Full-Stack Developer Assessment Template

You're building a task list. Tasks update optimistically when the user checks them, but the server may reject the update. What's the safest pattern?

• A.Disable the checkbox until the server responds
• B.Update UI immediately; revert on server error
• C.Update UI immediately; show success toast regardless
• D.Debounce all updates by 500ms

Build a simple task list feature across 3 files: 1. `db.sql` — create a tasks table with id, title, done, user_id, created_at 2. `api.ts` — Express routes for GET /tasks, POST /tasks, PATCH /tasks/:id 3. `TaskList.tsx` — React component that fetches, renders, and updates tasks optimistically Requirements: validation on POST, auth via JWT, optimistic updates with rollback.

Given `users(id, name)` and `tasks(id, user_id, title, done)`, write a query that returns each user's name plus the count of their incomplete tasks (0 if none). Order by count descending.

A user complains the task list is slow. Walk through how you'd investigate, starting from the browser. Include specific tools and metrics you'd check.

Which approach is best for storing a user's session after login?

• A.localStorage with plain JWT
• B.sessionStorage with refresh logic
• C.httpOnly secure cookie + CSRF protection
• D.IndexedDB encrypted with Web Crypto