# Cancel an order

Cancels an order that has not yet started preparation. This endpoint is
only available when fulfillment_status is PENDING or IN_PROGRESS.

Fulfillment restriction: Once the store begins preparing the order
(fulfillment_status is PREPARING or later), this endpoint returns 409
Conflict. Cancellation at that stage requires store intervention.

Automatic void/refund: When an order is cancelled, the server
automatically handles all attached payments:
- Payments in PENDING or AUTHORIZED status are voided (no charge).
- Payments in CAPTURED or COMPLETED status are refunded in full.
- Refunds follow the minimize-cash-refund strategy: loyalty points are
  refunded first, then gift cards, then credit/debit cards.

No separate refund request is needed after cancellation.

Idempotency: This endpoint requires the Idempotency-Key header.
If the order was already cancelled with the same key, the server returns
the current order state without re-processing.

Result: The order's status is set to CANCELLED, fulfillment_status
is set to CANCELLED, and all payments are voided or refunded.

Endpoint: POST /orders/{order_id}/cancel
Version: 1.0.0
Security: oauth2

## Path parameters:

  - `order_id` (string, required)
    Unique identifier for the order.

## Header parameters:

  - `Idempotency-Key` (string, required)
    A unique key (UUID v4) to ensure idempotent request processing.
Required on all POST, PUT, and DELETE requests.

If a request is retried with the same key within 24 hours,
the server returns the cached success response without re-processing.
Error responses are NOT cached -- retrying after an error with the
same key will re-execute the request.

Generate a new UUID v4 for each unique operation. Reuse the same key
only when retrying a failed or timed-out request.
    Example: "d7a8fbb3-07d4-4e3c-b5f2-9a6c8b1e0f23"

## Request fields (application/json):

  - `reason` (string,null)
    Optional human-readable reason for cancellation. Stored on the order
for reporting and analytics.
    Example: "Customer changed their mind"

## Response 200 fields (application/json):

  - `id` (string, required)
    Unique identifier for the order.

  - `cart_id` (string, required)
    The cart this order was created from.

  - `location_id` (string, required)
    The location (store) this order belongs to.

  - `customer_id` (string,null)
    Customer identifier from the cart at checkout time. Null for
anonymous orders. Locked at checkout -- cannot be changed after
the order is created.
    Example: "CUST-12345"

  - `status` (string, required)
    Order lifecycle status. Tracks the high-level state of the order from
creation through completion or cancellation.

- PENDING: Order created from cart checkout, awaiting payment.
- CONFIRMED: At least one payment completed; order accepted by the store.
- COMPLETED: Order fulfilled and closed.
- FAILED: Order could not be processed (e.g., all payments failed).
- VOIDED: Order voided before any fulfillment began.
- CANCELLED: Order cancelled by customer or system.

State transitions:
- PENDING -> CONFIRMED, FAILED, VOIDED, CANCELLED
- CONFIRMED -> COMPLETED, CANCELLED
- COMPLETED, FAILED, VOIDED, CANCELLED are terminal (no further transitions)
    Enum: "PENDING", "CONFIRMED", "COMPLETED", "FAILED", "VOIDED", "CANCELLED"

  - `payment_status` (string, required)
    Aggregate payment status across all payments on the order. This is a
server-computed summary -- do not set directly.

- UNPAID: No payments submitted yet.
- PROCESSING: At least one payment is in a non-terminal state (PENDING or AUTHORIZED).
- PARTIALLY_PAID: Some payments completed but total paid = order total. The order is fully covered.

State transitions:
- UNPAID -> PROCESSING, PARTIALLY_PAID, PAID
- PROCESSING -> PARTIALLY_PAID, PAID, UNPAID (if all payments fail)
- PARTIALLY_PAID -> PROCESSING, PAID
- PAID is terminal for forward flow (refunds revert to PARTIALLY_PAID or UNPAID)
    Enum: "UNPAID", "PROCESSING", "PARTIALLY_PAID", "PAID"

  - `fulfillment_status` (string, required)
    Fulfillment lifecycle status. Tracks the physical preparation and handoff
of the order. Maps directly from the backend fulfillment state machine.

- PENDING: Order created, not yet accepted by store.
- IN_PROGRESS: Store accepted the order and is queuing it.
- PREPARING: Store staff actively assembling the order.
- READY_FOR_PICKUP: Order assembled and waiting for customer (pickup/curbside).
- FULFILLED: Customer received the order (pickup/curbside/kiosk).
- DELIVERED: Order delivered to customer address (delivery orders).
- RETURNED: Order returned after fulfillment.
- CANCELLED: Fulfillment cancelled before completion.

