UCP Checkout

Checkout is the highest-leverage surface. Keep it deterministic, auditable, and idempotent.

Figure: Checkout flow.

What Checkout Should Cover

• Cart validation and price calculation.
• Taxes, fees, shipping options, and totals.
• Payment intent creation and confirmation.

Minimal Flow

1. Quote: agent requests a quote for items and options.
2. Confirm: agent confirms the exact total and policy terms.
3. Execute: payment is authorized and order is created.

Data Requirements (Keep It Small)

• Line items and quantities
• Pricing breakdown (subtotal, tax, shipping, total)
• Currency and region
• Payment method token or reference

Failure Handling

• Return explicit error codes for out-of-stock, pricing mismatch, or payment failure.
• Make confirmation idempotent to avoid double charges.

Observability

• Include a trace ID on every checkout attempt.
• Log status transitions: quoted -> confirmed -> paid.

Related

• Order Management
• Implementation Checklist