# Streaming

Source: https://docs.getworg.com/streaming

With "stream": true the answer arrives as server-sent events while the model writes it.

## Request a stream

```bash
curl -N https://api.getworg.com/v1/chat/completions \
  -H "Authorization: Bearer $WORG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "deepseek-v4.1-flash:cached",
    "messages": [{"role": "user", "content": "Count from 1 to 3."}],
    "max_tokens": 512,
    "stream": true,
    "stream_options": {"include_usage": true}
  }'
```

```python
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.getworg.com/v1",
    api_key=os.environ["WORG_API_KEY"],
)

stream = client.chat.completions.create(
    model="deepseek-v4.1-flash:cached",
    messages=[{"role": "user", "content": "Count from 1 to 3."}],
    max_tokens=512,
    stream=True,
)
for chunk in stream:
    if chunk.choices and chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="", flush=True)
print()
```

## Format

Stream (ids shortened):

```
: keepalive

data: {"id":"chatcmpl-req_Kzzo...","object":"chat.completion.chunk","created":1793729649,"model":"deepseek-v4.1-flash:cached","choices":[{"index":0,"delta":{"role":"assistant","content":""},"logprobs":null,"finish_reason":null}]}

data: {"id":"chatcmpl-req_Kzzo...","object":"chat.completion.chunk","created":1793729649,"model":"deepseek-v4.1-flash:cached","choices":[{"index":0,"delta":{"content":"1"},"logprobs":null,"finish_reason":null}]}

data: {"id":"chatcmpl-req_Kzzo...","object":"chat.completion.chunk","created":1793729649,"model":"deepseek-v4.1-flash:cached","choices":[{"index":0,"delta":{"content":","},"logprobs":null,"finish_reason":null}]}

data: {"id":"chatcmpl-req_Kzzo...","object":"chat.completion.chunk","created":1793729649,"model":"deepseek-v4.1-flash:cached","choices":[{"index":0,"delta":{"content":" 2, 3."},"logprobs":null,"finish_reason":null}]}

data: {"id":"chatcmpl-req_Kzzo...","object":"chat.completion.chunk","created":1793729649,"model":"deepseek-v4.1-flash:cached","choices":[{"index":0,"delta":{},"logprobs":null,"finish_reason":"stop"}]}

data: {"id":"chatcmpl-req_Kzzo...","object":"chat.completion.chunk","created":1793729649,"model":"deepseek-v4.1-flash:cached","choices":[],"usage":{"prompt_tokens":12,"completion_tokens":9,"total_tokens":21,"prompt_tokens_details":{"cached_tokens":0}}}

data: [DONE]
```

- Each event is one `data:` line with a JSON chunk, then a blank line. The stream ends with `data: [DONE]`.
- Text arrives in `delta.content`, reasoning in `delta.reasoning_content`. The chunk with `finish_reason` has an empty `delta`.
- Lines that start with a colon, such as `: keepalive`, are comments. SSE clients and the OpenAI SDKs skip them.
- Some chunks carry `"usage": null`. Read usage only from the usage chunk below.

## The usage chunk

With `"stream_options": {"include_usage": true}`, the last chunk before `[DONE]` has an empty `choices` array and the `usage` of the whole request. Without it there is no usage chunk. Worg bills the same either way.

## Tool calls in a stream

A function call arrives in pieces in `delta.tool_calls`. The first piece for each call has its `id` and function `name`; later pieces add to `function.arguments`. Join the pieces by `index`, and parse the arguments after the chunk with `finish_reason: "tool_calls"`. Some text in `delta.content` can come before the call.

## Errors

- Until the first chunk, nothing is sent: an error before then is a normal HTTP error with a JSON body, as on [Errors and retries](https://docs.getworg.com/errors). A combo can still move to its next lane.
- After the first chunk the status is already 200. If the model stops with an error, a chunk carries an `error` object with code `upstream_error`, and the request stays on that lane.
- A stream that ends without `data: [DONE]` was cut. Retry the whole request.

## When your client disconnects

The model keeps writing after your client leaves. Worg keeps reading the stream for up to 2 minutes after you disconnect and bills the tokens the model wrote. In one test a client that left after 2 seconds was billed for all 458 output tokens.

Set `max_tokens` to the most you want to pay for. Closing the connection does not stop the cost.

Next: [Tool calling](https://docs.getworg.com/tool-calling) · [Reasoning](https://docs.getworg.com/reasoning) · [Errors and retries](https://docs.getworg.com/errors)