---
url: /en/build/showcase/ai-review.md
description: >-
  Explains two methods for automatically performing AI code reviews on Pull
  Requests in CNB pipelines—using the AI Review plugin for automatic triggering
  or NPC events for on-demand reviews.
---
With AI capabilities, you can have pipelines automatically review Pull Requests (PRs), quickly discovering potential issues and improving code quality.

Cloud Native Build supports two ways to perform AI code review:

| Comparison | AI Review Plugin | NPC Event |
|------------|-----------------|-----------|
| Trigger | Automatically on PR events | On-demand via NPC mention in PR comment |
| Use case | Auto-review every PR | On-demand review, flexible control |
| Configuration | `.cnb.yml` in current repo | No config needed (custom NPC defined in NPC repo) |

Both methods use the `CNB_TOKEN` environment variable to call platform APIs. When mentioning a custom NPC role, the token represents the mentioned role's identity.

## Use AI Review Plugin

Use the [`cnbcool/code-review`](https://cnb.cool/cnb/plugins/cnbcool/code-review) plugin to automatically perform code review when PR events are triggered. This plugin is based on CodeBuddy CLI, supports multiple programming languages, automatically filters non-code files, and submits review results as comments on the PR.

### Configuration Example

```yaml title=".cnb.yml"
main:
  pull_request:
    - stages:
        - name: Code Review
          image: cnbcool/code-review:latest
          settings:
            comment: true
            max_comments: 10
            fail_on_critical: false
```

For more configuration options, see the [cnbcool/code-review plugin](https://cnb.cool/cnb/plugins/cnbcool/code-review).

## Trigger via NPC Event

Mention an NPC role in a PR comment to trigger the `pull_request.comment@npc` event, which runs an NPC pipeline to perform AI review.

### How to Trigger

* **System NPC**: Mention `@CodeBuddy` in the PR comment:

```text
@CodeBuddy Code review
```

* **Custom NPC**: First [configure a custom NPC role](../npc.md#custom-npc), then mention it in the PR comment:

```text
@cnb/feedback(Review Expert) Code review
```

### How It Works

1. Mentioning an NPC in a PR comment triggers the `pull_request.comment@npc` event.
2. The system loads the `.cnb.yml` from the NPC's repository and executes the corresponding event pipeline.
3. The pipeline uses `CNB_TOKEN` to call AI capabilities for review, and results are submitted as PR comments under the NPC's identity.

For detailed configuration, see [NPC documentation](../npc.md).

## Notes

* Both methods require the pipeline to have permissions to access the repository and submit comments.
* When triggered by an NPC event, the TOKEN permissions are limited to the current repository.
* If you need to modify code during review, enable [NPC Work Mode](../npc.md#work-mode).