Design a Collaborative Todo List

Design a collaborative to-do service centered on shared lists. Teammates can create lists, add and modify items, assign an item to an owner, set due dates, reorder items inside a list, mark items complete, and observe other collaborators’ edits appear in near real time on web and native mobile clients. Your design should explicitly cover the data model, the read and write path, real-time synchronization, concurrent editing behavior, permissions, and the consistency…