State transitions:
- PENDING -> IN_PROGRESS, CANCELLED
- IN_PROGRESS -> PREPARING, CANCELLED
- PREPARING -> READY_FOR_PICKUP, CANCELLED
- READY_FOR_PICKUP -> FULFILLED, DELIVERED, CANCELLED
- FULFILLED -> RETURNED
- DELIVERED -> RETURNED
- RETURNED, CANCELLED are terminal (no further transitions)

Cancellation restriction: Orders can only be cancelled via
POST /orders/{order_id}/cancel when fulfillment_status is PENDING or
IN_PROGRESS. Once preparation begins, cancellation requires store
intervention.
    Enum: "PENDING", "IN_PROGRESS", "PREPARING", "READY_FOR_PICKUP", "FULFILLED", "DELIVERED", "RETURNED", "CANCELLED"

  - `items` (array, required)
    Line items in the order (locked at checkout).

  - `items.id` (string, required)
    Unique identifier for this order item.

  - `items.menu_item_id` (string, required)
    Reference to the original menu item.

  - `items.name` (string, required)
    Display name of the item (locked at checkout).

  - `items.quantity` (integer, required)
    Number of this item in the order.

  - `items.base_price` (object, required)
    Base price per unit (locked at checkout).

  - `items.base_price.amount` (integer, required)
    Monetary value in the smallest currency unit (cents for USD).
Example: 1299 = $12.99.
    Example: 1299

  - `items.base_price.currency` (string, required)
    ISO 4217 currency code.
    Example: "USD"

  - `items.modifier_total` (object, required)
    Total price of all selected modifiers per unit (locked at checkout).

  - `items.item_total` (object, required)
    Total for this line item: (base_price + modifier_total) * quantity.
Locked at checkout.

  - `items.modifier_selections` (array, required)
    Modifiers selected for this item (locked at checkout).

  - `items.modifier_selections.modifier_group_id` (string, required)
    ID of the modifier group this selection belongs to.

  - `items.modifier_selections.modifier_id` (string, required)
    ID of the selected modifier within the group.

  - `items.modifier_selections.quantity` (integer)
    Quantity of this modifier. Relevant for modifier groups with
allows_duplicates: true (e.g., "Extra Cheese x2").

  - `items.modifier_selections.nested_selections` (array)
    Selections for nested modifier groups. For example, selecting
"Steak" as a protein, then choosing "Medium" from the steak
preparation sub-group. Supports up to 3 nesting levels,
matching the menu's modifier group depth.

  - `items.special_instructions` (string,null)
    Customer's special instructions for this item, locked at checkout.
Null if none were provided.

  - `items.age_verification_required` (boolean)
    True if this item requires age verification. Copied from the menu
item at checkout time.

  - `items.minimum_age` (integer,null)
    Minimum age required to purchase this item (e.g., 21 for alcohol).
Null if age verification is not required.

  - `payments` (array, required)
    Payments attached to this order. Empty array until the first payment
is submitted via POST /orders/{order_id}/payments.

  - `payments.id` (string, required)
    Unique identifier for the payment.

  - `payments.order_id` (string, required)
    The order this payment is attached to.

  - `payments.status` (string, required)
    Payment processing status. The typical online ordering flow is:
PENDING -> COMPLETED (immediate capture).

For pre-authorization flows: PENDING -> AUTHORIZED -> CAPTURED -> COMPLETED.

Terminal states: COMPLETED, VOIDED, REFUNDED, FAILED.

State transitions:
- PENDING -> AUTHORIZED, COMPLETED, FAILED
- AUTHORIZED -> CAPTURED, VOIDED, FAILED
- CAPTURED -> COMPLETED, REFUNDED, PARTIALLY_REFUNDED
- COMPLETED -> REFUNDED, PARTIALLY_REFUNDED
- VOIDED, REFUNDED, FAILED are terminal (no further transitions)
- PARTIALLY_REFUNDED -> REFUNDED (when remaining amount is refunded)
    Enum: "PENDING", "AUTHORIZED", "CAPTURED", "COMPLETED", "VOIDED", "REFUNDED", "PARTIALLY_REFUNDED", "FAILED"

  - `payments.payment_method` (string, required)
    The payment method used. These are the API-facing values; the server
maps them to internal payment processing types.

