Core

Chat completions

The endpoint the product exists for. Every OpenAI parameter is forwarded verbatim, and anything genuinely unsupported is rejected by name rather than dropped.

POST /v1/chat/completions

The request and response are OpenAI’s. Field names are theirs and are not tidied, because the whole migration story is that an unmodified client works.

Parameters

Field	Notes
`model`	Required. A model id or an alias. See Models
`messages`	Required. Roles `system`, `user`, `assistant`, `tool`. `content` is a string or an array of parts for multimodal input
`max_tokens`	Defaults to 1024, ceiling 32000. The reservation is priced off this
`temperature`, `top_p`, `stop`, `seed`	Forwarded. Ranges are OpenAI’s
`frequency_penalty`, `presence_penalty`	Forwarded
`stream`, `stream_options`	See Streaming
`tools`, `tool_choice`	See Tool calling
`response_format`	See Structured output
`reasoning_effort`	`none`, `low`, `medium`, `high`. See Models
`logprobs`, `top_logprobs`	Forwarded
`prompt_cache_key`	See Prompt caching

The response

{
  "id": "chatcmpl-8f2a1c",
  "object": "chat.completion",
  "created": 1785097284,
  "model": "llama-3.1-8b",
  "choices": [
    {
      "index": 0,
      "message": { "role": "assistant", "content": "The capital of Kenya is Nairobi." },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 21,
    "completion_tokens": 8,
    "total_tokens": 29,
    "prompt_tokens_details": { "cached_tokens": 0 }
  },
  "dawnstack": { "cost_micros": 6, "cost_usd": 0.000006, "request_id": "req_8f2a1c" }
}

dawnstack is additive and non-standard. An OpenAI client ignores unknown fields, so it costs you nothing, and it means you do not have to reconcile a call against your ledger afterwards to know what it cost. cost_micros is the integer of record; cost_usd is the same number in dollars.

finish_reason is passed through from the model. stop means it finished, length means it hit max_tokens, tool_calls means it wants you to call a function, and error means the stream failed after it had started.

Multi-turn

Send the whole conversation. There is no server-side state, no thread id, and nothing to clean up.

Python

messages = [{"role": "system", "content": "Answer in one sentence."}]

while True:
    messages.append({"role": "user", "content": input("> ")})
    reply = client.chat.completions.create(model="llama-3.1-8b", messages=messages)
    text = reply.choices[0].message.content
    messages.append({"role": "assistant", "content": text})
    print(text)

Set prompt_cache_key to the same value across a conversation’s turns and the repeated prefix gets cheaper. See Prompt caching.

What is not supported

n > 1 is not implemented: ask twice. Everything else that is missing is on Not supported yet.