Querying Perplexity AI using sonar-pro for: What is BrowserBase Stagehand? Explain its purpose, features, and how it's used. Include information about its LLM integration capabilities.
Browserbase Stagehand is an open-source framework for AI-powered web automation[4][5]. Its purpose is to bridge the gap between AI language models (LLMs) and web browser control, making browser automation more natural and robust[4].

Key features of Stagehand include:

1. Natural language interface with three core commands: act, extract, and observe[1][3][5].
2. Integration with LLMs for enhanced functionality and fault tolerance[4].
3. Built on top of Playwright, offering full interoperability[5].
4. Designed to work with Browserbase's headless browser infrastructure[6].

Stagehand is used by developers to build web agents and automate browser tasks. It can be utilized for tasks like logging into websites, searching for products, extracting data, and placing orders[5].

LLM integration capabilities:
- Stagehand can be integrated with LLMs to generate and execute Playwright code based on natural language instructions[4][5].
- It provides a lightweight, model-agnostic framework for web automation[5].
- LLMs can be used for step planning and higher-level decision making, while Stagehand handles the execution of specific browser actions[5].

Example usage with LangChain.js:

```javascript
import { StagehandToolkit } from "langchain/community/agents/toolkits/stagehand";
import { Stagehand } from "@browserbasehq/stagehand";

const stagehand = new Stagehand({
  env: "LOCAL",
  headless: false,
  verbose: 2,
  debugDom: true,
  enableCaching: false,
});

const stagehandToolkit = await StagehandToolkit.fromStagehand(stagehand);

// Use toolkit tools for navigation, action, extraction, and observation
const navigateTool = stagehandToolkit.tools.find(t => t.name === "stagehand_navigate");
```

This code sets up Stagehand with LangChain.js, allowing developers to create AI agents that can interact with web browsers using natural language commands[7].