> ## Documentation Index > Fetch the complete documentation index at: https://docs.usehasp.com/llms.txt > Use this file to discover all available pages before exploring further. # POST /v1/chat/completions > OpenAI Chat Completions-compatible drop-in endpoint. Point your existing openai SDK at HASP by changing the baseURL. OpenAI Chat Completions-compatible endpoint. Coding agents, IDE integrations, and any code built against the `openai` SDK need only change the `baseURL` — request shape, response shape, and streaming chunks are OpenAI's exact wire format. Requires the `ai:chat` scope. This surface is **stateless**: it never persists conversation content and does not accept a `conversation_id`. Audit events are still written for every request. If you need stored conversations, run management, or PHI entity metadata, use the native [`POST /v1/ai/chat`](/ai-api/reference/chat). ## Migrating from OpenAI ```javascript theme={null} import OpenAI from 'openai'; const client = new OpenAI({ baseURL: 'https://api.usehasp.com/v1', // ← only this line changes apiKey: 'hasp_key_live_...', }); const completion = await client.chat.completions.create({ model: 'gpt-5.4', // a HASP model id — see "Model selection" below messages: [{ role: 'user', content: 'Hello' }], }); ``` ## Request ``` POST https://api.usehasp.com/v1/chat/completions Authorization: Bearer hasp_key_live_... Content-Type: application/json ``` ### Body parameters | Parameter | Type | Required | Description | | ------------------------- | ---------------- | -------- | ------------------------------------------------------------------------------------------------ | | `model` | string | Yes | A HASP model id (see [Model selection](#model-selection)). Not the provider's public model name. | | `messages` | array | Yes | Conversation turns. Each has a `role` of `system`, `user`, `assistant`, or `tool`. | | `messages[].content` | string | — | Message text. Required for `tool` messages. | | `messages[].tool_call_id` | string | — | Required on `tool` messages; correlates the result to the assistant's tool call. | | `messages[].tool_calls` | array | — | Only valid on `assistant` messages; replays a prior tool call on the next turn. | | `tools` | array | No | Function-tool definitions: `{"type": "function", "function": {...}}`. | | `tool_choice` | string \| object | No | Standard OpenAI tool-choice control. | | `max_tokens` | integer | No | Max output tokens (1–32000). Defaults to your org's per-request cap. | | `stream` | boolean | No | Stream via SSE. **Default `false`.** | | `temperature` | number | No | 0–2. | **Accepted but ignored.** `top_p`, `n`, `frequency_penalty`, `presence_penalty`, `stop`, and `user` are validated for shape (so existing SDK payloads don't error) but do not affect inference — HASP's inference request does not model them. Unlike the native `/v1/ai/chat` endpoint, `stream` **defaults to `false`** here, matching OpenAI's default. ## Model selection The `model` field takes a **HASP registry model id**, not the provider's public name. The same identifiers work on every HASP surface: | Model ID | Provider | Relative cost | Access | | ------------------- | --------- | ------------- | -------- | | `claude-sonnet-4-6` | Anthropic | 1.0× | Standard | | `claude-haiku-4-5` | Anthropic | 0.3× | Standard | | `claude-opus-4-6` | Anthropic | 1.7× | Premium | | `claude-opus-4-7` | Anthropic | 1.7× | Premium | | `gpt-5.5` | OpenAI | 1.7× | Premium | | `gpt-5.5-pro` | OpenAI | 10.0× | Premium | | `gpt-5.4` | OpenAI | 0.8× | Standard | | `gpt-5.4-mini` | OpenAI | 0.25× | Standard | | `gpt-5.3-codex` | OpenAI | 0.6× | Standard | There is no requirement to pick an OpenAI model on this surface — you can drive a Claude model through the OpenAI wire format. Premium models require org enablement; a request for a model your org has not enabled returns