Check the Screen
Claude first opens the changed screen on your own computer and shows it to you. You ask for a preview only when you want to check with real data or email, or show it to someone else.
Two places to check
| The screen Claude opens (the usual one) | A preview (only when you ask) | |
|---|---|---|
| Where it runs | On your own computer | In a trial environment on the internet |
| The data in it | Made-up test data | A copy of the production data |
| Time to prepare | Seconds (a few minutes the very first time) | 10 to 20 minutes |
| Can others see it? | No | Yes, if you send them the link |
| Cost | None | It costs money while it runs |
Nothing you do in either place changes production data. Try things freely.
Check on the screen Claude opens
When the change is ready, Claude opens the app in the browser inside the Claude app and shows it to you. It runs only on your own computer. This way of checking is called checking locally.
If Claude does not open it, or you want to look again, ask like this.
- The first time takes a few minutes. A trial database is being fetched. From the second time on it opens in seconds.
- On Windows, the first time, you may be asked whether a Microsoft component may be installed. It is the Visual C++ Redistributable, which the trial database needs to run. Allow it.
- The data in it is made-up test data. The names of companies and people are invented. You may register and delete things. If it gets into a mess, ask "Please recreate the test data".
- It opens as an administrator. To look as someone else, ask "Please show it to me as staff" or "Please show it to me as a client".
- When you are done, ask "Please stop it". While it stays open, it keeps using your computer's memory. Claude stops it when the PR is created.
What to look at when you check:
- Is the change you asked for there? Check that it matches what the plan described.
- Is anything around it broken? Use the screens before and after the one that changed, and any feature that might be related.
- Try to break it. Save with nothing entered, enter a very long text, press a button twice in a row.
- Look at it with no data. Check that nothing looks wrong when not a single item is registered.
- Look at a phone's width too. If the app is used on phones, ask "Please show it to me at a phone's width".
What the screen Claude opens cannot tell you
| What you want to check | Why it cannot be checked there |
|---|---|
| How it looks with real data (speed with many items, names written in different ways) | Your computer only has made-up test data |
| Whether email arrives, files can be saved, or features that use Slack or AI work | The keys for connecting to outside services are not kept on your computer. The screen says "not set up" |
| Signing in, and what each person is allowed to do | The screen Claude opens needs no sign-in |
| Having someone else look at it | It can only be opened on your computer |
When you want to check these, ask for a preview.
Ask for a preview
Ask after the PR exists, in the same conversation that created it.
Claude also creates a preview when you say things like:
- "I want to try it with real data" or "I want to see it with the production data"
- "I want to try whether the email arrives" or "I want to try whether a file can be saved"
- "I want to show it to 【name】"
In 10 to 20 minutes, the "Preview deployment" comment on the PR turns into a link with the app's name.
- lost-and-found
- Open an app link above.
- Sign in when the sign-in page appears (e.g. request a magic link).
- You are sent back to the app — your session should persist while you test.
Why it was made: the preview label is on this PR.
It is removed automatically, and the label is taken off, 48 hours after it was last rebuilt. When you are done with it, remove the preview label and it is removed right away.
- PR Checks / check
- PR Preview (Neon + Staging Deploy) / Deploy to Staging (Preview)
- Open the link with the app's name inside the comment.
- If a sign-in screen appears, sign in with your usual email address.
- After you sign in, the preview of the app opens.
If it shows "Access denied", ask an administrator to let you open the app. If you cannot sign in, ask an administrator to let you sign in to previews as well.
This happens for the first PR of a new app and for a PR that changes how sign-in works. These changes can only be checked in a preview, so one is made automatically. When a change affects how email or file saving behaves, Claude tells you "I will create a preview".
Claude may ask this for a change that might be better seen with real data, such as a list that could become slow with many items. If you are unsure, you may reply "Go ahead without one". You can still ask for it later.
Remove a preview
A preview costs money while it runs. Remove it when you are done.
Even if you do not ask, it is removed automatically:
- when the PR is merged or closed
- 48 hours after it was last rebuilt
To use it again after it was removed, ask "Please create a preview".
Quiz
You had the text of a notification email changed. On the screen Claude opened, nothing arrives when you do the thing that sends the email. What do you do?