Implement node chat with websocket room sync

[4xmplme]

Summary

• implement a full-stack Node.js chat app (server + client)
• add username persistence in localStorage and submit username to server
• implement room create/rename/join/delete and room message history loading
• add WebSocket realtime updates for room list and new messages
• harden realtime edge cases (stable message id, duplicate append protection, reconnect safety, fallback room guard)

Test plan

• Run npm test
• Save username and verify persistence after reload
• Create, rename, join, and delete rooms (except General)
• Verify previous room messages are loaded on join
• Verify two tabs receive realtime room/message updates

[mateacademy-ai-mentor]

Review Summary

Your solution is approved. The implementation successfully delivers a complete full-stack Node.js chat application with all required functionality: username management with localStorage persistence, room operations (create/rename/delete/join), message handling with author/time/text fields, and WebSocket real-time updates. The code demonstrates solid error handling, input sanitization, and proper separation of concerns between the REST API and WebSocket layers. Previous messages are correctly fetched when joining a room via the loadMessages() function, and the fallback room protection ensures users always have a room to interact with. Great work on implementing all the core requirements in a well-structured manner.

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