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

# Anthropic API Engine

> @obversa/engine-anthropic-api runs engine requests directly through the Anthropic Messages API.

`@obversa/engine-anthropic-api` is an engine plugin that connects directly to the Anthropic Messages API. It provides token-level streaming and direct API communication without spawning a command-line subprocess.

## Requirements

* Node.js 22.12 or later
* An Anthropic API key (`ANTHROPIC_API_KEY` environment variable or `apiKey` option)

## Install

```bash theme={null}
pnpm add @obversa/engine-anthropic-api
```

## Identity

The plugin serves the Anthropic provider. It reports `provider: 'anthropic'`, defaulting to `claude-haiku-4-5-20251001` unless another model is requested.

## Usage

```ts theme={null}
import { AnthropicApiEngine } from '@obversa/engine-anthropic-api';

const engine = new AnthropicApiEngine({
  defaultModel: 'claude-haiku-4-5-20251001',
  apiKey: process.env.ANTHROPIC_API_KEY,
});
```

## Limits

* This engine makes direct network API calls and does not spawn local worker tools or execute bash commands directly.
* It ignores `AgentRequest.env` because no subprocess is spawned.
* Transient server errors (HTTP 5xx, timeouts) are retried automatically, while rate limits (HTTP 429) return typed limit errors with reset timings.