Design a Real-Time Collaborative Editing System
Last updated: May 21, 2025
Quick Overview
Design a system that enables multiple developers to edit the same file simultaneously in Cursor. Handle conflict resolution, cursor synchronization, and how AI suggestions interact with concurrent edits.
Cursor
May 21, 20258
6
3,569 solved
Design a system that enables multiple developers to edit the same file simultaneously in Cursor. Handle conflict resolution, cursor synchronization, and how AI suggestions interact with concurrent edits.
Real-time collaboration in a code editor is hard enough, but adding AI-generated edits creates unique challenges. This question tests your knowledge of CRDTs or OT, distributed systems, and how to maintain consistency when both humans and AI are modifying code simultaneously.
What the Interviewer Expects
- Choose and justify a conflict resolution strategy (CRDT vs OT)
- Design the synchronization protocol between multiple editor instances
- Handle AI-generated edits as a special participant in the collaboration
- Address latency and offline scenarios
- Discuss undo/redo semantics in a multi-user environment
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How would you handle a network partition where two users make conflicting edits?
- How do AI suggestions interact with a collaborator's cursor position?
- How would you scale this to support thousands of concurrent sessions?
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Practice System Design ProblemsSample Answer
Requirements
Functional Requirements
- Real-Time Collaboration: Multiple developers can edit the same file simultaneously with live updates.
- AI Suggestions: AI can propose code edits, which should ...
Capacity Estimation
Assuming Cursor has about 1 million users, and we expect 1% to use the collaborative editing feature concurrently:
- Concurrent Users: 10,000 active users.
- Edits Per User: Average of 5 edits...
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