clade-install-auth

# Anthropic Install & Auth

## Overview
Set up the Anthropic SDK and configure your API key to start using Claude models.

## Prerequisites
- Node.js 18+ or Python 3.10+
- Anthropic account at [console.anthropic.com](https://console.anthropic.com)
- API key from Settings → API Keys (starts with `sk-ant-`)

## Instructions

### Step 1: Install SDK
```bash
# Node.js / TypeScript
npm install @claude-ai/sdk

# Python
pip install anthropic
```

### Step 2: Configure API Key
```bash
# Set environment variable (recommended)
export ANTHROPIC_API_KEY="sk-ant-api03-..."

# Or add to .env file
echo 'ANTHROPIC_API_KEY=sk-ant-api03-...' >> .env
```

> **Important:** Never hardcode API keys. Use environment variables or a secrets manager. Keys start with `sk-ant-`.

### Step 3: Verify Connection
```typescript
import Anthropic from '@claude-ai/sdk';

const client = new Anthropic(); // reads ANTHROPIC_API_KEY from env

const message = await client.messages.create({
  model: 'claude-sonnet-4-20250514',
  max_tokens: 64,
  messages: [{ role: 'user', content: 'Say "connected" in one word.' }],
});
console.log(message.content[0].text); // "Connected"
```

```python
import anthropic

client = anthropic.Anthropic()  # reads ANTHROPIC_API_KEY from env

message = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=64,
    messages=[{"role": "user", "content": "Say 'connected' in one word."}],
)
print(message.content[0].text)  # "Connected"
```

## Output
- `@claude-ai/sdk` in node_modules or `anthropic` in site-packages
- `ANTHROPIC_API_KEY` environment variable set
- Successful Claude response confirming API access

## Error Handling
| Error | Cause | Solution |
|-------|-------|----------|
| `authentication_error` (401) | API key missing, invalid, or revoked | Check key at console.anthropic.com → API Keys |
| `permission_error` (403) | Key lacks access to requested model | Verify workspace has model access enabled |
| `ModuleNotFoundError` | SDK not installed | `pip install anthropic` or `npm i @claude-ai/sdk` |
| `Could not resolve host` | Network/DNS issue | Check internet connectivity and proxy settings |

## Examples

### TypeScript Setup
```typescript
import Anthropic from '@claude-ai/sdk';

// Default: reads ANTHROPIC_API_KEY from environment
const client = new Anthropic();

// Explicit key (for testing only — don't hardcode in production)
const client = new Anthropic({ apiKey: 'sk-ant-api03-...' });

// Custom base URL (for proxies or Vertex AI)
const client = new Anthropic({
  baseURL: 'https://your-proxy.example.com',
});
```

### Python Setup
```python
import anthropic

# Default: reads ANTHROPIC_API_KEY from environment
client = anthropic.Anthropic()

# Explicit key
client = anthropic.Anthropic(api_key="sk-ant-api03-...")

# Async client
client = anthropic.AsyncAnthropic()
```

## Resources
- [Anthropic API Docs](https://docs.anthropic.com/en/api/getting-started)
- [Console Dashboard](https://console.anthropic.com)
- [API Key Management](https://console.anthropic.com/settings/keys)
- [Anthropic Status](https://status.anthropic.com)

## Next Steps
After successful auth, proceed to `clade-hello-world` for your first Claude conversation.