The rule: no error shown to you requires engineering knowledge to interpret. When Prototo can’t recover on its own, it tells you what to do.
What you see, and what to do
| What you see | What to do |
|---|---|
| A component couldn’t be found | Click Reload in the toolbar under the iPhone |
| A screen has an error | Ask your agent: fix any errors in the [ScreenName] screen |
| Prototo is already running | Another Prototo window has the Simulator. Quit it, then try again |
| Prototo needs to update | Nothing to do: Prototo updates the project when you open it. If you had published it, click Publish once afterwards so your link opens on the new app. If the update fails, Publish and Export flow wait: click Try again in the message that appears (or Not now to keep working without updating) |
| “This prototype was made with an older version of Prototo” in the Prototo app, or “needs an update” on your share page | Open the project in Prototo Desktop. It updates itself, then click Publish. The link stays the same |
| Can’t reach your device | Check your iPhone and Mac are on the same Wi-Fi (or use your iPhone’s hotspot, see Preview on iPhone) |
| Something went wrong | Click Reload in the toolbar under the iPhone |
The escape hatch: Reload
Click Reload in the toolbar under the iPhone. This fixes most stuck states: Prototo clears its caches and restarts your prototype, then the preview comes back.
If taps stop landing on the preview but the picture keeps moving, choose View › Restart Preview instead.
A screen has an error
If your agent writes a screen that won’t run, Prototo tells you which one. Ask your agent:
fix any errors in the [ScreenName] screenIt reads the file, finds the issue, and rewrites it, without you seeing the underlying error.
The iPhone preview isn’t showing
Prototo checks Xcode and the iOS Simulator when it starts. If something is missing, it shows the step to fix it. If everything is installed and the preview still doesn’t appear, choose View › Restart Preview.
My agent isn’t reading my design system
AGENTS.md and DESIGN.md must be at the root of your project folder, not inside a subfolder. Prototo starts your agent in the project folder for you, so it picks them up automatically.
A custom component library isn’t generating the right screens
Add 2 or 3 component examples to an ## Examples section in DESIGN.md, then ask your agent to regenerate the screen. Two or three examples cover most libraries. It works out the rest.
I need to start fresh
Click New project in Prototo and give it a new name. Your old project stays in its folder until you delete it from Finder.
Still stuck?
Reach out via prototo.app .