---
title: "Models"
description: "Model slots, effort, and the decision model selection."
---

> Documentation Index
> Fetch the complete documentation index at: https://colmugx.github.io/cetas/llms.txt
> Use this file to discover all available pages before exploring further.

# Models

Cetas identifies a model slot with a `provider/model` id, for example
`deepseek/deepseek-flash` or `moonshot/kimi-k3`.

## Two slots, never interchangeable

The conversation model and the decision model cannot be swapped, and the two
pickers enforce it:

```text
/model      # conversation slots; rejects a decision slot
/decision   # decision slots, with the active one marked; rejects a chat slot
```

`/decision` with no argument lists what the configured providers offer. A build
that ships no decision backend simply has nothing to offer here.

The decision model matters for one setting in particular: `permission auto`
routes every non-read tool call through a semantic gate, and that gate needs a
decision model to judge — see
[Permissions](/cetas/en/configuration/permissions/).

## Where the selection lives, and who changes it

The active selection lives in settings — fields in the
[Settings reference](/cetas/en/reference/settings/). Three ways to change it:

| Surface | Behavior |
| --- | --- |
| Terminal | Successful `/model`, `/effort`, `/decision` changes are persisted |
| Editor (ACP) | Successful `model` / `effort` config-option changes are persisted |
| Automation (`cetas-run`) | `--model` and `--effort` are run-scoped overrides and are **not** persisted |

If provider configuration changes make the previous selection unavailable,
Cetas falls back to an available default instead of refusing to compose.

## Model lists

Discovered model catalogs are cached in `<CETAS_HOME>/.cetas/model_lists.json`, one record
array per provider. Pickers keep working from a warm cache, and a provider's
cached list is refreshed when it is re-discovered.

## Custom models

A provider that is not one of the built-ins is an OpenAI-compatible endpoint you
declare yourself, and model capabilities (context window, image input, efforts)
are declared in the same place. See
[Custom and self-hosted models](/cetas/en/configuration/custom-models/).

Source: https://colmugx.github.io/cetas/en/configuration/models/index.mdx