sku and item fix

Frontend/erp-system/lib/validations/master-data.ts

@@ -81,10 +81,14 @@ export function validateItemTypeName(name: string): Record<string, string> {
 }
 
 export function validateVariantItemForm(input: {
+  productName: string
   categoryId: number | null
   hasVariants: boolean
 }): Record<string, string> {
   const errors: Record<string, string> = {}
+  // Required: it names every generated item and leads its SKU, and neither reads sensibly
+  // when derived from the category instead ("Beverages - 500ml").
+  if (!input.productName.trim()) errors.productName = "Enter a product name"
   if (!input.categoryId) errors.categoryId = "Select a category"
   if (!input.hasVariants) errors.variants = "Check at least one variant category and add its values"
   return errors
@@ -95,6 +99,29 @@ export function validateVariantItemForm(input: {
  * (docs/20 §3.1). Returns a map keyed by variant key → message; empty when valid.
  * In "stock" mode there is nothing to validate (prices are sent as null).
  */
+/**
+ * Belt-and-braces sweep over the generated variants: each one's resolved content pair must be
+ * whole or wholly absent. It should never fire — `addValue` rejects a half or duplicate pair at
+ * entry — so it exists to catch stale state, not to guide the user.
+ *
+ * Keyed by variant key to mirror {@link validateVariantPrices}, but surfaced as ONE form-level
+ * message: content is *derived*, so unlike a price there is no per-row control to attach an
+ * error to.
+ */
+export function validateVariantContent(
+  variantKeys: string[],
+  contentFor: (key: string) => { qty: string; unit: string | null },
+): Record<string, string> {
+  const errors: Record<string, string> = {}
+  for (const key of variantKeys) {
+    const { qty, unit } = contentFor(key)
+    const pair = contentPairErrors(qty, unit)
+    const message = pair.contentQty ?? pair.contentUnit
+    if (message) errors[key] = message
+  }
+  return errors
+}
+
 export function validateVariantPrices(
   variantKeys: string[],
   priceFor: (key: string) => string,