Cursor rule

1---
2alwaysApply: false
3---
4 
5## Use Transitions for Non-Urgent Updates
6 
7Mark frequent, non-urgent state updates as transitions to maintain UI responsiveness.
8 
9**Incorrect (blocks UI on every scroll):**
10 
11```tsx
12function ScrollTracker() {
13  const [scrollY, setScrollY] = useState(0)
14  useEffect(() => {
15    const handler = () => setScrollY(window.scrollY)
16    window.addEventListener('scroll', handler, { passive: true })
17    return () => window.removeEventListener('scroll', handler)
18  }, [])
19}
20```
21 
22**Correct (non-blocking updates):**
23 
24```tsx
25import { startTransition } from 'react'
26 
27function ScrollTracker() {
28  const [scrollY, setScrollY] = useState(0)
29  useEffect(() => {
30    const handler = () => {
31      startTransition(() => setScrollY(window.scrollY))
32    }
33    window.addEventListener('scroll', handler, { passive: true })
34    return () => window.removeEventListener('scroll', handler)
35  }, [])
36}
37```
38