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+## Changelist
+
+- Created Express backend with Socket.IO support
+- Implemented real-time messaging between connected users
+- Added chat history for newly connected users
+- Added username persistence using localStorage
+- Added online user counter
+- Added join announcements with a 10-minute repeat window
+- Added message timestamps
+- Added Enter-to-send functionality, with Shift+Enter for a new line
+- Added auto-scroll to latest message
+- Added own-message highlighting to distinguish sent from received
+- Styled chat interface with responsive CSS
+- Configured CORS and Express middleware
+- Added a /health endpoint for deployment health checks
+- Rendered messages with textContent to prevent script injection
+- Validated and trimmed usernames on the server
+- Capped chat history at 200 messages and message length at 500 characters
+- Re-sent the username on every reconnect so messages keep the correct author
+- Cleared the message list before replaying history to prevent duplicates
+- Loaded the Socket.IO client from a pinned CDN version matching the server
+- Moved the backend URL into config.js so the frontend can be hosted separately
+- Added a build step to override the backend URL from an environment variable
+- Added .gitignore and removed node_modules from version control
+- Added netlify.toml and render.yaml to configure both deployments
+- Deployed the backend on Render and the frontend on Netlify
+
+## Known limitations
+
+- Messages are stored in memory, so the history resets when the backend restarts
+- The backend sleeps after 15 minutes idle on the free tier, so the first load can take around 50 seconds