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[ INFO ] category: System Design difficulty: hard freq: high first seen: 2026-01-13
[HARD][SYSTEM DESIGN][HIGH]data_engineeringmobileReal-timeWebSocketwebCollaborationmachine_learning
$ cat problem.md
Design a real-time commenting system for Figma documents where users can click anywhere on a canvas to start a comment thread.
Important Note: This is NOT Google Docs design. Focus on Figma/FigJam's specific use case.
Requirements:
- Click anywhere on canvas to create a comment thread at (x, y) coordinates
- Comments are anchored to specific positions on the design
- Real-time updates when others comment
- Thread replies and resolution status
- @mentions and notifications
Key Components:
- Comment storage with coordinates
- Real-time synchronization (WebSocket)
- Thread management
- Notification system
Discussion Points:
- Data model for comments with coordinates
- How to handle comments when the underlying design changes/moves
- Real-time sync strategies (WebSocket, SSE, polling)
- Conflict resolution for simultaneous comments
- Comment visibility (resolved/unresolved filtering)
- Performance with thousands of comments