Error Handling & Retry

APIError Class

All HTTP errors from the SDK are thrown as APIError instances. Inspect the status, message, and data properties to determine what went wrong.

import { APIError } from '@limitless-exchange/sdk';

try {
  await orderClient.createOrder({ /* ... */ });
} catch (error) {
  if (error instanceof APIError) {
    console.error('Status:', error.status);   // HTTP status code
    console.error('Message:', error.message);  // Human-readable error
    console.error('Data:', error.data);        // Raw response body (if any)
  }
}

APIError Properties

Property	Type	Description
`status`	`number`	HTTP status code (400, 401, 429, 500, etc.)
`message`	`string`	Error description from the server
`data`	`unknown`	Raw response body, useful for debugging

Common Status Codes

Code	Meaning	Action
`400`	Bad request (invalid parameters)	Fix request parameters
`401`	Unauthorized (invalid or missing credentials)	Check your scoped API token (`LMTS_TOKEN_ID` / `LMTS_TOKEN_SECRET`)
`403`	Forbidden (insufficient permissions)	Verify account permissions
`404`	Not found (invalid slug or resource)	Check market slug or resource ID
`425`	Too Early — receive-window or maintenance block	If `error.data.code` is a trading-mode code, refresh maintenance status and do not retry the same blocked action. Otherwise, treat `POST /orders` failures as receive-window failures and re-stamp `timestamp`.
`429`	Rate limited	Back off and retry with delay
`500`	Internal server error	Retry with exponential backoff
`502`	Bad gateway	Retry with exponential backoff
`503`	Service unavailable	Retry with exponential backoff
`504`	Gateway timeout	Retry with exponential backoff

withRetry Wrapper

The SDK provides a withRetry utility function that wraps any async operation with configurable retry logic.

import { withRetry, APIError } from '@limitless-exchange/sdk';

const result = await withRetry(
  () => orderClient.createOrder({
    marketSlug: 'btc-100k-weekly',
    tokenId: market.tokens.yes,
    side: 'BUY',
    price: 0.65,
    size: 100,
    orderType: 'GTC',
  }),
  {
    statusCodes: [429, 500, 502, 503, 504],
    maxRetries: 3,
    delays: [1, 2, 4], // Seconds between retries
    onRetry: (attempt, error, delay) => {
      console.warn(`Retry ${attempt} in ${delay}s: ${error.message}`);
    },
  }
);

withRetry Options

Option	Type	Default	Description
`statusCodes`	`number[]`	`[429, 500, 502, 503, 504]`	HTTP status codes that trigger a retry
`maxRetries`	`number`	`3`	Maximum number of retry attempts
`delays`	`number[]`	—	Explicit delays in seconds for each attempt. If omitted, exponential backoff is used. If fewer delays than retries, the last is reused.
`exponentialBase`	`number`	`2`	Base for exponential backoff when `delays` is omitted (`base^attempt` seconds)
`maxDelay`	`number`	`60`	Maximum backoff delay in seconds
`onRetry`	`(attempt: number, error: Error, delay: number) => void`	—	Callback invoked before each retry

Only APIError instances with a matching status code trigger retries. Other errors (network failures, timeouts) are thrown immediately.

@retryOnErrors Decorator

For class-based architectures, use the @retryOnErrors decorator to add retry logic to individual methods.

import { retryOnErrors } from '@limitless-exchange/sdk';

class TradingBot {
  private orderClient: OrderClient;

  constructor(orderClient: OrderClient) {
    this.orderClient = orderClient;
  }

  @retryOnErrors({
    statusCodes: [429, 500, 502, 503, 504],
    maxRetries: 5,
    exponentialBase: 2,
    maxDelay: 60,
  })
  async placeOrder(params: CreateOrderParams) {
    return this.orderClient.createOrder(params);
  }
}

Decorator Options

@retryOnErrors takes the same RetryConfigOptions as withRetry.

Option	Type	Default	Description
`statusCodes`	`number[]`	`[429, 500, 502, 503, 504]`	HTTP status codes that trigger a retry
`maxRetries`	`number`	`3`	Maximum number of retry attempts
`delays`	`number[]`	—	Explicit per-attempt delays in seconds (overrides exponential backoff)
`exponentialBase`	`number`	`2`	Base for exponential backoff when `delays` is omitted (`base^attempt` seconds)
`maxDelay`	`number`	`60`	Maximum backoff delay in seconds
`onRetry`	`(attempt: number, error: Error, delay: number) => void`	—	Callback invoked before each retry

When delays is omitted, the delay for each retry is calculated (in seconds) as:

delay = min(exponentialBase ^ attempt, maxDelay)

For example, with exponentialBase: 2 and maxDelay: 60:

Attempt	Delay
0	1 s
1	2 s
2	4 s
3	8 s
4	16 s
5	32 s
6	60 s (capped)

