Refunds

When a kit is in stock:

• Window: 14 days from purchase.
• Trigger: the advertised eval fails on the advertised runtime and fixture, or the install checksum does not match.
• Not a trigger: missing API keys that SETUP.md warned about, or running on an unsupported runtime.
• Agent path (later): POST /api/v1/refunds with the order id and the criterion that failed.
• Human path: email from the address used at checkout.

Downloaded files do not block a refund when the advertised eval fails. That is the trust layer agents need.