anthropics/anthropic-sdk-typescript — reverse-engineered prompt

Build me a TypeScript SDK that lets Node.js apps talk to Anthropic Claude through the official API. I want someone to be able to install it from npm, create a client with their Anthropic API key from an environment variable, send a message to Claude, and get the response back in a simple typed way.

Keep it focused on server side JavaScript and TypeScript, Node 18 and newer. Include a clear getting started example that shows a basic “Hello, Claude” request, plus enough docs so a developer understands how to set up the client and call the messages API. Add sensible tests, formatting, linting, and examples so the package feels production ready.

Please make it clean, reliable, and easy to publish as an npm package named @anthropic-ai/sdk. Look up the current Anthropic API docs online if you need to match the latest request and response shapes.