- CREDIT_CARD: Visa, Mastercard, Amex, Discover credit cards
- DEBIT_CARD: Debit cards with PIN or signature
- CASH: Customer pays cash at the pickup counter. Only meaningful for
  PICKUP and DINE_IN handoff modes. The order is submitted online but
  payment is collected in-store.
- GIFT_CARD: Store gift cards or third-party gift cards
- LOYALTY_POINTS: Loyalty program points redeemed as payment
- DIGITAL_WALLET: Apple Pay, Google Pay, or other digital wallets
- EBT: SNAP/EBT card. Item eligibility applies -- only SNAP-eligible
  items (generally food items, excluding hot prepared foods and tobacco)
  can be paid with EBT. Check allowed_tenders on each menu item.

Tolerant Reader: New payment method values may be added in future
API versions. Your integration should handle unknown enum values
gracefully (e.g., log a warning and skip) rather than failing.
    Enum: "CREDIT_CARD", "DEBIT_CARD", "CASH", "GIFT_CARD", "LOYALTY_POINTS", "DIGITAL_WALLET", "EBT"

  - `payments.amount` (object, required)
    The payment amount in cents.

  - `payments.tip_amount` (any)
    Tip amount included in this payment, if any. Null if no tip.

  - `payments.payment_details` (object,null)
    Method-specific details. Shape varies by payment_method:
- CREDIT_CARD / DEBIT_CARD: { "last_four": "4242", "brand": "visa", "exp_month": 12, "exp_year": 2027 }
- GIFT_CARD: { "last_four": "7890", "balance_remaining": { "amount": 1500, "currency": "USD" } }
- LOYALTY_POINTS: { "points_used": 500, "points_remaining": 1200 }
- DIGITAL_WALLET: { "wallet_type": "apple_pay" }

  - `payments.idempotency_key` (string)
    The idempotency key used when this payment was submitted.

  - `payments.created_at` (string, required)
    When the payment was created.

  - `payments.updated_at` (string, required)
    When the payment status was last updated.

  - `discounts` (array)
    Discounts applied to the order (locked at checkout).

  - `discounts.id` (string, required)
    Unique identifier for this discount. Server-generated opaque string
for reconciliation and tracking.

  - `discounts.name` (string, required)
    Display name of the discount (e.g., "10% Off First Order", "$2 Off Subs").

  - `discounts.type` (string, required)
    Whether this discount is a percentage off or a fixed amount.
PERCENTAGE: the value field contains the percentage (e.g., "10.00" for 10%).
FIXED: the amount field contains the fixed discount in cents.
    Enum: "PERCENTAGE", "FIXED"

  - `discounts.value` (string,null)
    For PERCENTAGE discounts, the percentage value as a decimal string
(e.g., "10.00" for 10%). Null for FIXED discounts.

  - `discounts.amount` (object, required)
    The calculated discount amount deducted (always positive, in cents).

  - `discounts.source` (string, required)
    Where this discount originated.
- AUTOMATIC: Discount applied automatically by the server based on rules
  (happy hour, spend threshold, item combo, location-specific).
- PROMO_CODE: Discount from a promo or coupon code entered by the customer.
- LOYALTY_REWARD: Discount from a loyalty program reward redemption.
- MANUAL: Discount applied manually by store staff or POS override.
    Enum: "AUTOMATIC", "PROMO_CODE", "LOYALTY_REWARD", "MANUAL"

  - `discounts.application_scope` (string, required)
    Whether this discount is applied before or after tax calculation.
PRE_TAX discounts reduce the taxable amount. POST_TAX discounts
reduce the total after tax. Most discounts are PRE_TAX.
    Enum: "PRE_TAX", "POST_TAX"

  - `promo_codes` (array)
    Promo codes that were active on the cart at checkout (locked at checkout).

  - `promo_codes.code` (string, required)
    The promo code string, normalized to uppercase. Codes are case-insensitive
on input ("summer25" and "SUMMER25" are treated identically) but always
returned as uppercase in responses.
    Example: "SUMMER25"

  - `promo_codes.status` (string, required)
    Current status of this promo code on the cart.
- ACTIVE: The code is applied and its discount is reflected in totals.
- EXPIRED: The code expired after being applied (e.g., time-limited promo).
- REDEEMED: The code was already used (single-use codes) and locked at checkout.
    Enum: "ACTIVE", "EXPIRED", "REDEEMED"

  - `promo_codes.discount_preview` (object)
    Estimated discount this promo code provides. Present when the code is
ACTIVE. The actual discount amount appears in the PriceCalculation
discounts array with source: PROMO_CODE.

