Agentic payment engine
Intent to instant payment
without the friction.
Enable secure, tokenized payments where authorized AI agents purchase
automatically or through a one-click approval—while you remain the
Merchant of Record.
Checkout, rethought
Keep the trust of checkout.
Lose the friction.
Traditional checkout depends on clicks, forms, and CVV fields.
HarnessBuy lets an agent act on an authorized buyer’s intent, while
preserving the controls merchants, gateways, and card networks
require.
01 / Dual-mode checkout
The right path for
every buyer.
↯
Returning buyer / auto_checkout
Autonomous
auto-checkout.
When a returning buyer instructs an agent to purchase, HarnessBuy
finds their stored payment token and completes an off-session
charge.
payment_method_id••••_token_82xmodeauto_checkout
✓ Payment succeeded No human action required
+
First-time buyer / checkout_url
One-click setup.
Every purchase after.
When no token exists, HarnessBuy creates a secure checkout URL.
After payment, it silently provisions the buyer and vaults the card
for future agent purchases.
checkout_urlpay.harnessbuy.com/...modecheckout_url
✓ Token vaulted Future checkout: automatic
02 / Multi-gateway abstraction
One agentic checkout.
Every payment rail.
HarnessBuy standardizes agent-initiated checkout across the rails
buyers and merchants already trust. Your store and your agents
integrate once.
Stripe Agentic Commerce ProtocolExecute seamless off-session charges and handle payment webhooks
through a unified flow.
Visa TAP & Mastercard Agent PayRoute passkeys and network tokens that are bound to agent spend
parameters and trusted payment context.
stripeACPOff-session execution
VISATAPPasskey & network token
mastercardAGENT PAYTokenized parameters
MPPUCPUniversal routing
AP2 consent mandateValid
MerchantStride Athletics
Agent sessionclaude_5a71
Spend ceilingUSD 150.00
Time windowNext 24 hours
Token scopeBound & encrypted
03 / AP2 mandate verification
Consent that is
as specific as intent.
Every transaction checks a cryptographic consent mandate before a card
can be charged—making the authorization evidence clear for buyers,
merchants, and issuers.
Spend ceilings & time windowsValidate that a proposed purchase remains inside the buyer’s
approved amount and period.
Consent-backed tokenizationBind tokens to an agent session, a merchant, or a pre-approved
amount to prevent runaway spending.
Technical execution flow
Intent in. Settlement
confirmed.
- 01
Intent triggerA buyer tells an agent: “Buy these running shoes.”
- 02
Payload submissionThe agent sends an A2A JSON-RPC payload with the buyer email and
X-UCP-Agent-ID.
- 03
Token lookupHarnessBuy checks for a valid payment_method_id or network token.
- 04
Execution routeUse an off-session charge when a token exists, or issue a
one-click checkout URL and provision a token after first payment.
- 05
Settlement & confirmationUpdate WooCommerce or merchant order status, then return order
details and payment_status: succeeded to the agent.
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