a `400 invalid_request_error` with `hasp_code` `MODEL_ACCESS_DENIED`. See [Model Selection](/ai-api/concepts/model-selection) for cost/access details. ## Non-streaming response When `stream` is omitted or `false`, the response is a single `chat.completion` object: ```json theme={null} { "id": "chatcmpl_01JQMSG000000000000000000", "object": "chat.completion", "created": 1775692800, "model": "gpt-5.4", "choices": [ { "index": 0, "message": { "role": "assistant", "content": "The HIPAA minimum necessary standard requires..." }, "finish_reason": "stop" } ], "usage": { "prompt_tokens": 18, "completion_tokens": 74, "total_tokens": 92 } } ``` When the model calls a tool, `message.content` is `null` and `message.tool_calls` carries the calls; `finish_reason` is `tool_calls`. ## Streaming response (SSE) When `stream: true`, the response is a `text/event-stream` of `chat.completion.chunk` objects in OpenAI's exact format — the same shape the `openai` SDK's streaming iterator expects: ``` data: {"id":"chatcmpl_...","object":"chat.completion.chunk","created":1775692800,"model":"gpt-5.4","choices":[{"index":0,"delta":{"role":"assistant","content":""},"finish_reason":null}]} data: {"id":"chatcmpl_...","object":"chat.completion.chunk","created":1775692800,"model":"gpt-5.4","choices":[{"index":0,"delta":{"content":"The HIPAA"},"finish_reason":null}]} data: {"id":"chatcmpl_...","object":"chat.completion.chunk","created":1775692800,"model":"gpt-5.4","choices":[{"index":0,"delta":{},"finish_reason":"stop"}]} data: {"id":"chatcmpl_...","object":"chat.completion.chunk","created":1775692800,"model":"gpt-5.4","choices":[],"usage":{"prompt_tokens":18,"completion_tokens":74,"total_tokens":92}} data: [DONE] ``` The first chunk carries the assistant role, content deltas stream in the middle, a penultimate chunk sets `finish_reason`, a final chunk carries `usage`, and the stream terminates with `data: [DONE]`. Tool calls stream as `delta.tool_calls[]` entries with a stable zero-based `index`. ## Compliance behavior All HASP compliance checks apply — PHI Guard, BAA enforcement, and credit metering — identically to every other surface. Compliance is a property of your organization, not the endpoint shape. * **PHI Guard** runs on all messages per your org's `phi_mode`. In `redact` mode PHI is replaced with placeholders before the upstream call; in `block` mode the request is rejected. * **BAA required.** No active BAA → a `permission_error` with `hasp_code` `BAA_REQUIRED`. * **Credit metering.** Credits are deducted after each successful response. ## Errors Errors are returned in OpenAI's error envelope. HASP's richer error vocabulary maps into OpenAI's error `type` set, with the original HASP code preserved as `code` (lowercased) and `hasp_code`: ```json theme={null} { "error": { "message": "Model 'gpt-5.5-pro' is not in the allowed model list for organization .", "type": "invalid_request_error", "param": null, "code": "model_access_denied", "hasp_code": "MODEL_ACCESS_DENIED" } } ``` | HTTP | OpenAI `type` | Example condition (`hasp_code`) | | ---- | ----------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | | 401 | `authentication_error` | Missing or revoked token (`INVALID_API_KEY`) | | 403 | `permission_error` | No active BAA (`BAA_REQUIRED`); credits exhausted (`CREDITS_EXHAUSTED`); AI paused (`AI_PAUSED`); feature not HIPAA-eligible (`FEATURE_NOT_HIPAA_ELIGIBLE`) | | 400 | `invalid_request_error` | Model not enabled or unknown (`MODEL_ACCESS_DENIED`); PHI blocked (`PHI_BLOCKED`); retired model (`MODEL_RETIRED`) | | 429 | `rate_limit_error` | RPM or daily limit exceeded (`RATE_LIMITED`) | | 500 | `api_error` | Upstream model provider error (`INFERENCE_UPSTREAM_FAILURE`) | During a stream, a mid-run failure is emitted as a terminal `data:` line carrying the same `error` envelope rather than an HTTP status change.