App preview
App preview runs your generated app on a temporary server so you can click through the real thing, with its real backend, before you deploy it.
You'll find it in the App preview tab of the Build workspace. It's available once at least one build run has produced code.
Start the preview
- Open the Build stage and select the App preview tab.
- Click Start preview server.
- Wait while the app boots (Starting preview...). It appears in the panel as soon as it responds.
Use the preview
| Button | What it does |
|---|---|
| Reload preview | Picks up the latest generated code changes. |
| Open preview in new browser tab | Opens the running app in a full browser tab. |
| Stop preview server | Stops the app and frees workspace resources. |
The preview sleeps after 15 minutes
To save resources, the preview stops after 15 minutes of inactivity. Click Start preview server to start it again. Nothing in your workspace changes. For an app that stays online, deploy it to the cloud.
Test before you deploy
Running the preview is the quickest way to confirm your app builds and works before you deploy it. If something looks wrong, describe it in the Build chat and the agent fixes it.
If the preview won't start
| Message | What to do |
|---|---|
| The preview failed to start. | Click Start preview server again. |
| The generated app did not respond after booting. | Check the Terminal tab for errors, then start it again. If the logs show an error, ask the agent in the Build chat to fix it. |
| The preview host could not be routed. | Start it again. If it keeps failing, contact support. |
| This preview was stopped for inactivity. | Start it again. Your work is untouched. |