> ## Documentation Index
> Fetch the complete documentation index at: https://www.narev.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Getting started

> First steps with OpenAI middleware for tracking AI costs.

## Installation

```bash npm theme={null}
npm install @ai-billing/openai @ai-billing/core @ai-sdk/openai ai
```

```bash pnpm theme={null}
pnpm add @ai-billing/openai @ai-billing/core @ai-sdk/openai ai
```

```bash yarn theme={null}
yarn add @ai-billing/openai @ai-billing/core @ai-sdk/openai ai
```

## Overview

The `@ai-billing/openai` package provides middleware for tracking token usage and calculating costs when using OpenAI models with the Vercel AI SDK.

It captures OpenAI-specific metrics, such as `inputCacheReadTokens` (for Prompt Caching) and `webSearch` (for search-enabled models), ensuring that all costs are accurately reflected.

## Usage

To use the middleware, wrap your OpenAI model using `wrapLanguageModel` from the `ai` package and pass the `createOpenAIMiddleware`.

**1. Initialize the OpenAI provider**

First, set up the OpenAI provider using your API key.

```typescript theme={null}
import { createOpenAI } from '@ai-sdk/openai';

const openai = createOpenAI({
  apiKey: process.env.OPENAI_API_KEY,
});
```

**2. Define model pricing**

Set up a price resolver to define the costs for the models you'll be using. For OpenAI, you can specify costs for standard prompt/completion tokens, cached tokens (`inputCacheReadTokens`), and even `webSearch` usage.

```typescript theme={null}
import { createObjectPriceResolver } from '@ai-billing/core';

const priceResolver = createObjectPriceResolver({
  'gpt-5': {
    promptTokens: 1.25 / 1_000_000,
    completionTokens: 10.0 / 1_000_000,
    inputCacheReadTokens: 0.125 / 1_000_000,
  }
});
```

**Using a Remote Pricing Provider (Narev):**

Instead of hardcoding prices, you can use a remote pricing provider like Narev to automatically fetch up-to-date pricing.

```typescript theme={null}
import { createNarevPriceResolver } from '@ai-billing/core';

const narevPriceResolver = createNarevPriceResolver({
  apiKey: process.env.NAREV_API_KEY ?? '',
});
```

**3. Create the billing middleware**

Initialize the OpenAI billing middleware. You need to provide a destination (such as `consoleDestination`) where billing events will be sent, along with your `priceResolver`.

```typescript theme={null}
import { createOpenAIMiddleware } from '@ai-billing/openai';
import { consoleDestination } from '@ai-billing/core';

const billingMiddleware = createOpenAIMiddleware({
  destinations: [consoleDestination()],
  priceResolver: priceResolver, // or narevPriceResolver
});
```

**4. Wrap the model**

Use `wrapLanguageModel` from the `ai` package to apply the billing middleware to your OpenAI model.

```typescript theme={null}
import { wrapLanguageModel } from 'ai';

const wrappedModel = wrapLanguageModel({
  model: openai('gpt-5'),
  middleware: billingMiddleware,
});
```

**5. Use the wrapped model**

Finally, use the wrapped model with AI SDK functions like `generateText` or `streamText`. The billing middleware will automatically track tokens and calculate costs.

```typescript theme={null}
import { generateText } from 'ai';

const result = await generateText({
  model: wrappedModel,
  prompt: 'What is the capital of Sweden?',
});
```

## Advanced Usage

### Web Search Models

When using models with web search capabilities like `gpt-4o-search-preview`, you can track the search costs by adding `webSearch` to your custom pricing map.

```typescript theme={null}
import { createObjectPriceResolver, consoleDestination } from '@ai-billing/core';
import { createOpenAIMiddleware } from '@ai-billing/openai';
import { wrapLanguageModel, generateText } from 'ai';
import { createOpenAI } from '@ai-sdk/openai';

const openai = createOpenAI({ apiKey: process.env.OPENAI_API_KEY });

const customPricingMap = {
  'gpt-4o-search-preview': {
    promptTokens: 2.5 / 1_000_000,
    completionTokens: 10.0 / 1_000_000,
    webSearch: 0.03, // cost per search
  },
};

const billingMiddleware = createOpenAIMiddleware({
  destinations: [consoleDestination()],
  priceResolver: createObjectPriceResolver(customPricingMap),
});

const wrappedModel = wrapLanguageModel({
  // Use .chat() for search-enabled models
  model: openai.chat('gpt-4o-search-preview'),
  middleware: billingMiddleware,
});

const result = await generateText({
  model: wrappedModel,
  prompt: 'What are the latest AI news from this week?',
});
```


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