@vetro-protocol/bridge

LayerZero V2 OFT/OFTAdapter bridge actions for viem clients. Generic — works with any pair of tokens that have OFT contracts deployed on the supported chains.

Installation

pnpm add @vetro-protocol/bridge viem viem-erc20

Overview

• Works with both pure OFT contracts and OFTAdapter contracts.
• Approval is auto-detected via on-chain approvalRequired(). When required, the underlying ERC20 is read from token() and the standard allowance/approve flow runs before the send.
• Caller owns chain/contract addressing; the package only knows the chainId → LayerZero EID mapping (see the table below).
• Slippage defaults to zero (minAmountLD === amount); pass minAmount to opt in to a tolerance.

Supported chains (chainId → LayerZero EID):

| Chain | chainId | EID | | ---------------- | ------- | ----- | | Ethereum mainnet | 1 | 30101 | | Optimism | 10 | 30111 | | BSC | 56 | 30102 | | Base | 8453 | 30184 | | Arbitrum | 42161 | 30110 | | Hemi | 43111 | 30329 |

Usage

import { quoteSend, send } from "@vetro-protocol/bridge/actions";
import { createPublicClient, createWalletClient, custom, http } from "viem";
import { hemi, mainnet } from "viem/chains";

const publicClient = createPublicClient({
  chain: mainnet,
  transport: http(),
});

const walletClient = createWalletClient({
  chain: mainnet,
  transport: custom(window.ethereum),
});

// 1. Quote the LayerZero messaging fee
const fee = await quoteSend(publicClient, {
  amount: 1_000_000_000_000_000_000n,
  destinationChainId: hemi.id,
  oftAddress: "0x5fFD0EAdc186AF9512542d0d5e5eAFC65d5aFc5B",
  recipient: "0x...",
});

// 2. Send (approval handled automatically when the OFT requires it)
const { emitter, promise } = send(walletClient, {
  amount: 1_000_000_000_000_000_000n,
  destinationChainId: hemi.id,
  oftAddress: "0x5fFD0EAdc186AF9512542d0d5e5eAFC65d5aFc5B",
  recipient: "0x...",
});

emitter.on("user-signed-send", (hash) => console.log("tx hash:", hash));
emitter.on("send-transaction-succeeded", (receipt) =>
  console.log("delivered:", receipt),
);

await promise;

The same actions are also available via .extend() factories (bridgePublicActions(), bridgeWalletActions()) for callers who prefer viem's extension pattern.

Events

The send wallet action emits the following events through the EventEmitter:

| Event | Payload | When | | ------------------------------- | ---------------------- | --------------------------------------------------------------------------------------------------------------------- | | pre-approve | [] | Before the ERC20 approval transaction (only when approvalRequired() === true and current allowance is insufficient) | | user-signed-approval | [Hash] | The user signed the approval transaction | | user-signing-approval-error | [Error] | The user rejected or otherwise failed to sign the approval | | approve-transaction-succeeded | [TransactionReceipt] | Approval transaction confirmed successfully | | approve-transaction-reverted | [TransactionReceipt] | Approval transaction reverted on-chain | | pre-send | [] | Before the OFT send transaction | | user-signed-send | [Hash] | The user signed the send transaction | | user-signing-send-error | [Error] | The user rejected or otherwise failed to sign the send | | send-transaction-succeeded | [TransactionReceipt] | Send transaction confirmed successfully | | send-transaction-reverted | [TransactionReceipt] | Send transaction reverted on-chain | | send-failed | [Error] | A transaction-receipt fetch failed | | send-failed-validation | [string] | Input validation failed; payload is a human-readable reason | | unexpected-error | [Error] | An unhandled error escaped the action | | send-settled | [] | Always emitted in the finally block |

API

• quoteSend(client, params) — public action; reads the LayerZero messaging fee for a send.
• approvalRequired(client, params) — public action; reads approvalRequired() on the OFT/OFTAdapter.
• token(client, params) — public action; reads the underlying ERC20 wrapped by an OFTAdapter.
• send(walletClient, params) — wallet action; runs the full bridge flow (auto-approval + send) and returns { emitter, promise }.
• encodeSend(params) — synchronous helper that returns the encoded send calldata. The caller must pre-quote the LayerZero fee (e.g. with quoteSend) and pass it in.
• bridgePublicActions() / bridgeWalletActions() — viem extension factories that wire the same actions onto a client via .extend().
• oftAbi — the minimal ABI subset used by the package (send, quoteSend, approvalRequired, token).
• Types: SendEvents.