{user.name}
// uses 1 field
+}
+```
+
+**Correct: serializes only 1 field**
+
+```tsx
+async function Page() {
+ const user = await fetchUser()
+ return {name}
+}
+```
+
+### 3.6 Parallel Data Fetching with Component Composition
+
+**Impact: CRITICAL (eliminates server-side waterfalls)**
+
+React Server Components execute sequentially within a tree. Restructure with composition to parallelize data fetching.
+
+**Incorrect: Sidebar waits for Page's fetch to complete**
+
+```tsx
+export default async function Page() {
+ const header = await fetchHeader()
+ return (
+
+
+ )
+}
+
+async function Sidebar() {
+ const items = await fetchSidebarItems()
+ return
+}
+```
+
+**Correct: both fetch simultaneously**
+
+```tsx
+async function Header() {
+ const data = await fetchHeader()
+ return {header}
+ {data}
+}
+
+async function Sidebar() {
+ const items = await fetchSidebarItems()
+ return
+}
+
+export default function Page() {
+ return (
+
+
+ )
+}
+```
+
+**Alternative with children prop:**
+
+```tsx
+async function Header() {
+ const data = await fetchHeader()
+ return {data}
+}
+
+async function Sidebar() {
+ const items = await fetchSidebarItems()
+ return
+}
+
+function Layout({ children }: { children: ReactNode }) {
+ return (
+
+
+ )
+}
+
+export default function Page() {
+ return (
+ {fullName}
+} +``` + +**Correct: derive during render** + +```tsx +function Form() { + const [firstName, setFirstName] = useState('First') + const [lastName, setLastName] = useState('Last') + const fullName = firstName + ' ' + lastName + + return{fullName}
+} +``` + +Reference: [https://react.dev/learn/you-might-not-need-an-effect](https://react.dev/learn/you-might-not-need-an-effect) + +### 5.2 Defer State Reads to Usage Point + +**Impact: MEDIUM (avoids unnecessary subscriptions)** + +Don't subscribe to dynamic state (searchParams, localStorage) if you only read it inside callbacks. + +**Incorrect: subscribes to all searchParams changes** + +```tsx +function ShareButton({ chatId }: { chatId: string }) { + const searchParams = useSearchParams() + + const handleShare = () => { + const ref = searchParams.get('ref') + shareChat(chatId, { ref }) + } + + return +} +``` + +**Correct: reads on demand, no subscription** + +```tsx +function ShareButton({ chatId }: { chatId: string }) { + const handleShare = () => { + const params = new URLSearchParams(window.location.search) + const ref = params.get('ref') + shareChat(chatId, { ref }) + } + + return +} +``` + +### 5.3 Do not wrap a simple expression with a primitive result type in useMemo + +**Impact: LOW-MEDIUM (wasted computation on every render)** + +When an expression is simple (few logical or arithmetical operators) and has a primitive result type (boolean, number, string), do not wrap it in `useMemo`. + +Calling `useMemo` and comparing hook dependencies may consume more resources than the expression itself. + +**Incorrect:** + +```tsx +function Header({ user, notifications }: Props) { + const isLoading = useMemo(() => { + return user.isLoading || notifications.isLoading + }, [user.isLoading, notifications.isLoading]) + + if (isLoading) return
+ {user.followers} followers
+ {user.posts} posts
+
+ )
+
+ return (
+
+
+ )
+}
+```
+
+Every time `UserProfile` renders, `Avatar` and `Stats` are new component types. React unmounts the old instances and mounts new ones, losing any internal state, running effects again, and recreating DOM nodes.
+
+**Correct: pass props instead**
+
+```tsx
+function Avatar({ src, theme }: { src: string; theme: string }) {
+ return (
+
+ {followers} followers
+ {posts} posts
+
+ )
+}
+
+function UserProfile({ user, theme }) {
+ return (
+
+
+ )
+}
+```
+
+**Symptoms of this bug:**
+
+- Input fields lose focus on every keystroke
+
+- Animations restart unexpectedly
+
+- `useEffect` cleanup/setup runs on every parent render
+
+- Scroll position resets inside the component
+
+### 5.5 Extract Default Non-primitive Parameter Value from Memoized Component to Constant
+
+**Impact: MEDIUM (restores memoization by using a constant for default value)**
+
+When memoized component has a default value for some non-primitive optional parameter, such as an array, function, or object, calling the component without that parameter results in broken memoization. This is because new value instances are created on every rerender, and they do not pass strict equality comparison in `memo()`.
+
+To address this issue, extract the default value into a constant.
+
+**Incorrect: `onClick` has different values on every rerender**
+
+```tsx
+const UserAvatar = memo(function UserAvatar({ onClick = () => {} }: { onClick?: () => void }) {
+ // ...
+})
+
+// Used without optional onClick
+{avatar}
+}
+```
+
+**Correct: skips computation when loading**
+
+```tsx
+const UserAvatar = memo(function UserAvatar({ user }: { user: User }) {
+ const id = useMemo(() => computeAvatarId(user), [user])
+ return
+
+ )
+}
+```
+
+**Note:** If your project has [React Compiler](https://react.dev/learn/react-compiler) enabled, manual memoization with `memo()` and `useMemo()` is not necessary. The compiler automatically optimizes re-renders.
+
+### 5.7 Narrow Effect Dependencies
+
+**Impact: LOW (minimizes effect re-runs)**
+
+Specify primitive dependencies instead of objects to minimize effect re-runs.
+
+**Incorrect: re-runs on any user field change**
+
+```tsx
+useEffect(() => {
+ console.log(user.id)
+}, [user])
+```
+
+**Correct: re-runs only when id changes**
+
+```tsx
+useEffect(() => {
+ console.log(user.id)
+}, [user.id])
+```
+
+**For derived state, compute outside effect:**
+
+```tsx
+// Incorrect: runs on width=767, 766, 765...
+useEffect(() => {
+ if (width < 768) {
+ enableMobileMode()
+ }
+}, [width])
+
+// Correct: runs only on boolean transition
+const isMobile = width < 768
+useEffect(() => {
+ if (isMobile) {
+ enableMobileMode()
+ }
+}, [isMobile])
+```
+
+### 5.8 Put Interaction Logic in Event Handlers
+
+**Impact: MEDIUM (avoids effect re-runs and duplicate side effects)**
+
+If a side effect is triggered by a specific user action (submit, click, drag), run it in that event handler. Do not model the action as state + effect; it makes effects re-run on unrelated changes and can duplicate the action.
+
+**Incorrect: event modeled as state + effect**
+
+```tsx
+function Form() {
+ const [submitted, setSubmitted] = useState(false)
+ const theme = useContext(ThemeContext)
+
+ useEffect(() => {
+ if (submitted) {
+ post('/api/register')
+ showToast('Registered', theme)
+ }
+ }, [submitted, theme])
+
+ return
+}
+```
+
+**Correct: do it in the handler**
+
+```tsx
+function Form() {
+ const theme = useContext(ThemeContext)
+
+ function handleSubmit() {
+ post('/api/register')
+ showToast('Registered', theme)
+ }
+
+ return
+}
+```
+
+Reference: [https://react.dev/learn/removing-effect-dependencies#should-this-code-move-to-an-event-handler](https://react.dev/learn/removing-effect-dependencies#should-this-code-move-to-an-event-handler)
+
+### 5.9 Split Combined Hook Computations
+
+**Impact: MEDIUM (avoids recomputing independent steps)**
+
+When a hook contains multiple independent tasks with different dependencies, split them into separate hooks. A combined hook reruns all tasks when any dependency changes, even if some tasks don't use the changed value.
+
+**Incorrect: changing `sortOrder` recomputes filtering**
+
+```tsx
+const sortedProducts = useMemo(() => {
+ const filtered = products.filter((p) => p.category === category)
+ const sorted = filtered.toSorted((a, b) =>
+ sortOrder === "asc" ? a.price - b.price : b.price - a.price
+ )
+ return sorted
+}, [products, category, sortOrder])
+```
+
+**Correct: filtering only recomputes when products or category change**
+
+```tsx
+const filteredProducts = useMemo(
+ () => products.filter((p) => p.category === category),
+ [products, category]
+)
+
+const sortedProducts = useMemo(
+ () =>
+ filteredProducts.toSorted((a, b) =>
+ sortOrder === "asc" ? a.price - b.price : b.price - a.price
+ ),
+ [filteredProducts, sortOrder]
+)
+```
+
+This pattern also applies to `useEffect` when combining unrelated side effects:
+
+**Incorrect: both effects run when either dependency changes**
+
+```tsx
+useEffect(() => {
+ analytics.trackPageView(pathname)
+ document.title = `${pageTitle} | My App`
+}, [pathname, pageTitle])
+```
+
+**Correct: effects run independently**
+
+```tsx
+useEffect(() => {
+ analytics.trackPageView(pathname)
+}, [pathname])
+
+useEffect(() => {
+ document.title = `${pageTitle} | My App`
+}, [pageTitle])
+```
+
+**Note:** If your project has [React Compiler](https://react.dev/learn/react-compiler) enabled, it automatically optimizes dependency tracking and may handle some of these cases for you.
+
+### 5.10 Subscribe to Derived State
+
+**Impact: MEDIUM (reduces re-render frequency)**
+
+Subscribe to derived boolean state instead of continuous values to reduce re-render frequency.
+
+**Incorrect: re-renders on every pixel change**
+
+```tsx
+function Sidebar() {
+ const width = useWindowWidth() // updates continuously
+ const isMobile = width < 768
+ return
+}
+```
+
+**Correct: re-renders only when boolean changes**
+
+```tsx
+function Sidebar() {
+ const isMobile = useMediaQuery('(max-width: 767px)')
+ return
+}
+```
+
+### 5.11 Use Functional setState Updates
+
+**Impact: MEDIUM (prevents stale closures and unnecessary callback recreations)**
+
+When updating state based on the current state value, use the functional update form of setState instead of directly referencing the state variable. This prevents stale closures, eliminates unnecessary dependencies, and creates stable callback references.
+
+**Incorrect: requires state as dependency**
+
+```tsx
+function TodoList() {
+ const [items, setItems] = useState(initialItems)
+
+ // Callback must depend on items, recreated on every items change
+ const addItems = useCallback((newItems: Item[]) => {
+ setItems([...items, ...newItems])
+ }, [items]) // ❌ items dependency causes recreations
+
+ // Risk of stale closure if dependency is forgotten
+ const removeItem = useCallback((id: string) => {
+ setItems(items.filter(item => item.id !== id))
+ }, []) // ❌ Missing items dependency - will use stale items!
+
+ return
+
+
+ )
+}
+```
+
+**When to use:**
+
+- Filtering/searching large lists
+
+- Expensive visualizations (charts, graphs) reacting to input
+
+- Any derived state that causes noticeable render delays
+
+**Note:** Wrap the expensive computation in `useMemo` with the deferred value as a dependency, otherwise it still runs on every render.
+
+Reference: [https://react.dev/reference/react/useDeferredValue](https://react.dev/reference/react/useDeferredValue)
+
+### 5.15 Use useRef for Transient Values
+
+**Impact: MEDIUM (avoids unnecessary re-renders on frequent updates)**
+
+When a value changes frequently and you don't want a re-render on every update (e.g., mouse trackers, intervals, transient flags), store it in `useRef` instead of `useState`. Keep component state for UI; use refs for temporary DOM-adjacent values. Updating a ref does not trigger a re-render.
+
+**Incorrect: renders every update**
+
+```tsx
+function Tracker() {
+ const [lastX, setLastX] = useState(0)
+
+ useEffect(() => {
+ const onMove = (e: MouseEvent) => setLastX(e.clientX)
+ window.addEventListener('mousemove', onMove)
+ return () => window.removeEventListener('mousemove', onMove)
+ }, [])
+
+ return (
+
+ )
+}
+```
+
+**Correct: no re-render for tracking**
+
+```tsx
+function Tracker() {
+ const lastXRef = useRef(0)
+ const dotRef = useRef` and animate the wrapper instead.
+
+**Incorrect: animating SVG directly - no hardware acceleration**
+
+```tsx
+function LoadingSpinner() {
+ return (
+
+ )
+}
+```
+
+**Correct: animating wrapper div - hardware accelerated**
+
+```tsx
+function LoadingSpinner() {
+ return (
+ ` to preserve state/DOM for expensive components that frequently toggle visibility.
+
+**Usage:**
+
+```tsx
+import { Activity } from 'react'
+
+function Dropdown({ isOpen }: Props) {
+ return (
+
+
+ )
+}
+```
+
+Avoids expensive re-renders and state loss.
+
+### 6.8 Use defer or async on Script Tags
+
+**Impact: HIGH (eliminates render-blocking)**
+
+Script tags without `defer` or `async` block HTML parsing while the script downloads and executes. This delays First Contentful Paint and Time to Interactive.
+
+- **`defer`**: Downloads in parallel, executes after HTML parsing completes, maintains execution order
+
+- **`async`**: Downloads in parallel, executes immediately when ready, no guaranteed order
+
+Use `defer` for scripts that depend on DOM or other scripts. Use `async` for independent scripts like analytics.
+
+**Incorrect: blocks rendering**
+
+```tsx
+export default function Document() {
+ return (
+
+
+
+
+
+ {/* content */}
+
+ )
+}
+```
+
+**Correct: non-blocking**
+
+```tsx
+import Script from 'next/script'
+
+export default function Page() {
+ return (
+ <>
+
+
+
+ )
+}
+```
+
+**Note:** In Next.js, prefer the `next/script` component with `strategy` prop instead of raw script tags:
+
+Reference: [https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script#defer](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script#defer)
+
+### 6.9 Use Explicit Conditional Rendering
+
+**Impact: LOW (prevents rendering 0 or NaN)**
+
+Use explicit ternary operators (`? :`) instead of `&&` for conditional rendering when the condition can be `0`, `NaN`, or other falsy values that render.
+
+**Incorrect: renders "0" when count is 0**
+
+```tsx
+function Badge({ count }: { count: number }) {
+ return (
+ {/* content */}
+}
+```
+
+**Example: preload critical fonts and styles**
+
+```tsx
+import { preload, preinit } from 'react-dom'
+
+export default function RootLayout({ children }) {
+ // Preload font file
+ preload('/fonts/inter.woff2', { as: 'font', type: 'font/woff2', crossOrigin: 'anonymous' })
+
+ // Fetch and apply critical stylesheet immediately
+ preinit('/styles/critical.css', { as: 'style' })
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+**Example: preload modules for code-split routes**
+
+```tsx
+import { preloadModule, preinitModule } from 'react-dom'
+
+function Navigation() {
+ const preloadDashboard = () => {
+ preloadModule('/dashboard.js', { as: 'script' })
+ }
+
+ return (
+
+ )
+}
+```
+
+**When to use each:**
+
+| API | Use case |
+
+|-----|----------|
+
+| `prefetchDNS` | Third-party domains you'll connect to later |
+
+| `preconnect` | APIs or CDNs you'll fetch from immediately |
+
+| `preload` | Critical resources needed for current page |
+
+| `preloadModule` | JS modules for likely next navigation |
+
+| `preinit` | Stylesheets/scripts that must execute early |
+
+| `preinitModule` | ES modules that must execute early |
+
+Reference: [https://react.dev/reference/react-dom#resource-preloading-apis](https://react.dev/reference/react-dom#resource-preloading-apis)
+
+### 6.11 Use useTransition Over Manual Loading States
+
+**Impact: LOW (reduces re-renders and improves code clarity)**
+
+Use `useTransition` instead of manual `useState` for loading states. This provides built-in `isPending` state and automatically manages transitions.
+
+**Incorrect: manual loading state**
+
+```tsx
+function SearchResults() {
+ const [query, setQuery] = useState('')
+ const [results, setResults] = useState([])
+ const [isLoading, setIsLoading] = useState(false)
+
+ const handleSearch = async (value: string) => {
+ setIsLoading(true)
+ setQuery(value)
+ const data = await fetchResults(value)
+ setResults(data)
+ setIsLoading(false)
+ }
+
+ return (
+ <>
+ handleSearch(e.target.value)} />
+ {isLoading && (null)
+
+ useEffect(() => {
+ if (ref.current && isHighlighted) {
+ ref.current.style.width = '100px'
+ const width = ref.current.offsetWidth // Forces layout
+ ref.current.style.height = '200px'
+ }
+ }, [isHighlighted])
+
+ return ()
+
+function cachedSlugify(text: string): string {
+ if (slugifyCache.has(text)) {
+ return slugifyCache.get(text)!
+ }
+ const result = slugify(text)
+ slugifyCache.set(text, result)
+ return result
+}
+
+function ProjectList({ projects }: { projects: Project[] }) {
+ return (
+ ()
+
+function getLocalStorage(key: string) {
+ if (!storageCache.has(key)) {
+ storageCache.set(key, localStorage.getItem(key))
+ }
+ return storageCache.get(key)
+}
+
+function setLocalStorage(key: string, value: string) {
+ localStorage.setItem(key, value)
+ storageCache.set(key, value) // keep cache in sync
+}
+```
+
+Use a Map (not a hook) so it works everywhere: utilities, event handlers, not just React components.
+
+**Cookie caching:**
+
+```typescript
+let cookieCache: Record | null = null
+
+function getCookie(name: string) {
+ if (!cookieCache) {
+ cookieCache = Object.fromEntries(
+ document.cookie.split('; ').map(c => c.split('='))
+ )
+ }
+ return cookieCache[name]
+}
+```
+
+**Important: invalidate on external changes**
+
+```typescript
+window.addEventListener('storage', (e) => {
+ if (e.key) storageCache.delete(e.key)
+})
+
+document.addEventListener('visibilitychange', () => {
+ if (document.visibilityState === 'visible') {
+ storageCache.clear()
+ }
+})
+```
+
+If storage can change externally (another tab, server-set cookies), invalidate cache:
+
+### 7.6 Combine Multiple Array Iterations
+
+**Impact: LOW-MEDIUM (reduces iterations)**
+
+Multiple `.filter()` or `.map()` calls iterate the array multiple times. Combine into one loop.
+
+**Incorrect: 3 iterations**
+
+```typescript
+const admins = users.filter(u => u.isAdmin)
+const testers = users.filter(u => u.isTester)
+const inactive = users.filter(u => !u.isActive)
+```
+
+**Correct: 1 iteration**
+
+```typescript
+const admins: User[] = []
+const testers: User[] = []
+const inactive: User[] = []
+
+for (const user of users) {
+ if (user.isAdmin) admins.push(user)
+ if (user.isTester) testers.push(user)
+ if (!user.isActive) inactive.push(user)
+}
+```
+
+### 7.7 Defer Non-Critical Work with requestIdleCallback
+
+**Impact: MEDIUM (keeps UI responsive during background tasks)**
+
+Use `requestIdleCallback()` to schedule non-critical work during browser idle periods. This keeps the main thread free for user interactions and animations, reducing jank and improving perceived performance.
+
+**Incorrect: blocks main thread during user interaction**
+
+```typescript
+function handleSearch(query: string) {
+ const results = searchItems(query)
+ setResults(results)
+
+ // These block the main thread immediately
+ analytics.track('search', { query })
+ saveToRecentSearches(query)
+ prefetchTopResults(results.slice(0, 3))
+}
+```
+
+**Correct: defers non-critical work to idle time**
+
+```typescript
+function handleSearch(query: string) {
+ const results = searchItems(query)
+ setResults(results)
+
+ // Defer non-critical work to idle periods
+ requestIdleCallback(() => {
+ analytics.track('search', { query })
+ })
+
+ requestIdleCallback(() => {
+ saveToRecentSearches(query)
+ })
+
+ requestIdleCallback(() => {
+ prefetchTopResults(results.slice(0, 3))
+ })
+}
+```
+
+**With timeout for required work:**
+
+```typescript
+// Ensure analytics fires within 2 seconds even if browser stays busy
+requestIdleCallback(
+ () => analytics.track('page_view', { path: location.pathname }),
+ { timeout: 2000 }
+)
+```
+
+**Chunking large tasks:**
+
+```typescript
+function processLargeDataset(items: Item[]) {
+ let index = 0
+
+ function processChunk(deadline: IdleDeadline) {
+ // Process items while we have idle time (aim for <50ms chunks)
+ while (index < items.length && deadline.timeRemaining() > 0) {
+ processItem(items[index])
+ index++
+ }
+
+ // Schedule next chunk if more items remain
+ if (index < items.length) {
+ requestIdleCallback(processChunk)
+ }
+ }
+
+ requestIdleCallback(processChunk)
+}
+```
+
+**With fallback for unsupported browsers:**
+
+```typescript
+const scheduleIdleWork = window.requestIdleCallback ?? ((cb: () => void) => setTimeout(cb, 1))
+
+scheduleIdleWork(() => {
+ // Non-critical work
+})
+```
+
+**When to use:**
+
+- Analytics and telemetry
+
+- Saving state to localStorage/IndexedDB
+
+- Prefetching resources for likely next actions
+
+- Processing non-urgent data transformations
+
+- Lazy initialization of non-critical features
+
+**When NOT to use:**
+
+- User-initiated actions that need immediate feedback
+
+- Rendering updates the user is waiting for
+
+- Time-sensitive operations
+
+### 7.8 Early Length Check for Array Comparisons
+
+**Impact: MEDIUM-HIGH (avoids expensive operations when lengths differ)**
+
+When comparing arrays with expensive operations (sorting, deep equality, serialization), check lengths first. If lengths differ, the arrays cannot be equal.
