A build is stuck or slow

Most builds finish quickly. A longer one is not automatically a problem, and the desk tells you which part of the wait you are in. Nothing here needs your attention unless the build has actually stopped — When a build does not work covers that case.

What the preview is telling you

Building preview… — "The app is being built. It will appear here automatically once ready." The build is either running or waiting for its turn.
Fixing an issue… — the build failed and the agent is repairing it on its own. The line underneath names the attempt it is on. This is not something you have to chase; When a build does not work explains what happens next.
A thin line under the chat shows the agent's checklist, and Planning goals… means it is still working out the steps. The line under the chat names the step it is on right now.
The box you type in reads Wait... while the agent is working.

Why a build can take a while

Builds wait their turn. When a lot of builds are happening at once, yours can wait a while before it starts. A build that is waiting looks exactly like one that is running.
Each build step is given time to finish. Getting everything the app needs, and then building it, are separate steps, and each one is allowed a fixed amount of time before the platform treats it as failed and asks the agent to repair the app. The repair runs by itself when that happens.
A fresh session has to fetch your app's files first, so the first open can be slower than later ones. The desk names the stage it is in: Preparing a fresh workspace…, then Fetching your app's files…, then Setting things up…, then Starting your agent…. The fetching stage is the long one and can take a minute or more.
A long agent turn is not cut off while it is still producing something. The session is only closed after a long stretch with nothing coming out of it.

You do not have to watch it

There is no setting to switch on to be told when the agent finishes. Your browser asks for permission to send notifications by itself — when the session opens, and again when you send your first message — and that answer is the only switch. Allow it if you would like to be told.

A notification appears only while the tab is in the background, and it says either that the agent finished or that it has a question for you. Selecting it brings the desk back.

If you missed one, nothing is lost. Reopen the app from your desk and the result is there.

If the preview looks out of date

Select Refresh preview in the preview toolbar. That reloads the app without building anything, and it is the first thing to try when the agent says it has finished but you are still looking at the old screen.

If it still has not changed after that, the build has stopped rather than being slow. When a build does not work takes it from there.

Stop sending the same request

Sending another message while the agent is working does not start a second run or speed up the first one — it joins what the agent is already doing, and the box reads Wait... until the agent is ready for you. Wait for the current work to finish, then read the result.

Change less at once

If the same request keeps taking a long time, it is probably doing a lot. Ask for one part, check it in the preview, then ask for the next. Smaller requests finish sooner and are easier to correct when something is not right.

If it still does not finish

Waiting for a build's turn is the one part with no fixed limit, which is why a busy moment can look like a stall. Once your build starts, each step is allowed a fixed amount of time before the platform treats it as failed and asks the agent to repair the app. If the app still has not come back, describe the problem in the chat.

You can also return to a version that worked — see Go back to an earlier version. If the same thing keeps happening, Get help and report a problem.