Card-First Agentic Payments: Making ‘Intent’ Safe on Today’s Rails

Contents:

• Why Identity and Consent are Harder When an Agent Pays
• The Building Blocks Already Exist on Cards
• Evidence in Production
• Where Protocols Fit
• Security: Relocating Defenses to the Intent Layer
• Economics in Transition
• The Standard to Build For
• Evolving Cards for Intent-Driven Payments

Agentic commerce is shifting the locus of trust in payments. As AI agents begin executing transactions on behalf of consumers and businesses, the decision to buy and the act of paying will increasingly occur in the same line of code.

The card ecosystem already holds most of the primitives needed to support this shift. Network tokens, virtual cards, EMV 3-D Secure, and message-level evidence are tools designed for digital payments; the difference now is where and when they’re applied.

Why Identity and Consent are Harder When an Agent Pays

Traditional card payments rely on implicit proofs: a logged-in session, a visible action (“Pay”), and a recognized device. When agents transact autonomously, those signals disappear. What must replace them are explicit, verifiable constructs that answer three questions:

• Who is acting?

A transaction must be traceable not to a card number, but to a specific agent instance running on a known device and linked to an authorized user or organization.

• Under what authority?

The action must reference a standing, conditional, and revocable mandate—for example, “buy under $300, economy only, within seven days.”

• How to audit later?

The system must generate durable evidence of who acted, under which limits, and when.

This is the thinking behind signed mandates—cryptographically verifiable instructions that travel with the payment context. Google’s AP2 framework describes these as “cart” and “intent” mandates¹: the former for immediate actions, the latter for conditional ones. The aim isn’t to invent a new payment rail, but to create portable proof of consent that existing rails can consume.

The Building Blocks Already Exist on Cards

Network tokens: safer, revocable credentials

A network token—issued through Visa’s VTS or Mastercard’s MDES—replaces the raw PAN with a credential bound to a device, merchant, or channel. In an agentic model, that binding can extend to a specific agent identity. Tokens can be revoked instantly if telemetry suggests misuse, without reissuing the underlying card.

Why this matters: Tokens confine risk and maintain continuity. Visa reports higher approval rates and lower fraud where tokenization replaces PAN use². A compromised token affects one scope, not the account.

Example: A travel agent running on a registered phone uses a token tied to that device and identity. If runtime data show impossible travel or signature drift, the token is deactivated; subsequent requests fail immediately, without a card reissue.

Virtual cards per mandate: consent expressed as a credential

Virtual cards already serve corporate controls and embedded-finance scenarios. In an agentic context, each card can represent a single mandate—a “mini account” with encoded limits such as MCC filters, spend caps, merchant binding, or validity windows.

Why this matters: The mandate becomes self-enforcing. Even if an agent deviates, the credential blocks over-spend or merchant drift automatically.

Example: A consumer pre-authorizes “buy under $300 when back in stock.” The issuer mints a merchant-bound virtual card capped at $300 for seven days. When the item reappears at $289, the agent completes payment; if code injection attempts to change vendor or shipping tier, the credential itself rejects it.

Evidence that travels in the message

Every transaction message already carries optional fields for private data. These can hold a Mandate ID, a policy snapshot hash, and an agent or device fingerprint through the ISO 8583 standard. Embedding these identifiers ensures that “who acted, under what rules, when” accompanies both authorization and clearing records.

Why this matters:

• Disputes start with verifiable evidence, not a reconstruction exercise.
• Declines can return explicit reasons (“revoked by mandate,” “limit exceeded”) instead of generic codes.
• Audit trails become inherent instead of appended.

Example: A SaaS finance team suspends an automated procurement mandate at 3:17 p.m. Later attempts fail with the clear code “revoked by policy.” If a chargeback arises, the issuer and merchant already share a common Mandate ID and policy version—no manual reconciliation.

Evidence in Production

Each of these mechanisms already exists at scale.

• Tokenization is default in digital issuance across Visa and Mastercard ecosystems.
• Virtual cards with constrained scope are mainstream in agentic trials at Stripe Issuing.

These primitives can be combined to govern agent behavior today, without waiting for new protocols.

Where Protocols Fit

Specifications such as AP2 (signed mandates), x402 (HTTP-level payment handshakes), and ATXP (per-tool billing) seek to formalize how intent and payment interact. Their role is to transport: they move proofs of identity and consent between layers.

A likely workflow: an agent presents an AP2 mandate (“buy < $300 if in stock”); a server responds with an x402 challenge (“402 Payment Required”); the processor executes using a tokenized card or virtual credential; the Mandate ID travels in the message. These frameworks are early, and their interoperability with card systems remains a work in progress—but they already outline how trust can be expressed upstream.

Security: Relocating Defenses to the Intent Layer

As execution moves earlier, so does exposure. The threats—prompt-injection, tool poisoning, agent hijack, and credential theft—mirror those in other AI-mediated systems but operate at financial speed. Countermeasures align naturally with the primitives described:

• Signed, time-boxed mandates (as in AP2) that invalidate altered instructions.
• Agent-to-device binding and anomaly checks to throttle or step-up on risk.
• Tool allowlists to restrict which APIs an agent may invoke.
• Contextual step-ups using 3DS when variance breaches policy.
• Immediate revocation of tokens or virtual cards, with explicit decline codes.
• Immutable receipts—Mandate IDs and hashes in the message—to accelerate dispute resolution.

The guiding shift: security must act at the decision, not just the transaction. 

Economics in Transition

Agentic optimization—choosing the cheapest compliant path—alters long-standing economics. Issuers and networks could experience margin compression as agents route around premium rails; merchants may lose pricing discretion as agents compare and negotiate automatically. Banks’ relevance will hinge less on brand at checkout and more on trust infrastructure: sub-second intent validation, expressive policy, and defensible evidence trails.

A near-term rise in first-party disputes and fraud attempts is expected as these models mature. Embedding proof of mandate directly in messages shortens dispute cycles and clarifies liability, even if it doesn’t cut volume immediately.

The Standard to Build For

• Time-to-trust (p95) intent → decision < 100 ms.
• Policy expressiveness: MCC/merchant/SKU scopes, spend/velocity caps, temporal and contextual triggers, instant revocation.
• Auth quality: balanced use of frictionless, decoupled, and 3RI flows to minimize false declines.
• Auditability: Mandate ID + policy snapshot stored in authorization and clearing messages.
• Operational resilience: real-time governance, prompt-injection defense, token/VC kill-switch < 1 s.

Evolving Cards for Intent-Driven Payments

The next phase of payments won’t be defined by new rails but by where trust begins. When the decision to pay moves to intent, the systems that prevail will be those that can prove identity, enforce consent as code, and carry evidence end-to-end. Card rails already supply the scaffolding—tokenization, virtual credentials, strong authentication, and message-level data. The work now is to wire these primitives to agentic behavior, so the trust that underpins card payments continues to hold even when no human presses “Pay.”

References:

1. Google Cloud | Powering AI commerce with the new Agent Payments Protocol (AP2) | 2025
2. Visa | Visa Issues 10 Billionth Token, Generating $40 Billion in Incremental E-commerce Globally | 2024