Custom rules

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You can use custom rules in the GitLab Duo Agent Platform to ensure that generated output (for example, code or documentation) aligns with your specific instructions, or any other requirements such as development style guides.

The following Agent Platform features support custom rules:

Create custom rules

You can create custom rules at two levels, depending on how you use GitLab Duo:

Level GitLab UI Editor extensions GitLab Duo CLI
User-level: Apply to all of your projects no yes yes
Project-level: Apply only to a specific project yes yes yes

If you use a multi-root workspace in your IDE, you can create project-level custom rules for each project in the workspace.

If both user-level and project-level rules exist, GitLab Duo Chat applies both to conversations.

Prerequisites:

Note

Conversations that existed before you created any custom rules do not follow those rules.

Create user-level custom rules

User-level custom rules apply to all of your projects in your local environment.

  1. Create a custom rules file in your home directory:

    • On Linux or macOS, create the file at ~/.gitlab/duo/chat-rules.md.
    • On Windows, create the file at %APPDATA%\GitLab\duo\chat-rules.md.

  2. Add custom rules to the file. For example:

    - Don't put comments in the generated code
- Be brief in your explanations
- Always use single quotes for JavaScript strings

  3. Save the file.

  4. To apply the new custom rules, do any of the following as appropriate:

    • Start a new GitLab Duo Chat conversation.
    • Use an agent in a Chat conversation, discussion, issue, or merge request.
    • Trigger a flow.

If you have set a specific environment variable, then you create the custom rules file in a different location:

  • If you have set the GLAB_CONFIG_DIR environment variable, create the file at $GLAB_CONFIG_DIR/chat-rules.md.
  • If you have set the XDG_CONFIG_HOME environment variable, create the file at $XDG_CONFIG_HOME/gitlab/duo/chat-rules.md.

Create project-level custom rules

Project-level custom rules apply only to a specific project. You can use this method to apply a set of custom rules to the project for your team. For example, you can apply a set of development style guides that your team uses.

  1. In the root of your project, create a custom rules file: .gitlab/duo/chat-rules.md.

  2. Add custom rules to the file. For example:

    - Don't put comments in the generated code
- Be brief in your explanations
- Always use single quotes for JavaScript strings

  3. Save the file.

  4. For a project: Add the .gitlab/duo/chat-rules.md file to the Git repository. Chat, agents, and flows then automatically read the custom rules from the repository into context.

  5. To apply the new custom rules, start a new GitLab Duo conversation.

    You must do this every time you change the custom rules.

For more information, see the Custom rules in GitLab Duo Chat tutorial blog.

Update custom rules

To update your custom rules, edit and save the custom rules file. Then, start a new GitLab Duo conversation to apply the updated rules.

You cannot use Chat to edit your custom rules file directly.

To manage who must approve any changes to custom rules, use Code Owners.

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