+
+In real-world applications, this optimization is especially valuable when the comparison runs in hot paths (event handlers, render loops).
+
+**Incorrect: always runs expensive comparison**
+
+```typescript
+function hasChanges(current: string[], original: string[]) {
+ // Always sorts and joins, even when lengths differ
+ return current.sort().join() !== original.sort().join()
+}
+```
+
+Two O(n log n) sorts run even when `current.length` is 5 and `original.length` is 100. There is also overhead of joining the arrays and comparing the strings.
+
+**Correct (O(1) length check first):**
+
+```typescript
+function hasChanges(current: string[], original: string[]) {
+ // Early return if lengths differ
+ if (current.length !== original.length) {
+ return true
+ }
+ // Only sort when lengths match
+ const currentSorted = current.toSorted()
+ const originalSorted = original.toSorted()
+ for (let i = 0; i < currentSorted.length; i++) {
+ if (currentSorted[i] !== originalSorted[i]) {
+ return true
+ }
+ }
+ return false
+}
+```
+
+This new approach is more efficient because:
+
+- It avoids the overhead of sorting and joining the arrays when lengths differ
+
+- It avoids consuming memory for the joined strings (especially important for large arrays)
+
+- It avoids mutating the original arrays
+
+- It returns early when a difference is found
+
+### 7.9 Early Return from Functions
+
+**Impact: LOW-MEDIUM (avoids unnecessary computation)**
+
+Return early when result is determined to skip unnecessary processing.
+
+**Incorrect: processes all items even after finding answer**
+
+```typescript
+function validateUsers(users: User[]) {
+ let hasError = false
+ let errorMessage = ''
+
+ for (const user of users) {
+ if (!user.email) {
+ hasError = true
+ errorMessage = 'Email required'
+ }
+ if (!user.name) {
+ hasError = true
+ errorMessage = 'Name required'
+ }
+ // Continues checking all users even after error found
+ }
+
+ return hasError ? { valid: false, error: errorMessage } : { valid: true }
+}
+```
+
+**Correct: returns immediately on first error**
+
+```typescript
+function validateUsers(users: User[]) {
+ for (const user of users) {
+ if (!user.email) {
+ return { valid: false, error: 'Email required' }
+ }
+ if (!user.name) {
+ return { valid: false, error: 'Name required' }
+ }
+ }
+
+ return { valid: true }
+}
+```
+
+### 7.10 Hoist RegExp Creation
+
+**Impact: LOW-MEDIUM (avoids recreation)**
+
+Don't create RegExp inside render. Hoist to module scope or memoize with `useMemo()`.
+
+**Incorrect: new RegExp every render**
+
+```tsx
+function Highlighter({ text, query }: Props) {
+ const regex = new RegExp(`(${query})`, 'gi')
+ const parts = text.split(regex)
+ return <>{parts.map((part, i) => ...)}
+}
+```
+
+**Correct: memoize or hoist**
+
+```tsx
+const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
+
+function Highlighter({ text, query }: Props) {
+ const regex = useMemo(
+ () => new RegExp(`(${escapeRegex(query)})`, 'gi'),
+ [query]
+ )
+ const parts = text.split(regex)
+ return <>{parts.map((part, i) => ...)}
+}
+```
+
+**Warning: global regex has mutable state**
+
+```typescript
+const regex = /foo/g
+regex.test('foo') // true, lastIndex = 3
+regex.test('foo') // false, lastIndex = 0
+```
+
+Global regex (`/g`) has mutable `lastIndex` state:
+
+### 7.11 Use flatMap to Map and Filter in One Pass
+
+**Impact: LOW-MEDIUM (eliminates intermediate array)**
+
+Chaining `.map().filter(Boolean)` creates an intermediate array and iterates twice. Use `.flatMap()` to transform and filter in a single pass.
+
+**Incorrect: 2 iterations, intermediate array**
+
+```typescript
+const userNames = users
+ .map(user => user.isActive ? user.name : null)
+ .filter(Boolean)
+```
+
+**Correct: 1 iteration, no intermediate array**
+
+```typescript
+const userNames = users.flatMap(user =>
+ user.isActive ? [user.name] : []
+)
+```
+
+**More examples:**
+
+```typescript
+// Extract valid emails from responses
+// Before
+const emails = responses
+ .map(r => r.success ? r.data.email : null)
+ .filter(Boolean)
+
+// After
+const emails = responses.flatMap(r =>
+ r.success ? [r.data.email] : []
+)
+
+// Parse and filter valid numbers
+// Before
+const numbers = strings
+ .map(s => parseInt(s, 10))
+ .filter(n => !isNaN(n))
+
+// After
+const numbers = strings.flatMap(s => {
+ const n = parseInt(s, 10)
+ return isNaN(n) ? [] : [n]
+})
+```
+
+**When to use:**
+
+- Transforming items while filtering some out
+
+- Conditional mapping where some inputs produce no output
+
+- Parsing/validating where invalid inputs should be skipped
+
+### 7.12 Use Loop for Min/Max Instead of Sort
+
+**Impact: LOW (O(n) instead of O(n log n))**
+
+Finding the smallest or largest element only requires a single pass through the array. Sorting is wasteful and slower.
+
+**Incorrect (O(n log n) - sort to find latest):**
+
+```typescript
+interface Project {
+ id: string
+ name: string
+ updatedAt: number
+}
+
+function getLatestProject(projects: Project[]) {
+ const sorted = [...projects].sort((a, b) => b.updatedAt - a.updatedAt)
+ return sorted[0]
+}
+```
+
+Sorts the entire array just to find the maximum value.
+
+**Incorrect (O(n log n) - sort for oldest and newest):**
+
+```typescript
+function getOldestAndNewest(projects: Project[]) {
+ const sorted = [...projects].sort((a, b) => a.updatedAt - b.updatedAt)
+ return { oldest: sorted[0], newest: sorted[sorted.length - 1] }
+}
+```
+
+Still sorts unnecessarily when only min/max are needed.
+
+**Correct (O(n) - single loop):**
+
+```typescript
+function getLatestProject(projects: Project[]) {
+ if (projects.length === 0) return null
+
+ let latest = projects[0]
+
+ for (let i = 1; i < projects.length; i++) {
+ if (projects[i].updatedAt > latest.updatedAt) {
+ latest = projects[i]
+ }
+ }
+
+ return latest
+}
+
+function getOldestAndNewest(projects: Project[]) {
+ if (projects.length === 0) return { oldest: null, newest: null }
+
+ let oldest = projects[0]
+ let newest = projects[0]
+
+ for (let i = 1; i < projects.length; i++) {
+ if (projects[i].updatedAt < oldest.updatedAt) oldest = projects[i]
+ if (projects[i].updatedAt > newest.updatedAt) newest = projects[i]
+ }
+
+ return { oldest, newest }
+}
+```
+
+Single pass through the array, no copying, no sorting.
+
+**Alternative: Math.min/Math.max for small arrays**
+
+```typescript
+const numbers = [5, 2, 8, 1, 9]
+const min = Math.min(...numbers)
+const max = Math.max(...numbers)
+```
+
+This works for small arrays, but can be slower or just throw an error for very large arrays due to spread operator limitations. Maximal array length is approximately 124000 in Chrome 143 and 638000 in Safari 18; exact numbers may vary - see [the fiddle](https://jsfiddle.net/qw1jabsx/4/). Use the loop approach for reliability.
+
+### 7.13 Use Set/Map for O(1) Lookups
+
+**Impact: LOW-MEDIUM (O(n) to O(1))**
+
+Convert arrays to Set/Map for repeated membership checks.
+
+**Incorrect (O(n) per check):**
+
+```typescript
+const allowedIds = ['a', 'b', 'c', ...]
+items.filter(item => allowedIds.includes(item.id))
+```
+
+**Correct (O(1) per check):**
+
+```typescript
+const allowedIds = new Set(['a', 'b', 'c', ...])
+items.filter(item => allowedIds.has(item.id))
+```
+
+### 7.14 Use toSorted() Instead of sort() for Immutability
+
+**Impact: MEDIUM-HIGH (prevents mutation bugs in React state)**
+
+`.sort()` mutates the array in place, which can cause bugs with React state and props. Use `.toSorted()` to create a new sorted array without mutation.
+
+**Incorrect: mutates original array**
+
+```typescript
+function UserList({ users }: { users: User[] }) {
+ // Mutates the users prop array!
+ const sorted = useMemo(
+ () => users.sort((a, b) => a.name.localeCompare(b.name)),
+ [users]
+ )
+ return > }) {
+ const [frames, setFrames] = useState(null)
+
+ useEffect(() => {
+ if (enabled && !frames && typeof window !== 'undefined') {
+ import('./animation-frames.js')
+ .then(mod => setFrames(mod.frames))
+ .catch(() => setEnabled(false))
+ }
+ }, [enabled, frames, setEnabled])
+
+ if (!frames) return
+ {children}
+
+}
+```
+
+The `typeof window !== 'undefined'` check prevents bundling preloaded modules for SSR, optimizing server bundle size and build speed.
diff --git a/.agents/skills/vercel-react-best-practices/rules/client-event-listeners.md b/.agents/skills/vercel-react-best-practices/rules/client-event-listeners.md
new file mode 100644
index 0000000..aad4ae9
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/client-event-listeners.md
@@ -0,0 +1,74 @@
+---
+title: Deduplicate Global Event Listeners
+impact: LOW
+impactDescription: single listener for N components
+tags: client, swr, event-listeners, subscription
+---
+
+## Deduplicate Global Event Listeners
+
+Use `useSWRSubscription()` to share global event listeners across component instances.
+
+**Incorrect (N instances = N listeners):**
+
+```tsx
+function useKeyboardShortcut(key: string, callback: () => void) {
+ useEffect(() => {
+ const handler = (e: KeyboardEvent) => {
+ if (e.metaKey && e.key === key) {
+ callback()
+ }
+ }
+ window.addEventListener('keydown', handler)
+ return () => window.removeEventListener('keydown', handler)
+ }, [key, callback])
+}
+```
+
+When using the `useKeyboardShortcut` hook multiple times, each instance will register a new listener.
+
+**Correct (N instances = 1 listener):**
+
+```tsx
+import useSWRSubscription from 'swr/subscription'
+
+// Module-level Map to track callbacks per key
+const keyCallbacks = new Map void>>()
+
+function useKeyboardShortcut(key: string, callback: () => void) {
+ // Register this callback in the Map
+ useEffect(() => {
+ if (!keyCallbacks.has(key)) {
+ keyCallbacks.set(key, new Set())
+ }
+ keyCallbacks.get(key)!.add(callback)
+
+ return () => {
+ const set = keyCallbacks.get(key)
+ if (set) {
+ set.delete(callback)
+ if (set.size === 0) {
+ keyCallbacks.delete(key)
+ }
+ }
+ }
+ }, [key, callback])
+
+ useSWRSubscription('global-keydown', () => {
+ const handler = (e: KeyboardEvent) => {
+ if (e.metaKey && keyCallbacks.has(e.key)) {
+ keyCallbacks.get(e.key)!.forEach(cb => cb())
+ }
+ }
+ window.addEventListener('keydown', handler)
+ return () => window.removeEventListener('keydown', handler)
+ })
+}
+
+function Profile() {
+ // Multiple shortcuts will share the same listener
+ useKeyboardShortcut('p', () => { /* ... */ })
+ useKeyboardShortcut('k', () => { /* ... */ })
+ // ...
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/client-localstorage-schema.md b/.agents/skills/vercel-react-best-practices/rules/client-localstorage-schema.md
new file mode 100644
index 0000000..d30a1a7
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/client-localstorage-schema.md
@@ -0,0 +1,71 @@
+---
+title: Version and Minimize localStorage Data
+impact: MEDIUM
+impactDescription: prevents schema conflicts, reduces storage size
+tags: client, localStorage, storage, versioning, data-minimization
+---
+
+## Version and Minimize localStorage Data
+
+Add version prefix to keys and store only needed fields. Prevents schema conflicts and accidental storage of sensitive data.
+
+**Incorrect:**
+
+```typescript
+// No version, stores everything, no error handling
+localStorage.setItem('userConfig', JSON.stringify(fullUserObject))
+const data = localStorage.getItem('userConfig')
+```
+
+**Correct:**
+
+```typescript
+const VERSION = 'v2'
+
+function saveConfig(config: { theme: string; language: string }) {
+ try {
+ localStorage.setItem(`userConfig:${VERSION}`, JSON.stringify(config))
+ } catch {
+ // Throws in incognito/private browsing, quota exceeded, or disabled
+ }
+}
+
+function loadConfig() {
+ try {
+ const data = localStorage.getItem(`userConfig:${VERSION}`)
+ return data ? JSON.parse(data) : null
+ } catch {
+ return null
+ }
+}
+
+// Migration from v1 to v2
+function migrate() {
+ try {
+ const v1 = localStorage.getItem('userConfig:v1')
+ if (v1) {
+ const old = JSON.parse(v1)
+ saveConfig({ theme: old.darkMode ? 'dark' : 'light', language: old.lang })
+ localStorage.removeItem('userConfig:v1')
+ }
+ } catch {}
+}
+```
+
+**Store minimal fields from server responses:**
+
+```typescript
+// User object has 20+ fields, only store what UI needs
+function cachePrefs(user: FullUser) {
+ try {
+ localStorage.setItem('prefs:v1', JSON.stringify({
+ theme: user.preferences.theme,
+ notifications: user.preferences.notifications
+ }))
+ } catch {}
+}
+```
+
+**Always wrap in try-catch:** `getItem()` and `setItem()` throw in incognito/private browsing (Safari, Firefox), when quota exceeded, or when disabled.
+
+**Benefits:** Schema evolution via versioning, reduced storage size, prevents storing tokens/PII/internal flags.
diff --git a/.agents/skills/vercel-react-best-practices/rules/client-passive-event-listeners.md b/.agents/skills/vercel-react-best-practices/rules/client-passive-event-listeners.md
new file mode 100644
index 0000000..ce39a88
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/client-passive-event-listeners.md
@@ -0,0 +1,48 @@
+---
+title: Use Passive Event Listeners for Scrolling Performance
+impact: MEDIUM
+impactDescription: eliminates scroll delay caused by event listeners
+tags: client, event-listeners, scrolling, performance, touch, wheel
+---
+
+## Use Passive Event Listeners for Scrolling Performance
+
+Add `{ passive: true }` to touch and wheel event listeners to enable immediate scrolling. Browsers normally wait for listeners to finish to check if `preventDefault()` is called, causing scroll delay.
+
+**Incorrect:**
+
+```typescript
+useEffect(() => {
+ const handleTouch = (e: TouchEvent) => console.log(e.touches[0].clientX)
+ const handleWheel = (e: WheelEvent) => console.log(e.deltaY)
+
+ document.addEventListener('touchstart', handleTouch)
+ document.addEventListener('wheel', handleWheel)
+
+ return () => {
+ document.removeEventListener('touchstart', handleTouch)
+ document.removeEventListener('wheel', handleWheel)
+ }
+}, [])
+```
+
+**Correct:**
+
+```typescript
+useEffect(() => {
+ const handleTouch = (e: TouchEvent) => console.log(e.touches[0].clientX)
+ const handleWheel = (e: WheelEvent) => console.log(e.deltaY)
+
+ document.addEventListener('touchstart', handleTouch, { passive: true })
+ document.addEventListener('wheel', handleWheel, { passive: true })
+
+ return () => {
+ document.removeEventListener('touchstart', handleTouch)
+ document.removeEventListener('wheel', handleWheel)
+ }
+}, [])
+```
+
+**Use passive when:** tracking/analytics, logging, any listener that doesn't call `preventDefault()`.
+
+**Don't use passive when:** implementing custom swipe gestures, custom zoom controls, or any listener that needs `preventDefault()`.
diff --git a/.agents/skills/vercel-react-best-practices/rules/client-swr-dedup.md b/.agents/skills/vercel-react-best-practices/rules/client-swr-dedup.md
new file mode 100644
index 0000000..2a430f2
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/client-swr-dedup.md
@@ -0,0 +1,56 @@
+---
+title: Use SWR for Automatic Deduplication
+impact: MEDIUM-HIGH
+impactDescription: automatic deduplication
+tags: client, swr, deduplication, data-fetching
+---
+
+## Use SWR for Automatic Deduplication
+
+SWR enables request deduplication, caching, and revalidation across component instances.
+
+**Incorrect (no deduplication, each instance fetches):**
+
+```tsx
+function UserList() {
+ const [users, setUsers] = useState([])
+ useEffect(() => {
+ fetch('/api/users')
+ .then(r => r.json())
+ .then(setUsers)
+ }, [])
+}
+```
+
+**Correct (multiple instances share one request):**
+
+```tsx
+import useSWR from 'swr'
+
+function UserList() {
+ const { data: users } = useSWR('/api/users', fetcher)
+}
+```
+
+**For immutable data:**
+
+```tsx
+import { useImmutableSWR } from '@/lib/swr'
+
+function StaticContent() {
+ const { data } = useImmutableSWR('/api/config', fetcher)
+}
+```
+
+**For mutations:**
+
+```tsx
+import { useSWRMutation } from 'swr/mutation'
+
+function UpdateButton() {
+ const { trigger } = useSWRMutation('/api/user', updateUser)
+ return
+}
+```
+
+Reference: [https://swr.vercel.app](https://swr.vercel.app)
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-batch-dom-css.md b/.agents/skills/vercel-react-best-practices/rules/js-batch-dom-css.md
new file mode 100644
index 0000000..a62d84e
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-batch-dom-css.md
@@ -0,0 +1,107 @@
+---
+title: Avoid Layout Thrashing
+impact: MEDIUM
+impactDescription: prevents forced synchronous layouts and reduces performance bottlenecks
+tags: javascript, dom, css, performance, reflow, layout-thrashing
+---
+
+## Avoid Layout Thrashing
+
+Avoid interleaving style writes with layout reads. When you read a layout property (like `offsetWidth`, `getBoundingClientRect()`, or `getComputedStyle()`) between style changes, the browser is forced to trigger a synchronous reflow.
+
+**This is OK (browser batches style changes):**
+```typescript
+function updateElementStyles(element: HTMLElement) {
+ // Each line invalidates style, but browser batches the recalculation
+ element.style.width = '100px'
+ element.style.height = '200px'
+ element.style.backgroundColor = 'blue'
+ element.style.border = '1px solid black'
+}
+```
+
+**Incorrect (interleaved reads and writes force reflows):**
+```typescript
+function layoutThrashing(element: HTMLElement) {
+ element.style.width = '100px'
+ const width = element.offsetWidth // Forces reflow
+ element.style.height = '200px'
+ const height = element.offsetHeight // Forces another reflow
+}
+```
+
+**Correct (batch writes, then read once):**
+```typescript
+function updateElementStyles(element: HTMLElement) {
+ // Batch all writes together
+ element.style.width = '100px'
+ element.style.height = '200px'
+ element.style.backgroundColor = 'blue'
+ element.style.border = '1px solid black'
+
+ // Read after all writes are done (single reflow)
+ const { width, height } = element.getBoundingClientRect()
+}
+```
+
+**Correct (batch reads, then writes):**
+```typescript
+function avoidThrashing(element: HTMLElement) {
+ // Read phase - all layout queries first
+ const rect1 = element.getBoundingClientRect()
+ const offsetWidth = element.offsetWidth
+ const offsetHeight = element.offsetHeight
+
+ // Write phase - all style changes after
+ element.style.width = '100px'
+ element.style.height = '200px'
+}
+```
+
+**Better: use CSS classes**
+```css
+.highlighted-box {
+ width: 100px;
+ height: 200px;
+ background-color: blue;
+ border: 1px solid black;
+}
+```
+```typescript
+function updateElementStyles(element: HTMLElement) {
+ element.classList.add('highlighted-box')
+
+ const { width, height } = element.getBoundingClientRect()
+}
+```
+
+**React example:**
+```tsx
+// Incorrect: interleaving style changes with layout queries
+function Box({ isHighlighted }: { isHighlighted: boolean }) {
+ const ref = useRef(null)
+
+ useEffect(() => {
+ if (ref.current && isHighlighted) {
+ ref.current.style.width = '100px'
+ const width = ref.current.offsetWidth // Forces layout
+ ref.current.style.height = '200px'
+ }
+ }, [isHighlighted])
+
+ return ()
+
+function cachedSlugify(text: string): string {
+ if (slugifyCache.has(text)) {
+ return slugifyCache.get(text)!
