> ## Documentation Index
> Fetch the complete documentation index at: https://gomodel-fix-headers-altering.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# xAI (Grok)

> Configure xAI Grok models in GoModel and understand how reasoning effort and prompt-cache affinity are handled.

xAI's API is OpenAI-compatible, including a native Responses API. Models such
as `grok-4.5` are discovered automatically from xAI's `/models` endpoint — no
configuration beyond the API key is needed.

## Configure

```bash theme={null}
XAI_API_KEY=...
```

Or in `config.yaml`:

```yaml theme={null}
providers:
  xai:
    type: xai
    base_url: "https://api.x.ai/v1"
    api_key: "${XAI_API_KEY}"
```

<Note>
  Voice models (e.g. `grok-voice-latest`) are not listed by xAI's `/models`
  endpoint. To route realtime sessions to them, add them explicitly via
  `XAI_MODELS=grok-voice-latest` or a configured model list.
</Note>

## Reasoning effort mapping

Grok reasoning models (e.g. `grok-4.5`, defaulting to `high`) accept
`reasoning_effort` as a top-level string on Chat Completions. GoModel rewrites
the OpenAI-shaped `"reasoning": {"effort": "..."}` into that flat field — no
client change required. On the Responses API the nested shape is xAI-native
and passes through unchanged.

| Client sends                       | xAI receives                                                                      |
| ---------------------------------- | --------------------------------------------------------------------------------- |
| `none` / `low` / `medium` / `high` | unchanged                                                                         |
| `xhigh` / `max`                    | `high` (`xhigh` on the multi-agent Grok family, where it selects the agent count) |
| anything else                      | passed through for xAI to judge                                                   |

Models without reasoning support reject the field upstream; omit `reasoning`
for those.

## Prompt-cache affinity

xAI routes a conversation's requests to the same server via the
`x-grok-conv-id` header; without it, cache hits are unreliable and input
tokens are often billed at the uncached price.

* **Chat Completions:** GoModel forwards a client-supplied `X-Grok-Conv-Id`
  header, and otherwise derives a stable one from the conversation's opening
  messages — cache affinity works with no client change.
* **Responses API:** pass `prompt_cache_key` in the request body; GoModel
  forwards it verbatim.