Checkout quote boundaries

Checkout quote boundaries define what the merchant can safely tell a customer about amount, crypto amount, rate, expiry, and finality. A checkout page can be simple, but the underlying records need enough precision to prevent disputes when markets move or payments arrive late.

0Base availability is account-gated. Build against capabilities, merchant status, environment mode, and settlement settings instead of assuming that every payment method, asset, network, cadence, or refund path is enabled for every merchant.

End-to-end picture

This flow is intentionally shown as product infrastructure: Order amount -> Quote or amount snapshot -> Checkout shown -> Customer pays -> Status finalizes -> Report records. The merchant application can make the customer experience simple, but the backend should keep each step visible enough for retries, support, and finance closeout.

Production contract

Status and state handling

Status handling should be strict even when the customer UI is friendly. Store raw 0Base statuses, map them to customer-safe labels at the edge, and keep the merchant order state separate from the payment object state. That separation lets you change customer copy without corrupting reconciliation.

Example implementation record

This is an application-side record shape for checkout quote boundaries. Keep exact request and response fields aligned with your enabled account contract when 0Base API access is released for your partner account; the point of this record is to keep product, support, and finance joined in your system.

{
  "merchant_order_id": "ord_quote_123",
  "checkout_id": "chk_live_123",
  "displayed_amount": "100.00",
  "displayed_currency": "EUR",
  "displayed_crypto_currency": "USDT",
  "quoted_rate": "1.08450000",
  "expires_at": "2026-06-28T21:00:00Z",
  "terms_snapshot_id": "terms_001"
}

Operational scenario

A checkout that displays a crypto estimate should keep the estimate tied to the checkout object and its expiry. If the customer pays after expiry, the merchant needs a recovery policy rather than silently applying a new quote.

In practice, production 0Base integrations make the happy path fast while keeping exceptions predictable: retries return the same object, delayed notifications can be repaired, expired sessions do not become mystery payments, and finance exports can be traced back to the original merchant order.

Before and after

Evidence to keep

This evidence is what makes the integration supportable at institutional scale. A developer should not need private operational knowledge to answer basic questions such as what the customer saw, which object owns the state, which event announced the change, and which ledger or report row closed the money movement.

Failure modes and recovery

Recovery should be idempotent and explainable. When the system is uncertain, preserve the current raw status, read the latest object state, attach a support reference, and avoid changing fulfillment or finance state until a trusted terminal condition is present.

API adjacency

For endpoint-level implementation, use the API reference as the source of truth for fields, enums, authentication, idempotency behavior, pagination, and response examples.

Why this matters for merchants and customers

Quote boundaries prevent checkout disputes. Customers should know what amount and terms they accepted; merchants should know which terms were current when payment was attempted.

At scale, the value of 0Base is not only that a payment can be created. The value is that the payment can be explained later: what the customer saw, which account capabilities allowed it, which backend state changed, which notification delivered it, and which ledger or report row closed it.

Worked API path

The example below shows the implementation shape for this page. Use merchant-specific capabilities, account settings, and API responses in production; the ids and values here are illustrative.

curl -X POST https://base-api-sandbox.0bit.app/v1/payment_intents \
  -H "Authorization: Bearer $OBIT_SECRET_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: ord_100045:base:v1" \
  -d '
{
    "amount": "89.00",
    "currency": "EUR",
    "cryptoCurrency": "USDT",
    "clientReference": "ord_100045",
    "settlementCurrency": "USDC",
    "settlementRail": "onchain"
}'

Example response shape:

{
  "intentId": "pi_test_456",
  "status": "requires_payment",
  "amount": "89.00",
  "currency": "EUR",
  "cryptoCurrency": "USDT",
  "clientReference": "ord_100045",
  "settlementCurrency": "USDC",
  "settlementRail": "onchain"
}

Implementation checkpoints:

• Store your merchant reference before calling 0Base.
• Attach the returned object id to the same business record.
• Record the request id, idempotency key, raw status, and environment.
• Use webhook and report reads to repair delayed or missed state changes.

Data join map

This join map is the reason 0Base is infrastructure rather than a payment button. A merchant can change checkout UX, support tooling, or finance exports without losing the chain from customer action to backend state and settlement evidence.

Operator runbook

The runbook should be available to support and finance teams before launch. A developer integration is not complete if only engineering can explain the state of a customer payment.

Developer checklist

• Treat displayed terms as a record, not a visual-only detail.
• Store expiry and terms snapshots.
• Do not compute payment amount in the browser.
• Avoid rate promises unless fields are returned for the current object.
• Make stale terms unreusable.
• Include quote boundary cases in launch testing.

Related pages