Build a preview of each delivered pull request on your own Vercel project, and open it from the Brief's Review tab.
The Vercel connection lets reviewers try a delivered change in the browser before they merge it. When a Delivery to a repository with previews on finishes successfully, Hamster asks your Vercel project to build the delivered commit as a preview deployment. The Preview chip in the Brief's Review header opens it.
The builds run on your team's own Vercel account and use its Vercel plan. Hamster requests the build, shows its status, and links to it. Hamster doesn't create Vercel projects, and the preview opens on Vercel in a new tab.
Previews work for repositories connected through GitHub, GitLab, or Bitbucket. Cursor Origin repositories don't get previews, and their Review header has no Preview chip.
The connection also lets Hamster use Vercel in chat, to look up projects, deployments, and build logs, and to make changes to projects and deployments.
Deliveries by Hamster Cloud, Cursor Agents, OpenAI Agents, and Claude Agents request a preview automatically when they finish successfully. A Cursor Agents delivery to a GitLab or Bitbucket repository doesn't request one on its own, and neither does a Hamster Local delivery. For those, and for a pull request you linked by hand, click Create preview in Review.
If Vercel already built a deployment of the delivered commit, for example from its own Git integration, Hamster uses that deployment instead of starting a second build. If that deployment is already finished, the thread goes straight to Preview ready.
A successful delivery doesn't mean the preview is ready, because Vercel builds it separately. If a preview fails before its build starts, the delivery thread shows nothing, so check the Preview chip in Review.
Hamster doesn't build later commits on its own. When the pull request has newer commits than the preview, the Preview details say This PR has newer commits, and Update preview builds the pull request's latest commit.
Connecting Vercel for the team, and turning previews on, needs the Creator role or higher. Before you turn previews on for a repository:
Then:
web · Acme for a Vercel team or web · Personal for a personal Vercel account. If several projects match a repository, Hamster picks one for you and shows Change so you can pick another.A repository stays off until someone turns it on. To pause previews, turn its switch off. Hamster keeps the setup, so you can turn it back on later.
You can't turn a repository on until its project has a ready production deployment. Until then, the row says the project "needs its first production deployment" and offers Check again and Open in Vercel. Deploy to production on Vercel, then click Check again. If none of your connected repositories has a Vercel project, the dialog offers Create project in Vercel and Check again.
Hamster lists projects from the connected personal Vercel account and up to 10 of its teams. If there are more teams, the dialog says "Showing projects from your first 10 Vercel teams."
If a repository's previews are set up on another Vercel connection, the row says so. When this connection has no project for that repository, the row has no switch, so manage it from the other connection. When it has one, the row warns that turning the switch on moves the repository's previews to this connection.
If a project was disconnected from its repository on Vercel, the row says the repository "is no longer linked to a Vercel project". Connect them again in the project's Git settings on Vercel and click Check again. If another project still matches, the row asks you to choose one.
Once Hamster has started builds, the dialog shows a usage line such as "Last 30 days: 12 preview builds, 41 build min". It counts only builds Hamster started, not deployments Hamster reused from Vercel.
The Preview chip sits in the Review header beside the pull request's state pill. When the preview is ready, click the chip to open it on Vercel in a new tab, or click the caret for the details: the status, the commit and branch it built, the build minutes when Hamster started the build, a button to copy the deployment URL, and Open preview. Until the preview is ready, click the chip itself for the details. While Vercel builds, the details update on their own.
The details offer the one action that applies:
Anyone on the team can see and open a preview. Creating, updating, retrying, or requesting a new preview needs the Creator role or higher. Reviewers see the status without those buttons, so they ask a Creator, Admin, or Owner to build the preview.
Vercel's Deployment Protection controls who can open a project's preview URLs, and it applies to the link Hamster shows. If the project is protected, people need access on Vercel to open the preview.
The delivery thread shows Preview failed with the error. In Review, the Preview details say Preview build failed and name the cause in plain words. The full error sits under Details.
If the details say Preview unavailable, the preview stopped before it was ready, for example because the pull request was unlinked from the Brief or Vercel was disconnected while it was building. Click Request new preview. If Vercel was disconnected, connect it again and turn the repository back on in Configure previews first.
The Preview details can also show a notice to people who can request previews:
If a delivery finished but its thread shows no preview, check that:
If a repository is missing from the Vercel previews dialog, check that:
Disconnecting the team's Vercel connection needs the Creator role or higher. Hover the Vercel card and click the x, or right-click it and choose Disconnect, then confirm with Delete.
Hamster removes the preview setup for every repository on that connection. Previews that were ready still open from Review. Previews still building become unavailable. Hamster deletes nothing on Vercel.