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Adem Isler
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Codex Desktop Custom Models

An open-source starter kit for running isolated Codex Desktop apps with custom model providers, separate state, and local automations.

Role
Systems design, provider bridge development, and packaging
Source
Public repository
Started
Last repository update
Core stack
  • JavaScript
  • Shell
  • Codex
  • OpenAI-compatible APIs
  • macOS
Table of Contents

Overview

Codex Desktop Custom Models is a starter kit for creating a second, isolated Codex Desktop application connected to a custom model provider. Each generated app has its own icon, application identity, configuration directory, provider bridge, port allocation, and automation state.

The reference implementation creates a Codex MiniMax app without modifying the user’s normal Codex installation.

The problem

Testing a custom provider inside an existing desktop application can contaminate the primary configuration, sessions, credentials, or automation state. A developer may want to compare providers side by side while keeping the original application untouched.

Product approach

The project duplicates the application shell while separating everything that should not be shared:

  • a unique application and bundle identity;
  • a dedicated CODEX_HOME directory;
  • a custom icon and launcher;
  • an isolated webview and provider bridge port;
  • provider-specific configuration and credentials;
  • independent automation state.

The bridge converts Codex Responses API calls into an OpenAI-compatible Chat Completions shape, including text and tool calls. MiniMax is the documented example, but the same structure can be adapted for other compatible providers.

Platform implementation

The project includes a macOS application-bundle workflow and a Linux desktop-shell workflow. Installation scripts generate launchers and service definitions, while removal scripts leave the isolated profile data intact unless the user explicitly deletes it.

A local automation MCP and runner are included because custom profiles do not automatically inherit host-provided automation tools.

My role

I designed the isolation model, built the provider translation bridge, created the installation and launch workflows, and documented the extension path for other model providers.

Current status

The project is open source and usable as a technical starter kit. It is intended for developers who already understand Codex Desktop, local services, and provider API configuration.