+ }
+ const result = slugify(text)
+ slugifyCache.set(text, result)
+ return result
+}
+
+function ProjectList({ projects }: { projects: Project[] }) {
+ return (
+ ()
+
+function getLocalStorage(key: string) {
+ if (!storageCache.has(key)) {
+ storageCache.set(key, localStorage.getItem(key))
+ }
+ return storageCache.get(key)
+}
+
+function setLocalStorage(key: string, value: string) {
+ localStorage.setItem(key, value)
+ storageCache.set(key, value) // keep cache in sync
+}
+```
+
+Use a Map (not a hook) so it works everywhere: utilities, event handlers, not just React components.
+
+**Cookie caching:**
+
+```typescript
+let cookieCache: Record | null = null
+
+function getCookie(name: string) {
+ if (!cookieCache) {
+ cookieCache = Object.fromEntries(
+ document.cookie.split('; ').map(c => c.split('='))
+ )
+ }
+ return cookieCache[name]
+}
+```
+
+**Important (invalidate on external changes):**
+
+If storage can change externally (another tab, server-set cookies), invalidate cache:
+
+```typescript
+window.addEventListener('storage', (e) => {
+ if (e.key) storageCache.delete(e.key)
+})
+
+document.addEventListener('visibilitychange', () => {
+ if (document.visibilityState === 'visible') {
+ storageCache.clear()
+ }
+})
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-combine-iterations.md b/.agents/skills/vercel-react-best-practices/rules/js-combine-iterations.md
new file mode 100644
index 0000000..044d017
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-combine-iterations.md
@@ -0,0 +1,32 @@
+---
+title: Combine Multiple Array Iterations
+impact: LOW-MEDIUM
+impactDescription: reduces iterations
+tags: javascript, arrays, loops, performance
+---
+
+## Combine Multiple Array Iterations
+
+Multiple `.filter()` or `.map()` calls iterate the array multiple times. Combine into one loop.
+
+**Incorrect (3 iterations):**
+
+```typescript
+const admins = users.filter(u => u.isAdmin)
+const testers = users.filter(u => u.isTester)
+const inactive = users.filter(u => !u.isActive)
+```
+
+**Correct (1 iteration):**
+
+```typescript
+const admins: User[] = []
+const testers: User[] = []
+const inactive: User[] = []
+
+for (const user of users) {
+ if (user.isAdmin) admins.push(user)
+ if (user.isTester) testers.push(user)
+ if (!user.isActive) inactive.push(user)
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-early-exit.md b/.agents/skills/vercel-react-best-practices/rules/js-early-exit.md
new file mode 100644
index 0000000..f46cb89
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-early-exit.md
@@ -0,0 +1,50 @@
+---
+title: Early Return from Functions
+impact: LOW-MEDIUM
+impactDescription: avoids unnecessary computation
+tags: javascript, functions, optimization, early-return
+---
+
+## Early Return from Functions
+
+Return early when result is determined to skip unnecessary processing.
+
+**Incorrect (processes all items even after finding answer):**
+
+```typescript
+function validateUsers(users: User[]) {
+ let hasError = false
+ let errorMessage = ''
+
+ for (const user of users) {
+ if (!user.email) {
+ hasError = true
+ errorMessage = 'Email required'
+ }
+ if (!user.name) {
+ hasError = true
+ errorMessage = 'Name required'
+ }
+ // Continues checking all users even after error found
+ }
+
+ return hasError ? { valid: false, error: errorMessage } : { valid: true }
+}
+```
+
+**Correct (returns immediately on first error):**
+
+```typescript
+function validateUsers(users: User[]) {
+ for (const user of users) {
+ if (!user.email) {
+ return { valid: false, error: 'Email required' }
+ }
+ if (!user.name) {
+ return { valid: false, error: 'Name required' }
+ }
+ }
+
+ return { valid: true }
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-flatmap-filter.md b/.agents/skills/vercel-react-best-practices/rules/js-flatmap-filter.md
new file mode 100644
index 0000000..ee0edf0
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-flatmap-filter.md
@@ -0,0 +1,60 @@
+---
+title: Use flatMap to Map and Filter in One Pass
+impact: LOW-MEDIUM
+impactDescription: eliminates intermediate array
+tags: javascript, arrays, flatMap, filter, performance
+---
+
+## Use flatMap to Map and Filter in One Pass
+
+**Impact: LOW-MEDIUM (eliminates intermediate array)**
+
+Chaining `.map().filter(Boolean)` creates an intermediate array and iterates twice. Use `.flatMap()` to transform and filter in a single pass.
+
+**Incorrect (2 iterations, intermediate array):**
+
+```typescript
+const userNames = users
+ .map(user => user.isActive ? user.name : null)
+ .filter(Boolean)
+```
+
+**Correct (1 iteration, no intermediate array):**
+
+```typescript
+const userNames = users.flatMap(user =>
+ user.isActive ? [user.name] : []
+)
+```
+
+**More examples:**
+
+```typescript
+// Extract valid emails from responses
+// Before
+const emails = responses
+ .map(r => r.success ? r.data.email : null)
+ .filter(Boolean)
+
+// After
+const emails = responses.flatMap(r =>
+ r.success ? [r.data.email] : []
+)
+
+// Parse and filter valid numbers
+// Before
+const numbers = strings
+ .map(s => parseInt(s, 10))
+ .filter(n => !isNaN(n))
+
+// After
+const numbers = strings.flatMap(s => {
+ const n = parseInt(s, 10)
+ return isNaN(n) ? [] : [n]
+})
+```
+
+**When to use:**
+- Transforming items while filtering some out
+- Conditional mapping where some inputs produce no output
+- Parsing/validating where invalid inputs should be skipped
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-hoist-regexp.md b/.agents/skills/vercel-react-best-practices/rules/js-hoist-regexp.md
new file mode 100644
index 0000000..dae3fef
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-hoist-regexp.md
@@ -0,0 +1,45 @@
+---
+title: Hoist RegExp Creation
+impact: LOW-MEDIUM
+impactDescription: avoids recreation
+tags: javascript, regexp, optimization, memoization
+---
+
+## Hoist RegExp Creation
+
+Don't create RegExp inside render. Hoist to module scope or memoize with `useMemo()`.
+
+**Incorrect (new RegExp every render):**
+
+```tsx
+function Highlighter({ text, query }: Props) {
+ const regex = new RegExp(`(${query})`, 'gi')
+ const parts = text.split(regex)
+ return <>{parts.map((part, i) => ...)}
+}
+```
+
+**Correct (memoize or hoist):**
+
+```tsx
+const EMAIL_REGEX = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
+
+function Highlighter({ text, query }: Props) {
+ const regex = useMemo(
+ () => new RegExp(`(${escapeRegex(query)})`, 'gi'),
+ [query]
+ )
+ const parts = text.split(regex)
+ return <>{parts.map((part, i) => ...)}
+}
+```
+
+**Warning (global regex has mutable state):**
+
+Global regex (`/g`) has mutable `lastIndex` state:
+
+```typescript
+const regex = /foo/g
+regex.test('foo') // true, lastIndex = 3
+regex.test('foo') // false, lastIndex = 0
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-index-maps.md b/.agents/skills/vercel-react-best-practices/rules/js-index-maps.md
new file mode 100644
index 0000000..9d357a0
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-index-maps.md
@@ -0,0 +1,37 @@
+---
+title: Build Index Maps for Repeated Lookups
+impact: LOW-MEDIUM
+impactDescription: 1M ops to 2K ops
+tags: javascript, map, indexing, optimization, performance
+---
+
+## Build Index Maps for Repeated Lookups
+
+Multiple `.find()` calls by the same key should use a Map.
+
+**Incorrect (O(n) per lookup):**
+
+```typescript
+function processOrders(orders: Order[], users: User[]) {
+ return orders.map(order => ({
+ ...order,
+ user: users.find(u => u.id === order.userId)
+ }))
+}
+```
+
+**Correct (O(1) per lookup):**
+
+```typescript
+function processOrders(orders: Order[], users: User[]) {
+ const userById = new Map(users.map(u => [u.id, u]))
+
+ return orders.map(order => ({
+ ...order,
+ user: userById.get(order.userId)
+ }))
+}
+```
+
+Build map once (O(n)), then all lookups are O(1).
+For 1000 orders × 1000 users: 1M ops → 2K ops.
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-length-check-first.md b/.agents/skills/vercel-react-best-practices/rules/js-length-check-first.md
new file mode 100644
index 0000000..8b89573
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-length-check-first.md
@@ -0,0 +1,49 @@
+---
+title: Early Length Check for Array Comparisons
+impact: MEDIUM-HIGH
+impactDescription: avoids expensive operations when lengths differ
+tags: javascript, arrays, performance, optimization, comparison
+---
+
+## Early Length Check for Array Comparisons
+
+When comparing arrays with expensive operations (sorting, deep equality, serialization), check lengths first. If lengths differ, the arrays cannot be equal.
+
+In real-world applications, this optimization is especially valuable when the comparison runs in hot paths (event handlers, render loops).
+
+**Incorrect (always runs expensive comparison):**
+
+```typescript
+function hasChanges(current: string[], original: string[]) {
+ // Always sorts and joins, even when lengths differ
+ return current.sort().join() !== original.sort().join()
+}
+```
+
+Two O(n log n) sorts run even when `current.length` is 5 and `original.length` is 100. There is also overhead of joining the arrays and comparing the strings.
+
+**Correct (O(1) length check first):**
+
+```typescript
+function hasChanges(current: string[], original: string[]) {
+ // Early return if lengths differ
+ if (current.length !== original.length) {
+ return true
+ }
+ // Only sort when lengths match
+ const currentSorted = current.toSorted()
+ const originalSorted = original.toSorted()
+ for (let i = 0; i < currentSorted.length; i++) {
+ if (currentSorted[i] !== originalSorted[i]) {
+ return true
+ }
+ }
+ return false
+}
+```
+
+This new approach is more efficient because:
+- It avoids the overhead of sorting and joining the arrays when lengths differ
+- It avoids consuming memory for the joined strings (especially important for large arrays)
+- It avoids mutating the original arrays
+- It returns early when a difference is found
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-min-max-loop.md b/.agents/skills/vercel-react-best-practices/rules/js-min-max-loop.md
new file mode 100644
index 0000000..4b6656e
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-min-max-loop.md
@@ -0,0 +1,82 @@
+---
+title: Use Loop for Min/Max Instead of Sort
+impact: LOW
+impactDescription: O(n) instead of O(n log n)
+tags: javascript, arrays, performance, sorting, algorithms
+---
+
+## Use Loop for Min/Max Instead of Sort
+
+Finding the smallest or largest element only requires a single pass through the array. Sorting is wasteful and slower.
+
+**Incorrect (O(n log n) - sort to find latest):**
+
+```typescript
+interface Project {
+ id: string
+ name: string
+ updatedAt: number
+}
+
+function getLatestProject(projects: Project[]) {
+ const sorted = [...projects].sort((a, b) => b.updatedAt - a.updatedAt)
+ return sorted[0]
+}
+```
+
+Sorts the entire array just to find the maximum value.
+
+**Incorrect (O(n log n) - sort for oldest and newest):**
+
+```typescript
+function getOldestAndNewest(projects: Project[]) {
+ const sorted = [...projects].sort((a, b) => a.updatedAt - b.updatedAt)
+ return { oldest: sorted[0], newest: sorted[sorted.length - 1] }
+}
+```
+
+Still sorts unnecessarily when only min/max are needed.
+
+**Correct (O(n) - single loop):**
+
+```typescript
+function getLatestProject(projects: Project[]) {
+ if (projects.length === 0) return null
+
+ let latest = projects[0]
+
+ for (let i = 1; i < projects.length; i++) {
+ if (projects[i].updatedAt > latest.updatedAt) {
+ latest = projects[i]
+ }
+ }
+
+ return latest
+}
+
+function getOldestAndNewest(projects: Project[]) {
+ if (projects.length === 0) return { oldest: null, newest: null }
+
+ let oldest = projects[0]
+ let newest = projects[0]
+
+ for (let i = 1; i < projects.length; i++) {
+ if (projects[i].updatedAt < oldest.updatedAt) oldest = projects[i]
+ if (projects[i].updatedAt > newest.updatedAt) newest = projects[i]
+ }
+
+ return { oldest, newest }
+}
+```
+
+Single pass through the array, no copying, no sorting.
+
+**Alternative (Math.min/Math.max for small arrays):**
+
+```typescript
+const numbers = [5, 2, 8, 1, 9]
+const min = Math.min(...numbers)
+const max = Math.max(...numbers)
+```
+
+This works for small arrays, but can be slower or just throw an error for very large arrays due to spread operator limitations. Maximal array length is approximately 124000 in Chrome 143 and 638000 in Safari 18; exact numbers may vary - see [the fiddle](https://jsfiddle.net/qw1jabsx/4/). Use the loop approach for reliability.
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-request-idle-callback.md b/.agents/skills/vercel-react-best-practices/rules/js-request-idle-callback.md
new file mode 100644
index 0000000..d81927e
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-request-idle-callback.md
@@ -0,0 +1,105 @@
+---
+title: Defer Non-Critical Work with requestIdleCallback
+impact: MEDIUM
+impactDescription: keeps UI responsive during background tasks
+tags: javascript, performance, idle, scheduling, analytics
+---
+
+## Defer Non-Critical Work with requestIdleCallback
+
+**Impact: MEDIUM (keeps UI responsive during background tasks)**
+
+Use `requestIdleCallback()` to schedule non-critical work during browser idle periods. This keeps the main thread free for user interactions and animations, reducing jank and improving perceived performance.
+
+**Incorrect (blocks main thread during user interaction):**
+
+```typescript
+function handleSearch(query: string) {
+ const results = searchItems(query)
+ setResults(results)
+
+ // These block the main thread immediately
+ analytics.track('search', { query })
+ saveToRecentSearches(query)
+ prefetchTopResults(results.slice(0, 3))
+}
+```
+
+**Correct (defers non-critical work to idle time):**
+
+```typescript
+function handleSearch(query: string) {
+ const results = searchItems(query)
+ setResults(results)
+
+ // Defer non-critical work to idle periods
+ requestIdleCallback(() => {
+ analytics.track('search', { query })
+ })
+
+ requestIdleCallback(() => {
+ saveToRecentSearches(query)
+ })
+
+ requestIdleCallback(() => {
+ prefetchTopResults(results.slice(0, 3))
+ })
+}
+```
+
+**With timeout for required work:**
+
+```typescript
+// Ensure analytics fires within 2 seconds even if browser stays busy
+requestIdleCallback(
+ () => analytics.track('page_view', { path: location.pathname }),
+ { timeout: 2000 }
+)
+```
+
+**Chunking large tasks:**
+
+```typescript
+function processLargeDataset(items: Item[]) {
+ let index = 0
+
+ function processChunk(deadline: IdleDeadline) {
+ // Process items while we have idle time (aim for <50ms chunks)
+ while (index < items.length && deadline.timeRemaining() > 0) {
+ processItem(items[index])
+ index++
+ }
+
+ // Schedule next chunk if more items remain
+ if (index < items.length) {
+ requestIdleCallback(processChunk)
+ }
+ }
+
+ requestIdleCallback(processChunk)
+}
+```
+
+**With fallback for unsupported browsers:**
+
+```typescript
+const scheduleIdleWork = window.requestIdleCallback ?? ((cb: () => void) => setTimeout(cb, 1))
+
+scheduleIdleWork(() => {
+ // Non-critical work
+})
+```
+
+**When to use:**
+
+- Analytics and telemetry
+- Saving state to localStorage/IndexedDB
+- Prefetching resources for likely next actions
+- Processing non-urgent data transformations
+- Lazy initialization of non-critical features
+
+**When NOT to use:**
+
+- User-initiated actions that need immediate feedback
+- Rendering updates the user is waiting for
+- Time-sensitive operations
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-set-map-lookups.md b/.agents/skills/vercel-react-best-practices/rules/js-set-map-lookups.md
new file mode 100644
index 0000000..680a489
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-set-map-lookups.md
@@ -0,0 +1,24 @@
+---
+title: Use Set/Map for O(1) Lookups
+impact: LOW-MEDIUM
+impactDescription: O(n) to O(1)
+tags: javascript, set, map, data-structures, performance
+---
+
+## Use Set/Map for O(1) Lookups
+
+Convert arrays to Set/Map for repeated membership checks.
+
+**Incorrect (O(n) per check):**
+
+```typescript
+const allowedIds = ['a', 'b', 'c', ...]
+items.filter(item => allowedIds.includes(item.id))
+```
+
+**Correct (O(1) per check):**
+
+```typescript
+const allowedIds = new Set(['a', 'b', 'c', ...])
+items.filter(item => allowedIds.has(item.id))
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-tosorted-immutable.md b/.agents/skills/vercel-react-best-practices/rules/js-tosorted-immutable.md
new file mode 100644
index 0000000..eae8b3f
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-tosorted-immutable.md
@@ -0,0 +1,57 @@
+---
+title: Use toSorted() Instead of sort() for Immutability
+impact: MEDIUM-HIGH
+impactDescription: prevents mutation bugs in React state
+tags: javascript, arrays, immutability, react, state, mutation
+---
+
+## Use toSorted() Instead of sort() for Immutability
+
+`.sort()` mutates the array in place, which can cause bugs with React state and props. Use `.toSorted()` to create a new sorted array without mutation.
+
+**Incorrect (mutates original array):**
+
+```typescript
+function UserList({ users }: { users: User[] }) {
+ // Mutates the users prop array!
+ const sorted = useMemo(
+ () => users.sort((a, b) => a.name.localeCompare(b.name)),
+ [users]
+ )
+ return ` to preserve state/DOM for expensive components that frequently toggle visibility.
+
+**Usage:**
+
+```tsx
+import { Activity } from 'react'
+
+function Dropdown({ isOpen }: Props) {
+ return (
+
+
+ )
+}
+```
+
+Avoids expensive re-renders and state loss.
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-animate-svg-wrapper.md b/.agents/skills/vercel-react-best-practices/rules/rendering-animate-svg-wrapper.md
new file mode 100644
index 0000000..646744c
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-animate-svg-wrapper.md
@@ -0,0 +1,47 @@
+---
+title: Animate SVG Wrapper Instead of SVG Element
+impact: LOW
+impactDescription: enables hardware acceleration
+tags: rendering, svg, css, animation, performance
+---
+
+## Animate SVG Wrapper Instead of SVG Element
+
+Many browsers don't have hardware acceleration for CSS3 animations on SVG elements. Wrap SVG in a `
+
+
+ )
+}
+```
+
+This applies to all CSS transforms and transitions (`transform`, `opacity`, `translate`, `scale`, `rotate`). The wrapper div allows browsers to use GPU acceleration for smoother animations.
+
+### 6.2 CSS content-visibility for Long Lists
+
+**Impact: HIGH (faster initial render)**
+
+Apply `content-visibility: auto` to defer off-screen rendering.
+
+**CSS:**
+
+```css
+.message-item {
+ content-visibility: auto;
+ contain-intrinsic-size: 0 80px;
+}
+```
+
+**Example:**
+
+```tsx
+function MessageList({ messages }: { messages: Message[] }) {
+ return (
+
+ {messages.map(msg => (
+
+ )
+}
+```
+
+For 1000 messages, browser skips layout/paint for ~990 off-screen items (10× faster initial render).
+
+### 6.3 Hoist Static JSX Elements
+
+**Impact: LOW (avoids re-creation)**
+
+Extract static JSX outside components to avoid re-creation.
+
+**Incorrect: recreates element every render**
+
+```tsx
+function LoadingSkeleton() {
+ return
+}
+
+function Container() {
+ return (
+
+
+ ))}
+ {msg.content}
+
+ {loading &&
+ )
+}
+```
+
+**Correct: reuses same element**
+
+```tsx
+const loadingSkeleton = (
+
+)
+
+function Container() {
+ return (
+
+ {loading && loadingSkeleton}
+
+ )
+}
+```
+
+This is especially helpful for large and static SVG nodes, which can be expensive to recreate on every render.
+
+**Note:** If your project has [React Compiler](https://react.dev/learn/react-compiler) enabled, the compiler automatically hoists static JSX elements and optimizes component re-renders, making manual hoisting unnecessary.
+
+### 6.4 Optimize SVG Precision
+
+**Impact: LOW (reduces file size)**
+
+Reduce SVG coordinate precision to decrease file size. The optimal precision depends on the viewBox size, but in general reducing precision should be considered.
+
+**Incorrect: excessive precision**
+
+```svg
+
+ {children}
+
+ )
+}
+```
+
+Server-side rendering will fail because `localStorage` is undefined.
+
+**Incorrect: visual flickering**
+
+```tsx
+function ThemeWrapper({ children }: { children: ReactNode }) {
+ const [theme, setTheme] = useState('light')
+
+ useEffect(() => {
+ // Runs after hydration - causes visible flash
+ const stored = localStorage.getItem('theme')
+ if (stored) {
+ setTheme(stored)
+ }
+ }, [])
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+Component first renders with default value (`light`), then updates after hydration, causing a visible flash of incorrect content.
