Inventory must satisfy its nonnegative contract.

# Inventory must satisfy its nonnegative contract.

Repository-owned synthetic case: negative-stock

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,-1
000124,Reading light,"24,50",EUR,8

```