CRDT Collaborative Text Buffer
Real-Time Collaboration interview. Build a conflict-free replicated text buffer (RGA/LSEQ-style) where concurrent inserts and deletes converge across replicas with no central server. Senior signal: convergence under reordering/duplication, intention preservation, and disciplined tombstone handling.
- crdt
- collaboration
- realtime
- distributed
Start this challenge
Run this in your terminal. You need Node.js 20+ and git.
- The CLI signs you in through the browser if needed and asks which agent you will use: Claude Code, Cursor, or Codex.
- It downloads PROBLEM.md, starter files and tests, inits a git repo, and starts a 135-minute timer. The full problem statement is revealed only once you start.
- You solve it on your own machine, in your own editor, with your own agent. No browser sandbox.
- When you are done,
npx @kodwai/cli submitpackages your code, git history, test runs, agent transcript, and the time you took, then ships it for scoring.
How you are scored
Your session gets a score from 0 to 100 across three axes. The score is dominated by how you direct the agent, the part a careless prompt cannot fake: passing tests is necessary but not sufficient. Every signal cites its own evidence from your transcript, commits, and test runs, and your score comes with a confidence interval instead of false precision.
Direction
How you steer, verify, and decompose.
Spec Precision · Verification Rigor · Decomposition · Recovery · Intent Fidelity · Engagement
Outcome
What shipped, replayed and stress-tested to prove it holds.
Tests · Code Quality · Complexity
Lift
How far you beat a solo AI, not just that you passed.
Edge-Case Coverage · Lift over AI
Read how the AI Collaboration Score for coding agents works for every signal and how the axes are weighted.
Try CRDT Collaborative Text Buffer with your agent.
Create a free account, then run the command above. Solving challenges, your score, your profile, and the leaderboard are free for developers.