  - `promo_codes.discount_preview.estimated_discount` (object)
    Estimated discount amount in cents.

  - `promo_codes.discount_preview.description` (string)
    Human-readable description of the discount.
    Example: "25% off your order (up to $10)"

  - `promo_codes.applied_at` (string, required)
    When this promo code was applied to the cart.

  - `handoff` (any)

  - `notes` (string,null)
    Customer notes from checkout (e.g., "No onions please").
Null if no notes were provided.

  - `subtotal` (object, required)
    Sum of all item totals before tax and discounts.

  - `total_tax` (object, required)
    Total tax amount for the order.

  - `total_discount` (object)
    Total of cart-level discounts applied to the order (locked at checkout).
Item-level discounts are reflected in each item's total.

  - `fees` (array)
    Fees applied to this order (locked at checkout).

  - `fees.id` (string, required)
    Unique identifier for this fee. Server-generated opaque string
used for reconciliation and tracking.

  - `fees.name` (string, required)
    Display name of the fee (e.g., "Delivery Fee", "Service Fee",
"Bag Fee"). Use this for detailed receipt views.

  - `fees.fee_type` (string, required)
    Category of the fee.
- DELIVERY: Fee for delivering the order to the customer.
- SERVICE: Platform or convenience service fee.
- BAG: Per-bag charge required by local regulations.
- SMALL_ORDER: Surcharge applied when the cart subtotal is below
  the location's minimum order amount. The fee covers the shortfall.
- OTHER: Fees that do not fit the above categories.
    Enum: "DELIVERY", "SERVICE", "BAG", "SMALL_ORDER", "OTHER"

  - `fees.label` (string, required)
    Short display label for UI rendering (e.g., "Delivery", "Service",
"Bag fee"). Use this for compact summary views.

  - `fees.type` (string)
    How the fee amount was calculated.
- FLAT: A fixed amount regardless of cart contents.
- PERCENTAGE: Calculated as a percentage of the subtotal.
    Enum: "FLAT", "PERCENTAGE"

  - `fees.value` (string,null)
    For PERCENTAGE fees, the percentage as a decimal string
(e.g., "5.00" for 5%). Null for FLAT fees.

  - `fees.amount` (object, required)
    The calculated fee amount in cents (always positive). For PERCENTAGE
fees, this is the result of applying the percentage to the subtotal.

  - `fees.taxable` (boolean, required)
    Whether tax applies to this fee. The server decides per fee based
on local tax rules. When true, this fee's amount is included in the
taxable_amount on the PriceCalculation response.

  - `total_fees` (object)
    Sum of all fee amounts (locked at checkout).

  - `total` (object, required)
    Grand total: subtotal + total_tax + total_fees - total_discount. Locked at checkout.

  - `total_paid` (object, required)
    Sum of all completed payment amounts. Updated as payments reach
COMPLETED status.

  - `balance_due` (object, required)
    Remaining amount to be paid (total - total_paid). Zero when the
order is fully paid.

  - `age_verification_required` (boolean)
    True if any item requires age verification. When true, the consumer
will be verified at pickup or delivery (offline verification).

  - `age_verification_notice` (string,null)
    Human-readable notice about age verification requirements.
Null when no age-restricted items are in the order.

  - `estimated_ready_at` (string,null)
    Estimated time the order will be ready for pickup or delivery, as an
ISO 8601 datetime (e.g., "2026-03-15T14:30:00-05:00"). Null when the
estimate is not yet available (e.g., before the order is confirmed by
the store). Updated as the order progresses -- poll the order or
listen for order.status.changed webhooks to get updated estimates.

  - `created_at` (string, required)
    When the order was created (checkout time).

  - `updated_at` (string, required)
    When the order was last modified.

## Response 401 fields (application/json):

  - `error` (object, required)

  - `error.code` (string, required)
    Machine-readable error category. Use this field for programmatic
error handling (e.g., retry on RATE_LIMIT_ERROR, re-authenticate
on AUTHENTICATION_ERROR).
    Enum: "AUTHENTICATION_ERROR", "INVALID_REQUEST_ERROR", "RATE_LIMIT_ERROR", "NOT_FOUND_ERROR", "CONFLICT_ERROR", "INTERNAL_ERROR"

  - `error.message` (string, required)
    Human-readable error description. Safe to display to developers
in logs or debugging tools. Do not display to end users.

