Introducing Mobile Dev: full mobile dev tooling right in your Codex app
Authors
Codex now supports plugins with interactive interfaces embedded directly in the app. That opens up room for the tools we need when building mobile apps with agents: device previews, visual feedback, logs, and performance profiling, all in the workspace where we’re already building.
Today, we’re sharing an initial preview of Mobile Dev for Codex. It brings those capabilities together, with built-in agent-device support so your agent can interact with the app alongside you.
Our work is changing
Agents have changed how we build software. We describe what we want, give the agent context, and let it work through the implementation. More of our time goes into supervising that work, inspecting the result, and deciding what should happen next.
As Codex becomes the place where we build, the tools for working with the app should be available there too. Historically, we’ve moved between separate tools for development, debugging, profiling, and QA. There’s now an opportunity to bring those workflows together around how we work with agents.
At Callstack, we’ve spent the last ten years building mobile apps and the tools developers use to ship them. Mobile Dev brings that experience into this new way of working, starting with tools we use every day.
Features
Mobile Dev works with Expo, React Native, SwiftUI, and other native mobile projects. Here’s what you can do with the initial preview.
Live devices beside your chat
Stream iOS simulators, Android emulators, and connected iPhones, iPads, and Android devices beside your conversation. Open Mobile Dev from the Codex sidebar for a dedicated fullscreen workspace with iOS and Android previews side by side.
Device control, inspection and annotations
Select and boot simulators or emulators, interact with taps and drags, type on supported devices, and let Codex inspect accessibility elements and control your app through MCP tools. Select an element or screen region and leave instructions for Codex, with React Native component and source details when available.
Native and JavaScript logs
Read iOS unified logs, Android logcat, and Metro console messages together. Follow the foreground app, search and filter logs, and send an error and its stack trace to chat.
Live performance monitoring and improvements
Track app CPU and memory, expand individual thread charts, and view device-wide Display FPS on supported devices. Ask Codex to record an interaction, inspect interactive charts in chat, compare runs, and analyze selected ranges. Overlay a baseline and an updated recording in the same performance card to see whether a change helped. Android recordings include display frame pacing and jank statistics.
A foundation we’ll keep building on
We’ll continue adding capabilities for developing, debugging, and reviewing mobile apps with agents, shaped by what we learn from using the tools and hearing from other developers.
The integration builds on MCP and MCP Apps, which provide tools and embedded interactive interfaces for compatible AI clients. OpenAI’s extensions add integration points such as sidebar views and conversation panels.
We’re starting with the Codex desktop experience, while keeping the underlying tools accessible through MCP. Our goal is to make this useful wherever you build mobile apps with agents.
Get started
You can install the preview today using the installation instructions on GitHub, where you’ll also find the platform requirements. Mobile Dev will soon be available in the Codex marketplace.
After installing, open a new chat in Codex. Open Mobile Dev from the sidebar or ask Codex to open a preview beside the conversation, select your devices, and launch your app using your project’s usual workflow.
Try it on something you’re already building. Annotate a screen that needs work, investigate a crash, or compare performance before and after an agent’s change.
Tell us what helps and what’s missing. This preview is the beginning of the mobile development workspace we’ll continue building.