+
+**Correct: no flicker, no hydration mismatch**
+
+```tsx
+function ThemeWrapper({ children }: { children: ReactNode }) {
+ return (
+ <>
+
+ {children}
+
+
+
+ )
+}
+```
+
+The inline script executes synchronously before showing the element, ensuring the DOM already has the correct value. No flickering, no hydration mismatch.
+
+This pattern is especially useful for theme toggles, user preferences, authentication states, and any client-only data that should render immediately without flashing default values.
+
+### 6.6 Suppress Expected Hydration Mismatches
+
+**Impact: LOW-MEDIUM (avoids noisy hydration warnings for known differences)**
+
+In SSR frameworks (e.g., Next.js), some values are intentionally different on server vs client (random IDs, dates, locale/timezone formatting). For these *expected* mismatches, wrap the dynamic text in an element with `suppressHydrationWarning` to prevent noisy warnings. Do not use this to hide real bugs. Don’t overuse it.
+
+**Incorrect: known mismatch warnings**
+
+```tsx
+function Timestamp() {
+ return {new Date().toLocaleString()}
+}
+```
+
+**Correct: suppress expected mismatch only**
+
+```tsx
+function Timestamp() {
+ return (
+
+ {new Date().toLocaleString()}
+
+ )
+}
+```
+
+### 6.7 Use Activity Component for Show/Hide
+
+**Impact: MEDIUM (preserves state/DOM)**
+
+Use React's `
+ {count && {count}}
+
+ )
+}
+
+// When count = 0, renders: 0
+// When count = 5, renders: 5
+```
+
+**Correct: renders nothing when count is 0**
+
+```tsx
+function Badge({ count }: { count: number }) {
+ return (
+
+ {count > 0 ? {count} : null}
+
+ )
+}
+
+// When count = 0, renders:
+// When count = 5, renders: 5
+```
+
+### 6.10 Use React DOM Resource Hints
+
+**Impact: HIGH (reduces load time for critical resources)**
+
+React DOM provides APIs to hint the browser about resources it will need. These are especially useful in server components to start loading resources before the client even receives the HTML.
+
+- **`prefetchDNS(href)`**: Resolve DNS for a domain you expect to connect to
+
+- **`preconnect(href)`**: Establish connection (DNS + TCP + TLS) to a server
+
+- **`preload(href, options)`**: Fetch a resource (stylesheet, font, script, image) you'll use soon
+
+- **`preloadModule(href)`**: Fetch an ES module you'll use soon
+
+- **`preinit(href, options)`**: Fetch and evaluate a stylesheet or script
+
+- **`preinitModule(href)`**: Fetch and evaluate an ES module
+
+**Example: preconnect to third-party APIs**
+
+```tsx
+import { preconnect, prefetchDNS } from 'react-dom'
+
+export default function App() {
+ prefetchDNS('https://analytics.example.com')
+ preconnect('https://api.example.com')
+
+ return Content
+}
+
+// Correct: toggle class
+function Box({ isHighlighted }: { isHighlighted: boolean }) {
+ return (
+
+ Content
+
+ )
+}
+```
+
+Prefer CSS classes over inline styles when possible. CSS files are cached by the browser, and classes provide better separation of concerns and are easier to maintain.
+
+See [this gist](https://gist.github.com/paulirish/5d52fb081b3570c81e3a) and [CSS Triggers](https://csstriggers.com/) for more information on layout-forcing operations.
+
+### 7.2 Build Index Maps for Repeated Lookups
+
+**Impact: LOW-MEDIUM (1M ops to 2K ops)**
+
+Multiple `.find()` calls by the same key should use a Map.
+
+**Incorrect (O(n) per lookup):**
+
+```typescript
+function processOrders(orders: Order[], users: User[]) {
+ return orders.map(order => ({
+ ...order,
+ user: users.find(u => u.id === order.userId)
+ }))
+}
+```
+
+**Correct (O(1) per lookup):**
+
+```typescript
+function processOrders(orders: Order[], users: User[]) {
+ const userById = new Map(users.map(u => [u.id, u]))
+
+ return orders.map(order => ({
+ ...order,
+ user: userById.get(order.userId)
+ }))
+}
+```
+
+Build map once (O(n)), then all lookups are O(1).
+
+For 1000 orders × 1000 users: 1M ops → 2K ops.
+
+### 7.3 Cache Property Access in Loops
+
+**Impact: LOW-MEDIUM (reduces lookups)**
+
+Cache object property lookups in hot paths.
+
+**Incorrect: 3 lookups × N iterations**
+
+```typescript
+for (let i = 0; i < arr.length; i++) {
+ process(obj.config.settings.value)
+}
+```
+
+**Correct: 1 lookup total**
+
+```typescript
+const value = obj.config.settings.value
+const len = arr.length
+for (let i = 0; i < len; i++) {
+ process(value)
+}
+```
+
+### 7.4 Cache Repeated Function Calls
+
+**Impact: MEDIUM (avoid redundant computation)**
+
+Use a module-level Map to cache function results when the same function is called repeatedly with the same inputs during render.
+
+**Incorrect: redundant computation**
+
+```typescript
+function ProjectList({ projects }: { projects: Project[] }) {
+ return (
+
+ {projects.map(project => {
+ // slugify() called 100+ times for same project names
+ const slug = slugify(project.name)
+
+ return
+ )
+}
+```
+
+**Correct: cached results**
+
+```typescript
+// Module-level cache
+const slugifyCache = new Map
+ {projects.map(project => {
+ // Computed only once per unique project name
+ const slug = cachedSlugify(project.name)
+
+ return
+ )
+}
+```
+
+**Simpler pattern for single-value functions:**
+
+```typescript
+let isLoggedInCache: boolean | null = null
+
+function isLoggedIn(): boolean {
+ if (isLoggedInCache !== null) {
+ return isLoggedInCache
+ }
+
+ isLoggedInCache = document.cookie.includes('auth=')
+ return isLoggedInCache
+}
+
+// Clear cache when auth changes
+function onAuthChange() {
+ isLoggedInCache = null
+}
+```
+
+Use a Map (not a hook) so it works everywhere: utilities, event handlers, not just React components.
+
+Reference: [https://vercel.com/blog/how-we-made-the-vercel-dashboard-twice-as-fast](https://vercel.com/blog/how-we-made-the-vercel-dashboard-twice-as-fast)
+
+### 7.5 Cache Storage API Calls
+
+**Impact: LOW-MEDIUM (reduces expensive I/O)**
+
+`localStorage`, `sessionStorage`, and `document.cookie` are synchronous and expensive. Cache reads in memory.
+
+**Incorrect: reads storage on every call**
+
+```typescript
+function getTheme() {
+ return localStorage.getItem('theme') ?? 'light'
+}
+// Called 10 times = 10 storage reads
+```
+
+**Correct: Map cache**
+
+```typescript
+const storageCache = new Map{sorted.map(renderUser)}
+}
+```
+
+**Correct: creates new array**
+
+```typescript
+function UserList({ users }: { users: User[] }) {
+ // Creates new sorted array, original unchanged
+ const sorted = useMemo(
+ () => users.toSorted((a, b) => a.name.localeCompare(b.name)),
+ [users]
+ )
+ return {sorted.map(renderUser)}
+}
+```
+
+**Why this matters in React:**
+
+1. Props/state mutations break React's immutability model - React expects props and state to be treated as read-only
+
+2. Causes stale closure bugs - Mutating arrays inside closures (callbacks, effects) can lead to unexpected behavior
+
+**Browser support: fallback for older browsers**
+
+```typescript
+// Fallback for older browsers
+const sorted = [...items].sort((a, b) => a.value - b.value)
+```
+
+`.toSorted()` is available in all modern browsers (Chrome 110+, Safari 16+, Firefox 115+, Node.js 20+). For older environments, use spread operator:
+
+**Other immutable array methods:**
+
+- `.toSorted()` - immutable sort
+
+- `.toReversed()` - immutable reverse
+
+- `.toSpliced()` - immutable splice
+
+- `.with()` - immutable element replacement
+
+---
+
+## 8. Advanced Patterns
+
+**Impact: LOW**
+
+Advanced patterns for specific cases that require careful implementation.
+
+### 8.1 Initialize App Once, Not Per Mount
+
+**Impact: LOW-MEDIUM (avoids duplicate init in development)**
+
+Do not put app-wide initialization that must run once per app load inside `useEffect([])` of a component. Components can remount and effects will re-run. Use a module-level guard or top-level init in the entry module instead.
+
+**Incorrect: runs twice in dev, re-runs on remount**
+
+```tsx
+function Comp() {
+ useEffect(() => {
+ loadFromStorage()
+ checkAuthToken()
+ }, [])
+
+ // ...
+}
+```
+
+**Correct: once per app load**
+
+```tsx
+let didInit = false
+
+function Comp() {
+ useEffect(() => {
+ if (didInit) return
+ didInit = true
+ loadFromStorage()
+ checkAuthToken()
+ }, [])
+
+ // ...
+}
+```
+
+Reference: [https://react.dev/learn/you-might-not-need-an-effect#initializing-the-application](https://react.dev/learn/you-might-not-need-an-effect#initializing-the-application)
+
+### 8.2 Store Event Handlers in Refs
+
+**Impact: LOW (stable subscriptions)**
+
+Store callbacks in refs when used in effects that shouldn't re-subscribe on callback changes.
+
+**Incorrect: re-subscribes on every render**
+
+```tsx
+function useWindowEvent(event: string, handler: (e) => void) {
+ useEffect(() => {
+ window.addEventListener(event, handler)
+ return () => window.removeEventListener(event, handler)
+ }, [event, handler])
+}
+```
+
+**Correct: stable subscription**
+
+```tsx
+import { useEffectEvent } from 'react'
+
+function useWindowEvent(event: string, handler: (e) => void) {
+ const onEvent = useEffectEvent(handler)
+
+ useEffect(() => {
+ window.addEventListener(event, onEvent)
+ return () => window.removeEventListener(event, onEvent)
+ }, [event])
+}
+```
+
+**Alternative: use `useEffectEvent` if you're on latest React:**
+
+`useEffectEvent` provides a cleaner API for the same pattern: it creates a stable function reference that always calls the latest version of the handler.
+
+### 8.3 useEffectEvent for Stable Callback Refs
+
+**Impact: LOW (prevents effect re-runs)**
+
+Access latest values in callbacks without adding them to dependency arrays. Prevents effect re-runs while avoiding stale closures.
+
+**Incorrect: effect re-runs on every callback change**
+
+```tsx
+function SearchInput({ onSearch }: { onSearch: (q: string) => void }) {
+ const [query, setQuery] = useState('')
+
+ useEffect(() => {
+ const timeout = setTimeout(() => onSearch(query), 300)
+ return () => clearTimeout(timeout)
+ }, [query, onSearch])
+}
+```
+
+**Correct: using React's useEffectEvent**
+
+```tsx
+import { useEffectEvent } from 'react';
+
+function SearchInput({ onSearch }: { onSearch: (q: string) => void }) {
+ const [query, setQuery] = useState('')
+ const onSearchEvent = useEffectEvent(onSearch)
+
+ useEffect(() => {
+ const timeout = setTimeout(() => onSearchEvent(query), 300)
+ return () => clearTimeout(timeout)
+ }, [query])
+}
+```
+
+---
+
+## References
+
+1. [https://react.dev](https://react.dev)
+2. [https://nextjs.org](https://nextjs.org)
+3. [https://swr.vercel.app](https://swr.vercel.app)
+4. [https://github.com/shuding/better-all](https://github.com/shuding/better-all)
+5. [https://github.com/isaacs/node-lru-cache](https://github.com/isaacs/node-lru-cache)
+6. [https://vercel.com/blog/how-we-optimized-package-imports-in-next-js](https://vercel.com/blog/how-we-optimized-package-imports-in-next-js)
+7. [https://vercel.com/blog/how-we-made-the-vercel-dashboard-twice-as-fast](https://vercel.com/blog/how-we-made-the-vercel-dashboard-twice-as-fast)
diff --git a/.agents/skills/vercel-react-best-practices/README.md b/.agents/skills/vercel-react-best-practices/README.md
new file mode 100644
index 0000000..f283e1c
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/README.md
@@ -0,0 +1,123 @@
+# React Best Practices
+
+A structured repository for creating and maintaining React Best Practices optimized for agents and LLMs.
+
+## Structure
+
+- `rules/` - Individual rule files (one per rule)
+ - `_sections.md` - Section metadata (titles, impacts, descriptions)
+ - `_template.md` - Template for creating new rules
+ - `area-description.md` - Individual rule files
+- `src/` - Build scripts and utilities
+- `metadata.json` - Document metadata (version, organization, abstract)
+- __`AGENTS.md`__ - Compiled output (generated)
+- __`test-cases.json`__ - Test cases for LLM evaluation (generated)
+
+## Getting Started
+
+1. Install dependencies:
+ ```bash
+ pnpm install
+ ```
+
+2. Build AGENTS.md from rules:
+ ```bash
+ pnpm build
+ ```
+
+3. Validate rule files:
+ ```bash
+ pnpm validate
+ ```
+
+4. Extract test cases:
+ ```bash
+ pnpm extract-tests
+ ```
+
+## Creating a New Rule
+
+1. Copy `rules/_template.md` to `rules/area-description.md`
+2. Choose the appropriate area prefix:
+ - `async-` for Eliminating Waterfalls (Section 1)
+ - `bundle-` for Bundle Size Optimization (Section 2)
+ - `server-` for Server-Side Performance (Section 3)
+ - `client-` for Client-Side Data Fetching (Section 4)
+ - `rerender-` for Re-render Optimization (Section 5)
+ - `rendering-` for Rendering Performance (Section 6)
+ - `js-` for JavaScript Performance (Section 7)
+ - `advanced-` for Advanced Patterns (Section 8)
+3. Fill in the frontmatter and content
+4. Ensure you have clear examples with explanations
+5. Run `pnpm build` to regenerate AGENTS.md and test-cases.json
+
+## Rule File Structure
+
+Each rule file should follow this structure:
+
+```markdown
+---
+title: Rule Title Here
+impact: MEDIUM
+impactDescription: Optional description
+tags: tag1, tag2, tag3
+---
+
+## Rule Title Here
+
+Brief explanation of the rule and why it matters.
+
+**Incorrect (description of what's wrong):**
+
+```typescript
+// Bad code example
+```
+
+**Correct (description of what's right):**
+
+```typescript
+// Good code example
+```
+
+Optional explanatory text after examples.
+
+Reference: [Link](https://example.com)
+
+## File Naming Convention
+
+- Files starting with `_` are special (excluded from build)
+- Rule files: `area-description.md` (e.g., `async-parallel.md`)
+- Section is automatically inferred from filename prefix
+- Rules are sorted alphabetically by title within each section
+- IDs (e.g., 1.1, 1.2) are auto-generated during build
+
+## Impact Levels
+
+- `CRITICAL` - Highest priority, major performance gains
+- `HIGH` - Significant performance improvements
+- `MEDIUM-HIGH` - Moderate-high gains
+- `MEDIUM` - Moderate performance improvements
+- `LOW-MEDIUM` - Low-medium gains
+- `LOW` - Incremental improvements
+
+## Scripts
+
+- `pnpm build` - Compile rules into AGENTS.md
+- `pnpm validate` - Validate all rule files
+- `pnpm extract-tests` - Extract test cases for LLM evaluation
+- `pnpm dev` - Build and validate
+
+## Contributing
+
+When adding or modifying rules:
+
+1. Use the correct filename prefix for your section
+2. Follow the `_template.md` structure
+3. Include clear bad/good examples with explanations
+4. Add appropriate tags
+5. Run `pnpm build` to regenerate AGENTS.md and test-cases.json
+6. Rules are automatically sorted by title - no need to manage numbers!
+
+## Acknowledgments
+
+Originally created by [@shuding](https://x.com/shuding) at [Vercel](https://vercel.com).
diff --git a/.agents/skills/vercel-react-best-practices/SKILL.md b/.agents/skills/vercel-react-best-practices/SKILL.md
new file mode 100644
index 0000000..df17a29
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/SKILL.md
@@ -0,0 +1,145 @@
+---
+name: vercel-react-best-practices
+description: React and Next.js performance optimization guidelines from Vercel Engineering. This skill should be used when writing, reviewing, or refactoring React/Next.js code to ensure optimal performance patterns. Triggers on tasks involving React components, Next.js pages, data fetching, bundle optimization, or performance improvements.
+license: MIT
+metadata:
+ author: vercel
+ version: "1.0.0"
+---
+
+# Vercel React Best Practices
+
+Comprehensive performance optimization guide for React and Next.js applications, maintained by Vercel. Contains 65 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.
+
+## When to Apply
+
+Reference these guidelines when:
+- Writing new React components or Next.js pages
+- Implementing data fetching (client or server-side)
+- Reviewing code for performance issues
+- Refactoring existing React/Next.js code
+- Optimizing bundle size or load times
+
+## Rule Categories by Priority
+
+| Priority | Category | Impact | Prefix |
+|----------|----------|--------|--------|
+| 1 | Eliminating Waterfalls | CRITICAL | `async-` |
+| 2 | Bundle Size Optimization | CRITICAL | `bundle-` |
+| 3 | Server-Side Performance | HIGH | `server-` |
+| 4 | Client-Side Data Fetching | MEDIUM-HIGH | `client-` |
+| 5 | Re-render Optimization | MEDIUM | `rerender-` |
+| 6 | Rendering Performance | MEDIUM | `rendering-` |
+| 7 | JavaScript Performance | LOW-MEDIUM | `js-` |
+| 8 | Advanced Patterns | LOW | `advanced-` |
+
+## Quick Reference
+
+### 1. Eliminating Waterfalls (CRITICAL)
+
+- `async-defer-await` - Move await into branches where actually used
+- `async-parallel` - Use Promise.all() for independent operations
+- `async-dependencies` - Use better-all for partial dependencies
+- `async-api-routes` - Start promises early, await late in API routes
+- `async-suspense-boundaries` - Use Suspense to stream content
+
+### 2. Bundle Size Optimization (CRITICAL)
+
+- `bundle-barrel-imports` - Import directly, avoid barrel files
+- `bundle-dynamic-imports` - Use next/dynamic for heavy components
+- `bundle-defer-third-party` - Load analytics/logging after hydration
+- `bundle-conditional` - Load modules only when feature is activated
+- `bundle-preload` - Preload on hover/focus for perceived speed
+
+### 3. Server-Side Performance (HIGH)
+
+- `server-auth-actions` - Authenticate server actions like API routes
+- `server-cache-react` - Use React.cache() for per-request deduplication
+- `server-cache-lru` - Use LRU cache for cross-request caching
+- `server-dedup-props` - Avoid duplicate serialization in RSC props
+- `server-hoist-static-io` - Hoist static I/O (fonts, logos) to module level
+- `server-serialization` - Minimize data passed to client components
+- `server-parallel-fetching` - Restructure components to parallelize fetches
+- `server-parallel-nested-fetching` - Chain nested fetches per item in Promise.all
+- `server-after-nonblocking` - Use after() for non-blocking operations
+
+### 4. Client-Side Data Fetching (MEDIUM-HIGH)
+
+- `client-swr-dedup` - Use SWR for automatic request deduplication
+- `client-event-listeners` - Deduplicate global event listeners
+- `client-passive-event-listeners` - Use passive listeners for scroll
+- `client-localstorage-schema` - Version and minimize localStorage data
+
+### 5. Re-render Optimization (MEDIUM)
+
+- `rerender-defer-reads` - Don't subscribe to state only used in callbacks
+- `rerender-memo` - Extract expensive work into memoized components
+- `rerender-memo-with-default-value` - Hoist default non-primitive props
+- `rerender-dependencies` - Use primitive dependencies in effects
+- `rerender-derived-state` - Subscribe to derived booleans, not raw values
+- `rerender-derived-state-no-effect` - Derive state during render, not effects
+- `rerender-functional-setstate` - Use functional setState for stable callbacks
+- `rerender-lazy-state-init` - Pass function to useState for expensive values
+- `rerender-simple-expression-in-memo` - Avoid memo for simple primitives
+- `rerender-split-combined-hooks` - Split hooks with independent dependencies
+- `rerender-move-effect-to-event` - Put interaction logic in event handlers
+- `rerender-transitions` - Use startTransition for non-urgent updates
+- `rerender-use-deferred-value` - Defer expensive renders to keep input responsive
+- `rerender-use-ref-transient-values` - Use refs for transient frequent values
+- `rerender-no-inline-components` - Don't define components inside components
+
+### 6. Rendering Performance (MEDIUM)
+
+- `rendering-animate-svg-wrapper` - Animate div wrapper, not SVG element
+- `rendering-content-visibility` - Use content-visibility for long lists
+- `rendering-hoist-jsx` - Extract static JSX outside components
+- `rendering-svg-precision` - Reduce SVG coordinate precision
+- `rendering-hydration-no-flicker` - Use inline script for client-only data
+- `rendering-hydration-suppress-warning` - Suppress expected mismatches
+- `rendering-activity` - Use Activity component for show/hide
+- `rendering-conditional-render` - Use ternary, not && for conditionals
+- `rendering-usetransition-loading` - Prefer useTransition for loading state
+- `rendering-resource-hints` - Use React DOM resource hints for preloading
+- `rendering-script-defer-async` - Use defer or async on script tags
+
+### 7. JavaScript Performance (LOW-MEDIUM)
+
+- `js-batch-dom-css` - Group CSS changes via classes or cssText
+- `js-index-maps` - Build Map for repeated lookups
+- `js-cache-property-access` - Cache object properties in loops
+- `js-cache-function-results` - Cache function results in module-level Map
+- `js-cache-storage` - Cache localStorage/sessionStorage reads
+- `js-combine-iterations` - Combine multiple filter/map into one loop
+- `js-length-check-first` - Check array length before expensive comparison
+- `js-early-exit` - Return early from functions
+- `js-hoist-regexp` - Hoist RegExp creation outside loops
+- `js-min-max-loop` - Use loop for min/max instead of sort
+- `js-set-map-lookups` - Use Set/Map for O(1) lookups
+- `js-tosorted-immutable` - Use toSorted() for immutability
+- `js-flatmap-filter` - Use flatMap to map and filter in one pass
+- `js-request-idle-callback` - Defer non-critical work to browser idle time
+
+### 8. Advanced Patterns (LOW)
+
+- `advanced-event-handler-refs` - Store event handlers in refs
+- `advanced-init-once` - Initialize app once per app load
+- `advanced-use-latest` - useLatest for stable callback refs
+
+## How to Use
+
+Read individual rule files for detailed explanations and code examples:
+
+```
+rules/async-parallel.md
+rules/bundle-barrel-imports.md
+```
+
+Each rule file contains:
+- Brief explanation of why it matters
+- Incorrect code example with explanation
+- Correct code example with explanation
+- Additional context and references
+
+## Full Compiled Document
+
+For the complete guide with all rules expanded: `AGENTS.md`
diff --git a/.agents/skills/vercel-react-best-practices/rules/_sections.md b/.agents/skills/vercel-react-best-practices/rules/_sections.md
new file mode 100644
index 0000000..4d20c14
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/_sections.md
@@ -0,0 +1,46 @@
+# Sections
+
+This file defines all sections, their ordering, impact levels, and descriptions.
