# AI use cases for Codex Mobile Dev Plugin (callstackincubator/codex-mobile-dev-plugin) Repo: [callstackincubator/codex-mobile-dev-plugin](https://github.com/callstackincubator/codex-mobile-dev-plugin) | Use cases: 4 | Page: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/ Mobile Dev is a Codex plugin that shows iOS and Android devices beside a Codex desktop chat, with device control, combined logs, and performance monitoring for mobile app work. This file holds every use case of this repo. Each one starts with a "## " heading and ends with its URL. - Run an Expo app in a simulator beside your chat: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/run-expo-app-in-simulator-beside-chat/ - Debug an app error from combined native and JS logs: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/debug-app-errors-from-combined-logs/ - Point Codex at a UI element to fix it: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/annotate-ui-element-for-codex-fix/ - Record CPU, memory, and FPS and compare two runs: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/record-and-compare-app-performance/ ## How to run an Expo app in a simulator beside your chat with Codex Mobile Dev Plugin Repo: [callstackincubator/codex-mobile-dev-plugin](https://github.com/callstackincubator/codex-mobile-dev-plugin) | Difficulty: Intermediate | Time: 30 minutes | Basis: From the README Install Mobile Dev, pick a simulator, and have Codex build and run your app in view. **Who it is for:** A mobile developer working on an Expo or React Native app in Codex who wants to see the app running while asking Codex for changes. **The problem:** Switching between the chat, a separate simulator window, and the build terminal slows down every change-and-check loop. **The outcome:** The app builds and runs on a simulator shown next to the Codex chat, and you can keep iterating from the same conversation. ### Steps 1. Run `codex plugin marketplace add https://github.com/callstackincubator/codex-mobile-dev-plugin.git --ref release/latest` 2. Run `codex plugin add mobile-dev@mobile-dev` 3. Open a new chat in Codex, then open Mobile Dev from the sidebar. 4. Pick a device from the toolbar; selecting a stopped simulator boots it. 5. Ask Codex: "Build and run my Expo app in the simulator beside this chat." ### Prompt to paste into your agent ```text Using the callstackincubator/codex-mobile-dev-plugin Mobile Dev plugin, build and run the Expo app at on the simulator named . Expected output: the app launches on that simulator and is visible beside the chat. Verify the device panel shows the running app before reporting success. ``` ### Caveat The prebuilt plugin targets Codex desktop on an Apple Silicon Mac, and the app project's own tools still build and launch the app. Disclaimer: Third-party repos we don't own or vouch for. AI-generated use cases can be wrong: review everything and run at your own risk. Full text: https://dedupedai.com/disclaimer/ URL: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/run-expo-app-in-simulator-beside-chat/ ## How to debug an app error from combined native and JS logs with Codex Mobile Dev Plugin Repo: [callstackincubator/codex-mobile-dev-plugin](https://github.com/callstackincubator/codex-mobile-dev-plugin) | Difficulty: Intermediate | Time: 30 minutes | Basis: From the README Read iOS, Android, and Metro logs together and send a failing stack trace to Codex. **Who it is for:** A developer whose app shows a crash or runtime error and who needs the native and JavaScript side of the failure in one place. **The problem:** Native logs, Android logcat, and Metro console output are usually in separate tools, so tracing one error across them takes time. **The outcome:** Codex receives the error and its stack trace from the logs and proposes a fix grounded in the actual failure. ### Steps 1. Open Logs in Mobile Dev for the selected device. 2. Follow the foreground app and use search or filters to narrow to the error. 3. Send the error and its stack trace to chat. 4. Ask Codex to explain the cause and propose a fix in your project. ### Prompt to paste into your agent ```text Using the callstackincubator/codex-mobile-dev-plugin Mobile Dev plugin, read the logs for the foreground app on and find the error matching . Expected output: a summary of the error with its stack trace and a proposed fix in . Verify the stack trace quoted matches the log entry before editing any file. ``` ### Caveat Metro logs need an existing local Metro server, so the JavaScript side is only available when Metro is running. Disclaimer: Third-party repos we don't own or vouch for. AI-generated use cases can be wrong: review everything and run at your own risk. Full text: https://dedupedai.com/disclaimer/ URL: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/debug-app-errors-from-combined-logs/ ## How to point Codex at a UI element to fix it with Codex Mobile Dev Plugin Repo: [callstackincubator/codex-mobile-dev-plugin](https://github.com/callstackincubator/codex-mobile-dev-plugin) | Difficulty: Beginner | Time: 15 minutes | Basis: From the README Select an element on the device and attach an instruction with component details. **Who it is for:** A developer or designer who sees a layout or behavior problem on screen and wants Codex to fix the exact component. **The problem:** Describing a UI element in words is slow and often points Codex at the wrong component. **The outcome:** Codex receives the selected element with its instruction and, when available, React Native component and source details, and edits the right code. ### Steps 1. Open the device in Mobile Dev beside your chat. 2. Use Select to pick an element or screen region. 3. Write the instruction for the change you want. 4. Send it to Codex and ask it to apply the fix in your project. ### Prompt to paste into your agent ```text Using the callstackincubator/codex-mobile-dev-plugin Mobile Dev plugin, take the annotated element on with the instruction and apply the change in . Expected output: the component source edited to match the instruction. Verify the component named in the annotation is the file that changed. ``` ### Caveat React Native component and source details appear only when they are available, so some elements will only give screen-level context. Disclaimer: Third-party repos we don't own or vouch for. AI-generated use cases can be wrong: review everything and run at your own risk. Full text: https://dedupedai.com/disclaimer/ URL: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/annotate-ui-element-for-codex-fix/ ## How to record CPU, memory, and FPS and compare two runs with Codex Mobile Dev Plugin Repo: [callstackincubator/codex-mobile-dev-plugin](https://github.com/callstackincubator/codex-mobile-dev-plugin) | Difficulty: Advanced | Time: 1 hour | Basis: From the README Capture an interaction on a device and ask Codex to compare it with an earlier run. **Who it is for:** A developer who suspects a screen got slower or janky after a change and needs measured numbers before and after. **The problem:** Performance regressions are hard to prove from memory, and manual profiling is slow to repeat. **The outcome:** You get recorded CPU, memory, and Display FPS data for an interaction, plus a comparison of two runs in chat. ### Steps 1. Open Performance in Mobile Dev for the selected device. 2. Ask Codex to record CPU and memory during the interaction, for example scrolling a list for 30 seconds. 3. Repeat the same interaction after your change. 4. Ask Codex to compare the two recordings and analyze the selected range. ### Prompt to paste into your agent ```text Using the callstackincubator/codex-mobile-dev-plugin Mobile Dev plugin, record CPU and memory on during before and after my change in , then compare the two runs. Expected output: a comparison of CPU, memory, and Display FPS between the runs. Verify both recordings cover the same interaction length before drawing a conclusion. ``` ### Caveat Physical iOS CPU and memory need iOS 17.4 or later with a development-signed app, and iOS simulators do not support Display FPS. Disclaimer: Third-party repos we don't own or vouch for. AI-generated use cases can be wrong: review everything and run at your own risk. Full text: https://dedupedai.com/disclaimer/ URL: https://dedupedai.com/use-cases/callstackincubator-codex-mobile-dev-plugin/record-and-compare-app-performance/