Frontend System Design Essentials: Client Schema Drift Explained

👉 Frontend System Design Essentials — Course: https://icodeit.thinkific.com/courses/frontend-system-design-essentials 👉 Frontend System Design Essentials — Book: https://leanpub.com/frontend-system-design-essentials/ We spend a lot of time on backend API contracts, database migrations, and backward compatibility. But there is a hidden data store we often change without enough thought: localStorage. When you change the shape of data in the browser, that is a schema change — except you cannot run one migration for every user device, and you cannot undo a value once it is written. In this video I recreate a real production failure using a board app. A simple assignee-filter feature goes from a CSV string to a JSON object. The deploy looks fine. The rollback looks fine. The app can still be broken. 00:00 localStorage is a schema change 01:21 About the channel 01:37 The feature — Version 1 (CSV) 03:32 Changing the format — Version 2 (JSON) 05:45 Why this is easy to miss 06:23 Rollback failure — old code, new data 08:27 A better mental model 09:14 How to make it safer 09:24 Pattern 1 — Defensive reading 10:51 Pattern 2 — Version tag 12:14 Pattern 3 — Key versioning 13:23 Summary 📘 MY BOOKS & COURSES 👉 Frontend System Design Essentials (Course): https://icodeit.thinkific.com/courses/frontend-system-design-essentials 👉 Frontend System Design Essentials (Book): https://leanpub.com/frontend-system-design-essentials/ 👉 React Anti-Patterns (Amazon): https://www.amazon.com/dp/1805123971 👉 More Tutorials on Advanced Patterns: https://icodeit.com.au/tutorials/advanced-network-patterns-react 📩 STAY CONNECTED 🧠 Newsletter (system design & clean code): https://juntao.substack.com 🌐 Website & Blog: https://icodeit.com.au 🐦 Twitter / X: http://twitter.com/JuntaoQiu 📺 YouTube (subscribe): https://www.youtube.com/@icodeit.juntao --- #frontend #systemdesign #localStorage #webdevelopment #react #frontendarchitecture #deployment #rollback #seniordeveloper