Autumn Checkout Guide

When to Use This Skill

• Debugging Autumn checkout creation, retrieval, preview, or confirmation
• Understanding why billing.attach returned an Autumn checkout URL
• Working on server/src/internal/checkouts/
• Changing how checkout previews are rendered or confirmed
• Determining whether a flow should use autumn_checkout, stripe_checkout, or no checkout
• Explaining the attach confirmation flow to another agent quickly

Core Concept

Autumn checkout is not a separate billing engine. It is a thin confirmation layer around the existing V2 attach action.

• attach() still does the normal setup -> compute -> evaluate flow
• If the attach context resolves to checkoutMode === "autumn_checkout", Autumn does not execute billing immediately
• Instead, it stores a lightweight checkout object containing the original attach params
• Public checkout routes later re-run attach from those stored params to build a fresh preview or to execute billing on confirm