SKU uniqueness is a blocking approved constraint.

# SKU uniqueness is a blocking approved constraint.

Repository-owned synthetic case: duplicate-sku

Expected and observed outcome: rejected

The mapping and contract are the published EUR supplier fixture. No customer data or comparative superiority claim appears here.

Input fixture:

```csv
product_code,product_name,unit_price,currency,available
000123,Desk lamp,"19,90",EUR,12
000123,Reading light,"24,50",EUR,8

```