  - `error.detail` (string)
    Additional context about the error, including suggestions for
resolution. May include specific field values or limits that
were exceeded.

  - `error.request_id` (string, required)
    Unique identifier for this request. Include this value when
contacting Tote Developer Support for troubleshooting.

  - `error.field` (string,null)
    JSON pointer to the field that caused the error.
Null if the error is not field-specific.
    Example: "items[0].modifier_groups[1].modifiers"

  - `error.change_reasons` (array)
    Machine-readable reasons why the resource state changed, causing
the conflict. Present on checkout 409 responses when expected_total
does not match the current total. Clients should re-fetch the cart
and call POST /carts/{cart_id}/calculate to get the updated total
before retrying checkout.
    Enum: "PROMO_EXPIRED", "DISCOUNT_CHANGED", "ITEM_PRICE_CHANGED", "ITEM_UNAVAILABLE", "FEE_CHANGED"

## Response 404 fields (application/json):

  - `error` (object, required)

  - `error.code` (string, required)
    Machine-readable error category. Use this field for programmatic
error handling (e.g., retry on RATE_LIMIT_ERROR, re-authenticate
on AUTHENTICATION_ERROR).
    Enum: "AUTHENTICATION_ERROR", "INVALID_REQUEST_ERROR", "RATE_LIMIT_ERROR", "NOT_FOUND_ERROR", "CONFLICT_ERROR", "INTERNAL_ERROR"

  - `error.message` (string, required)
    Human-readable error description. Safe to display to developers
in logs or debugging tools. Do not display to end users.

  - `error.detail` (string)
    Additional context about the error, including suggestions for
resolution. May include specific field values or limits that
were exceeded.

  - `error.request_id` (string, required)
    Unique identifier for this request. Include this value when
contacting Tote Developer Support for troubleshooting.

  - `error.field` (string,null)
    JSON pointer to the field that caused the error.
Null if the error is not field-specific.
    Example: "items[0].modifier_groups[1].modifiers"

  - `error.change_reasons` (array)
    Machine-readable reasons why the resource state changed, causing
the conflict. Present on checkout 409 responses when expected_total
does not match the current total. Clients should re-fetch the cart
and call POST /carts/{cart_id}/calculate to get the updated total
before retrying checkout.
    Enum: "PROMO_EXPIRED", "DISCOUNT_CHANGED", "ITEM_PRICE_CHANGED", "ITEM_UNAVAILABLE", "FEE_CHANGED"

## Response 409 fields (application/json):

  - `error` (object, required)

  - `error.code` (string, required)
    Machine-readable error category. Use this field for programmatic
error handling (e.g., retry on RATE_LIMIT_ERROR, re-authenticate
on AUTHENTICATION_ERROR).
    Enum: "AUTHENTICATION_ERROR", "INVALID_REQUEST_ERROR", "RATE_LIMIT_ERROR", "NOT_FOUND_ERROR", "CONFLICT_ERROR", "INTERNAL_ERROR"

  - `error.message` (string, required)
    Human-readable error description. Safe to display to developers
in logs or debugging tools. Do not display to end users.

  - `error.detail` (string)
    Additional context about the error, including suggestions for
resolution. May include specific field values or limits that
were exceeded.

  - `error.request_id` (string, required)
    Unique identifier for this request. Include this value when
contacting Tote Developer Support for troubleshooting.

  - `error.field` (string,null)
    JSON pointer to the field that caused the error.
Null if the error is not field-specific.
    Example: "items[0].modifier_groups[1].modifiers"

  - `error.change_reasons` (array)
    Machine-readable reasons why the resource state changed, causing
the conflict. Present on checkout 409 responses when expected_total
does not match the current total. Clients should re-fetch the cart
and call POST /carts/{cart_id}/calculate to get the updated total
before retrying checkout.
    Enum: "PROMO_EXPIRED", "DISCOUNT_CHANGED", "ITEM_PRICE_CHANGED", "ITEM_UNAVAILABLE", "FEE_CHANGED"

## Response 422 fields (application/json):

  - `error` (object, required)

  - `error.code` (string, required)
    Machine-readable error category. Use this field for programmatic
error handling (e.g., retry on RATE_LIMIT_ERROR, re-authenticate
on AUTHENTICATION_ERROR).
    Enum: "AUTHENTICATION_ERROR", "INVALID_REQUEST_ERROR", "RATE_LIMIT_ERROR", "NOT_FOUND_ERROR", "CONFLICT_ERROR", "INTERNAL_ERROR"

  - `error.message` (string, required)
    Human-readable error description. Safe to display to developers
in logs or debugging tools. Do not display to end users.

