Streaming

Set stream: true and the response is an text/event-stream of chat.completion.chunk objects ending with data: [DONE].

curl -N https://api.vichar.io/v1/chat/completions \
  -H "Authorization: Bearer $VICHAR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"vichar-sonnet-5.5","stream":true,"messages":[{"role":"user","content":"Hello"}]}'

stream = client.chat.completions.create(
    model="vichar-sonnet-5.5",
    messages=[{"role": "user", "content": "Hello"}],
    stream=True,
)
for chunk in stream:
    print(chunk.choices[0].delta.content or "", end="")

Chunks arrive as delta fragments. Tool calls arrive as delta.tool_calls fragments; the final chunk carries finish_reason and, when requested, usage.

Set "stream_options": {"include_usage": true} to get a final usage chunk with token counts and cost.