# Streaming

Source: https://staging-docs.aiand.com/capabilities/streaming/

All generative endpoints support streaming — set `stream: true` on the request and the response is delivered as Server-Sent Events (SSE).

## Enabling streaming

<Tabs>
<TabItem label="OpenAI SDK">

```python
stream = client.chat.completions.create(
    model="...",
    messages=[{"role": "user", "content": "Hello"}],
    stream=True,
    stream_options={"include_usage": True},
)
for chunk in stream:
    print(chunk.choices[0].delta.content or "", end="")
```

</TabItem>
<TabItem label="Anthropic SDK">

```python
with client.messages.stream(
    model="...",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello"}],
) as stream:
    for text in stream.text_stream:
        print(text, end="")
```

</TabItem>
<TabItem label="curl">

```bash
curl https://api.aiand.com/v1/chat/completions \
  -H "Authorization: Bearer sk-..." \
  -d '{"model":"...","stream":true,"messages":[{"role":"user","content":"Hello"}]}'
```

</TabItem>
</Tabs>

## What you receive

- **OpenAI shape**: `data: {...}` events with `choices[].delta` chunks; final `data: [DONE]`.
- **Anthropic shape**: typed events — `message_start`, `content_block_delta`, `message_delta`, `message_stop`.
- **ai& trailer** (OpenAI shape, opt-in): with the `X-Aiand-Metrics: true` request header, ai& appends a `metrics` event with token counts, cost, and currency after the model's terminal event. See [Streaming Events](/reference/streaming-events/).

## Usage and cost in streams

Set `stream_options.include_usage = true` (OpenAI shape) to get the final `usage` block before the trailer event. Anthropic streams always carry usage in `message_delta`.

<Aside type="caution">
  Don't close the connection on the first chunk — the `metrics` trailer event is emitted **after** the model's terminal event.
</Aside>