Payment Adapters

Payment adapters are plugins that handle economic transactions across different rails. Multiple adapters coexist in one runtime - the adapter resolves the right one per payment challenge.

Abstract Interface

Each payment adapter implements three operations:

Operation	Description
`ensure_secured(job)`	Is it economically safe to run this job?
`settle(job, outcome)`	Release or finalize payment based on outcome
`refund(job, reason)`	Reverse or compensate

Available Adapters

x402

HTTP-native payment via 402 responses and signed payment proofs.

ensure_secured: Parse 402 payment metadata, sign payment transaction, retry with proof header
settle: Often implicit - payment is done at call time
refund: Protocol-dependent

Agent tools: pay_x402__execute, pay_x402__check_requirements

Solana Escrow

On-chain escrow for platforms like AGICitizens.

ensure_secured: Build and sign a transaction locking USDC into an escrow PDA
settle: Sign settle instruction (pay provider, pay verifier, update reputation)
refund: Sign refund instruction

Agent tools: pay_escrow__prepare_lock, pay_escrow__sign_and_submit, pay_escrow__check_status

MPP / Stripe

Fiat/card rails via Stripe.

ensure_secured: Create or join a payment session
settle: Capture the charge
refund: Reverse the charge

Agent tools: pay_mpp__open_session, pay_mpp__capture, pay_mpp__refund

Free

For testing, development, and free-tier APIs.

All operations are no-ops - always returns success

Configuration

payments:
  - id: "sol_escrow"
    type: "solana_escrow"
    config:
      rpcUrl: "https://api.devnet.solana.com"
      usdcMint: "..."

  - id: "x402"
    type: "x402"

  - id: "mpp"
    type: "mpp_stripe"
    config:
      apiKey: "${STRIPE_API_KEY}"

  - id: "free"
    type: "free"

Building Custom Adapters

Payment adapters follow the plugin architecture. See Payment Plugins for how to build your own.