+The section ID (in parentheses) is the filename prefix used to group rules.
+
+---
+
+## 1. Eliminating Waterfalls (async)
+
+**Impact:** CRITICAL
+**Description:** Waterfalls are the #1 performance killer. Each sequential await adds full network latency. Eliminating them yields the largest gains.
+
+## 2. Bundle Size Optimization (bundle)
+
+**Impact:** CRITICAL
+**Description:** Reducing initial bundle size improves Time to Interactive and Largest Contentful Paint.
+
+## 3. Server-Side Performance (server)
+
+**Impact:** HIGH
+**Description:** Optimizing server-side rendering and data fetching eliminates server-side waterfalls and reduces response times.
+
+## 4. Client-Side Data Fetching (client)
+
+**Impact:** MEDIUM-HIGH
+**Description:** Automatic deduplication and efficient data fetching patterns reduce redundant network requests.
+
+## 5. Re-render Optimization (rerender)
+
+**Impact:** MEDIUM
+**Description:** Reducing unnecessary re-renders minimizes wasted computation and improves UI responsiveness.
+
+## 6. Rendering Performance (rendering)
+
+**Impact:** MEDIUM
+**Description:** Optimizing the rendering process reduces the work the browser needs to do.
+
+## 7. JavaScript Performance (js)
+
+**Impact:** LOW-MEDIUM
+**Description:** Micro-optimizations for hot paths can add up to meaningful improvements.
+
+## 8. Advanced Patterns (advanced)
+
+**Impact:** LOW
+**Description:** Advanced patterns for specific cases that require careful implementation.
diff --git a/.agents/skills/vercel-react-best-practices/rules/_template.md b/.agents/skills/vercel-react-best-practices/rules/_template.md
new file mode 100644
index 0000000..1e9e707
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/_template.md
@@ -0,0 +1,28 @@
+---
+title: Rule Title Here
+impact: MEDIUM
+impactDescription: Optional description of impact (e.g., "20-50% improvement")
+tags: tag1, tag2
+---
+
+## Rule Title Here
+
+**Impact: MEDIUM (optional impact description)**
+
+Brief explanation of the rule and why it matters. This should be clear and concise, explaining the performance implications.
+
+**Incorrect (description of what's wrong):**
+
+```typescript
+// Bad code example here
+const bad = example()
+```
+
+**Correct (description of what's right):**
+
+```typescript
+// Good code example here
+const good = example()
+```
+
+Reference: [Link to documentation or resource](https://example.com)
diff --git a/.agents/skills/vercel-react-best-practices/rules/advanced-event-handler-refs.md b/.agents/skills/vercel-react-best-practices/rules/advanced-event-handler-refs.md
new file mode 100644
index 0000000..97e7ade
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/advanced-event-handler-refs.md
@@ -0,0 +1,55 @@
+---
+title: Store Event Handlers in Refs
+impact: LOW
+impactDescription: stable subscriptions
+tags: advanced, hooks, refs, event-handlers, optimization
+---
+
+## Store Event Handlers in Refs
+
+Store callbacks in refs when used in effects that shouldn't re-subscribe on callback changes.
+
+**Incorrect (re-subscribes on every render):**
+
+```tsx
+function useWindowEvent(event: string, handler: (e) => void) {
+ useEffect(() => {
+ window.addEventListener(event, handler)
+ return () => window.removeEventListener(event, handler)
+ }, [event, handler])
+}
+```
+
+**Correct (stable subscription):**
+
+```tsx
+function useWindowEvent(event: string, handler: (e) => void) {
+ const handlerRef = useRef(handler)
+ useEffect(() => {
+ handlerRef.current = handler
+ }, [handler])
+
+ useEffect(() => {
+ const listener = (e) => handlerRef.current(e)
+ window.addEventListener(event, listener)
+ return () => window.removeEventListener(event, listener)
+ }, [event])
+}
+```
+
+**Alternative: use `useEffectEvent` if you're on latest React:**
+
+```tsx
+import { useEffectEvent } from 'react'
+
+function useWindowEvent(event: string, handler: (e) => void) {
+ const onEvent = useEffectEvent(handler)
+
+ useEffect(() => {
+ window.addEventListener(event, onEvent)
+ return () => window.removeEventListener(event, onEvent)
+ }, [event])
+}
+```
+
+`useEffectEvent` provides a cleaner API for the same pattern: it creates a stable function reference that always calls the latest version of the handler.
diff --git a/.agents/skills/vercel-react-best-practices/rules/advanced-init-once.md b/.agents/skills/vercel-react-best-practices/rules/advanced-init-once.md
new file mode 100644
index 0000000..73ee38e
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/advanced-init-once.md
@@ -0,0 +1,42 @@
+---
+title: Initialize App Once, Not Per Mount
+impact: LOW-MEDIUM
+impactDescription: avoids duplicate init in development
+tags: initialization, useEffect, app-startup, side-effects
+---
+
+## Initialize App Once, Not Per Mount
+
+Do not put app-wide initialization that must run once per app load inside `useEffect([])` of a component. Components can remount and effects will re-run. Use a module-level guard or top-level init in the entry module instead.
+
+**Incorrect (runs twice in dev, re-runs on remount):**
+
+```tsx
+function Comp() {
+ useEffect(() => {
+ loadFromStorage()
+ checkAuthToken()
+ }, [])
+
+ // ...
+}
+```
+
+**Correct (once per app load):**
+
+```tsx
+let didInit = false
+
+function Comp() {
+ useEffect(() => {
+ if (didInit) return
+ didInit = true
+ loadFromStorage()
+ checkAuthToken()
+ }, [])
+
+ // ...
+}
+```
+
+Reference: [Initializing the application](https://react.dev/learn/you-might-not-need-an-effect#initializing-the-application)
diff --git a/.agents/skills/vercel-react-best-practices/rules/advanced-use-latest.md b/.agents/skills/vercel-react-best-practices/rules/advanced-use-latest.md
new file mode 100644
index 0000000..9c7cb50
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/advanced-use-latest.md
@@ -0,0 +1,39 @@
+---
+title: useEffectEvent for Stable Callback Refs
+impact: LOW
+impactDescription: prevents effect re-runs
+tags: advanced, hooks, useEffectEvent, refs, optimization
+---
+
+## useEffectEvent for Stable Callback Refs
+
+Access latest values in callbacks without adding them to dependency arrays. Prevents effect re-runs while avoiding stale closures.
+
+**Incorrect (effect re-runs on every callback change):**
+
+```tsx
+function SearchInput({ onSearch }: { onSearch: (q: string) => void }) {
+ const [query, setQuery] = useState('')
+
+ useEffect(() => {
+ const timeout = setTimeout(() => onSearch(query), 300)
+ return () => clearTimeout(timeout)
+ }, [query, onSearch])
+}
+```
+
+**Correct (using React's useEffectEvent):**
+
+```tsx
+import { useEffectEvent } from 'react';
+
+function SearchInput({ onSearch }: { onSearch: (q: string) => void }) {
+ const [query, setQuery] = useState('')
+ const onSearchEvent = useEffectEvent(onSearch)
+
+ useEffect(() => {
+ const timeout = setTimeout(() => onSearchEvent(query), 300)
+ return () => clearTimeout(timeout)
+ }, [query])
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/async-api-routes.md b/.agents/skills/vercel-react-best-practices/rules/async-api-routes.md
new file mode 100644
index 0000000..6feda1e
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/async-api-routes.md
@@ -0,0 +1,38 @@
+---
+title: Prevent Waterfall Chains in API Routes
+impact: CRITICAL
+impactDescription: 2-10× improvement
+tags: api-routes, server-actions, waterfalls, parallelization
+---
+
+## Prevent Waterfall Chains in API Routes
+
+In API routes and Server Actions, start independent operations immediately, even if you don't await them yet.
+
+**Incorrect (config waits for auth, data waits for both):**
+
+```typescript
+export async function GET(request: Request) {
+ const session = await auth()
+ const config = await fetchConfig()
+ const data = await fetchData(session.user.id)
+ return Response.json({ data, config })
+}
+```
+
+**Correct (auth and config start immediately):**
+
+```typescript
+export async function GET(request: Request) {
+ const sessionPromise = auth()
+ const configPromise = fetchConfig()
+ const session = await sessionPromise
+ const [config, data] = await Promise.all([
+ configPromise,
+ fetchData(session.user.id)
+ ])
+ return Response.json({ data, config })
+}
+```
+
+For operations with more complex dependency chains, use `better-all` to automatically maximize parallelism (see Dependency-Based Parallelization).
diff --git a/.agents/skills/vercel-react-best-practices/rules/async-defer-await.md b/.agents/skills/vercel-react-best-practices/rules/async-defer-await.md
new file mode 100644
index 0000000..ea7082a
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/async-defer-await.md
@@ -0,0 +1,80 @@
+---
+title: Defer Await Until Needed
+impact: HIGH
+impactDescription: avoids blocking unused code paths
+tags: async, await, conditional, optimization
+---
+
+## Defer Await Until Needed
+
+Move `await` operations into the branches where they're actually used to avoid blocking code paths that don't need them.
+
+**Incorrect (blocks both branches):**
+
+```typescript
+async function handleRequest(userId: string, skipProcessing: boolean) {
+ const userData = await fetchUserData(userId)
+
+ if (skipProcessing) {
+ // Returns immediately but still waited for userData
+ return { skipped: true }
+ }
+
+ // Only this branch uses userData
+ return processUserData(userData)
+}
+```
+
+**Correct (only blocks when needed):**
+
+```typescript
+async function handleRequest(userId: string, skipProcessing: boolean) {
+ if (skipProcessing) {
+ // Returns immediately without waiting
+ return { skipped: true }
+ }
+
+ // Fetch only when needed
+ const userData = await fetchUserData(userId)
+ return processUserData(userData)
+}
+```
+
+**Another example (early return optimization):**
+
+```typescript
+// Incorrect: always fetches permissions
+async function updateResource(resourceId: string, userId: string) {
+ const permissions = await fetchPermissions(userId)
+ const resource = await getResource(resourceId)
+
+ if (!resource) {
+ return { error: 'Not found' }
+ }
+
+ if (!permissions.canEdit) {
+ return { error: 'Forbidden' }
+ }
+
+ return await updateResourceData(resource, permissions)
+}
+
+// Correct: fetches only when needed
+async function updateResource(resourceId: string, userId: string) {
+ const resource = await getResource(resourceId)
+
+ if (!resource) {
+ return { error: 'Not found' }
+ }
+
+ const permissions = await fetchPermissions(userId)
+
+ if (!permissions.canEdit) {
+ return { error: 'Forbidden' }
+ }
+
+ return await updateResourceData(resource, permissions)
+}
+```
+
+This optimization is especially valuable when the skipped branch is frequently taken, or when the deferred operation is expensive.
diff --git a/.agents/skills/vercel-react-best-practices/rules/async-dependencies.md b/.agents/skills/vercel-react-best-practices/rules/async-dependencies.md
new file mode 100644
index 0000000..0484eba
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/async-dependencies.md
@@ -0,0 +1,51 @@
+---
+title: Dependency-Based Parallelization
+impact: CRITICAL
+impactDescription: 2-10× improvement
+tags: async, parallelization, dependencies, better-all
+---
+
+## Dependency-Based Parallelization
+
+For operations with partial dependencies, use `better-all` to maximize parallelism. It automatically starts each task at the earliest possible moment.
+
+**Incorrect (profile waits for config unnecessarily):**
+
+```typescript
+const [user, config] = await Promise.all([
+ fetchUser(),
+ fetchConfig()
+])
+const profile = await fetchProfile(user.id)
+```
+
+**Correct (config and profile run in parallel):**
+
+```typescript
+import { all } from 'better-all'
+
+const { user, config, profile } = await all({
+ async user() { return fetchUser() },
+ async config() { return fetchConfig() },
+ async profile() {
+ return fetchProfile((await this.$.user).id)
+ }
+})
+```
+
+**Alternative without extra dependencies:**
+
+We can also create all the promises first, and do `Promise.all()` at the end.
+
+```typescript
+const userPromise = fetchUser()
+const profilePromise = userPromise.then(user => fetchProfile(user.id))
+
+const [user, config, profile] = await Promise.all([
+ userPromise,
+ fetchConfig(),
+ profilePromise
+])
+```
+
+Reference: [https://github.com/shuding/better-all](https://github.com/shuding/better-all)
diff --git a/.agents/skills/vercel-react-best-practices/rules/async-parallel.md b/.agents/skills/vercel-react-best-practices/rules/async-parallel.md
new file mode 100644
index 0000000..64133f6
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/async-parallel.md
@@ -0,0 +1,28 @@
+---
+title: Promise.all() for Independent Operations
+impact: CRITICAL
+impactDescription: 2-10× improvement
+tags: async, parallelization, promises, waterfalls
+---
+
+## Promise.all() for Independent Operations
+
+When async operations have no interdependencies, execute them concurrently using `Promise.all()`.
+
+**Incorrect (sequential execution, 3 round trips):**
+
+```typescript
+const user = await fetchUser()
+const posts = await fetchPosts()
+const comments = await fetchComments()
+```
+
+**Correct (parallel execution, 1 round trip):**
+
+```typescript
+const [user, posts, comments] = await Promise.all([
+ fetchUser(),
+ fetchPosts(),
+ fetchComments()
+])
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/async-suspense-boundaries.md b/.agents/skills/vercel-react-best-practices/rules/async-suspense-boundaries.md
new file mode 100644
index 0000000..1fbc05b
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/async-suspense-boundaries.md
@@ -0,0 +1,99 @@
+---
+title: Strategic Suspense Boundaries
+impact: HIGH
+impactDescription: faster initial paint
+tags: async, suspense, streaming, layout-shift
+---
+
+## Strategic Suspense Boundaries
+
+Instead of awaiting data in async components before returning JSX, use Suspense boundaries to show the wrapper UI faster while data loads.
+
+**Incorrect (wrapper blocked by data fetching):**
+
+```tsx
+async function Page() {
+ const data = await fetchData() // Blocks entire page
+
+ return (
+
+
+ )
+}
+```
+
+The entire layout waits for data even though only the middle section needs it.
+
+**Correct (wrapper shows immediately, data streams in):**
+
+```tsx
+function Page() {
+ return (
+ Sidebar
+ Header
+
+
+ Footer
+
+
+ )
+}
+
+async function DataDisplay() {
+ const data = await fetchData() // Only blocks this component
+ return Sidebar
+ Header
+
+
+ Footer
+ {data.content}
+}
+```
+
+Sidebar, Header, and Footer render immediately. Only DataDisplay waits for data.
+
+**Alternative (share promise across components):**
+
+```tsx
+function Page() {
+ // Start fetch immediately, but don't await
+ const dataPromise = fetchData()
+
+ return (
+
+
+ )
+}
+
+function DataDisplay({ dataPromise }: { dataPromise: Promise }) {
+ const data = use(dataPromise) // Unwraps the promise
+ return Sidebar
+ Header
+ Footer
+ {data.content}
+}
+
+function DataSummary({ dataPromise }: { dataPromise: Promise }) {
+ const data = use(dataPromise) // Reuses the same promise
+ return {data.summary}
+}
+```
+
+Both components share the same promise, so only one fetch occurs. Layout renders immediately while both components wait together.
+
+**When NOT to use this pattern:**
+
+- Critical data needed for layout decisions (affects positioning)
+- SEO-critical content above the fold
+- Small, fast queries where suspense overhead isn't worth it
+- When you want to avoid layout shift (loading → content jump)
+
+**Trade-off:** Faster initial paint vs potential layout shift. Choose based on your UX priorities.
diff --git a/.agents/skills/vercel-react-best-practices/rules/bundle-barrel-imports.md b/.agents/skills/vercel-react-best-practices/rules/bundle-barrel-imports.md
new file mode 100644
index 0000000..22d1050
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/bundle-barrel-imports.md
@@ -0,0 +1,60 @@
+---
+title: Avoid Barrel File Imports
+impact: CRITICAL
+impactDescription: 200-800ms import cost, slow builds
+tags: bundle, imports, tree-shaking, barrel-files, performance
+---
+
+## Avoid Barrel File Imports
+
+Import directly from source files instead of barrel files to avoid loading thousands of unused modules. **Barrel files** are entry points that re-export multiple modules (e.g., `index.js` that does `export * from './module'`).
+
+Popular icon and component libraries can have **up to 10,000 re-exports** in their entry file. For many React packages, **it takes 200-800ms just to import them**, affecting both development speed and production cold starts.
+
+**Why tree-shaking doesn't help:** When a library is marked as external (not bundled), the bundler can't optimize it. If you bundle it to enable tree-shaking, builds become substantially slower analyzing the entire module graph.
+
+**Incorrect (imports entire library):**
+
+```tsx
+import { Check, X, Menu } from 'lucide-react'
+// Loads 1,583 modules, takes ~2.8s extra in dev
+// Runtime cost: 200-800ms on every cold start
+
+import { Button, TextField } from '@mui/material'
+// Loads 2,225 modules, takes ~4.2s extra in dev
+```
+
+**Correct - Next.js 13.5+ (recommended):**
+
+```js
+// next.config.js - automatically optimizes barrel imports at build time
+module.exports = {
+ experimental: {
+ optimizePackageImports: ['lucide-react', '@mui/material']
+ }
+}
+```
+
+```tsx
+// Keep the standard imports - Next.js transforms them to direct imports
+import { Check, X, Menu } from 'lucide-react'
+// Full TypeScript support, no manual path wrangling
+```
+
+This is the recommended approach because it preserves TypeScript type safety and editor autocompletion while still eliminating the barrel import cost.
+
+**Correct - Direct imports (non-Next.js projects):**
+
+```tsx
+import Button from '@mui/material/Button'
+import TextField from '@mui/material/TextField'
+// Loads only what you use
+```
+
+> **TypeScript warning:** Some libraries (notably `lucide-react`) don't ship `.d.ts` files for their deep import paths. Importing from `lucide-react/dist/esm/icons/check` resolves to an implicit `any` type, causing errors under `strict` or `noImplicitAny`. Prefer `optimizePackageImports` when available, or verify the library exports types for its subpaths before using direct imports.
+
+These optimizations provide 15-70% faster dev boot, 28% faster builds, 40% faster cold starts, and significantly faster HMR.
