> ## 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 Perplexity middleware for tracking AI costs.

## Installation

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

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

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

## Overview

The `@ai-billing/perplexity` package provides middleware for tracking token usage and calculating costs
when using Perplexity models (the `sonar` family) with the Vercel AI SDK.

All Perplexity `sonar` models are web-search-grounded and bill a flat per-request search fee
(`request_cost`) on top of token costs. In reality, that fee also varies by `search_context_size`
(low/medium/high) — this middleware models it as a single flat `request` rate per resolved model, the same
simplification used for other "flat request fee" providers. If you need to bill different
`search_context_size` tiers differently, resolve a distinct `modelId` per tier in your `priceResolver`.

Perplexity has no prompt-caching feature today, so cache-read/cache-write tokens are always reported as
`0`. Reasoning models (`sonar-reasoning`, `sonar-reasoning-pro`, `sonar-deep-research`) report
`reasoning_tokens` separately, which you can price with `internalReasoningTokens`.

## Usage

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

**1. Initialize the Perplexity provider**

First, set up the provider using `@ai-sdk/perplexity` and your API key.

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

const perplexity = createPerplexity({
  apiKey: process.env.PERPLEXITY_API_KEY,
});
```

**2. Define model pricing**

Set up a price resolver to define the costs for the models you'll be using. For Perplexity, you can
specify a flat per-request search fee (`request`) in addition to prompt/completion token rates, and
optionally `internalReasoningTokens` for reasoning models.

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

const priceResolver = createObjectPriceResolver({
  'sonar-pro': {
    promptTokens: 3.0 / 1_000_000, // $3.00 per 1M input tokens
    completionTokens: 15.0 / 1_000_000, // $15.00 per 1M output tokens
    request: 6.0 / 1_000, // flat per-request search fee (low search_context_size rate)
  },
});
```

**3. Create the billing middleware**

Initialize the Perplexity 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 { createPerplexityMiddleware } from '@ai-billing/perplexity';
import { consoleDestination } from '@ai-billing/core';

const billingMiddleware = createPerplexityMiddleware({
  destinations: [consoleDestination()],
  priceResolver: priceResolver,
});
```

**4. Wrap the model**

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

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

const wrappedModel = wrapLanguageModel({
  model: perplexity('sonar-pro'),
  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, count returned sources/citations as `webSearchCount`, and
calculate costs.

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

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


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