calculate_landed_cost
ChatGPTUse this when a seller asks what each unit of a purchase order or shipment really costs once freight, duty and fees are added (landed cost per unit), how to split freight, duty and fees across a PO, including lines with different duty rates, or what their margin is once shipping and duty are included. Do not use for the cost to make a product from its materials, or for a what-if on a tariff rate that has not been charged. Needs the PO lines (SKU, quantity, unit cost; optional unit weight or CBM, sell price, per-line duty rate) and the shipment costs the user provides: freight, insurance, brokerage and other fees as amounts, and duty as a percentage of goods value or as an amount. Splits freight and fees by goods value, quantity, weight or volume, adds duty on value, and returns landed unit cost, uplift over the purchase cost and, when sell prices are given, margin per SKU. It does not look up freight quotes or duty rates. Read-only; stores nothing.
