## ADDED Requirements

### Requirement: Order aftersale eligibility and refund summary
Order and order-item responses SHALL expose the configured after-sale deadline after confirmation of delivery, whether each line has an active aftersale, its remaining refundable integer minor-unit amount, and the order's authoritative `refund_total_minor`. The API SHALL allow applications for paid or shipped orders while the configured window is open, and SHALL reject new applications after the deadline. The refund summary SHALL be sourced from completed `aftersales` records and updated only by a guarded refund-completion transaction.

#### Scenario: confirmed order remains eligible during the window
- **WHEN** a customer views a completed order before the configured N-day after-sale window expires
- **THEN** the order detail includes an after-sale deadline and each refundable line exposes its remaining amount and application action

#### Scenario: expired window hides the action
- **WHEN** the configured after-sale deadline has passed
- **THEN** the order and item responses mark after-sale unavailable and an application returns 409

#### Scenario: order refund total is authoritative
- **WHEN** an aftersale completes a refund
- **THEN** the order response's `refund_total_minor` equals the sum of completed aftersale amounts and is not client-calculated

### Requirement: Order item ownership and state safety
After-sale eligibility SHALL resolve the order item through the authenticated customer's order ownership (or the owning shop's `own_shop` scope for merchant actions), and every refund total update SHALL use a conditional status/amount guard so concurrent completions cannot refund more than the paid order amount.

#### Scenario: cross-customer item is hidden
- **WHEN** a customer submits another customer's order item id
- **THEN** the API returns 404 without disclosing order or refund data

#### Scenario: concurrent refunds stay within paid amount
- **WHEN** concurrent aftersales would make completed refunds exceed the line or order paid amount
- **THEN** the guarded update rejects the excess completion and stored refund totals remain within the paid amount