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When your agent completes a checkout itself, call Conto at two points: right before it opens the payment method, and right before it submits the payment. Conto checks the agent’s rules at both, counts the amount toward its limits in between, and records the outcome your agent reports.

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The two checkpoints

If any call fails, stop the checkout. A denial at either checkpoint returns an error, and the amount stops counting toward the agent’s limits.

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HTTP endpoints

If your integration calls the HTTP API directly, use an agent SDK key with the scope for each step. All paths below begin with /api/sdk and return { "checkpoint": { ... } } with an id, stage, nextAction, and expiresAt. Begin with a stable idempotencyKey, merchant ID, name and HTTPS checkout URL, amount in USD cents, purpose, and a cart with line items and totals. Continue only after APPROVED with CONFIRM_BEFORE_PAYING. Confirm with the final amountMinor, currency, and, when available, the final cart and pageUrl. The raw HTTP confirm refuses a changed total; cancel the old checkpoint, begin a new one at the final total with a new idempotency key, and confirm that one. The SDK checkout.confirm() helper performs that replacement automatically. Submit payment only after CONFIRMED with PAY_THEN_REPORT_OUTCOME. After submission, report PAID, NOT_PAID, or UNKNOWN on the same checkpoint. Read its status before retrying after a timeout; never submit the payment twice. A reported outcome has settlementVerified: false and is not proof of settlement. If Conto returns 503 PAYMENTS_PAUSED, stop checkout and ask the owner to check payment availability. See error handling.

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When the total changes

Tax and shipping often appear only after the buyer signs in and enters an address. The final total still has to pass the agent’s rules. If it differs from the approved total, confirm() replaces the approval with one for the final total before it confirms. If the final total breaks a rule, the payment stops there. Pass pageUrl to confirm() to check that the payment is submitted on the merchant’s site or the payment method’s own pages.

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Report the outcome

  • PAID keeps the amount counted toward the agent’s limits.
  • NOT_PAID releases it.
  • UNKNOWN keeps it counted until you report again.
An approved checkpoint that is never confirmed is released when its approval expires, 30 minutes after begin(). If a confirmed checkpoint never gets an outcome, the owner gets an alert to check the order.

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MCP tools

An MCP agent can use the same flow without code: checkout_checkpoint_begin, checkout_checkpoint_confirm, and checkout_checkpoint_report_outcome, plus checkout_checkpoint_cancel and checkout_checkpoint_status. See MCP tools.

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How strong this control is

Checkpoints are the lightweight way to add Conto to a checkout. Conto decides, and your checkout acts on the answer. Conto does not see the card or the charge, so it does not check a payment your agent makes without calling the checkpoints, and it records the outcome you report. For control at the moment of payment, pay through Conto: a managed wallet, or a connected card whose single-use credential Conto releases only after the controls pass.