fix: variant update now sets attribute values and default variant on WC

- Update path sends attributes per variation (was missing, causing
  "Any COLOR..." on WC)
- Sets default_attributes on parent product (first variant's values)
- Better API error logging with response body

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fusion-woo-odoo/fusion_woocommerce/lib/woo_api_client.py

@@ -39,6 +39,11 @@ class WooApiClient:
                     params=params,
                     timeout=self.timeout,
                 )
+                if response.status_code >= 400:
+                    _logger.error(
+                        "WC API %s %s returned %s: %s",
+                        method, endpoint, response.status_code, response.text[:500],
+                    )
                 response.raise_for_status()
                 return response.json()
             except Exception as exc:

fusion-woo-odoo/fusion_woocommerce/wizard/woo_variant_push.py

@@ -105,15 +105,29 @@ class WooVariantPushWizard(models.TransientModel):
                 'options': wc_terms,
             })
 
-        # Step 2: Convert product to variable with attributes
+        # Step 2: Update product as variable with attributes + set default
+        # Default attribute = first included variant's attribute values
+        default_attrs = []
+        first_included = self.line_ids.filtered('include')[:1]
+        if first_included and first_included.product_id:
+            for ptav in first_included.product_id.product_template_attribute_value_ids:
+                default_attrs.append({
+                    'name': ptav.attribute_id.name,
+                    'option': ptav.name,
+                })
+
+        parent_update = {
+            'type': 'variable',
+            'attributes': wc_attributes,
+        }
+        if default_attrs:
+            parent_update['default_attributes'] = default_attrs
+
         try:
-            client.update_product(pm.woo_product_id, {
-                'type': 'variable',
-                'attributes': wc_attributes,
-            })
+            client.update_product(pm.woo_product_id, parent_update)
             pm.woo_product_type = 'variable'
         except Exception as e:
-            raise UserError("Failed to convert WC product to variable: %s" % str(e))
+            raise UserError("Failed to update WC product: %s" % str(e))
 
         # Step 3: Create NEW variations
         created = 0
@@ -217,9 +231,18 @@ class WooVariantPushWizard(models.TransientModel):
             if not wc_var_id:
                 continue
 
+            # Build variation attributes from Odoo
+            var_attributes = []
+            for ptav in variant.product_template_attribute_value_ids:
+                var_attributes.append({
+                    'name': ptav.attribute_id.name,
+                    'option': ptav.name,
+                })
+
             var_data = {
                 'regular_price': str(line.regular_price),
                 'sku': line.sku or '',
+                'attributes': var_attributes,
                 'manage_stock': True,
                 'stock_quantity': int(variant.qty_available),
             }