+
+Libraries commonly affected: `lucide-react`, `@mui/material`, `@mui/icons-material`, `@tabler/icons-react`, `react-icons`, `@headlessui/react`, `@radix-ui/react-*`, `lodash`, `ramda`, `date-fns`, `rxjs`, `react-use`.
+
+Reference: [How we optimized package imports in Next.js](https://vercel.com/blog/how-we-optimized-package-imports-in-next-js)
diff --git a/.agents/skills/vercel-react-best-practices/rules/bundle-conditional.md b/.agents/skills/vercel-react-best-practices/rules/bundle-conditional.md
new file mode 100644
index 0000000..99d6fc9
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/bundle-conditional.md
@@ -0,0 +1,31 @@
+---
+title: Conditional Module Loading
+impact: HIGH
+impactDescription: loads large data only when needed
+tags: bundle, conditional-loading, lazy-loading
+---
+
+## Conditional Module Loading
+
+Load large data or modules only when a feature is activated.
+
+**Example (lazy-load animation frames):**
+
+```tsx
+function AnimationPlayer({ enabled, setEnabled }: { enabled: boolean; setEnabled: React.DispatchContent
+}
+
+// Correct: toggle class
+function Box({ isHighlighted }: { isHighlighted: boolean }) {
+ return (
+
+ Content
+
+ )
+}
+```
+
+Prefer CSS classes over inline styles when possible. CSS files are cached by the browser, and classes provide better separation of concerns and are easier to maintain.
+
+See [this gist](https://gist.github.com/paulirish/5d52fb081b3570c81e3a) and [CSS Triggers](https://csstriggers.com/) for more information on layout-forcing operations.
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-cache-function-results.md b/.agents/skills/vercel-react-best-practices/rules/js-cache-function-results.md
new file mode 100644
index 0000000..180f8ac
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-cache-function-results.md
@@ -0,0 +1,80 @@
+---
+title: Cache Repeated Function Calls
+impact: MEDIUM
+impactDescription: avoid redundant computation
+tags: javascript, cache, memoization, performance
+---
+
+## Cache Repeated Function Calls
+
+Use a module-level Map to cache function results when the same function is called repeatedly with the same inputs during render.
+
+**Incorrect (redundant computation):**
+
+```typescript
+function ProjectList({ projects }: { projects: Project[] }) {
+ return (
+
+ {projects.map(project => {
+ // slugify() called 100+ times for same project names
+ const slug = slugify(project.name)
+
+ return
+ )
+}
+```
+
+**Correct (cached results):**
+
+```typescript
+// Module-level cache
+const slugifyCache = new Map
+ {projects.map(project => {
+ // Computed only once per unique project name
+ const slug = cachedSlugify(project.name)
+
+ return
+ )
+}
+```
+
+**Simpler pattern for single-value functions:**
+
+```typescript
+let isLoggedInCache: boolean | null = null
+
+function isLoggedIn(): boolean {
+ if (isLoggedInCache !== null) {
+ return isLoggedInCache
+ }
+
+ isLoggedInCache = document.cookie.includes('auth=')
+ return isLoggedInCache
+}
+
+// Clear cache when auth changes
+function onAuthChange() {
+ isLoggedInCache = null
+}
+```
+
+Use a Map (not a hook) so it works everywhere: utilities, event handlers, not just React components.
+
+Reference: [How we made the Vercel Dashboard twice as fast](https://vercel.com/blog/how-we-made-the-vercel-dashboard-twice-as-fast)
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-cache-property-access.md b/.agents/skills/vercel-react-best-practices/rules/js-cache-property-access.md
new file mode 100644
index 0000000..39eec90
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-cache-property-access.md
@@ -0,0 +1,28 @@
+---
+title: Cache Property Access in Loops
+impact: LOW-MEDIUM
+impactDescription: reduces lookups
+tags: javascript, loops, optimization, caching
+---
+
+## Cache Property Access in Loops
+
+Cache object property lookups in hot paths.
+
+**Incorrect (3 lookups × N iterations):**
+
+```typescript
+for (let i = 0; i < arr.length; i++) {
+ process(obj.config.settings.value)
+}
+```
+
+**Correct (1 lookup total):**
+
+```typescript
+const value = obj.config.settings.value
+const len = arr.length
+for (let i = 0; i < len; i++) {
+ process(value)
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/js-cache-storage.md b/.agents/skills/vercel-react-best-practices/rules/js-cache-storage.md
new file mode 100644
index 0000000..aa4a30c
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/js-cache-storage.md
@@ -0,0 +1,70 @@
+---
+title: Cache Storage API Calls
+impact: LOW-MEDIUM
+impactDescription: reduces expensive I/O
+tags: javascript, localStorage, storage, caching, performance
+---
+
+## Cache Storage API Calls
+
+`localStorage`, `sessionStorage`, and `document.cookie` are synchronous and expensive. Cache reads in memory.
+
+**Incorrect (reads storage on every call):**
+
+```typescript
+function getTheme() {
+ return localStorage.getItem('theme') ?? 'light'
+}
+// Called 10 times = 10 storage reads
+```
+
+**Correct (Map cache):**
+
+```typescript
+const storageCache = new Map{sorted.map(renderUser)}
+}
+```
+
+**Correct (creates new array):**
+
+```typescript
+function UserList({ users }: { users: User[] }) {
+ // Creates new sorted array, original unchanged
+ const sorted = useMemo(
+ () => users.toSorted((a, b) => a.name.localeCompare(b.name)),
+ [users]
+ )
+ return {sorted.map(renderUser)}
+}
+```
+
+**Why this matters in React:**
+
+1. Props/state mutations break React's immutability model - React expects props and state to be treated as read-only
+2. Causes stale closure bugs - Mutating arrays inside closures (callbacks, effects) can lead to unexpected behavior
+
+**Browser support (fallback for older browsers):**
+
+`.toSorted()` is available in all modern browsers (Chrome 110+, Safari 16+, Firefox 115+, Node.js 20+). For older environments, use spread operator:
+
+```typescript
+// Fallback for older browsers
+const sorted = [...items].sort((a, b) => a.value - b.value)
+```
+
+**Other immutable array methods:**
+
+- `.toSorted()` - immutable sort
+- `.toReversed()` - immutable reverse
+- `.toSpliced()` - immutable splice
+- `.with()` - immutable element replacement
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-activity.md b/.agents/skills/vercel-react-best-practices/rules/rendering-activity.md
new file mode 100644
index 0000000..c957a49
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-activity.md
@@ -0,0 +1,26 @@
+---
+title: Use Activity Component for Show/Hide
+impact: MEDIUM
+impactDescription: preserves state/DOM
+tags: rendering, activity, visibility, state-preservation
+---
+
+## Use Activity Component for Show/Hide
+
+Use React's `` and animate the wrapper instead.
+
+**Incorrect (animating SVG directly - no hardware acceleration):**
+
+```tsx
+function LoadingSpinner() {
+ return (
+
+ )
+}
+```
+
+**Correct (animating wrapper div - hardware accelerated):**
+
+```tsx
+function LoadingSpinner() {
+ return (
+ {/* content */}
+}
+```
+
+**Example (preload critical fonts and styles):**
+
+```tsx
+import { preload, preinit } from 'react-dom'
+
+export default function RootLayout({ children }) {
+ // Preload font file
+ preload('/fonts/inter.woff2', { as: 'font', type: 'font/woff2', crossOrigin: 'anonymous' })
+
+ // Fetch and apply critical stylesheet immediately
+ preinit('/styles/critical.css', { as: 'style' })
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+**Example (preload modules for code-split routes):**
+
+```tsx
+import { preloadModule, preinitModule } from 'react-dom'
+
+function Navigation() {
+ const preloadDashboard = () => {
+ preloadModule('/dashboard.js', { as: 'script' })
+ }
+
+ return (
+
+ )
+}
+```
+
+**When to use each:**
+
+| API | Use case |
+|-----|----------|
+| `prefetchDNS` | Third-party domains you'll connect to later |
+| `preconnect` | APIs or CDNs you'll fetch from immediately |
+| `preload` | Critical resources needed for current page |
+| `preloadModule` | JS modules for likely next navigation |
+| `preinit` | Stylesheets/scripts that must execute early |
+| `preinitModule` | ES modules that must execute early |
+
+Reference: [React DOM Resource Preloading APIs](https://react.dev/reference/react-dom#resource-preloading-apis)
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-script-defer-async.md b/.agents/skills/vercel-react-best-practices/rules/rendering-script-defer-async.md
new file mode 100644
index 0000000..ee275ed
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-script-defer-async.md
@@ -0,0 +1,68 @@
+---
+title: Use defer or async on Script Tags
+impact: HIGH
+impactDescription: eliminates render-blocking
+tags: rendering, script, defer, async, performance
+---
+
+## Use defer or async on Script Tags
+
+**Impact: HIGH (eliminates render-blocking)**
+
+Script tags without `defer` or `async` block HTML parsing while the script downloads and executes. This delays First Contentful Paint and Time to Interactive.
+
+- **`defer`**: Downloads in parallel, executes after HTML parsing completes, maintains execution order
+- **`async`**: Downloads in parallel, executes immediately when ready, no guaranteed order
+
+Use `defer` for scripts that depend on DOM or other scripts. Use `async` for independent scripts like analytics.
+
+**Incorrect (blocks rendering):**
+
+```tsx
+export default function Document() {
+ return (
+
+
+
+
+
+ {/* content */}
+
+ )
+}
+```
+
+**Correct (non-blocking):**
+
+```tsx
+export default function Document() {
+ return (
+
+
+ {/* Independent script - use async */}
+
+ {/* DOM-dependent script - use defer */}
+
+
+ {/* content */}
+
+ )
+}
+```
+
+**Note:** In Next.js, prefer the `next/script` component with `strategy` prop instead of raw script tags:
+
+```tsx
+import Script from 'next/script'
+
+export default function Page() {
+ return (
+ <>
+
+
+
+ )
+}
+```
+
+Reference: [MDN - Script element](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script#defer)
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-svg-precision.md b/.agents/skills/vercel-react-best-practices/rules/rendering-svg-precision.md
new file mode 100644
index 0000000..6d77128
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-svg-precision.md
@@ -0,0 +1,28 @@
+---
+title: Optimize SVG Precision
+impact: LOW
+impactDescription: reduces file size
+tags: rendering, svg, optimization, svgo
+---
+
+## Optimize SVG Precision
+
+Reduce SVG coordinate precision to decrease file size. The optimal precision depends on the viewBox size, but in general reducing precision should be considered.
+
+**Incorrect (excessive precision):**
+
+```svg
+
+ )
+
+ // Defined inside to access `user` - BAD
+ const Stats = () => (
+ 
+ )
+}
+
+function Stats({ followers, posts }: { followers: number; posts: number }) {
+ return (
+ (null)
+
+ useEffect(() => {
+ const onMove = (e: MouseEvent) => {
+ lastXRef.current = e.clientX
+ const node = dotRef.current
+ if (node) {
+ node.style.transform = `translateX(${e.clientX}px)`
+ }
+ }
+ window.addEventListener('mousemove', onMove)
+ return () => window.removeEventListener('mousemove', onMove)
+ }, [])
+
+ return (
+
+ )
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-after-nonblocking.md b/.agents/skills/vercel-react-best-practices/rules/server-after-nonblocking.md
new file mode 100644
index 0000000..e8f5b26
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-after-nonblocking.md
@@ -0,0 +1,73 @@
+---
+title: Use after() for Non-Blocking Operations
+impact: MEDIUM
+impactDescription: faster response times
+tags: server, async, logging, analytics, side-effects
+---
+
+## Use after() for Non-Blocking Operations
+
+Use Next.js's `after()` to schedule work that should execute after a response is sent. This prevents logging, analytics, and other side effects from blocking the response.
+
+**Incorrect (blocks response):**
+
+```tsx
+import { logUserAction } from '@/app/utils'
+
+export async function POST(request: Request) {
+ // Perform mutation
+ await updateDatabase(request)
+
+ // Logging blocks the response
+ const userAgent = request.headers.get('user-agent') || 'unknown'
+ await logUserAction({ userAgent })
+
+ return new Response(JSON.stringify({ status: 'success' }), {
+ status: 200,
+ headers: { 'Content-Type': 'application/json' }
+ })
+}
+```
+
+**Correct (non-blocking):**
+
+```tsx
+import { after } from 'next/server'
+import { headers, cookies } from 'next/headers'
+import { logUserAction } from '@/app/utils'
+
+export async function POST(request: Request) {
+ // Perform mutation
+ await updateDatabase(request)
+
+ // Log after response is sent
+ after(async () => {
+ const userAgent = (await headers()).get('user-agent') || 'unknown'
+ const sessionCookie = (await cookies()).get('session-id')?.value || 'anonymous'
+
+ logUserAction({ sessionCookie, userAgent })
+ })
+
+ return new Response(JSON.stringify({ status: 'success' }), {
+ status: 200,
+ headers: { 'Content-Type': 'application/json' }
+ })
+}
+```
+
+The response is sent immediately while logging happens in the background.
+
+**Common use cases:**
+
+- Analytics tracking
+- Audit logging
+- Sending notifications
+- Cache invalidation
+- Cleanup tasks
+
+**Important notes:**
+
+- `after()` runs even if the response fails or redirects
+- Works in Server Actions, Route Handlers, and Server Components
+
+Reference: [https://nextjs.org/docs/app/api-reference/functions/after](https://nextjs.org/docs/app/api-reference/functions/after)
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-auth-actions.md b/.agents/skills/vercel-react-best-practices/rules/server-auth-actions.md
new file mode 100644
index 0000000..ee82c04
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-auth-actions.md
@@ -0,0 +1,96 @@
+---
+title: Authenticate Server Actions Like API Routes
+impact: CRITICAL
+impactDescription: prevents unauthorized access to server mutations
+tags: server, server-actions, authentication, security, authorization
+---
+
+## Authenticate Server Actions Like API Routes
+
+**Impact: CRITICAL (prevents unauthorized access to server mutations)**
+
+Server Actions (functions with `"use server"`) are exposed as public endpoints, just like API routes. Always verify authentication and authorization **inside** each Server Action—do not rely solely on middleware, layout guards, or page-level checks, as Server Actions can be invoked directly.
+
+Next.js documentation explicitly states: "Treat Server Actions with the same security considerations as public-facing API endpoints, and verify if the user is allowed to perform a mutation."
+
+**Incorrect (no authentication check):**
+
+```typescript
+'use server'
+
+export async function deleteUser(userId: string) {
+ // Anyone can call this! No auth check
+ await db.user.delete({ where: { id: userId } })
+ return { success: true }
+}
+```
+
+**Correct (authentication inside the action):**
+
+```typescript
+'use server'
+
+import { verifySession } from '@/lib/auth'
+import { unauthorized } from '@/lib/errors'
+
+export async function deleteUser(userId: string) {
+ // Always check auth inside the action
+ const session = await verifySession()
+
+ if (!session) {
+ throw unauthorized('Must be logged in')
+ }
+
+ // Check authorization too
+ if (session.user.role !== 'admin' && session.user.id !== userId) {
+ throw unauthorized('Cannot delete other users')
+ }
+
+ await db.user.delete({ where: { id: userId } })
+ return { success: true }
+}
+```
+
+**With input validation:**
+
+```typescript
+'use server'
+
+import { verifySession } from '@/lib/auth'
+import { z } from 'zod'
+
+const updateProfileSchema = z.object({
+ userId: z.string().uuid(),
+ name: z.string().min(1).max(100),
+ email: z.string().email()
+})
+
+export async function updateProfile(data: unknown) {
+ // Validate input first
+ const validated = updateProfileSchema.parse(data)
+
+ // Then authenticate
+ const session = await verifySession()
+ if (!session) {
+ throw new Error('Unauthorized')
+ }
+
+ // Then authorize
+ if (session.user.id !== validated.userId) {
+ throw new Error('Can only update own profile')
+ }
+
+ // Finally perform the mutation
+ await db.user.update({
+ where: { id: validated.userId },
+ data: {
+ name: validated.name,
+ email: validated.email
+ }
+ })
+
+ return { success: true }
+}
+```
+
+Reference: [https://nextjs.org/docs/app/guides/authentication](https://nextjs.org/docs/app/guides/authentication)
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-cache-lru.md b/.agents/skills/vercel-react-best-practices/rules/server-cache-lru.md
new file mode 100644
index 0000000..ef6938a
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-cache-lru.md
@@ -0,0 +1,41 @@
+---
+title: Cross-Request LRU Caching
+impact: HIGH
+impactDescription: caches across requests
+tags: server, cache, lru, cross-request
+---
+
+## Cross-Request LRU Caching
+
+`React.cache()` only works within one request. For data shared across sequential requests (user clicks button A then button B), use an LRU cache.
+
+**Implementation:**
+
+```typescript
+import { LRUCache } from 'lru-cache'
+
+const cache = new LRUCache({
+ max: 1000,
+ ttl: 5 * 60 * 1000 // 5 minutes
+})
+
+export async function getUser(id: string) {
+ const cached = cache.get(id)
+ if (cached) return cached
+
+ const user = await db.user.findUnique({ where: { id } })
+ cache.set(id, user)
+ return user
+}
+
+// Request 1: DB query, result cached
+// Request 2: cache hit, no DB query
+```
+
+Use when sequential user actions hit multiple endpoints needing the same data within seconds.
+
+**With Vercel's [Fluid Compute](https://vercel.com/docs/fluid-compute):** LRU caching is especially effective because multiple concurrent requests can share the same function instance and cache. This means the cache persists across requests without needing external storage like Redis.
+
+**In traditional serverless:** Each invocation runs in isolation, so consider Redis for cross-process caching.
+
+Reference: [https://github.com/isaacs/node-lru-cache](https://github.com/isaacs/node-lru-cache)
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-cache-react.md b/.agents/skills/vercel-react-best-practices/rules/server-cache-react.md
new file mode 100644
index 0000000..87c9ca3
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-cache-react.md
@@ -0,0 +1,76 @@
+---
+title: Per-Request Deduplication with React.cache()
+impact: MEDIUM
+impactDescription: deduplicates within request
+tags: server, cache, react-cache, deduplication
+---
+
+## Per-Request Deduplication with React.cache()
+
+Use `React.cache()` for server-side request deduplication. Authentication and database queries benefit most.
+
+**Usage:**
+
+```typescript
+import { cache } from 'react'
+
+export const getCurrentUser = cache(async () => {
+ const session = await auth()
+ if (!session?.user?.id) return null
+ return await db.user.findUnique({
+ where: { id: session.user.id }
+ })
+})
+```
+
+Within a single request, multiple calls to `getCurrentUser()` execute the query only once.
+
+**Avoid inline objects as arguments:**
+
+`React.cache()` uses shallow equality (`Object.is`) to determine cache hits. Inline objects create new references each call, preventing cache hits.
+
+**Incorrect (always cache miss):**
+
+```typescript
+const getUser = cache(async (params: { uid: number }) => {
+ return await db.user.findUnique({ where: { id: params.uid } })
+})
+
+// Each call creates new object, never hits cache
+getUser({ uid: 1 })
+getUser({ uid: 1 }) // Cache miss, runs query again
+```
+
+**Correct (cache hit):**
+
+```typescript
+const getUser = cache(async (uid: number) => {
+ return await db.user.findUnique({ where: { id: uid } })
+})
+
+// Primitive args use value equality
+getUser(1)
+getUser(1) // Cache hit, returns cached result
+```
+
+If you must pass objects, pass the same reference:
+
+```typescript
+const params = { uid: 1 }
+getUser(params) // Query runs
+getUser(params) // Cache hit (same reference)
+```
+
+**Next.js-Specific Note:**
+
+In Next.js, the `fetch` API is automatically extended with request memoization. Requests with the same URL and options are automatically deduplicated within a single request, so you don't need `React.cache()` for `fetch` calls. However, `React.cache()` is still essential for other async tasks:
+
+- Database queries (Prisma, Drizzle, etc.)
+- Heavy computations
+- Authentication checks
+- File system operations
+- Any non-fetch async work
+
+Use `React.cache()` to deduplicate these operations across your component tree.
+
+Reference: [React.cache documentation](https://react.dev/reference/react/cache)
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-dedup-props.md b/.agents/skills/vercel-react-best-practices/rules/server-dedup-props.md
new file mode 100644
index 0000000..fb24a25
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-dedup-props.md
@@ -0,0 +1,65 @@
+---
+title: Avoid Duplicate Serialization in RSC Props
+impact: LOW
+impactDescription: reduces network payload by avoiding duplicate serialization
+tags: server, rsc, serialization, props, client-components
+---
+
+## Avoid Duplicate Serialization in RSC Props
+
+**Impact: LOW (reduces network payload by avoiding duplicate serialization)**
+
+RSC→client serialization deduplicates by object reference, not value. Same reference = serialized once; new reference = serialized again. Do transformations (`.toSorted()`, `.filter()`, `.map()`) in client, not server.
