---
title: Codex builds
description: Codex builds compose many isolated builds into a knowledge base environment where repositories publish independently under a shared domain. Unlike assembler...
url: https://docs-v3-preview.elastic.dev/docs-builder/documentation/codex
products:
  - Elastic Docs Builder
---

# Codex builds
Codex builds compose many [isolated builds](https://docs-v3-preview.elastic.dev/docs-builder/documentation/isolated) into a knowledge base environment where repositories publish independently under a shared domain. Unlike assembler builds, there is no centralized navigation composition — each repository maintains its own navigation and publishes on its own schedule.

## How it works

A codex environment is a shared publishing target. Repositories opt in by setting `registry:` in their `docset.yml`. Each repository builds in isolation and publishes independently — the codex environment aggregates all participating repositories into a unified landing page.

## URL structure

- **Repositories**: `/r/<repo-name>/` — each repo gets its own URL prefix
- **Groups**: `/g/<group-name>/` — repos can optionally be grouped together


## Cross-linking

Repositories within a codex environment can link to each other using cross-link syntax:
```markdown
See the [setup guide](repo-name://path/to/file.md).
```

Links are validated against the [link index](https://docs-v3-preview.elastic.dev/docs-builder/documentation/distributed-builds), ensuring references stay correct even though each repo builds independently.

## Key differences from assembler


|            | Assembler                              | Codex                                          |
|------------|----------------------------------------|------------------------------------------------|
| Navigation | Centralized global nav                 | Each repo owns its own nav                     |
| Publishing | All repos built and deployed together  | Repos publish independently                    |
| Setup      | Requires assembler configuration files | Each repo just sets `registry` in `docset.yml` |
| Use case   | Public documentation sites             | Knowledge bases, internal docs                 |