Open Channel

Opens and funds a TIP-20 channel reserve channel.

Usage

import { client } from './viem.config'
 
const { receipt, ...opened } = await client.channel.openSync({
  deposit: 100000000n,
  operator: '0x3C44CdDdB6a900fa2b585dd299e03d12FA4293BC',
  payee: '0x70997970C51812dc3A010C7d01b50e0d17dc79C8',
  salt: '0x0000000000000000000000000000000000000000000000000000000000000101',
  token: '0x20c0000000000000000000000000000000000001',
})
 
console.log('Opened:', opened)
Opened: { channelId: '0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef', payer: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb', payee: '0x70997970C51812dc3A010C7d01b50e0d17dc79C8', operator: '0x3C44CdDdB6a900fa2b585dd299e03d12FA4293BC', token: '0x20c0000000000000000000000000000000000001', authorizedSigner: '0x0000000000000000000000000000000000000000', salt: '0x0000000000000000000000000000000000000000000000000000000000000101', expiringNonceHash: '0x0000000000000000000000000000000000000000000000000000000000000000', deposit: 100000000n }

import { Account, Client } from 'viem/tempo'
 
export const client = Client.create({
  account: Account.fromSecp256k1('0x...'),
})

Asynchronous Usage

The examples above use a *Sync variant of the action, that will wait for the transaction to be included before returning.

If you are optimizing for performance, you should use the non-sync channel.open action and wait for inclusion manually:

import { Actions } from 'viem/tempo'
import { client } from './viem.config'
 
const hash = await client.channel.open({
  deposit: 100000000n,
  payee: '0x70997970C51812dc3A010C7d01b50e0d17dc79C8',
  token: '0x20c0000000000000000000000000000000000001',
})
const receipt = await client.transaction.waitForReceipt({ hash }).receipt
 
const { args } = Actions.channel.open.extractEvent(receipt.logs)

Recipes

Open a Channel and Sign the First Voucher

Combine channel.openSync with channel.signVoucher to start paying for a metered service the moment the channel exists.

import { client } from './viem.config'
 
const { channelId } = await client.channel.openSync({
  deposit: 100_000000n,
  payee: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
  token: '0x20c0000000000000000000000000000000000000',
})
 
const signature = await client.channel.signVoucher({
  channel: channelId,
  cumulativeAmount: 1_000000n,
})

import { Account, Client } from 'viem/tempo'
 
export const client = Client.create({
  account: Account.fromSecp256k1('0x...'),
})

Delegate Voucher Signing to a Hot Key

Pass authorizedSigner when a dedicated service key signs vouchers through channel.signVoucher's account option, keeping the treasury key that funded the channel offline.

import { client } from './viem.config'
 
await client.channel.openSync({
  authorizedSigner: '0x8ba1f109551bD432803012645Ac136ddd64DBA72',
  deposit: 500_000000n,
  payee: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
  token: '0x20c0000000000000000000000000000000000000',
})

import { Account, Client } from 'viem/tempo'
 
export const client = Client.create({
  account: Account.fromSecp256k1('0x...'),
})

Run a Channel per Project with Deterministic Salts

Derive salt from an internal identifier to keep several channels open to the same payee and token, one per project, with reproducible channel identities.

import { Hex } from 'viem/utils'
import { client } from './viem.config'
 
const projectId = 'project-atlas'
 
const { channelId } = await client.channel.openSync({
  deposit: 100_000000n,
  payee: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
  salt: Hex.fromString(projectId, { size: 32 }),
  token: '0x20c0000000000000000000000000000000000000',
})

import { Account, Client } from 'viem/tempo'
 
export const client = Client.create({
  account: Account.fromSecp256k1('0x...'),
})

Return Value

type ReturnType = {
  /** Channel ID. */
  channelId: Hex
  /** Channel payer. */
  payer: Address
  /** Channel payee. */
  payee: Address
  /** Channel operator. */
  operator: Address
  /** Token address. */
  token: Address
  /** Authorized voucher signer. */
  authorizedSigner: Address
  /** Channel salt. */
  salt: Hex
  /** Expiring nonce hash. */
  expiringNonceHash: Hex
  /** Initial deposit. */
  deposit: bigint
  /** Transaction receipt. */
  receipt: TransactionReceipt
}

The transaction receipt and decoded event data.

Parameters

authorizedSigner

• Type: Address

Optional signer for vouchers. Zero means payer signs.

deposit

• Type: bigint

Amount of TIP-20 token to deposit.

operator

• Type: Address

Optional relayer allowed to submit settle for the payee.

payee

• Type: Address

Account that receives settled voucher payments.

salt

• Type: Hex

User-supplied salt to distinguish otherwise identical channels.

token

• Type: Address | bigint

TIP-20 token address or ID held by the channel.

account (optional)

• Type: Account | Address

Account that will be used to send the transaction.

feePayer (optional)

• Type: Account | boolean

Fee payer for the transaction (TIP-1 gas sponsorship).

Pass true to defer the fee token to an external fee payer (e.g. a relay), or a local Account to co-sign the transaction as the fee payer.

feeToken (optional)

• Type: Address | bigint

Fee token for the transaction.

Can be an unpaused USD-denominated TIP-20 token address or ID.

gas (optional)

• Type: bigint

Gas limit for the transaction.

keyAuthorization (optional)

• Type: KeyAuthorization

Signed key authorization to include with the transaction, authorizing an access key to act for the sending account.

maxFeePerGas (optional)

• Type: bigint

Max fee per gas for the transaction.

maxPriorityFeePerGas (optional)

• Type: bigint

Max priority fee per gas for the transaction.

nonce (optional)

• Type: number

Nonce for the transaction.

nonceKey (optional)

• Type: 'expiring' | 'random' | bigint

Nonce key for the transaction (TIP-1009 2D nonces).

Use 'expiring' to select an expiring nonce, which enables concurrent transaction submission without nonce ordering. Use 'random' to select a random key.

throwOnReceiptRevert (optional)

• Type: boolean
• Default: true

Whether a Sync action throws when the receipt reports a revert.

validAfter (optional)

• Type: number

Unix timestamp after which the transaction can be included.

validBefore (optional)

• Type: number

Unix timestamp before which the transaction must be included.