+
+**Incorrect (duplicates array):**
+
+```tsx
+// RSC: sends 6 strings (2 arrays × 3 items)
+ u.active)} />
+
+
+ )
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-parallel-nested-fetching.md b/.agents/skills/vercel-react-best-practices/rules/server-parallel-nested-fetching.md
new file mode 100644
index 0000000..be1dc25
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-parallel-nested-fetching.md
@@ -0,0 +1,34 @@
+---
+title: Parallel Nested Data Fetching
+impact: CRITICAL
+impactDescription: eliminates server-side waterfalls
+tags: server, rsc, parallel-fetching, promise-chaining
+---
+
+## Parallel Nested Data Fetching
+
+When fetching nested data in parallel, chain dependent fetches within each item's promise so a slow item doesn't block the rest.
+
+**Incorrect (a single slow item blocks all nested fetches):**
+
+```tsx
+const chats = await Promise.all(
+ chatIds.map(id => getChat(id))
+)
+
+const chatAuthors = await Promise.all(
+ chats.map(chat => getUser(chat.author))
+)
+```
+
+If one `getChat(id)` out of 100 is extremely slow, the authors of the other 99 chats can't start loading even though their data is ready.
+
+**Correct (each item chains its own nested fetch):**
+
+```tsx
+const chatAuthors = await Promise.all(
+ chatIds.map(id => getChat(id).then(chat => getUser(chat.author)))
+)
+```
+
+Each item independently chains `getChat` → `getUser`, so a slow chat doesn't block author fetches for the others.
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-serialization.md b/.agents/skills/vercel-react-best-practices/rules/server-serialization.md
new file mode 100644
index 0000000..39c5c41
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-serialization.md
@@ -0,0 +1,38 @@
+---
+title: Minimize Serialization at RSC Boundaries
+impact: HIGH
+impactDescription: reduces data transfer size
+tags: server, rsc, serialization, props
+---
+
+## Minimize Serialization at RSC Boundaries
+
+The React Server/Client boundary serializes all object properties into strings and embeds them in the HTML response and subsequent RSC requests. This serialized data directly impacts page weight and load time, so **size matters a lot**. Only pass fields that the client actually uses.
+
+**Incorrect (serializes all 50 fields):**
+
+```tsx
+async function Page() {
+ const user = await fetchUser() // 50 fields
+ return ` component, causing a hard crash in production.
+
+**Incorrect: crashes if count is 0 or name is ""**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ return (
+
+ {name && {name} }
+ {count && {count} items }
+
+ )
+}
+// If name="" or count=0, renders the falsy value → crash
+```
+
+**Correct: ternary with null**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ return (
+
+ {name ? {name} : null}
+ {count ? {count} items : null}
+
+ )
+}
+```
+
+**Correct: explicit boolean coercion**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ return (
+
+ {!!name && {name} }
+ {!!count && {count} items }
+
+ )
+}
+```
+
+**Best: early return**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ if (!name) return null
+
+ return (
+
+ {name}
+ {count > 0 ? {count} items : null}
+
+ )
+}
+```
+
+Early returns are clearest. When using conditionals inline, prefer ternary or
+
+explicit boolean checks.
+
+**Lint rule:** Enable `react/jsx-no-leaked-render` from
+
+[eslint-plugin-react](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-leaked-render.md)
+
+to catch this automatically.
+
+### 1.2 Wrap Strings in Text Components
+
+**Impact: CRITICAL (prevents runtime crash)**
+
+Strings must be rendered inside ``. React Native crashes if a string is a
+
+direct child of ``.
+
+**Incorrect: crashes**
+
+```tsx
+import { View } from 'react-native'
+
+function Greeting({ name }: { name: string }) {
+ return Hello, {name}!
+}
+// Error: Text strings must be rendered within a component.
+```
+
+**Correct:**
+
+```tsx
+import { View, Text } from 'react-native'
+
+function Greeting({ name }: { name: string }) {
+ return (
+
+ Hello, {name}!
+
+ )
+}
+```
+
+---
+
+## 2. List Performance
+
+**Impact: HIGH**
+
+Optimizing virtualized lists (FlatList, LegendList, FlashList)
+for smooth scrolling and fast updates.
+
+### 2.1 Avoid Inline Objects in renderItem
+
+**Impact: HIGH (prevents unnecessary re-renders of memoized list items)**
+
+Don't create new objects inside `renderItem` to pass as props. Inline objects
+
+create new references on every render, breaking memoization. Pass primitive
+
+values directly from `item` instead.
+
+**Incorrect: inline object breaks memoization**
+
+```tsx
+function UserList({ users }: { users: User[] }) {
+ return (
+ (
+ (
+ // Good: pass the item directly
+ {/* ... */}
+})
+```
+
+**Correct: hoist static styles in module scope**
+
+```tsx
+const activeStyle = { backgroundColor: 'green' }
+const inactiveStyle = { backgroundColor: 'gray' }
+
+renderItem={({ item }) => (
+ {
+ // bad: creates a new callback on each render
+ const onPress = () => handlePress(item.id)
+ return (
+ {/* ... */}
+}
+```
+
+**Correct: lightweight list item**
+
+```tsx
+function ProductRow({ name, price, imageUrl }: Props) {
+ // Good: receives only primitives, minimal hooks
+ return (
+
+ {name}
+ {price}
+
+ )
+}
+```
+
+**Move data fetching to parent:**
+
+```tsx
+// Parent fetches all data once
+function ProductList() {
+ const { data: products } = useQuery(['products'], fetchProducts)
+
+ return (
+ (
+ {domain}
+}
+```
+
+**Updating parent array reference:**
+
+```tsx
+// good: creates a new array instance without mutating the inner objects
+// good: parent array reference is unaffected by typing and updating "keyword"
+const sortedTlds = tlds.toSorted((a, b) => a.name.localeCompare(b.name))
+
+return {user.name}
+})
+
+renderItem={({ item }) => {name}
+})
+
+renderItem={({ item }) => (
+ handlePress(item.id)} />
+
+// Correct: pass ID, handle in child
+{name}
+ {items.map((item) => (
+
+ )
+}
+// 50 items = 50 components mounted, even if only 10 visible
+```
+
+**Correct: virtualizer renders only visible items**
+
+```tsx
+import { LegendList } from '@legendapp/list'
+
+function Feed({ items }: { items: Item[] }) {
+ return (
+
+ {/* 4000x3000 image loaded for a 100x100 thumbnail */}
+ {product.name}
+
+ )
+}
+```
+
+**Correct: request appropriately-sized image**
+
+```tsx
+function ProductItem({ product }: { product: Product }) {
+ // Request a 200x200 image (2x for retina)
+ const thumbnailUrl = `${product.imageUrl}?w=200&h=200&fit=cover`
+
+ return (
+
+ {product.name}
+
+ )
+}
+```
+
+Use an optimized image component with built-in caching and placeholder support,
+
+such as `expo-image` or `SolitoImage` (which uses `expo-image` under the hood).
+
+Request images at 2x the display size for retina screens.
+
+### 2.8 Use Item Types for Heterogeneous Lists
+
+**Impact: HIGH (efficient recycling, less layout thrashing)**
+
+When a list has different item layouts (messages, images, headers, etc.), use a
+
+`type` field on each item and provide `getItemType` to the list. This puts items
+
+into separate recycling pools so a message component never gets recycled into an
+
+image component.
+
+[LegendList getItemType](https://legendapp.com/open-source/list/api/props/#getitemtype-v2)
+
+**Incorrect: single component with conditionals**
+
+```tsx
+type Item = { id: string; text?: string; imageUrl?: string; isHeader?: boolean }
+
+function ListItem({ item }: { item: Item }) {
+ if (item.isHeader) {
+ return item.id}
+ getItemType={(item) => item.type}
+ renderItem={({ item }) => {
+ switch (item.type) {
+ case 'header':
+ return item.id}
+ getItemType={(item) => item.type}
+ getEstimatedItemSize={(index, item, itemType) => {
+ switch (itemType) {
+ case 'header':
+ return 48
+ case 'message':
+ return 72
+ case 'image':
+ return 300
+ default:
+ return 72
+ }
+ }}
+ renderItem={({ item }) => {
+ /* ... */
+ }}
+ recycleItems
+/>
+```
+
+- **Recycling efficiency**: Items with the same type share a recycling pool
+
+- **No layout thrashing**: A header never recycles into an image cell
+
+- **Type safety**: TypeScript can narrow the item type in each branch
+
+- **Better size estimation**: Use `getEstimatedItemSize` with `itemType` for
+
+ accurate estimates per type
+
+---
+
+## 3. Animation
+
+**Impact: HIGH**
+
+GPU-accelerated animations, Reanimated patterns, and avoiding
+render thrashing during gestures.
+
+### 3.1 Animate Transform and Opacity Instead of Layout Properties
+
+**Impact: HIGH (GPU-accelerated animations, no layout recalculation)**
+
+Avoid animating `width`, `height`, `top`, `left`, `margin`, or `padding`. These trigger layout recalculation on every frame. Instead, use `transform` (scale, translate) and `opacity` which run on the GPU without triggering layout.
+
+**Incorrect: animates height, triggers layout every frame**
+
+```tsx
+import Animated, { useAnimatedStyle, withTiming } from 'react-native-reanimated'
+
+function CollapsiblePanel({ expanded }: { expanded: boolean }) {
+ const animatedStyle = useAnimatedStyle(() => ({
+ height: withTiming(expanded ? 200 : 0), // triggers layout on every frame
+ overflow: 'hidden',
+ }))
+
+ return {children}
+}
+```
+
+**Correct: animates scaleY, GPU-accelerated**
+
+```tsx
+import Animated, { useAnimatedStyle, withTiming } from 'react-native-reanimated'
+
+function CollapsiblePanel({ expanded }: { expanded: boolean }) {
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [
+ { scaleY: withTiming(expanded ? 1 : 0) },
+ ],
+ opacity: withTiming(expanded ? 1 : 0),
+ }))
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+**Correct: animates translateY for slide animations**
+
+```tsx
+import Animated, { useAnimatedStyle, withTiming } from 'react-native-reanimated'
+
+function SlideIn({ visible }: { visible: boolean }) {
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [
+ { translateY: withTiming(visible ? 0 : 100) },
+ ],
+ opacity: withTiming(visible ? 1 : 0),
+ }))
+
+ return {children}
+}
+```
+
+GPU-accelerated properties: `transform` (translate, scale, rotate), `opacity`. Everything else triggers layout.
+
+### 3.2 Prefer useDerivedValue Over useAnimatedReaction
+
+**Impact: MEDIUM (cleaner code, automatic dependency tracking)**
+
+When deriving a shared value from another, use `useDerivedValue` instead of
+
+`useAnimatedReaction`. Derived values are declarative, automatically track
+
+dependencies, and return a value you can use directly. Animated reactions are
+
+for side effects, not derivations.
+
+[Reanimated useDerivedValue](https://docs.swmansion.com/react-native-reanimated/docs/core/useDerivedValue)
+
+**Incorrect: useAnimatedReaction for derivation**
+
+```tsx
+import { useSharedValue, useAnimatedReaction } from 'react-native-reanimated'
+
+function MyComponent() {
+ const progress = useSharedValue(0)
+ const opacity = useSharedValue(1)
+
+ useAnimatedReaction(
+ () => progress.value,
+ (current) => {
+ opacity.value = 1 - current
+ }
+ )
+
+ // ...
+}
+```
+
+**Correct: useDerivedValue**
+
+```tsx
+import { useSharedValue, useDerivedValue } from 'react-native-reanimated'
+
+function MyComponent() {
+ const progress = useSharedValue(0)
+
+ const opacity = useDerivedValue(() => 1 - progress.get())
+
+ // ...
+}
+```
+
+Use `useAnimatedReaction` only for side effects that don't produce a value
+
+(e.g., triggering haptics, logging, calling `runOnJS`).
+
+### 3.3 Use GestureDetector for Animated Press States
+
+**Impact: MEDIUM (UI thread animations, smoother press feedback)**
+
+For animated press states (scale, opacity on press), use `GestureDetector` with
+
+`Gesture.Tap()` and shared values instead of Pressable's
+
+`onPressIn`/`onPressOut`. Gesture callbacks run on the UI thread as worklets—no
+
+JS thread round-trip for press animations.
+
+[Gesture Handler Tap Gesture](https://docs.swmansion.com/react-native-gesture-handler/docs/gestures/tap-gesture)
+
+**Incorrect: Pressable with JS thread callbacks**
+
+```tsx
+import { Pressable } from 'react-native'
+import Animated, {
+ useSharedValue,
+ useAnimatedStyle,
+ withTiming,
+} from 'react-native-reanimated'
+
+function AnimatedButton({ onPress }: { onPress: () => void }) {
+ const scale = useSharedValue(1)
+
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [{ scale: scale.value }],
+ }))
+
+ return (
+ (scale.value = withTiming(0.95))}
+ onPressOut={() => (scale.value = withTiming(1))}
+ >
+
+ Press me
+
+
+ )
+}
+```
+
+**Correct: GestureDetector with UI thread worklets**
+
+```tsx
+import { Gesture, GestureDetector } from 'react-native-gesture-handler'
+import Animated, {
+ useSharedValue,
+ useAnimatedStyle,
+ withTiming,
+ interpolate,
+ runOnJS,
+} from 'react-native-reanimated'
+
+function AnimatedButton({ onPress }: { onPress: () => void }) {
+ // Store the press STATE (0 = not pressed, 1 = pressed)
+ const pressed = useSharedValue(0)
+
+ const tap = Gesture.Tap()
+ .onBegin(() => {
+ pressed.set(withTiming(1))
+ })
+ .onFinalize(() => {
+ pressed.set(withTiming(0))
+ })
+ .onEnd(() => {
+ runOnJS(onPress)()
+ })
+
+ // Derive visual values from the state
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [
+ { scale: interpolate(withTiming(pressed.get()), [0, 1], [1, 0.95]) },
+ ],
+ }))
+
+ return (
+
+
+ Press me
+
+
+ )
+}
+```
+
+Store the press **state** (0 or 1), then derive the scale via `interpolate`.
+
+This keeps the shared value as ground truth. Use `runOnJS` to call JS functions
+
+from worklets. Use `.set()` and `.get()` for React Compiler compatibility.
+
+---
+
+## 4. Scroll Performance
+
+**Impact: HIGH**
+
+Tracking scroll position without causing render thrashing.
+
+### 4.1 Never Track Scroll Position in useState
+
+**Impact: HIGH (prevents render thrashing during scroll)**
+
+Never store scroll position in `useState`. Scroll events fire rapidly—state
+
+updates cause render thrashing and dropped frames. Use a Reanimated shared value
+
+for animations or a ref for non-reactive tracking.
+
+**Incorrect: useState causes jank**
+
+```tsx
+import { useState } from 'react'
+import {
+ ScrollView,
+ NativeSyntheticEvent,
+ NativeScrollEvent,
+} from 'react-native'
+
+function Feed() {
+ const [scrollY, setScrollY] = useState(0)
+
+ const onScroll = (e: NativeSyntheticEvent) => {
+ setScrollY(e.nativeEvent.contentOffset.y) // re-renders on every frame
+ }
+
+ return ) => {
+ scrollY.current = e.nativeEvent.contentOffset.y // no re-render
+ }
+
+ return
+
+ )
+}
+```
+
+**Correct: native stack with react-navigation**
+
+```tsx
+import { createNativeStackNavigator } from '@react-navigation/native-stack'
+
+const Stack = createNativeStackNavigator()
+
+function App() {
+ return (
+
+
+ )
+}
+```
+
+**Correct: expo-router uses native stack by default**
+
+```tsx
+// app/_layout.tsx
+import { Stack } from 'expo-router'
+
+export default function Layout() {
+ return
+
+ )
+}
+```
+
+**Correct: native bottom tabs with react-navigation**
+
+```tsx
+import { createNativeBottomTabNavigator } from '@bottom-tabs/react-navigation'
+
+const Tab = createNativeBottomTabNavigator()
+
+function App() {
+ return (
+
+ ({ sfSymbol: 'house' }),
+ }}
+ />
+ ({ sfSymbol: 'gear' }),
+ }}
+ />
+
+ )
+}
+```
+
+**Correct: expo-router native tabs**
+
+```tsx
+// app/(tabs)/_layout.tsx
+import { NativeTabs } from 'expo-router/unstable-native-tabs'
+
+export default function TabLayout() {
+ return (
+
+
+ Home
+
+
+ Settings
+
+
+ )
+}
+```
+
+On iOS, native tabs automatically enable `contentInsetAdjustmentBehavior` on the
+
+first `ScrollView` at the root of each tab screen, so content scrolls correctly
+
+behind the translucent tab bar. If you need to disable this, use
+
+`disableAutomaticContentInsets` on the trigger.
+
+**Incorrect: custom header component**
+
+```tsx
+
+ {itemCount} items
+ Total: ${total}
+
+ )
+}
+```
+
+**Correct: derived values**
+
+```tsx
+function Cart({ items }: { items: Item[] }) {
+ const total = items.reduce((sum, item) => sum + item.price, 0)
+ const itemCount = items.length
+
+ return (
+
+ {itemCount} items
+ Total: ${total}
+
+ )
+}
+```
+
+**Another example:**
+
+```tsx
+// Incorrect: storing both firstName, lastName, AND fullName
+const [firstName, setFirstName] = useState('')
+const [lastName, setLastName] = useState('')
+const [fullName, setFullName] = useState('')
+
+// Correct: derive fullName
+const [firstName, setFirstName] = useState('')
+const [lastName, setLastName] = useState('')
+const fullName = `${firstName} ${lastName}`
+```
+
+State should be the minimal source of truth. Everything else is derived.
+
+Reference: [https://react.dev/learn/choosing-the-state-structure](https://react.dev/learn/choosing-the-state-structure)
+
+### 6.2 Use fallback state instead of initialState
+
+**Impact: MEDIUM (reactive fallbacks without syncing)**
+
+Use `undefined` as initial state and nullish coalescing (`??`) to fall back to
+
+parent or server values. State represents user intent only—`undefined` means
+
+"user hasn't chosen yet." This enables reactive fallbacks that update when the
+
+source changes, not just on initial render.
+
+**Incorrect: syncs state, loses reactivity**
+
+```tsx
+type Props = { fallbackEnabled: boolean }
+
+function Toggle({ fallbackEnabled }: Props) {
+ const [enabled, setEnabled] = useState(defaultEnabled)
+ // If fallbackEnabled changes, state is stale
+ // State mixes user intent with default value
+
+ return (undefined)
+ const enabled = _enabled ?? defaultEnabled
+ // undefined = user hasn't touched it, falls back to prop
+ // If defaultEnabled changes, component reflects it
+ // Once user interacts, their choice persists
+
+ return (undefined)
+ const theme = _theme ?? data.theme
+ // Shows server value until user overrides
+ // Server refetch updates the fallback automatically
+
+ return (undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ // size may be stale in this closure
+ if (size?.width !== width || size?.height !== height) {
+ setSize({ width, height })
+ }
+}
+```
+
+**Correct: dispatch updater**
+
+```tsx
+const [size, setSize] = useState(undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize((prev) => {
+ if (prev?.width === width && prev?.height === height) return prev
+ return { width, height }
+ })
+}
+```
+
+Returning the previous value from the updater skips the re-render.
+
+For primitive states, you don't need to compare values before firing a
+
+re-render.
+
+**Incorrect: unnecessary comparison for primitive state**
+
+```tsx
+const [size, setSize] = useState(undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize((prev) => (prev === width ? prev : width))
+}
+```
+
+**Correct: sets primitive state directly**
+
+```tsx
+const [size, setSize] = useState(undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize(width)
+}
+```
+
+However, if the next state depends on the current state, you should still use a
+
+dispatch updater.
+
+**Incorrect: reads state directly from the callback**
+
+```tsx
+const [count, setCount] = useState(0)
+
+const onTap = () => {
+ setCount(count + 1)
+}
+```
+
+**Correct: dispatch updater**
+
+```tsx
+const [count, setCount] = useState(0)
+
+const onTap = () => {
+ setCount((prev) => prev + 1)
+}
+```
+
+---
+
+## 7. State Architecture
+
+**Impact: MEDIUM**
+
+Ground truth principles for state variables and derived values.
+
+### 7.1 State Must Represent Ground Truth
+
+**Impact: HIGH (cleaner logic, easier debugging, single source of truth)**
+
+State variables—both React `useState` and Reanimated shared values—should
+
+represent the actual state of something (e.g., `pressed`, `progress`, `isOpen`),
+
+not derived visual values (e.g., `scale`, `opacity`, `translateY`). Derive
+
+visual values from state using computation or interpolation.
