---
summary: "Expose an OpenAI-compatible /v1/chat/completions HTTP endpoint from the Gateway"
read_when:
  - Integrating tools that expect OpenAI Chat Completions
title: "OpenAI Chat Completions"
---

# OpenAI Chat Completions (HTTP)

Gensparx’s Gateway can serve a small OpenAI-compatible Chat Completions endpoint.

This endpoint is **disabled by default**. Enable it in config first.

- `POST /v1/chat/completions`
- Same port as the Gateway (WS + HTTP multiplex): `http://<gateway-host>:<port>/v1/chat/completions`

Under the hood, requests are executed as a normal Gateway agent run (same codepath as `gensparx agent`), so routing/permissions/config match your Gateway.

## Authentication

Uses the Gateway auth configuration. Send a bearer token:

- `Authorization: Bearer <token>`

Notes:

- When `gateway.auth.mode="token"`, use `gateway.auth.token` (or `GENSPARX_GATEWAY_TOKEN`).
- When `gateway.auth.mode="password"`, use `gateway.auth.password` (or `GENSPARX_GATEWAY_PASSWORD`).
- If `gateway.auth.rateLimit` is configured and too many auth failures occur, the endpoint returns `429` with `Retry-After`.

## Security boundary (important)

Treat this endpoint as a **full operator-access** surface for the gateway instance.

- HTTP bearer auth here is not a narrow per-user scope model.
- A valid Gateway token/password for this endpoint should be treated like an owner/operator credential.
- Requests run through the same control-plane agent path as trusted operator actions.
- If the target agent policy allows sensitive tools, this endpoint can use them.
- Keep this endpoint on loopback/tailnet/private ingress only; do not expose it directly to the public internet.

See [Security](/gateway/security) and [Remote access](/gateway/remote).

## Choosing an agent

No custom headers required: encode the agent id in the OpenAI `model` field:

- `model: "gensparx:<agentId>"` (example: `"gensparx:main"`, `"gensparx:beta"`)
- `model: "agent:<agentId>"` (alias)

Or target a specific gensparx agent by header:

- `x-gensparx-agent-id: <agentId>` (default: `main`)

Advanced:

- `x-gensparx-session-key: <sessionKey>` to fully control session routing.

## Enabling the endpoint

Set `gateway.http.endpoints.chatCompletions.enabled` to `true`:

```json5
{
  gateway: {
    http: {
      endpoints: {
        chatCompletions: { enabled: true },
      },
    },
  },
}
```

## Disabling the endpoint

Set `gateway.http.endpoints.chatCompletions.enabled` to `false`:

```json5
{
  gateway: {
    http: {
      endpoints: {
        chatCompletions: { enabled: false },
      },
    },
  },
}
```

## Session behavior

By default the endpoint is **stateless per request** (a new session key is generated each call).

If the request includes an OpenAI `user` string, the Gateway derives a stable session key from it, so repeated calls can share an agent session.

## Streaming (SSE)

Set `stream: true` to receive Server-Sent Events (SSE):

- `Content-Type: text/event-stream`
- Each event line is `data: <json>`
- Stream ends with `data: [DONE]`

## Examples

Non-streaming:

```bash
curl -sS http://127.0.0.1:18789/v1/chat/completions \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  -H 'Content-Type: application/json' \
  -H 'x-gensparx-agent-id: main' \
  -d '{
    "model": "gensparx",
    "messages": [{"role":"user","content":"hi"}]
  }'
```

Streaming:

```bash
curl -N http://127.0.0.1:18789/v1/chat/completions \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  -H 'Content-Type: application/json' \
  -H 'x-gensparx-agent-id: main' \
  -d '{
    "model": "gensparx",
    "stream": true,
    "messages": [{"role":"user","content":"hi"}]
  }'
```
