Chat Completions API

OpenAI-compatible chat completion endpoint with optional streaming. Prefer Anthropic's wire format? See Messages — both run through the same model routing, guardrails, and provider gateway.

Endpoint

POST /api/client/v1/chat/completions

Request

{
  "model": "gpt-4",
  "messages": [
    { "role": "system", "content": "You are a helpful assistant." },
    { "role": "user", "content": "What is the capital of France?" }
  ],
  "temperature": 0.7,
  "max_tokens": 1000,
  "stream": false,
  "request_id": "optional-correlation-id"
}

Parameters

Field	Type	Required	Description
model	string	Yes	Model key configured in the dashboard
messages	array	Yes	Array of message objects
temperature	number	No	Sampling temperature (0-2)
max_tokens	number	No	Maximum tokens in response
max_completion_tokens	number	No	Alternative to max_tokens
stream	boolean	No	Enable SSE streaming (default: false)
request_id	string	No	Client-provided correlation ID

Message Format

{ "role": "system" | "user" | "assistant" | "tool", "content": "..." }

Response (Non-Streaming)

{
  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "model": "gpt-4",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "The capital of France is Paris."
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 25,
    "completion_tokens": 8,
    "total_tokens": 33
  },
  "request_id": "req_abc123"
}

Response (Streaming)

When stream: true, the response is a Server-Sent Events stream:

HTTP/1.1 200 OK
Content-Type: text/event-stream
X-Request-Id: req_abc123

data: {"id":"chatcmpl-abc","object":"chat.completion.chunk","choices":[{"delta":{"role":"assistant"},"index":0}]}

data: {"id":"chatcmpl-abc","object":"chat.completion.chunk","choices":[{"delta":{"content":"The"},"index":0}]}

data: {"id":"chatcmpl-abc","object":"chat.completion.chunk","choices":[{"delta":{"content":" capital"},"index":0}]}

data: [DONE]

Guardrail Blocking

If a guardrail blocks the request:

{
  "error": {
    "message": "Content blocked by guardrail",
    "type": "guardrail_block",
    "guardrail_key": "pii-checker",
    "action": "block",
    "findings": [
      { "category": "email", "message": "PII detected" }
    ]
  }
}

Status code: 400

Errors

Status	Description
400	Missing model or messages, guardrail block
401	Invalid API token
500	Model not found
500	Model is not configured for chat completions
429	Rate limit or quota exceeded
500	Provider error (circuit breaker / upstream)

Examples

cURL

curl -X POST https://gateway.example.com/api/client/v1/chat/completions \
  -H "Authorization: Bearer cpeer_your_token" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Python

import requests

response = requests.post(
    "https://gateway.example.com/api/client/v1/chat/completions",
    headers={"Authorization": "Bearer cpeer_your_token"},
    json={
        "model": "gpt-4",
        "messages": [{"role": "user", "content": "Hello"}]
    }
)
print(response.json())

Node.js

const response = await fetch('https://gateway.example.com/api/client/v1/chat/completions', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer cpeer_your_token',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'gpt-4',
    messages: [{ role: 'user', content: 'Hello' }],
  }),
});
const data = await response.json();