Hemi Viem

Viem extension for the Hemi network. It includes:

• Chain definitions!
• Bitcoin finality helper!
• Bitcoin Kit wrappers!

Installation

npm install viem hemi-viem

Example

// example.js

import { createPublicClient, http } from "viem";

import {
  hemiPublicBitcoinKitActions,
  hemiPublicOpNodeActions,
  hemiSepolia,
} from "hemi-viem";

const parameters = { chain: hemiSepolia, transport: http() };
const client = createPublicClient(parameters)
  .extend(hemiPublicOpNodeActions())
  .extend(hemiPublicBitcoinKitActions());

const blockNumber = await client.getBlockNumber();
const block = await client.getBlock({ blockNumber: blockNumber - 100n });

const btcFinality = await client.getBtcFinalityByBlockHash(block);
console.log(btcFinality);

const bitcoinKitAddress = "0x0000000000000000000000000000000000000000"; // example address
const btcHeader = await client.getLastHeader({ bitcoinKitAddress });
console.log(btcHeader);

Output:

$ node example.js
{
  l2_keystone: {
    version: 1,
    l1_block_number: 5868140,
    l2_block_number: 596350,
    parent_ep_hash: '3fe407f9eec38ce9fa0f6d159adca4ac8739013d380e1d7215b721c7e345ae88',
    prev_ep_keystone_hash: '6b65018eb33048494f2e21ffdd081ae376b125f12e62ab88e77b1461503540fb',
    state_root: 'b3b9f5b810038466290a7c4bff08a260a472d67fed230a27d89de1322490fb51',
    ep_hash: 'd186c2da80f2c79490f644e4af714ee1f5790a4e806028cac0e64a2010a41974'
  },
  btc_pub_height: 2814228,
  btc_pub_header_hash: '1a262fa78618f4b7fa8d5d37eed32f3a0bb67ab09d808e035500000000000000',
  btc_finality: 8
}
{
  height: 2814236,
  blockHash: '0x00000000f71ba71af42fb2a356affa1439bc2adea0bf67880fc30f28237622e7',
  version: 536870912,
  previousBlockHash: '0x000000000000002f3cc7a5f9ed589b734808fff6d67c0f8a9385f6146c80297b',
  merkleRoot: '0x1799d4002cd58d15a764cee0919edf358bf36ace4fa4c6e78250336eafe12184',
  timestamp: 1715273381,
  bits: 486604799,
  nonce: 4137790000
}

Development

This project uses pnpm as its package manager. The exact version is pinned in the packageManager field of package.json.

Enabling pnpm with corepack

Corepack ships with Node.js and manages the pnpm version for you, so it always matches the one pinned in this repo. Just enable it once:

corepack enable

From then on, running any pnpm command inside the project automatically uses the pinned version—no manual install needed.

Common commands

pnpm install         # install dependencies
pnpm run build       # build ESM, CJS and type declarations
pnpm test            # run unit tests
pnpm run test:e2e    # run end-to-end tests
pnpm run lint        # lint with ESLint
pnpm run format:check # check formatting with Prettier
pnpm run tsc         # type-check without emitting