Rate Limiting with OrderQueue

For high-frequency trading scenarios, implement an OrderQueue to throttle outgoing requests and avoid 429 errors:

import { APIError } from '@limitless-exchange/sdk';

class OrderQueue {
  private queue: Array<() => Promise<void>> = [];
  private processing = false;
  private minDelayMs: number;

  constructor(minDelayMs = 200) {
    this.minDelayMs = minDelayMs;
  }

  async enqueue<T>(fn: () => Promise<T>): Promise<T> {
    return new Promise((resolve, reject) => {
      this.queue.push(async () => {
        try {
          resolve(await fn());
        } catch (error) {
          reject(error);
        }
      });
      this.processQueue();
    });
  }

  private async processQueue() {
    if (this.processing) return;
    this.processing = true;

    while (this.queue.length > 0) {
      const task = this.queue.shift()!;
      await task();
      await new Promise((r) => setTimeout(r, this.minDelayMs));
    }

    this.processing = false;
  }
}

// Usage
const orderQueue = new OrderQueue(250); // 250ms between requests

const result = await orderQueue.enqueue(() =>
  orderClient.createOrder({
    marketSlug: 'btc-100k-weekly',
    tokenId: market.tokens.yes,
    side: 'BUY',
    price: 0.65,
    size: 100,
    orderType: 'GTC',
  })
);

Best Practices

Always handle APIError specifically

Catch APIError separately from other errors. Network failures, JSON parse errors, and timeouts are not APIError instances and should be handled differently.

try {
  await orderClient.createOrder({ /* ... */ });
} catch (error) {
  if (error instanceof APIError) {
    // Server responded with an error status
    handleApiError(error);
  } else if (error instanceof TypeError) {
    // Network error (DNS, connection refused, etc.)
    console.error('Network error:', error.message);
  } else {
    // Unexpected error
    throw error;
  }
}

Do not retry 400 or 401 errors

Client errors (400, 401, 403) indicate a problem with your request or credentials. Retrying them wastes time and API quota. Only retry transient server errors (429, 5xx).

Use exponential backoff for 429 responses

When rate limited, the server may include a Retry-After header. If available, respect it. Otherwise, use exponential backoff starting at 1 second.

Combine retry with OrderQueue

For the most robust setup, use OrderQueue to throttle request rate and withRetry or @retryOnErrors to handle transient failures:

const result = await orderQueue.enqueue(() =>
  withRetry(
    () => orderClient.createOrder({ /* ... */ }),
    { statusCodes: [429, 500, 502, 503, 504], maxRetries: 3 }
  )
);

Logging

The SDK provides optional logging through a simple ILogger interface. Logging is completely opt-in with zero overhead by default.

Quick Start

import { HttpClient, ConsoleLogger } from '@limitless-exchange/sdk';

const logger = new ConsoleLogger('info');

const httpClient = new HttpClient({
  baseURL: 'https://api.limitless.exchange',
  hmacCredentials: {
    tokenId: process.env.LMTS_TOKEN_ID,
    secret: process.env.LMTS_TOKEN_SECRET,
  },
  logger,
});

Log Levels

Level	What’s Logged
`debug`	Request headers (API key redacted), request/response bodies, WebSocket events
`info`	API requests (method + URL), successful responses, order creation/cancellation
`warn`	Warnings only
`error`	API errors (with status code), network errors, WebSocket connection errors

Custom Logger for Production

Implement the ILogger interface to integrate with your own logging infrastructure:

import { ILogger } from '@limitless-exchange/sdk';

class MyLogger implements ILogger {
  debug(message: string, meta?: Record<string, any>): void { /* ... */ }
  info(message: string, meta?: Record<string, any>): void { /* ... */ }
  warn(message: string, meta?: Record<string, any>): void { /* ... */ }
  error(message: string, error?: Error, meta?: Record<string, any>): void { /* ... */ }
}

const httpClient = new HttpClient({
  baseURL: 'https://api.limitless.exchange',
  hmacCredentials: {
    tokenId: process.env.LMTS_TOKEN_ID,
    secret: process.env.LMTS_TOKEN_SECRET,
  },
  logger: new MyLogger(),
});

Passing Logger to SDK Components

All SDK components accept an optional logger:

const logger = new ConsoleLogger('info');

const httpClient = new HttpClient({ baseURL: '...', logger });
const marketFetcher = new MarketFetcher(httpClient, logger);
const orderClient = new OrderClient({ httpClient, wallet, logger });

The SDK automatically redacts API keys in logs (shown as ***). Private keys are never logged.

Getting Started

Quick Start

TypeScript SDK

Python SDK

Go SDK

Rust SDK

WebSocket

APIError Class

APIError Properties

Common Status Codes

withRetry Wrapper

withRetry Options

@retryOnErrors Decorator

Decorator Options

Rate Limiting with OrderQueue

Best Practices

Logging

Quick Start

Log Levels

Custom Logger for Production

Passing Logger to SDK Components

​APIError Class

​APIError Properties

​Common Status Codes

​withRetry Wrapper

​withRetry Options

​@retryOnErrors Decorator

​Decorator Options

​Rate Limiting with OrderQueue

​Best Practices

​Logging

​Quick Start

​Log Levels

​Custom Logger for Production

​Passing Logger to SDK Components

APIError Class

APIError Properties

Common Status Codes

withRetry Wrapper

withRetry Options

@retryOnErrors Decorator

Decorator Options

Rate Limiting with OrderQueue

Best Practices

Logging

Quick Start

Log Levels

Custom Logger for Production

Passing Logger to SDK Components