Expo Simulators: your coding agent now has to show the tape
Expo just turned "trust me, it works" into a video file. Expo Simulators, launched Thursday, starts a cloud iOS Simulator or Android Emulator with one command, no Mac and no nested virtualization needed. Your agent, your CI job or a teammate can boot one from anywhere. Each session runs on its own VM, so ten parallel agents don't trample each other. Launch post: https://expo.dev/blog/introducing-expo-simulators-cloud-simulators-built-for-agents, docs at https://docs.expo.dev/eas/simulators/introduction/
The interesting part is what each session leaves behind. Every run records full video, screenshots, logs, network traffic and CPU and memory use. Expo says it plainly: "Verification is one of the new bottlenecks." And the line that sums up the product: "Instead of 500 lines that just look about right, the reviewer gets a recording that shows the change works." Their example is an agent that ran an app at the largest text size, found the overflow, fixed it and attached before and after screenshots to the PR. A human can open a live browser view and take over mid-session, or share the session link with a designer who never installs Xcode.
There's also a quiet piece of agent hygiene. No session runs longer than two hours, and you can set a shorter cap plus an idle timeout, so cleanup doesn't depend on an agent remembering to clean up. Pricing is $0.10 per simulator minute on any paid EAS plan, with 60 free minutes a month on Starter, Production and Enterprise until 2027. It plugs into Claude Code, Codex and Cursor through a published skill: https://github.com/expo/skills/tree/main/plugins/expo/skills/eas-simulator
This is the same idea as AWS Emulator a day earlier, from the other end of the stack. AWS made real AWS the answer key for agent-written code. Expo makes a recording the answer key for agent-written UI. When code gets cheap, the thing you actually buy is proof. Expect every dev-tool company to ship some version of "evidence attached" within a year.
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The interesting part is what each session leaves behind. Every run records full video, screenshots, logs, network traffic and CPU and memory use. Expo says it plainly: "Verification is one of the new bottlenecks." And the line that sums up the product: "Instead of 500 lines that just look about right, the reviewer gets a recording that shows the change works." Their example is an agent that ran an app at the largest text size, found the overflow, fixed it and attached before and after screenshots to the PR. A human can open a live browser view and take over mid-session, or share the session link with a designer who never installs Xcode.
There's also a quiet piece of agent hygiene. No session runs longer than two hours, and you can set a shorter cap plus an idle timeout, so cleanup doesn't depend on an agent remembering to clean up. Pricing is $0.10 per simulator minute on any paid EAS plan, with 60 free minutes a month on Starter, Production and Enterprise until 2027. It plugs into Claude Code, Codex and Cursor through a published skill: https://github.com/expo/skills/tree/main/plugins/expo/skills/eas-simulator
This is the same idea as AWS Emulator a day earlier, from the other end of the stack. AWS made real AWS the answer key for agent-written code. Expo makes a recording the answer key for agent-written UI. When code gets cheap, the thing you actually buy is proof. Expect every dev-tool company to ship some version of "evidence attached" within a year.
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