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Browser Preview

As you build your app with CatDoes, a live browser preview appears in a panel alongside your conversation. Every change the agent makes — new screens, design tweaks, feature additions — is reflected in the preview automatically. The preview panel is resizable on desktop and tablet. On mobile devices, you can switch between the conversation and preview using tabs.

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Auto-Refresh

The preview refreshes automatically when:
  • The agent finishes writing or modifying code files
  • A codebase scan completes
  • The agent explicitly reloads the preview after installing packages or making structural changes
You can also manually refresh the preview at any time using the refresh button in the preview panel.

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Hard Reload vs Soft Reload

CatDoes supports two types of preview reloads:
  • Soft reload — Refreshes the preview pane without restarting the development server. Used for most code changes.
  • Hard reload — Fully restarts the development server. Used after installing new packages or making changes that require a fresh server start.
The agent automatically chooses the appropriate reload type based on the changes it makes.

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Runtime Errors

If your app encounters a runtime error during preview, CatDoes captures it and makes it available to the agent. The agent can inspect these errors and attempt to fix them automatically as part of its workflow.

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Mobile Preview with Expo Go

Beyond the browser preview, you can test your app on a physical mobile device using Expo Go.
  1. Download Expo Go on your iOS or Android device.
  2. Use the Scan QR Code option in the preview panel to get a QR code for your project.
  3. Scan the QR code with your device to open the app in Expo Go.
This lets you test touch interactions, native features, and real-world performance directly on your phone.
The browser preview renders your app in a web view, which may look or behave slightly differently from the native mobile experience. Use the Expo Go preview on a physical device to verify native-specific behavior.
Use the QR code to share your in-progress app with teammates or stakeholders for quick feedback — no install required, just the Expo Go app.