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

# LLM Configuration

> API key, model selection, and research settings.

Central config for the reasoning layer.

## API key

Your Anthropic key, encrypted at rest per-user. See [Bringing your API key](/getting-started/api-key).

## Model selection

Two choices for research + agentic paths:

* **Sonnet 4.6** — recommended default. Fast, capable, \~5× cheaper than Opus.
* **Opus 4.8** — most capable. Use for hardest reasoning tasks.
* **Haiku 4.5** — fastest, cheapest. Good for lightweight jobs.

Change applies immediately to new runs; in-flight runs finish on their original model.

## Research window

Default 90 days. See [Research window](/signals/research-window).

## Cost visibility

Every LLM call is logged in **Activity log** (Settings tab) with token counts. Use it to see where your spend is going.