Apps break, that is normal. FlutterGo is built so that most breakage fixes itself. After each change, FlutterGo checks your code with flutter analyze and sends what it finds to the agent. Build and runtime errors come with a Fix with AI button, and fixing build errors does not use a credit.
Here we show you the testing loop: run the app, read what went wrong, let the agent fix it, start fresh when the preview acts strangely, and test like a user, on other screen sizes and on a real phone.
You don't need to install anything. Everything below happens in the cloud preview.
What you need#
- Your project has generated code. If the preview says "Ask the agent to scaffold pubspec.yaml and lib/main.dart, then click Build.", send a prompt first.
- You know the right panel: the run button, Analysis, Ship and Show code. See Preview, run & build.
- On the Free plan, credits on your account: the preview runs only while you have credits left.
How to do it#
1. Run the app#
Press the round button at the top of the right panel: Run app, or Rebuild once the app has run. The app builds in the cloud and opens in the phone frame. The small square on the edge of the button is Stop.
After the agent changes your app, you usually don't need to press it: FlutterGo checks the code and rebuilds the preview by itself.
2. Read the Analysis box#
FlutterGo runs flutter analyze before each build and after every change the agent makes. While it runs, Analysis at the top of the right panel says "Running flutter analyze…". If it finds errors, it shows how many, for example 5 errors:
- Click the count to open Project issues. Click an issue to open that file at the line.
- Fix with AI sends the errors to the agent.
- Check again runs the check once more. Use it after you changed code yourself, or when the list looks out of date.
When the code is clean, the box disappears.
From Build your first app: Analysis finds five errors, and the agent fixes them while the preview waits.
3. Let the automatic repair work#
Auto-repair is always on. When the check finds errors after the agent's turn, FlutterGo often sends them back to the agent on its own. If you press Rebuild while errors remain, it sends them too: "Sent 5 errors to the agent to fix (no credit charge)". When the agent is done, FlutterGo checks again and rebuilds the preview.
When something still needs you, Fix with AI appears in three places:
- in Analysis, for errors the check found;
- on the phone, when it says "The build did not finish";
- under the run button, next to Runtime errors (browser console), when the running app hits an error.
Fixing build errors does not use a credit. The chat says so: "Fixing build errors, which does not use your credit."
4. Ask the agent to fix it#
The fastest debugging tool is the conversation. Say what you did, what you expected and what happened, and name the screen: "On the cart screen, tapping Checkout does nothing." If you have an error message, paste it into the same message. The agent finds the cause and fixes the code, and the preview rebuilds when it is done.
Tip: Not sure what is wrong? Switch the chat to Plan first. The agent looks into it and explains without changing your code; switch back to Build to apply the fix. Each message costs 1 credit.
5. Start fresh: Stop, then Rebuild#
The cloud studio has no Clean, Pub get, Hot reload or Hot restart buttons. FlutterGo takes care of packages when it builds. When the preview behaves strangely:
- Click Stop (the small square on the run button).
- Press the run button again (Rebuild).
- Still wrong? Ask the agent: "the preview looks wrong after the last change, please check it and rebuild".
Every rebuild starts your app from its first screen, with fresh state. Asking the agent for "hot reload" or "hot restart" rebuilds the preview too.
Success: Most fix-and-check loops look like this: the agent fixes, FlutterGo checks and rebuilds, you confirm in the preview.
6. Test like a user#
Before calling a screen done:
- Click through every button and back gesture in the phone frame.
- Try empty and very long input in every text field.
- Switch the device in the dock beside the phone: try a small phone (iPhone SE), a tablet (iPad Pro 11″) and Web / PWA.
- Try it on a real phone. Share, under Ship, gives a link and a QR code for any phone's browser. On Starter and up, Build APK gives an Android file you can install. For iPhones, publish a TestFlight build: see Publishing to the App Store.
Troubleshooting#
Problem: The preview won't start or looks stuck. Possible causes: The agent is still writing code, a first build is still running, or, on the Free plan, your credits ran out. Solution:
- Read the status under the run button. Writing code… means the agent is still working: wait for it.
- Click Stop, then the run button again.
- If Analysis shows errors, click Fix with AI.
- On the Free plan, if a message says you are out of credits, buy a credit pack or upgrade.
Problem: The build succeeds but the screen is gray or blank. Possible causes: The app hit an error while starting. Solution:
- Look under the run button for Runtime errors (browser console), and click Fix with AI next to it.
- Otherwise click Rebuild.
- Still blank? Tell the agent what you see and on which screen.
Problem: "Running flutter analyze…" shows issues after generation. Possible causes: That's normal while the agent works: it repairs its own findings. Solution:
- Wait for the run to finish. Most issues disappear on their own.
- If errors stay, click Fix with AI, or Check again to run the check once more.
Problem: A rebuild stops with "… analyze errors — fix or send to AI before build". Possible causes: The code has errors, for example after a hand edit or an interrupted agent run. Solution:
- FlutterGo sends the errors to the agent for you. Wait for the agent to finish.
- If the errors stay, click Fix with AI in Analysis, then Rebuild.
Problem: The phone says "The build did not finish". Possible causes: A compile problem, or a problem on FlutterGo's builder. Solution:
- Click Fix with AI on the phone.
- When the agent is done, click Rebuild.
- "The builder ran out of disk space" is a problem on FlutterGo's side: wait a moment, then click Rebuild.
Problem: My change doesn't show up in the preview. Possible causes: The agent is still working, the check found errors, or the rebuild hasn't run yet. Solution:
- Wait until the status under the run button no longer says Writing code….
- Check Analysis for errors and click Fix with AI.
- Press Rebuild.
FAQ#
Do I have to run the analyzer myself? No. FlutterGo runs flutter analyze before each build and after the agent's changes, and the agent fixes the findings. Check again runs it on demand.
Where are Hot reload, Hot restart, Clean and Pub get? Not in the cloud studio. Every Rebuild restarts the app from its first screen, and FlutterGo takes care of packages when it builds. Asking the agent for a hot reload or a hot restart rebuilds the preview.
Where do I see print/log output from my app? The studio has no log console. Errors the running app throws appear under the run button as Runtime errors (browser console), with Fix with AI. To check a value while you test, ask the agent to show it on screen.
Can I test on a real device? Yes. Open the Share link, or scan its QR code, on any phone. On Starter and up, use Build APK (1 credit, refunded if the build fails) to install the Android app. For iPhones, use TestFlight (Pro and up). FlutterGo has no emulator or iOS Simulator of its own.
What should I tell the agent when asking for a fix? The screen you were on, what you did, what you expected and what happened. Paste any error text you have.
Does fixing errors cost credits? Fix with AI and the automatic repairs don't. A message you type costs 1 credit.
Where to go next#
- Preview, run & build, every control in the right panel.
- Working with the AI agent, writing the fix prompt.
- Troubleshooting & FAQ, product-wide fixes beyond code errors.