Comments on Objects
Comments enable teams to add contextual notes and discussions directly to traces, observations, sessions, and prompts within Langfuse. This feature facilitates collaboration by allowing team members to:
- Flag issues or anomalies in specific traces
- Share insights about particular model outputs
- Document edge cases and debugging notes
- Coordinate on prompt improvements
- Leave feedback during development and review cycles
Supported Object Types
Comments can be added to the following Langfuse objects:
- Traces - Comment on complete execution flows
- Observations - Add notes to specific LLM calls, spans, or events
- Sessions - Discuss user interaction patterns
- Prompts - Collaborate on prompt versions and improvements
Adding Comments
Each supported object page displays a comment button in the interface. The button shows:
- The current comment count (capped at “99+” for readability)
- A disabled state if you don’t have read permissions
- An active state when comments are available or you can create them
Clicking the comment button opens a side drawer containing:
- Comment Thread - All existing comments displayed chronologically
- Composer - Text area for writing new comments (if you have write permissions)
- Markdown - Support basic markdown formatting
- @Mentions - Tag team members in comments using @mentions
- Reactions - Add emoji reactions to comments
Comment authors can only delete their own comments. Project admins cannot delete other users’ comments through the UI.
@Mentions
You can tag team members in comments using @mentions to notify them about important findings or discussions. This is especially useful when you need someone’s attention on a specific trace, observation, or issue.
How to Use @Mentions
- Start typing
@in the comment composer - An autocomplete menu appears showing all project members
- Select a team member from the list or continue typing to filter
- The mention is inserted into your comment as a clickable badge
Email Notifications
When you mention someone in a comment:
- They receive an email notification with the comment content and context
- The email includes a direct link to the object (trace, observation, session, or prompt)
- Users can manage their notification preferences per project
Managing Notification Preferences
Team members can control when they receive email notifications for mentions:
- Navigate to project settings to configure notification preferences
- Choose to enable or disable mention notifications per project
- Preferences apply to all future mentions in that project
Only project members can be mentioned in comments. The autocomplete menu automatically filters to show only users who have access to the current project.
Reactions
Add emoji reactions to comments for quick acknowledgments without writing a full response. Reactions are a lightweight way to show agreement, appreciation, or simply acknowledge that you’ve seen a comment.
How to Add Reactions
- Hover over any comment to reveal the reaction button
- Click to select an emoji from the reaction picker
- Your reaction appears next to the comment with your name
- Click your existing reaction again to remove it
Reactions help keep comment threads focused while still allowing team members to provide quick feedback and show engagement with the discussion.