tmpPath := tmpFile.Name()
+	defer os.Remove(tmpPath)
+
+	if _, err := io.Copy(tmpFile, r); err != nil {
+		tmpFile.Close()
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to write temp file: %w", err)
+	}
+	tmpFile.Close()
+
+	// Load the tensor using MLX's native loader
+	st, err := mlx.LoadSafetensorsNative(tmpPath)
+	if err != nil {
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to load safetensors: %w", err)
+	}
+	defer st.Free()
+
+	// Get the tensor (it's stored as "data" in our minimal safetensors format)
+	arr := st.Get("data")
+	if arr == nil {
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("tensor 'data' not found in safetensors")
+	}
+
+	// Convert to BFloat16 if needed (quantize expects float type)
+	if arr.Dtype() != mlx.DtypeBFloat16 && arr.Dtype() != mlx.DtypeFloat32 && arr.Dtype() != mlx.DtypeFloat16 {
+		arr = mlx.AsType(arr, mlx.DtypeBFloat16)
+		mlx.Eval(arr)
+	}
+
+	// Quantize based on quantization type
+	var qweight, scales, qbiases *mlx.Array
+	switch quantize {
+	case "fp8":
+		// affine mode: group_size=32, bits=8
+		qweight, scales, qbiases = mlx.Quantize(arr, 32, 8, "affine")
+	default:
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("unsupported quantization type: %s", quantize)
+	}
+
+	// Eval and make contiguous for data access
+	qweight = mlx.Contiguous(qweight)
+	scales = mlx.Contiguous(scales)
+	if qbiases != nil {
+		qbiases = mlx.Contiguous(qbiases)
+		mlx.Eval(qweight, scales, qbiases)
+	} else {
+		mlx.Eval(qweight, scales)
+	}
+
+	// Get shapes
+	qweightShape = qweight.Shape()
+	scalesShape = scales.Shape()
+
+	// Save quantized weight using MLX's native safetensors (correctly handles uint32 dtype)
+	qweightPath := filepath.Join(tmpDir, "qweight.safetensors")
+	defer os.Remove(qweightPath)
+	if err := mlx.SaveSafetensors(qweightPath, map[string]*mlx.Array{"data": qweight}); err != nil {
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to save quantized weight: %w", err)
+	}
+	qweightData, err = os.ReadFile(qweightPath)
+	if err != nil {
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to read quantized weight: %w", err)
+	}
+
+	// Save scales using MLX's native safetensors
+	scalesPath := filepath.Join(tmpDir, "scales.safetensors")
+	defer os.Remove(scalesPath)
+	if err := mlx.SaveSafetensors(scalesPath, map[string]*mlx.Array{"data": scales}); err != nil {
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to save scales: %w", err)
+	}
+	scalesData, err = os.ReadFile(scalesPath)
+	if err != nil {
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to read scales: %w", err)
+	}
+
+	// Affine mode returns qbiases for zero-point offset
+	if qbiases != nil {
+		qbiasShape = qbiases.Shape()
+		qbiasPath := filepath.Join(tmpDir, "qbias.safetensors")
+		defer os.Remove(qbiasPath)
+		if err := mlx.SaveSafetensors(qbiasPath, map[string]*mlx.Array{"data": qbiases}); err != nil {
+			return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to save qbiases: %w", err)
+		}
+		qbiasData, err = os.ReadFile(qbiasPath)
+		if err != nil {
+			return nil, nil, nil, nil, nil, nil, fmt.Errorf("failed to read qbiases: %w", err)
+		}
+	}
+
+	return qweightData, scalesData, qbiasData, qweightShape, scalesShape, qbiasShape, nil
+}
+
+// QuantizeSupported returns true if quantization is supported (MLX build)
+func QuantizeSupported() bool {
+	return true
+}
+
+// ensureTempDir creates the temp directory for quantization if it doesn't exist
+func ensureTempDir() string {
+	tmpDir := filepath.Join(os.TempDir(), "ollama-quantize")
+	os.MkdirAll(tmpDir, 0755)
+	return tmpDir
+}