> ## Documentation Index
> Fetch the complete documentation index at: https://docs.langchain.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Preview builds

> Create temporary preview deployments for pull requests to test Agent Server changes before merging.

Preview builds create temporary **preview deployments** for pull requests. Use a preview deployment to test Agent Server changes in isolation before you merge them into the branch that runs your parent deployment.

When a pull request triggers a preview build, LangSmith builds the latest commit from the source branch as the preview deployment's first revision. Each subsequent commit to that branch triggers a new revision.

<Note>
  Preview builds are in public beta and are available only on LangSmith Cloud for deployments created through the GitHub integration.
</Note>

## Enable preview builds

To enable preview builds:

1. From the **Deployments** view, select a deployment.
2. In the top-right corner, select the gear icon (**Deployment Settings**).
3. Scroll to the **Preview Builds** section.
4. Select **Enable preview builds**.
5. Select a trigger mode:
   * **Every PR**: Any pull request against the deployment branch triggers a preview build.
   * **Label only**: A pull request triggers a preview build only when it has the configured label.
6. Configure the preview limits:
   * **Idle TTL**: The time a preview deployment can remain inactive after its latest revision before LangSmith deletes it.
   * **Max concurrent previews**: The maximum number of preview deployments that can run concurrently for the parent deployment.
7. Select **Save**.

## Manage secrets

A preview deployment inherits the parent deployment's secrets when LangSmith creates it. You can override the inherited secrets on the preview deployment.

Changes to the parent deployment's secrets do not propagate to existing preview deployments.

## Delete preview deployments

LangSmith deletes a preview deployment when its idle TTL expires. You can also delete it manually at any time.

Deleting the parent deployment deletes all of its preview deployments.

## See also

* [Deploy on Cloud](/langsmith/deploy-to-cloud)
* [Implement a CI/CD pipeline](/langsmith/cicd-pipeline-example)

***

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