  - `error.detail` (string)
    Additional context about the error, including suggestions for
resolution. May include specific field values or limits that
were exceeded.

  - `error.request_id` (string, required)
    Unique identifier for this request. Include this value when
contacting Tote Developer Support for troubleshooting.

  - `error.field` (string,null)
    JSON pointer to the field that caused the error.
Null if the error is not field-specific.
    Example: "items[0].modifier_groups[1].modifiers"

  - `error.change_reasons` (array)
    Machine-readable reasons why the resource state changed, causing
the conflict. Present on checkout 409 responses when expected_total
does not match the current total. Clients should re-fetch the cart
and call POST /carts/{cart_id}/calculate to get the updated total
before retrying checkout.
    Enum: "PROMO_EXPIRED", "DISCOUNT_CHANGED", "ITEM_PRICE_CHANGED", "ITEM_UNAVAILABLE", "FEE_CHANGED"

## Response 429 fields (application/json):

  - `error` (object, required)

  - `error.code` (string, required)
    Machine-readable error category. Use this field for programmatic
error handling (e.g., retry on RATE_LIMIT_ERROR, re-authenticate
on AUTHENTICATION_ERROR).
    Enum: "AUTHENTICATION_ERROR", "INVALID_REQUEST_ERROR", "RATE_LIMIT_ERROR", "NOT_FOUND_ERROR", "CONFLICT_ERROR", "INTERNAL_ERROR"

  - `error.message` (string, required)
    Human-readable error description. Safe to display to developers
in logs or debugging tools. Do not display to end users.

  - `error.detail` (string)
    Additional context about the error, including suggestions for
resolution. May include specific field values or limits that
were exceeded.

  - `error.request_id` (string, required)
    Unique identifier for this request. Include this value when
contacting Tote Developer Support for troubleshooting.

  - `error.field` (string,null)
    JSON pointer to the field that caused the error.
Null if the error is not field-specific.
    Example: "items[0].modifier_groups[1].modifiers"

  - `error.change_reasons` (array)
    Machine-readable reasons why the resource state changed, causing
the conflict. Present on checkout 409 responses when expected_total
does not match the current total. Clients should re-fetch the cart
and call POST /carts/{cart_id}/calculate to get the updated total
before retrying checkout.
    Enum: "PROMO_EXPIRED", "DISCOUNT_CHANGED", "ITEM_PRICE_CHANGED", "ITEM_UNAVAILABLE", "FEE_CHANGED"

## Response 500 fields (application/json):

  - `error` (object, required)

  - `error.code` (string, required)
    Machine-readable error category. Use this field for programmatic
error handling (e.g., retry on RATE_LIMIT_ERROR, re-authenticate
on AUTHENTICATION_ERROR).
    Enum: "AUTHENTICATION_ERROR", "INVALID_REQUEST_ERROR", "RATE_LIMIT_ERROR", "NOT_FOUND_ERROR", "CONFLICT_ERROR", "INTERNAL_ERROR"

  - `error.message` (string, required)
    Human-readable error description. Safe to display to developers
in logs or debugging tools. Do not display to end users.

  - `error.detail` (string)
    Additional context about the error, including suggestions for
resolution. May include specific field values or limits that
were exceeded.

  - `error.request_id` (string, required)
    Unique identifier for this request. Include this value when
contacting Tote Developer Support for troubleshooting.

  - `error.field` (string,null)
    JSON pointer to the field that caused the error.
Null if the error is not field-specific.
    Example: "items[0].modifier_groups[1].modifiers"

  - `error.change_reasons` (array)
    Machine-readable reasons why the resource state changed, causing
the conflict. Present on checkout 409 responses when expected_total
does not match the current total. Clients should re-fetch the cart
and call POST /carts/{cart_id}/calculate to get the updated total
before retrying checkout.
    Enum: "PROMO_EXPIRED", "DISCOUNT_CHANGED", "ITEM_PRICE_CHANGED", "ITEM_UNAVAILABLE", "FEE_CHANGED"