vmall/openspec/changes/archive/2026-09-17-fulfillment-invoices/tasks.md

Tasks: fulfillment-invoices

1. Schema

• Migration: shipments, shipment_items, invoices; status enums; shipment_no/invoice_no sequences

2. Shipments

• POST /api/shop/orders/{id}/shipments (qty validation vs unshipped remainder)
• POST /api/shop/shipments/{id}/ship; order status propagation (fulfilling/shipped)
• GET /api/shipments (customer), POST /api/shipments/{id}/confirm-delivered → order completed when done
• GET /api/shop/shipments

3. Invoices

• POST /api/orders/{id}/invoice (one open invoice per order; amount = order total)
• GET /api/invoices (customer), GET /api/shop/invoices, POST /api/shop/invoices/{id}/issue

4. Tests

• cargo test: partial shipment qty math, order status propagation, duplicate invoice rejected, issue flow