agent-pay

Open-source USDC autopay client for agents (402 exact scheme) on Base.

Highlights

• Non-custodial: keys never leave your machine.
• Wizard-first init with non-interactive flags for agents.
• Strict exact 402 scheme, fail-closed parsing.
• Minimal dependencies: ethers, commander, native fetch.

Install

npm install -g @humanmenu/agent-pay

The binary is still agent-pay.

Canonical Base USDC

Default USDC address (Base mainnet):

0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

Quickstart

agent-pay init
agent-pay doctor
agent-pay send --to 0xRecipient --amount 0.10
agent-pay pay-url "https://example.com/api/paid"

How It Works

agent-pay supports two payment modes:

1. Direct USDC transfer with agent-pay send.
2. 402 autopay with agent-pay pay-url. Flow: request URL → if 402 parse invoice → transfer USDC → wait confirmations → retry with X-Payment and X-Invoice-Id.

The 402 flow is strict by design: if an invoice field is missing or mismatched, the client fails closed.

Config

Config path:

~/.agent-pay/config.json

Environment overrides:

• AGENT_PAY_RPC_URL
• AGENT_PAY_PRIVATE_KEY
• AGENT_PAY_CHAIN_ID
• AGENT_PAY_USDC_ADDRESS
• AGENT_PAY_ASSETS_JSON
• AGENT_PAY_MAX_PER_TX_USDC
• AGENT_PAY_MAX_PER_DAY_USDC
• AGENT_PAY_ALLOWLIST_DOMAINS

Defaults:

• AGENT_PAY_CHAIN_ID defaults to 8453 (Base mainnet)
• AGENT_PAY_USDC_ADDRESS defaults to Base USDC

Assets allowlist (optional):

export AGENT_PAY_ASSETS_JSON='{
  "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913": { "symbol": "USDC", "decimals": 6 }
}'

Only assets in this allowlist can be paid via invoices or sent with send-token.

CLI Commands

agent-pay init

Interactive wizard (or --non-interactive). Writes config and runs doctor.

agent-pay doctor

Validates RPC, chain ID, address, ETH + USDC balances.

agent-pay address

Prints the configured wallet address.

agent-pay balance

Prints ETH and USDC balances.

agent-pay send

agent-pay send --to 0xRecipient --amount 0.10

Notes:

• Sends USDC on Base (ERC‑20).
• Enforces optional limits (MAX_PER_TX_USDC, MAX_PER_DAY_USDC) if configured.

agent-pay send-eth

agent-pay send-eth --to 0xRecipient --amount 0.001

Options:

• --show-balance (print ETH balance before sending)
• --confirmations <n> (wait for n confirmations)

Notes:

• Sends native ETH on the configured chain (Base by default).
• Use --confirmations 1 if you want the command to block until confirmed.

agent-pay send-token

agent-pay send-token --asset 0xToken --to 0xRecipient --amount 1.5

Options:

• --confirmations <n> (wait for n confirmations)

Notes:

• Only allowlisted assets can be sent.
• Use AGENT_PAY_ASSETS_JSON to add assets.

agent-pay pay-url

agent-pay pay-url "https://example.com/paid" \
  --method POST \
  --header "Authorization: Bearer ..." \
  --data '{"task_id": 3}' \
  --content-type application/json \
  --timeout 120

Options:

• --method <M>
• --header "K: V" (repeatable)
• --data <raw>
• --content-type <mime>
• --timeout <seconds>
• --allowlist <domains>
• --yes (skip confirmation)
• --json (machine output)

Note: In non-interactive environments, spending actions require --yes.

Common Gotchas

• Invoice expiry: expiresAt must be in the future. If it’s “right now,” clients may reject it.
• Allowlist: if ALLOWLIST_DOMAINS is set, the target domain must match.
• Assets: invoices for non‑allowlisted assets will be rejected.
• Custodial wallets: exchange deposit addresses can delay/deny small deposits. For payouts, use a self‑custody Base wallet when possible.

JSON Output

All JSON output includes:

• schemaVersion: 1
• ok: boolean
• command: string

Errors include:

{
  "schemaVersion": 1,
  "ok": false,
  "command": "send",
  "error": {
    "code": "...",
    "message": "...",
    "details": {}
  }
}

Security

agent-pay is non-custodial and intentionally minimal. You are responsible for key safety, RPC trust, and operational security.

See SECURITY.md for disclaimers.

Spec

Full v1 spec lives in SPEC.md.