# Installation and Configuration

> TypeScript/JavaScript client for Zert's routing API — tokens, chains, pairs, quotes, swaps, execution, and limit orders.

The Routing Engine SDK calls **Zert's backend only**. The base URL is fixed in the package as **`DEFAULT_API_BASE_URL`** (see `routing-engine-sdk` exports); you cannot override it via config.

**All API requests require an API key.** Pass `api.apiKey` when creating the SDK; it is sent as the **`x-api-key`** header on every request (header name is also available as **`API_KEY_HEADER`**).

## How to integrate the SDK

**Step 1 — Install the SDK**

```bash
npm install routing-engine-sdk
```

Or with yarn, pnpm, or bun:

```bash
yarn add routing-engine-sdk
# or: pnpm add routing-engine-sdk
# or: bun add routing-engine-sdk
```

**Step 2 — Create and configure the SDK**

```typescript
import { RoutingEngineSDK, DEFAULT_API_BASE_URL, API_KEY_HEADER } from 'routing-engine-sdk';

const sdk = new RoutingEngineSDK({
  api: {
    apiKey: 'your-api-key',
  },
});
```

Optional: timeout and headers:

```typescript
const sdk = new RoutingEngineSDK({
  api: {
    apiKey: 'your-api-key',
    timeout: 15000,
    baseHeaders: {
      headers: { 'X-Custom': 'value' },
    },
  },
});
```

**Step 3 — Call the API**

Use layers (e.g. `sdk.tokens`, `sdk.quote`) or flat methods (`getTokens`, `requestQuote`, `createLimit`):

```typescript
const tokens = await sdk.getTokens();
const quote = await sdk.requestQuote({
  fromChain: 'arbitrum',
  toChain: 'avax',
  tokenIn: 'TBTC',
  tokenOut: 'WETH',
  network: 'mainnet',
  amount: '100.00',
  slippageBps: 75,
  recipient: '0x1234567890123456789012345678901234567890',
});
const build = await sdk.buildSwap({
  quoteId: quote.data.quoteId,
  routeId: quote.data.routes[0].routeId,
  recipient: '0x1234567890123456789012345678901234567890',
});
const signing = await sdk.getSwapSigning(build.data.swapId);
await sdk.submitSwapSigning(build.data.swapId, { rawTx: '0xsigned_raw_tx' });

const order = await sdk.createLimit({
  timeInForce: 'GTC',
  minAmountOut: '1',
  fromChain: 'arbitrum',
  toChain: 'avax',
  tokenIn: 'TBTC',
  tokenOut: 'WETH',
  network: 'mainnet',
  amount: '100.00',
  slippageBps: 75,
  recipient: '0x1234567890123456789012345678901234567890',
});
const status = await sdk.getTransactionStatus('0xhash', { chainRef: 'eth-mainnet' });
const health = await sdk.getHealth();
```

**Step 4 — Handle errors**

See Error Handling. API failures throw `RoutingEngineAPIError`. Invalid or unsupported config (e.g. wrong types, or passing `baseURL`) can throw `ConfigTypeError` in development.

### API surface

| Layer / access | Doc              |
| -------------- | ---------------- |
| `sdk.tokens`   | Token Management |
| `sdk.chains`   | Chains           |
| `sdk.pairs`    | Pairs            |
| `sdk.quote`    | Quote            |
| `sdk.swap`     | Swap             |
| `sdk.limit`    | Limit orders     |
| `sdk.status`   | Status           |
| `sdk.health`   | Health           |

`sdk.api` exposes the same layers for backward compatibility.

### Flat API

| Flat method                                                                    | Delegates to                                                |
| ------------------------------------------------------------------------------ | ----------------------------------------------------------- |
| `getTokens(params?)`, `getChains()`, `getPairs(params?)`                       | `tokens.get(params?)`, `chains.get()`, `pairs.get(params?)` |
| `requestQuote(body)`                                                           | `quote.request(body)`                                       |
| `buildSwap(body)`, `getSwapSigning(swapId)`, `submitSwapSigning(swapId, body)` | matching `swap.*` methods                                   |
| `createLimit`, `getLimit`, `cancelLimit`, `replaceLimit`, `listLimits`         | matching `limit.*` methods                                  |
| `getTransactionStatus(txHash, params)`, `getHealth()`                          | `status.getTransaction(...)`, `health.get()`                |

## Configuration reference (`api` option)

| Field         | Description                                                                                     |
| ------------- | ----------------------------------------------------------------------------------------------- |
| `apiKey`      | Required for authenticated Zert API calls; sent as `x-api-key`.                                 |
| `timeout`     | Request timeout in ms (default `10000`).                                                        |
| `baseHeaders` | Optional `{ known?, headers?, only? }` maps merged into default headers (after `Content-Type`). |
| `onError`     | Optional callback invoked before throwing `RoutingEngineAPIError`.                              |

Unsupported: **`baseURL`** — the SDK always uses `DEFAULT_API_BASE_URL`.


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