# Streaming

> Receive tokens as they are generated, as server-sent events.

Source: https://www.lyber.ai/docs/capabilities/streaming/ · Markdown: https://www.lyber.ai/docs/md/capabilities/streaming.md

Set `stream: true` on a chat completion. The response is a stream of server-sent events: each `data:` line carries a JSON chunk, and the stream ends with `data: [DONE]`. The OpenAI SDKs parse it for you.

Python (`main.py`):

```python
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://lyber-paid-acceptance-gateway-production.up.railway.app/v1",
    api_key=os.environ["LYBER_API_KEY"],
)

stream = client.chat.completions.create(
    model="minimax-m3.1-flash-abliterated",
    messages=[{"role": "user", "content": "Write a haiku about open weights."}],
    max_tokens=1024,
    stream=True,
    stream_options={"include_usage": True},
)
for chunk in stream:
    if chunk.choices and chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="", flush=True)
    if chunk.usage:
        print("\n", chunk.usage)
```

TypeScript (`main.ts`):

```ts
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://lyber-paid-acceptance-gateway-production.up.railway.app/v1",
  apiKey: process.env.LYBER_API_KEY,
});

const stream = await client.chat.completions.create({
  model: "minimax-m3.1-flash-abliterated",
  messages: [{ role: "user", content: "Write a haiku about open weights." }],
  max_tokens: 1024,
  stream: true,
  stream_options: { include_usage: true },
});
for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content ?? "");
  if (chunk.usage) console.log("\n", chunk.usage);
}
```

curl (`request.sh`):

```bash
curl -N https://lyber-paid-acceptance-gateway-production.up.railway.app/v1/chat/completions \
  -H "Authorization: Bearer $LYBER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "minimax-m3.1-flash-abliterated",
    "messages": [{"role": "user", "content": "Write a haiku about open weights."}],
    "max_tokens": 1024,
    "stream": true,
    "stream_options": {"include_usage": true}
  }'
```

## Usage in streams

Streams report token usage only when you ask: set `stream_options: {"include_usage": true}` and the last chunk before `[DONE]` carries `usage`, with an empty `choices` array. Without it, Lyber still bills the request; the usage just isn't sent to you.

```text
data: {"id":"chatcmpl-…","object":"chat.completion.chunk","model":"minimax-m3.1-flash-abliterated","choices":[{"index":0,"delta":{"content":"Open"}}]}

data: {"id":"chatcmpl-…","object":"chat.completion.chunk","model":"minimax-m3.1-flash-abliterated","choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}

data: {"id":"chatcmpl-…","object":"chat.completion.chunk","model":"minimax-m3.1-flash-abliterated","choices":[],"usage":{"prompt_tokens":18,"completion_tokens":41,"total_tokens":59}}

data: [DONE]
```

## Reasoning and tool calls

- Reasoning arrives in `delta.reasoning_content` before the answer's `delta.content`. See [Thinking](https://www.lyber.ai/docs/capabilities/thinking/).
- Tool calls arrive in pieces: append each `delta.tool_calls[i].function.arguments` fragment by `index` until a chunk reports `finish_reason: "tool_calls"`.
- Lines starting with `:` are keep-alive comments. SDKs ignore them; a hand-written parser should too.

## Errors during a stream

Errors before the first token come back as a normal HTTP error. If the model fails after streaming has started, the status is already `200`, so Lyber sends an error event and then `[DONE]`:

```text
data: {"error":{"message":"Stream interrupted","code":"upstream_error"}}

data: [DONE]
```

A stream that hits the request timeout ends without `[DONE]`. Treat a stream that ends early as incomplete. Lyber never retries a request on your behalf.