@seer-pm/api-gateway

Shared TypeScript types and small helpers used by the Seer API gateway and clients:

• SigningContext and parseSigningContext for ERC-4337 / Safe signing metadata
• ENTRY_POINT_* / SAFE_ACCOUNT_VERSION constants
• SUPPORTED_CHAINS, getChainById, getSigningContext
• gatewayRequest — gatewayRequest(baseUrl) returns a fluent client (.split(), .merge(), .quote(), .relay(), …); use .request({ path, method, body }) for ad-hoc paths. fetch + JSON + optional relayHint.
• signUserOperation — Safe account + signUserOperation (permissionless)

Peer dependencies: viem ^2, permissionless ^0.3.

Install

npm install @seer-pm/api-gateway viem permissionless

yarn add @seer-pm/api-gateway viem permissionless

Usage

gatewayRequest(baseUrl)

Call gatewayRequest with your API base URL (no trailing slash required). It returns a client with typed helpers for each route. Non-OK HTTP status codes throw; responses that include userOperation must also include a valid signingContext or the client throws.

import { gatewayRequest } from "@seer-pm/api-gateway";

const api = gatewayRequest("https://your-gateway.example.com/api");

// Convenience methods (paths match the Netlify/API handler)
const health = await api.health();

const split = await api.split(chainId, marketAddress, {
  owner: "0x…",
  amount: "1000000000000000000",
  useMainCollateral: true
});

// When the gateway returns a UserOperation to sign, `relayHint` is set:
const hint = split.relayHint;
if (hint) {
  const { intentId, userOperation, signingContext } = hint;
  // … sign with signUserOperation, then submit:
  await api.relay(chainId, {
    intentId,
    userOperation: { /* …signed op with `signature` field set… */ }
  });
}

// Ad-hoc path when you already have path/method/body:
await api.request({
  path: `/markets/${chainId}/${marketAddress}/merge`,
  method: "POST",
  body: { /* … */ }
});

Other methods include merge, redeem, quote, executeTrade, createMarket, predictWallet, and userOperationReceipt.

signUserOperation

After a POST that returns userOperation + signingContext, use signUserOperation with a viem walletClient, the Safe owners (EOA account(s) or EIP-1193 provider(s), depending on your setup), and the same chainId as the request. The helper builds the Safe smart account from signingContext and returns the ERC-4337 signature.

import type { UserOperation } from "viem/account-abstraction";
import { createWalletClient, http } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { gnosis } from "viem/chains";
import { gatewayRequest, signUserOperation } from "@seer-pm/api-gateway";

const account = privateKeyToAccount(process.env.OWNER_PRIVATE_KEY as `0x${string}`);
const walletClient = createWalletClient({
  account,
  chain: gnosis,
  transport: http()
});

const build = await gatewayRequest(API_BASE_URL).split(CHAIN_ID, MARKET_ADDRESS, {
  owner: account.address,
  amount: "10000000",
  useMainCollateral: true
});

if (!build.relayHint) {
  throw new Error("Expected relayHint from gateway");
}

const { intentId, userOperation, signingContext } = build.relayHint;

const { signature, userOperation: signedOp } = await signUserOperation({
  walletClient,
  signingContext,
  userOperation: {
    ...(userOperation as Record<string, unknown>),
    signature: "0x"
  } as unknown as UserOperation,
  chainId: CHAIN_ID,
  owners: [account],
  saltNonce: 0n // optional; must match the salt your Safe uses if non-default
});

await gatewayRequest(API_BASE_URL).relay(CHAIN_ID, {
  intentId,
  userOperation: {
    ...signedOp,
    signature
  }
});

In browser apps with wagmi, owners is often [eip1193Provider] and you pass the wallet client from getWalletClient. Align chainId with signingContext.chainId and the chain the user selected.

Publishing (maintainers)

From the repo root after yarn install (which builds dist/ via postinstall):

cd packages/api-gateway
npm version patch   # or minor / major
npm publish --access public

Ensure the @seer scope exists on npm and you are logged in (npm login).