Glossia separates repository instructions from model-provider credentials. Repositories describe what should be translated, while accounts decide which [large language model](https://en.wikipedia.org/wiki/Large_language_model) performs the work.

## Why models belong to accounts

A team often translates several repositories with the same provider relationship. Account-scoped models let administrators rotate a provider key or switch the underlying model once without editing every repository.

This boundary also keeps credentials out of source control. A repository contains a readable handle such as `translation-default`, not the provider key.

## Handles provide stable intent

The `model` field in `GLOSSIA.md` refers to an account model handle:

```yaml
model: translation-default
```

The handle expresses the repository's intent. An administrator can later update which provider model that handle selects while the repository configuration stays stable.

## How several models are used

Glossia uses one configured model for each document translation. Adding several models does not create an ensemble, a fallback chain, or an automatic quality tier. The repository author chooses their purpose through stable handles such as `translation-default`, `long-form`, or `japanese-specialist`.

Selection follows the context hierarchy for the document and target locale:

1. The closest `GLOSSIA/<locale>.md` file that declares `model` wins for that locale.
2. Otherwise, the closest `GLOSSIA.md` file that declares `model` wins for its directory.
3. Parent `GLOSSIA.md` settings are inherited when a closer file does not declare a model.
4. When no applicable context file declares a handle, Glossia uses the account default.

An explicitly configured handle must exist. Glossia reports an error for an unknown handle instead of silently switching to the account default.

## Default selection

Project setup needs a model before a repository has its own `GLOSSIA.md`. Glossia therefore selects the account default. The first model added to an account becomes the default, and an administrator can make another model the default from its settings page.

Once a repository has `GLOSSIA.md`, using an explicit handle makes its choice clear to reviewers. Omitting `model` keeps the repository on the account default.

## The human review boundary

Model output is proposed work, not an automatic merge. Setup and translation activity stays visible in Glossia, while repository changes are published through a pull request for the team to review. This preserves the same quality and ownership boundary teams already use for code.