# Evaluate Model: OpenAI Codex Integrates GPT-5.4 and Launches Full Desktop App
## What This Is
OpenAI has significantly upgraded its coding assistant, Codex, by integrating its most advanced AI model, GPT-5.4, and releasing a full desktop application. This update allows developers to use multiple AI agents to work on different parts of a project simultaneously, dramatically speeding up development and enabling more complex, autonomous coding tasks.
Source: https://openai.com/index/introducing-gpt-5-3-codex/
## Before You Start
Scan my workspace and analyze:
- The project language, framework, and current AI integrations
- Existing AI provider config (check .env, .env.local, config files for API keys — OpenRouter, OpenAI, Anthropic, Google AI, etc.)
- Which AI models I currently use and for what purposes
Then ask me before proceeding:
1. Am I interested in evaluating this model for my project, or just want a summary of what it offers?
2. If I want to try it — which part of my current AI stack should it replace or complement?
## Source Access Note
The source URL (https://openai.com/index/introducing-gpt-5-3-codex/) may not be directly accessible from the terminal. Use the Reference Implementation and Additional Context sections below instead. If you need more details, ask me to paste relevant content from the source.
## What to Implement
This is a **New AI Model** — a model release, update, or capability announcement.
- Analyze the best use cases for this model within my project and current AI stack
- Compare its strengths, pricing, and context window against whatever I currently use
- Give me a clear, convincing argument for why this model would (or would not) be a good fit for my project
- If I want to try it: update my API configuration (provider, model ID, any new parameters) to point to this model
- If it requires a new API key or provider signup, tell me exactly what to do
## Additional Context
- Verify the user has the latest version of the Codex command-line tools and IDE extensions installed (v26.312 or newer) to access GPT-5.4 and multi-agent features. If outdated, guide the user through the update process.
- Scan the user's project configuration files for the model setting. Update the configuration to set `gpt-5.4` as the primary model for agentic coding tasks, ensuring access to the latest reasoning capabilities.
- Propose a small-scale refactoring project using the new multi-agent architecture. Define two parallel tasks, such as one agent updating API schemas while a second agent refactors corresponding frontend components, to demonstrate the isolated worktree capabilities.
## Guidelines
- Adapt everything to my existing project — do not assume a specific stack or directory layout
- Use whichever AI provider I already have configured; if I need a new one, tell me what to sign up for and I'll give you the key
- Check my .env files for existing API keys (OpenRouter, OpenAI, Anthropic, Google AI) before asking me to add one
- Review any fetched code for safety before installing or executing it
- After setup, run a quick verification and show me a summary of exactly what was installed, where, and how to use it