Initial Marktplaats SDK scaffold

Clone the twdehands SDK into mrktplaats and retarget naming and defaults for app.marktplaats.nl while keeping the same request/response bodies and endpoint behavior.

saleability.go

@@ -0,0 +1,53 @@
+package mrktplaats
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"mime/multipart"
+)
+
+// SaleabilityService handles image recognition for listings.
+type SaleabilityService struct {
+	t *transport
+}
+
+// Prediction is an image recognition result.
+type Prediction struct {
+	CategoryID   int     `json:"categoryId"`
+	CategoryName string  `json:"categoryName"`
+	Confidence   float64 `json:"confidence"`
+	Attributes   []any   `json:"attributes"`
+}
+
+// RecognizeResponse contains image recognition predictions.
+type RecognizeResponse struct {
+	Predictions []Prediction `json:"predictions"`
+}
+
+// Recognize uploads an image and returns category/attribute predictions.
+// Large images are automatically compressed to stay within the API size limit.
+func (s *SaleabilityService) Recognize(ctx context.Context, img io.Reader, filename string) (*RecognizeResponse, error) {
+	data, err := autoCompressImage(img)
+	if err != nil {
+		return nil, fmt.Errorf("mrktplaats: reading image: %w", err)
+	}
+
+	var buf bytes.Buffer
+	w := multipart.NewWriter(&buf)
+	part, err := w.CreateFormFile("picture", filename)
+	if err != nil {
+		return nil, fmt.Errorf("mrktplaats: creating form file: %w", err)
+	}
+	if _, err := io.Copy(part, bytes.NewReader(data)); err != nil {
+		return nil, fmt.Errorf("mrktplaats: copying image: %w", err)
+	}
+	w.Close()
+
+	var resp RecognizeResponse
+	if err := s.t.postMultipart(ctx, "/app/saleability/v4/recognize", nil, nil, w.FormDataContentType(), &buf, &resp); err != nil {
+		return nil, err
+	}
+	return &resp, nil
+}