doppelt.digital Application Platform Documentation
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Working on your project

Working with Codex

OpenAI's AI agent as a CLI or desktop app – preconfigured for your platform projects.

On this page

Codex is OpenAI’s AI agent. Like Claude Code, it works directly on your project: reading code, writing changes, and running commands – as a terminal CLI or desktop app.

Installation

The setup app installs Codex during developer setup (CLI and desktop variant). Then start the agent in the project folder:

cd ~/Documents/application-platform/<organization>/<project>
codex

In VS Code you can additionally use the ChatGPT/Codex extension – the welcome page of the Application Platform extension links to it directly.

Preconfigured for the platform

The project folder contains (symlinked from local-configuration):

  • AGENTS.md – read automatically by Codex. It contains the shared platform rules: start applications with ap run-local, don’t change .gitlab-ci.yml or env/*.generated.env, put your own values into env/*.custom.env, never put secrets into commits or answers.
  • .codex/ – Codex-specific configuration.
Tip
Start Codex in the parent project folder, not inside a single repository – the agent then knows backend, app, and configuration at the same time.

Your own rules

How to give Codex (and all other AI tools) your own working instructions – e.g. committing and pushing after every task – is covered in Telling the AI how to work.