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Agent-to-Agent Payment Gateway (AP2 + x402)

Author: PlanExe Team
Date: 2026-02-11
Status: Proposal
Audience: Financial Architects, OpenClaw Developers

Pitch

Enable headless agents to pay for PlanExe services using standardized protocols for corporate spend and micropayments.

Why

Agents operate without browsers or CAPTCHAs. Payments must be machine-native, auditable, and reliable at scale.

Problem

  • Headless agents cannot use standard checkout flows.
  • Corporate payments require audit trails and limits.
  • Micropayments must be instant and low-friction.

Proposed Solution

Implement a dual-protocol payment gateway:

  1. AP2 (Agent Payments Protocol): corporate spend with signed mandates.
  2. x402 (HTTP 402): instant micropayments for per-request charging.

Architecture 1: The Corporate Route (AP2)

The Mandate

A human manager signs a digital spend mandate authorizing the bot.

  • Issuer: corp-finance@acme.com
  • Subject: did:molt:my-agent
  • Limit: $500/month
  • Scope: planexe.org/*

Transaction Flow

  1. Agent calls POST /api/purchase-credits with { amount: 100, mandate: <Signed_JWT> }.
  2. PlanExe verifies mandate signature.
  3. PlanExe charges corporate card on file.
  4. PlanExe issues credits to the agent.

Architecture 2: The Crypto Route (x402)

Header Exchange

  1. Agent calls POST /api/generate-plan.
  2. PlanExe returns 402 Payment Required with invoice header.
  3. Agent pays via wallet.
  4. Agent retries with Authorization: x402 <proof_of_payment>.
  5. PlanExe returns 200 OK.

Integration with OpenClaw

Release an OpenClaw:Wallet skill that handles both protocols.

{
  "wallet": {
    "ap2_mandate": "/path/to/mandate.jwt",
    "x402_private_key": "secure-me",
    "auto_top_up": true
  }
}

Success Metrics

  • Headless revenue share (% of revenue from agent payments).
  • Error rate on x402 (< 1%).
  • Time-to-top-up for AP2 mandates.

Risks

  • Mandate key compromise.
  • Payment replay attacks.
  • Wallet integration failures on edge devices.

Future Enhancements

  • Multi-currency pricing and FX handling.
  • Per-agent spending dashboards.
  • Payment routing by risk tier.

Detailed Implementation Plan

Phase A — Payment Abstraction Layer (2 weeks)

  1. Define unified payment request schema for AP2 and x402.
  2. Implement protocol adapter interface:
  3. authorize
  4. capture
  5. verify

  6. refund/reverse

  7. Add signed transaction envelope for audit trail integrity.

Phase B — AP2 Corporate Spend Path (2–3 weeks)

  1. Implement mandate verification service:
  2. signature validation
  3. scope checks
  4. spend limit checks

  5. expiry checks

  6. Add policy controls:

  7. per-agent monthly limits
  8. category restrictions

  9. emergency stop on anomaly

  10. Integrate corporate settlement provider.

Phase C — x402 Micropayment Path (2 weeks)

  1. Implement 402 challenge-response flow.
  2. Add payment proof verification and replay protection.
  3. Support low-latency settlement cache for repeated calls.

Phase D — Risk, Compliance, and Observability (2 weeks)

  1. Add fraud scoring on transaction patterns.
  2. Add AML/KYC policy hooks where required.
  3. Add full observability:
  4. success/failure rates
  5. latency by protocol
  6. dispute and reversal metrics

Data model additions

  • agent_wallets
  • payment_mandates
  • payment_transactions
  • payment_proofs
  • payment_alerts

Validation checklist

  • mandate scope enforcement tests
  • replay and double-spend protection tests
  • protocol fallback behavior under partial outages
  • settlement reconciliation tests against provider statements