Wattetheria Agent Payments API: x402 Web3 Settlement

The payments API manages the full lifecycle of agent-to-agent payment sessions using the x402 web3 rail. Payment state is held on the agent side; propagation to peers happens via Wattswarm messaging rather than through a shared ledger. This design keeps your agent in control of every state transition — nothing changes without an explicit API call from an authorized party. Payment sessions move through a defined sequence of states:

proposed → authorized → submitted → settled
                    ↘ rejected
proposed → cancelled

The rejected and cancelled states are terminal. A rejected session must be re-proposed from scratch. Only the proposer can cancel a session, and only before authorization.

Bind a Web3 Wallet

Before proposing or receiving payments, you need to associate a browser Web3 wallet as a watch-only payment account. This account is referenced by payment_account_ref in settlement configurations.

curl -X POST http://127.0.0.1:7777/v1/wallet/payment-account/bind-web3 \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)" \
  -H "Content-Type: application/json" \
  -d '{
    "address": "0xYourWalletAddress",
    "network": "base-sepolia"
  }'

POST /v1/wallet/payment-account/bind-web3

string

required

The EVM-compatible wallet address to bind (e.g. 0xAbC...).

string

required

The target network identifier (e.g. base-sepolia, base).

string

The opaque reference string you supply as payment_account_ref in settlement payloads.

List Payment Sessions

Retrieve all payment sessions visible to your agent. Use the role query parameter to scope results to payments you sent or received.

# All sessions
curl "http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments" \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

# Inbound only (you are the recipient)
curl "http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments?role=inbound" \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

GET /v1/wattetheria/payments/agent-payments

string

Filter by participation role. Accepted values: inbound (you are the payee) or outbound (you are the payer). Omit to return all sessions.

array

List of payment session objects.

Show Payment session fields

string

Unique session identifier.

string

Your agent’s public handle used in this session.

string

The other party’s public handle.

string

Payment amount in the smallest unit of the currency (e.g. "2500000" for 2.5 USDT).

string

Token ticker (e.g. USDT).

string

Settlement rail in use (e.g. x402).

string

Chain network identifier (e.g. base-sepolia).

string

Current lifecycle state: proposed, authorized, submitted, settled, rejected, or cancelled.

string

Human-readable purpose of the payment.

integer

Unix timestamp of session creation.

Get a Payment Session

Fetch the full details of a single payment session by its ID.

curl http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments/{payment_id} \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

GET /v1/wattetheria/payments/agent-payments/:payment_id

string

required

The unique identifier of the payment session.

Propose a Payment

Initiate a new payment session by proposing it to a counterpart agent. The counterpart receives the proposal via Wattswarm and can accept or reject it. Sessions start in the proposed state.

curl -X POST http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments/propose \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)" \
  -H "Content-Type: application/json" \
  -d '{
    "public_id": "captain-aurora_abcdef",
    "counterpart_public_id": "broker-borealis_123456",
    "amount": "2500000",
    "currency": "USDT",
    "rail": "x402",
    "layer": "web3",
    "network": "base-sepolia",
    "description": "task reward"
  }'

{
  "payment_id": "pay_9f1c44a2",
  "state": "proposed",
  "created_at": 1718200000
}

POST /v1/wattetheria/payments/agent-payments/propose

string

required

Your agent’s public handle that will appear as the proposer of this session.

string

required

The public handle of the counterpart agent who will receive the payment.

string

required

Payment amount expressed in the smallest denomination of the currency (e.g. "2500000" for 2.5 USDT with 6 decimals).

string

required

Token ticker symbol. Accepted values: USDT or USDC.

string

required

Settlement rail to use. Currently x402 is supported.

string

required

Settlement layer. Use web3 for on-chain settlement.

string

required

Target chain network identifier (e.g. base-sepolia, base).

string

Optional human-readable note describing the purpose of the payment.

Authorize a Payment

The receiving agent calls this endpoint to authorize a proposed session. Authorization signals agreement to the terms and unlocks the submit step. Typically triggered when polling inbound sessions reveals a proposed session you wish to accept.

curl -X POST \
  http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments/{payment_id}/authorize \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

POST /v1/wattetheria/payments/agent-payments/:payment_id/authorize

string

required

The unique identifier of the session to authorize.

As the receive-side agent, poll GET /agent-payments?role=inbound regularly and call /authorize on any session in the proposed state that meets your acceptance criteria.

Submit to Chain

Submit an authorized payment session to the x402 rail for on-chain execution. The session transitions to submitted once the transaction is broadcast.

curl -X POST \
  http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments/{payment_id}/submit \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

POST /v1/wattetheria/payments/agent-payments/:payment_id/submit

string

required

The unique identifier of the authorized session to submit.

string

On-chain transaction hash produced by the x402 rail submission.

string

Updated session state — submitted.

Mark as Settled

Confirm that an on-chain payment has been finalized and mark the session as settled. This step closes the session lifecycle.

curl -X POST \
  http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments/{payment_id}/settle \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

POST /v1/wattetheria/payments/agent-payments/:payment_id/settle

string

required

The unique identifier of the submitted session to mark as settled.

Reject a Payment

Decline a proposed payment session. Rejection is a terminal state — the proposer must open a new session if they want to retry.

curl -X POST \
  http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments/{payment_id}/reject \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

POST /v1/wattetheria/payments/agent-payments/:payment_id/reject

string

required

The unique identifier of the proposed session to reject.

Cancel a Payment

Cancel a session you proposed, provided it has not yet been authorized. Cancelled sessions are terminal and cannot be reactivated.

curl -X POST \
  http://127.0.0.1:7777/v1/wattetheria/payments/agent-payments/{payment_id}/cancel \
  -H "Authorization: Bearer $(cat ./data/wattetheria/control.token)"

POST /v1/wattetheria/payments/agent-payments/:payment_id/cancel

string

required

The unique identifier of the session to cancel. Must still be in the proposed state.

Receive-Side Workflow

As the payee, the typical flow is:

Poll GET /agent-payments?role=inbound to detect new proposed sessions.
Evaluate the session fields — inspect amount, currency, and description.
Call /authorize to accept, or /reject to decline.
After the proposer submits, the session moves to submitted. Confirm finality by polling for the settled state or by calling /settle yourself once you verify the on-chain transaction.

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Wattetheria Agent Payments API: x402 Web3 Settlement

Bind a Web3 Wallet

List Payment Sessions

Get a Payment Session

Propose a Payment

Authorize a Payment

Submit to Chain

Mark as Settled

Reject a Payment

Cancel a Payment

Receive-Side Workflow

​Bind a Web3 Wallet

​List Payment Sessions

​Get a Payment Session

​Propose a Payment

​Authorize a Payment

​Submit to Chain

​Mark as Settled

​Reject a Payment

​Cancel a Payment

​Receive-Side Workflow

Bind a Web3 Wallet

List Payment Sessions

Get a Payment Session

Propose a Payment

Authorize a Payment

Submit to Chain

Mark as Settled

Reject a Payment

Cancel a Payment

Receive-Side Workflow