@steamlink/types

Shared branded types and the canonical NexusError taxonomy for the Nexus SDK.

What it is

Nexus is a fully onchain, turn-based game engine SDK for Base. @steamlink/types is its dependency-free base package: it holds the branded primitive types (addresses, hex, token amounts), the Base chain constants, and the one canonical NexusError / error-code taxonomy that every other @steamlink/* package imports. Defining errors and primitives once here keeps the whole SDK typed end to end.

Install

npm install @steamlink/types

pnpm add @steamlink/types
# or
yarn add @steamlink/types

What's inside

Branded primitive types (branded.ts) — nominal at compile time, plain strings/bigints at runtime:

• Types: Hex, Address, Bytes32, TokenAmount, TokenSymbol
• Validators / constructors: asHex, asAddress, isAddress, asBytes32, asTokenAmount

Chain constants (chain.ts) — Base only:

• CHAINS (config for base and base-sepolia, including canonical USDC addresses)
• ChainKey type, isChainKey guard, chainConfig lookup

Errors (errors.ts) — the canonical error surface:

• NexusError class with code, retryable, context, txHash, plus toJSON() and the static guards NexusError.is / NexusError.has
• NEXUS_ERROR_CODES (the full code list) and the NexusErrorCode union — e.g. NOT_YOUR_TURN, BUDGET_EXCEEDED, DELEGATION_EXPIRED, TARGET_MISMATCH, PAYMENT_REQUIRED, RNG_PENDING, INTERNAL
• NexusErrorOptions for constructor options
• codeFromRevert — maps an on-chain enforcer revert string to a NexusErrorCode

Usage

Construct and narrow a branded type:

import { asAddress, type Address } from "@steamlink/types";

const player: Address = asAddress("0x036CbD53842c5426634e7929541eC2318f3dCF7e");
// throws TypeError if the input isn't a 20-byte 0x address

Throw and handle a typed error:

import { NexusError } from "@steamlink/types";

try {
  throw new NexusError("NOT_YOUR_TURN", "It is not your turn to move.");
} catch (e) {
  if (NexusError.has(e, "NOT_YOUR_TURN")) {
    // narrowed to NexusError with code "NOT_YOUR_TURN"
    console.log(e.code, e.retryable);
  }
}

Part of Nexus

Peer packages: @steamlink/core, @steamlink/react, @steamlink/server, @steamlink/relayer, @steamlink/secrets, @steamlink/cli. Base only.