GitLab Duo (Classic) AI models
- Tier: Premium, Ultimate
- Add-on: GitLab Duo Core, Pro or Enterprise
- Offering: GitLab.com, GitLab Self-Managed, GitLab Dedicated
Every GitLab Duo (Classic) feature uses a default model. GitLab might update default models to optimize performance. You can select a different model for a feature, which persists until you change it.
Default models
The following table lists the default model for each GitLab Duo feature.
| Feature | Model |
|---|---|
| Code Suggestions | |
| Code Generation | Claude Sonnet 4 Vertex |
| Code Completion | Codestral 25.01 Fireworks |
| GitLab Duo Chat | |
| General Chat | Claude Sonnet 4.5 Vertex |
| Code Explanation | Claude Sonnet 4 |
| Test Generation | Claude Sonnet 4.5 Vertex |
| Refactor Code | Claude Sonnet 4.5 Vertex |
| Fix Code | Claude Sonnet 4.5 Vertex |
| Root Cause Analysis | Claude Sonnet 4 Vertex |
| GitLab Duo for merge requests | |
| Merge Commit Message Generation | Claude Sonnet 4 Vertex |
| Merge Request Summary | Claude Sonnet 4 Vertex |
| Code Review Summary | Claude Sonnet 4 Vertex |
| Code Review | Claude Sonnet 4 Vertex |
| Other GitLab Duo features | |
| Vulnerability Explanation | Claude Sonnet 4.5 Vertex |
| Vulnerability Resolution | Claude Sonnet 4.5 |
| Discussion Summary | Claude Sonnet 4.5 Vertex |
| GitLab Duo for CLI | Claude Haiku 4.5 |
Supported models
The following tables list the models you can select for each feature.
Code Suggestions
| Model | Code Generation | Code Completion |
|---|---|---|
| Claude Sonnet 4 | ||
| Claude Sonnet 4 Vertex | ||
| Claude Sonnet 4.5 | ||
| Codestral 25.01 Fireworks | No | |
| Codestral 25.01 Vertex | No | |
| Codestral 25.08 Fireworks | No | |
| Codestral 25.08 Vertex | No | |
| Gemini 2.5 Flash | No |
GitLab Duo Chat (Classic)
| Model | General Chat | Code Explanation | Test Generation | Refactor Code | Fix Code | Root Cause Analysis |
|---|---|---|---|---|---|---|
| Claude Haiku 4.5 | No | No | ||||
| Claude Sonnet 3 | No | No | ||||
| Claude Sonnet 4 | ||||||
| Claude Sonnet 4 Vertex | ||||||
| Claude Sonnet 4.5 | ||||||
| Claude Sonnet 4.5 Vertex |
GitLab Duo for merge requests
| Model | Merge Commit Message Generation | Merge Request Summary | Code Review Summary | Code Review |
|---|---|---|---|---|
| Claude Sonnet 4 | ||||
| Claude Sonnet 4 Vertex | ||||
| Claude Sonnet 4.5 |
Other GitLab Duo features
| Model | Vulnerability Explanation | Vulnerability Resolution | GitLab Duo for CLI | Discussion Summary |
|---|---|---|---|---|
| Claude Haiku 3 | No | No | ||
| Claude Haiku 4.5 | No | No | ||
| Claude Sonnet 4 | ||||
| Claude Sonnet 4 Vertex | ||||
| Claude Sonnet 4.5 | ||||
| Claude Sonnet 4.5 Vertex |
Select a model for a feature
- Offering: GitLab.com
You can select a model for a feature in a top-level group. The model that you select applies to that feature for all child groups and projects.
Prerequisites:
- You have the Owner role for the group.
- The group that you select models for is a top-level group.
- In GitLab 18.3 or later, if you belong to multiple GitLab Duo namespaces, you must assign a default namespace.
To select a model for a feature:
- On the top bar, select Search or go to and find your group.
- Select Settings > GitLab Duo.
- Select Configure features.
- For the feature you want to configure, select a model from the dropdown list.
- Optional. To apply the model to all features in the section, select Apply to all.
Troubleshooting
When selecting models other than the default, you might encounter the following issues.
Model is not available
If you are using the default GitLab model for a GitLab Duo AI-native feature, GitLab might change the default model without notifying the user to maintain optimal performance and reliability.
If you have selected a specific model for a GitLab Duo AI-native feature, and that model is not available, there is no automatic fallback. The feature that uses this model is unavailable.
No default GitLab Duo namespace
When using a GitLab Duo feature with a selected model, you might get an error that states that you have not selected a default GitLab Duo namespace. For example, on:
- GitLab Duo Code Suggestions, you might get
Error 422: No default Duo group found. Select a default Duo group in your user preferences and try again. - GitLab Duo Chat, you might get
Error G3002: I'm sorry, you have not selected a default GitLab Duo namespace. Please go to GitLab and in user Preferences - Behavior, select a default namespace for GitLab Duo.
This issue occurs when you belong to multiple GitLab Duo namespaces, but have not chosen one as your default namespace.
To resolve this, set a default GitLab Duo namespace.