+
+**Incorrect: storing the visual output**
+
+```tsx
+const scale = useSharedValue(1)
+
+const tap = Gesture.Tap()
+ .onBegin(() => {
+ scale.set(withTiming(0.95))
+ })
+ .onFinalize(() => {
+ scale.set(withTiming(1))
+ })
+
+const animatedStyle = useAnimatedStyle(() => ({
+ transform: [{ scale: scale.get() }],
+}))
+```
+
+**Correct: storing the state, deriving the visual**
+
+```tsx
+const pressed = useSharedValue(0) // 0 = not pressed, 1 = pressed
+
+const tap = Gesture.Tap()
+ .onBegin(() => {
+ pressed.set(withTiming(1))
+ })
+ .onFinalize(() => {
+ pressed.set(withTiming(0))
+ })
+
+const animatedStyle = useAnimatedStyle(() => ({
+ transform: [{ scale: interpolate(pressed.get(), [0, 1], [1, 0.95]) }],
+}))
+```
+
+**Why this matters:**
+
+State variables should represent real "state", not necessarily a desired end
+
+result.
+
+1. **Single source of truth** — The state (`pressed`) describes what's
+
+ happening; visuals are derived
+
+2. **Easier to extend** — Adding opacity, rotation, or other effects just
+
+ requires more interpolations from the same state
+
+3. **Debugging** — Inspecting `pressed = 1` is clearer than `scale = 0.95`
+
+4. **Reusable logic** — The same `pressed` value can drive multiple visual
+
+ properties
+
+**Same principle for React state:**
+
+```tsx
+// Incorrect: storing derived values
+const [isExpanded, setIsExpanded] = useState(false)
+const [height, setHeight] = useState(0)
+
+useEffect(() => {
+ setHeight(isExpanded ? 200 : 0)
+}, [isExpanded])
+
+// Correct: derive from state
+const [isExpanded, setIsExpanded] = useState(false)
+const height = isExpanded ? 200 : 0
+```
+
+State is the minimal truth. Everything else is derived.
+
+---
+
+## 8. React Compiler
+
+**Impact: MEDIUM**
+
+Compatibility patterns for React Compiler with React Native and
+Reanimated.
+
+### 8.1 Destructure Functions Early in Render (React Compiler)
+
+**Impact: HIGH (stable references, fewer re-renders)**
+
+This rule is only applicable if you are using the React Compiler.
+
+Destructure functions from hooks at the top of render scope. Never dot into
+
+objects to call functions. Destructured functions are stable references; dotting
+
+creates new references and breaks memoization.
+
+**Incorrect: dotting into object**
+
+```tsx
+import { useRouter } from 'expo-router'
+
+function SaveButton(props) {
+ const router = useRouter()
+
+ // bad: react-compiler will key the cache on "props" and "router", which are objects that change each render
+ const handlePress = () => {
+ props.onSave()
+ router.push('/success') // unstable reference
+ }
+
+ return
+}
+```
+
+**Correct: destructure early**
+
+```tsx
+import { useRouter } from 'expo-router'
+
+function SaveButton({ onSave }) {
+ const { push } = useRouter()
+
+ // good: react-compiler will key on push and onSave
+ const handlePress = () => {
+ onSave()
+ push('/success') // stable reference
+ }
+
+ return
+}
+```
+
+### 8.2 Use .get() and .set() for Reanimated Shared Values (not .value)
+
+**Impact: LOW (required for React Compiler compatibility)**
+
+With React Compiler enabled, use `.get()` and `.set()` instead of reading or
+
+writing `.value` directly on Reanimated shared values. The compiler can't track
+
+property access—explicit methods ensure correct behavior.
+
+**Incorrect: breaks with React Compiler**
+
+```tsx
+import { useSharedValue } from 'react-native-reanimated'
+
+function Counter() {
+ const count = useSharedValue(0)
+
+ const increment = () => {
+ count.value = count.value + 1 // opts out of react compiler
+ }
+
+ return
+}
+```
+
+**Correct: React Compiler compatible**
+
+```tsx
+import { useSharedValue } from 'react-native-reanimated'
+
+function Counter() {
+ const count = useSharedValue(0)
+
+ const increment = () => {
+ count.set(count.get() + 1)
+ }
+
+ return
+}
+```
+
+See the
+
+[Reanimated docs](https://docs.swmansion.com/react-native-reanimated/docs/core/useSharedValue/#react-compiler-support)
+
+for more.
+
+---
+
+## 9. User Interface
+
+**Impact: MEDIUM**
+
+Native UI patterns for images, menus, modals, styling, and
+platform-consistent interfaces.
+
+### 9.1 Measuring View Dimensions
+
+**Impact: MEDIUM (synchronous measurement, avoid unnecessary re-renders)**
+
+Use both `useLayoutEffect` (synchronous) and `onLayout` (for updates). The sync
+
+measurement gives you the initial size immediately; `onLayout` keeps it current
+
+when the view changes. For non-primitive states, use a dispatch updater to
+
+compare values and avoid unnecessary re-renders.
+
+**Height only:**
+
+```tsx
+import { useLayoutEffect, useRef, useState } from 'react'
+import { View, LayoutChangeEvent } from 'react-native'
+
+function MeasuredBox({ children }: { children: React.ReactNode }) {
+ const ref = useRef(null)
+ const [height, setHeight] = useState(undefined)
+
+ useLayoutEffect(() => {
+ // Sync measurement on mount (RN 0.82+)
+ const rect = ref.current?.getBoundingClientRect()
+ if (rect) setHeight(rect.height)
+ // Pre-0.82: ref.current?.measure((x, y, w, h) => setHeight(h))
+ }, [])
+
+ const onLayout = (e: LayoutChangeEvent) => {
+ setHeight(e.nativeEvent.layout.height)
+ }
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+**Both dimensions:**
+
+```tsx
+import { useLayoutEffect, useRef, useState } from 'react'
+import { View, LayoutChangeEvent } from 'react-native'
+
+type Size = { width: number; height: number }
+
+function MeasuredBox({ children }: { children: React.ReactNode }) {
+ const ref = useRef(null)
+ const [size, setSize] = useState(undefined)
+
+ useLayoutEffect(() => {
+ const rect = ref.current?.getBoundingClientRect()
+ if (rect) setSize({ width: rect.width, height: rect.height })
+ }, [])
+
+ const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize((prev) => {
+ // for non-primitive states, compare values before firing a re-render
+ if (prev?.width === width && prev?.height === height) return prev
+ return { width, height }
+ })
+ }
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+Use functional setState to compare—don't read state directly in the callback.
+
+### 9.2 Modern React Native Styling Patterns
+
+**Impact: MEDIUM (consistent design, smoother borders, cleaner layouts)**
+
+Follow these styling patterns for cleaner, more consistent React Native code.
+
+**Always use `borderCurve: 'continuous'` with `borderRadius`:**
+
+**Use `gap` instead of margin for spacing between elements:**
+
+```tsx
+// Incorrect – margin on children
+
+ Title
+ Subtitle
+
+
+// Correct – gap on parent
+
+ Title
+ Subtitle
+
+```
+
+**Use `padding` for space within, `gap` for space between:**
+
+```tsx
+
+ First
+ Second
+
+```
+
+**Use `experimental_backgroundImage` for linear gradients:**
+
+```tsx
+// Incorrect – third-party gradient library
+Title
+Subtitle
+Caption
+
+// Correct – consistent size, vary weight and color
+Title
+Subtitle
+Caption
+```
+
+Limiting font sizes creates visual consistency. Use `fontWeight` (bold/semibold)
+
+and grayscale colors for hierarchy instead.
+
+### 9.3 Use contentInset for Dynamic ScrollView Spacing
+
+**Impact: LOW (smoother updates, no layout recalculation)**
+
+When adding space to the top or bottom of a ScrollView that may change
+
+(keyboard, toolbars, dynamic content), use `contentInset` instead of padding.
+
+Changing `contentInset` doesn't trigger layout recalculation—it adjusts the
+
+scroll area without re-rendering content.
+
+**Incorrect: padding causes layout recalculation**
+
+```tsx
+function Feed({ bottomOffset }: { bottomOffset: number }) {
+ return (
+
+ {children}
+
+ )
+}
+// Changing bottomOffset triggers full layout recalculation
+```
+
+**Correct: contentInset for dynamic spacing**
+
+```tsx
+function Feed({ bottomOffset }: { bottomOffset: number }) {
+ return (
+
+ {children}
+
+ )
+}
+// Changing bottomOffset only adjusts scroll bounds
+```
+
+Use `scrollIndicatorInsets` alongside `contentInset` to keep the scroll
+
+indicator aligned. For static spacing that never changes, padding is fine.
+
+### 9.4 Use contentInsetAdjustmentBehavior for Safe Areas
+
+**Impact: MEDIUM (native safe area handling, no layout shifts)**
+
+Use `contentInsetAdjustmentBehavior="automatic"` on the root ScrollView instead of wrapping content in SafeAreaView or manual padding. This lets iOS handle safe area insets natively with proper scroll behavior.
+
+**Incorrect: SafeAreaView wrapper**
+
+```tsx
+import { SafeAreaView, ScrollView, View, Text } from 'react-native'
+
+function MyScreen() {
+ return (
+
+
+
+ Content
+
+
+
+ )
+}
+```
+
+**Incorrect: manual safe area padding**
+
+```tsx
+import { ScrollView, View, Text } from 'react-native'
+import { useSafeAreaInsets } from 'react-native-safe-area-context'
+
+function MyScreen() {
+ const insets = useSafeAreaInsets()
+
+ return (
+
+
+ Content
+
+
+ )
+}
+```
+
+**Correct: native content inset adjustment**
+
+```tsx
+import { ScrollView, View, Text } from 'react-native'
+
+function MyScreen() {
+ return (
+
+
+ Content
+
+
+ )
+}
+```
+
+The native approach handles dynamic safe areas (keyboard, toolbars) and allows content to scroll behind the status bar naturally.
+
+### 9.5 Use expo-image for Optimized Images
+
+**Impact: HIGH (memory efficiency, caching, blurhash placeholders, progressive loading)**
+
+Use `expo-image` instead of React Native's `Image`. It provides memory-efficient caching, blurhash placeholders, progressive loading, and better performance for lists.
+
+**Incorrect: React Native Image**
+
+```tsx
+import { Image } from 'react-native'
+
+function Avatar({ url }: { url: string }) {
+ return (null)
+
+ return (
+ <>
+ {urls.map((url) => (
+ setSelected(url)}>
+
+ ))}
+ setSelected(null)}>
+
+
+ )
+}
+```
+
+**Correct: Galeria with expo-image**
+
+```tsx
+import { Galeria } from '@nandorojo/galeria'
+import { Image } from 'expo-image'
+
+function ImageGallery({ urls }: { urls: string[] }) {
+ return (
+
+ {urls.map((url, index) => (
+
+
+ ))}
+
+ )
+}
+```
+
+**Single image:**
+
+```tsx
+import { Galeria } from '@nandorojo/galeria'
+import { Image } from 'expo-image'
+
+function Avatar({ url }: { url: string }) {
+ return (
+
+
+
+
+ )
+}
+```
+
+**With low-res thumbnails and high-res fullscreen:**
+
+```tsx
+
+ {lowResUrls.map((url, index) => (
+
+
+ ))}
+
+```
+
+**With FlashList:**
+
+```tsx
+
+ (
+
+
+ )}
+ numColumns={3}
+ estimatedItemSize={100}
+ />
+
+```
+
+Works with `expo-image`, `SolitoImage`, `react-native` Image, or any image
+
+component.
+
+Reference: [https://github.com/nandorojo/galeria](https://github.com/nandorojo/galeria)
+
+### 9.7 Use Native Menus for Dropdowns and Context Menus
+
+**Impact: HIGH (native accessibility, platform-consistent UX)**
+
+Use native platform menus instead of custom JS implementations. Native menus
+
+provide built-in accessibility, consistent platform UX, and better performance.
+
+Use [zeego](https://zeego.dev) for cross-platform native menus.
+
+**Incorrect: custom JS menu**
+
+```tsx
+import { useState } from 'react'
+import { View, Pressable, Text } from 'react-native'
+
+function MyMenu() {
+ const [open, setOpen] = useState(false)
+
+ return (
+
+ setOpen(!open)}>
+ Open Menu
+
+ {open && (
+
+ console.log('edit')}>
+ Edit
+
+ console.log('delete')}>
+ Delete
+
+
+ )}
+
+ )
+}
+```
+
+**Correct: native menu with zeego**
+
+```tsx
+import * as DropdownMenu from 'zeego/dropdown-menu'
+
+function MyMenu() {
+ return (
+
+
+
+ Open Menu
+
+
+
+
+ console.log('edit')}>
+ Edit
+
+
+ console.log('delete')}
+ >
+ Delete
+
+
+
+ )
+}
+```
+
+**Context menu: long-press**
+
+```tsx
+import * as ContextMenu from 'zeego/context-menu'
+
+function MyContextMenu() {
+ return (
+
+
+
+ Long press me
+
+
+
+
+ console.log('copy')}>
+ Copy
+
+
+ console.log('paste')}>
+ Paste
+
+
+
+ )
+}
+```
+
+**Checkbox items:**
+
+```tsx
+import * as DropdownMenu from 'zeego/dropdown-menu'
+
+function SettingsMenu() {
+ const [notifications, setNotifications] = useState(true)
+
+ return (
+
+
+
+ Settings
+
+
+
+
+ setNotifications((prev) => !prev)}
+ >
+ Notifications
+
+
+
+ )
+}
+```
+
+**Submenus:**
+
+```tsx
+import * as DropdownMenu from 'zeego/dropdown-menu'
+
+function MenuWithSubmenu() {
+ return (
+
+
+
+ Options
+
+
+
+
+ console.log('home')}>
+ Home
+
+
+
+
+ More Options
+
+
+
+
+ Settings
+
+
+
+ Help
+
+
+
+
+
+ )
+}
+```
+
+Reference: [https://zeego.dev/components/dropdown-menu](https://zeego.dev/components/dropdown-menu)
+
+### 9.8 Use Native Modals Over JS-Based Bottom Sheets
+
+**Impact: HIGH (native performance, gestures, accessibility)**
+
+Use native `` with `presentationStyle="formSheet"` or React Navigation
+
+v7's native form sheet instead of JS-based bottom sheet libraries. Native modals
+
+have built-in gestures, accessibility, and better performance. Rely on native UI
+
+for low-level primitives.
+
+**Incorrect: JS-based bottom sheet**
+
+```tsx
+import BottomSheet from 'custom-js-bottom-sheet'
+
+function MyScreen() {
+ const sheetRef = useRef(null)
+
+ return (
+
+
+ )
+}
+```
+
+**Correct: native Modal with formSheet**
+
+```tsx
+import { Modal, View, Text, Button } from 'react-native'
+
+function MyScreen() {
+ const [visible, setVisible] = useState(false)
+
+ return (
+
+
+ )
+}
+```
+
+**Correct: React Navigation v7 native form sheet**
+
+```tsx
+// In your navigator
+
+ Press me
+
+ )
+}
+```
+
+**Correct: Pressable**
+
+```tsx
+import { Pressable } from 'react-native'
+
+function MyButton({ onPress }: { onPress: () => void }) {
+ return (
+
+ Press me
+
+ )
+}
+```
+
+**Correct: Pressable from gesture handler for lists**
+
+```tsx
+import { Pressable } from 'react-native-gesture-handler'
+
+function ListItem({ onPress }: { onPress: () => void }) {
+ return (
+
+ Item
+
+ )
+}
+```
+
+Use `react-native-gesture-handler` Pressable inside scrollable lists for better
+
+gesture coordination, as long as you are using the ScrollView from
+
+`react-native-gesture-handler` as well.
+
+**For animated press states (scale, opacity changes):** Use `GestureDetector`
+
+with Reanimated shared values instead of Pressable's style callback. See the
+
+`animation-gesture-detector-press` rule.
+
+---
+
+## 10. Design System
+
+**Impact: MEDIUM**
+
+Architecture patterns for building maintainable component
+libraries.
+
+### 10.1 Use Compound Components Over Polymorphic Children
+
+**Impact: MEDIUM (flexible composition, clearer API)**
+
+Don't create components that can accept a string if they aren't a text node. If
+
+a component can receive a string child, it must be a dedicated `*Text`
+
+component. For components like buttons, which can have both a View (or
+
+Pressable) together with text, use compound components, such a `Button`,
+
+`ButtonText`, and `ButtonIcon`.
+
+**Incorrect: polymorphic children**
+
+```tsx
+import { Pressable, Text } from 'react-native'
+
+type ButtonProps = {
+ children: string | React.ReactNode
+ icon?: React.ReactNode
+}
+
+function Button({ children, icon }: ButtonProps) {
+ return (
+
+ {icon}
+ {typeof children === 'string' ? {children} : children}
+
+ )
+}
+
+// Usage is ambiguous
+}>Save
+
+```
+
+**Correct: compound components**
+
+```tsx
+import { Pressable, Text } from 'react-native'
+
+function Button({ children }: { children: React.ReactNode }) {
+ return {children}
+}
+
+function ButtonText({ children }: { children: React.ReactNode }) {
+ return {children}
+}
+
+function ButtonIcon({ children }: { children: React.ReactNode }) {
+ return <>{children}
+}
+
+// Usage is explicit and composable
+
+
+
+```
+
+---
+
+## 11. Monorepo
+
+**Impact: LOW**
+
+Dependency management and native module configuration in
+monorepos.
+
+### 11.1 Install Native Dependencies in App Directory
+
+**Impact: CRITICAL (required for autolinking to work)**
+
+In a monorepo, packages with native code must be installed in the native app's
+
+directory directly. Autolinking only scans the app's `node_modules`—it won't
+
+find native dependencies installed in other packages.
+
+**Incorrect: native dep in shared package only**
+
+```typescript
+packages/
+ ui/
+ package.json # has react-native-reanimated
+ app/
+ package.json # missing react-native-reanimated
+```
+
+Autolinking fails—native code not linked.
+
+**Correct: native dep in app directory**
+
+```json
+// packages/app/package.json
+{
+ "dependencies": {
+ "react-native-reanimated": "3.16.1"
+ }
+}
+```
+
+Even if the shared package uses the native dependency, the app must also list it
+
+for autolinking to detect and link the native code.
+
+### 11.2 Use Single Dependency Versions Across Monorepo
+
+**Impact: MEDIUM (avoids duplicate bundles, version conflicts)**
+
+Use a single version of each dependency across all packages in your monorepo.
+
+Prefer exact versions over ranges. Multiple versions cause duplicate code in
+
+bundles, runtime conflicts, and inconsistent behavior across packages.
+
+Use a tool like syncpack to enforce this. As a last resort, use yarn resolutions
+
+or npm overrides.
+
+**Incorrect: version ranges, multiple versions**
+
+```json
+// packages/app/package.json
+{
+ "dependencies": {
+ "react-native-reanimated": "^3.0.0"
+ }
+}
+
+// packages/ui/package.json
+{
+ "dependencies": {
+ "react-native-reanimated": "^3.5.0"
+ }
+}
+```
+
+**Correct: exact versions, single source of truth**
+
+```json
+// package.json (root)
+{
+ "pnpm": {
+ "overrides": {
+ "react-native-reanimated": "3.16.1"
+ }
+ }
+}
+
+// packages/app/package.json
+{
+ "dependencies": {
+ "react-native-reanimated": "3.16.1"
+ }
+}
+
+// packages/ui/package.json
+{
+ "dependencies": {
+ "react-native-reanimated": "3.16.1"
+ }
+}
+```
+
+Use your package manager's override/resolution feature to enforce versions at
+
+the root. When adding dependencies, specify exact versions without `^` or `~`.
+
+---
+
+## 12. Third-Party Dependencies
+
+**Impact: LOW**
+
+Wrapping and re-exporting third-party dependencies for
+maintainability.
+
+### 12.1 Import from Design System Folder
+
+**Impact: LOW (enables global changes and easy refactoring)**
+
+Re-export dependencies from a design system folder. App code imports from there,
+
+not directly from packages. This enables global changes and easy refactoring.
+
+**Incorrect: imports directly from package**
+
+```tsx
+import { View, Text } from 'react-native'
+import { Button } from '@ui/button'
+
+function Profile() {
+ return (
+
+ Hello
+
+
+ )
+}
+```
+
+**Correct: imports from design system**
+
+```tsx
+import { View } from '@/components/view'
+import { Text } from '@/components/text'
+import { Button } from '@/components/button'
+
+function Profile() {
+ return (
+
+ Hello
+
+
+ )
+}
+```
+
+Start by simply re-exporting. Customize later without changing app code.
+
+---
+
+## 13. JavaScript
+
+**Impact: LOW**
+
+Micro-optimizations like hoisting expensive object creation.
+
+### 13.1 Hoist Intl Formatter Creation
+
+**Impact: LOW-MEDIUM (avoids expensive object recreation)**
+
+Don't create `Intl.DateTimeFormat`, `Intl.NumberFormat`, or
+
+`Intl.RelativeTimeFormat` inside render or loops. These are expensive to
+
+instantiate. Hoist to module scope when the locale/options are static.
+
+**Incorrect: new formatter every render**
+
+```tsx
+function Price({ amount }: { amount: number }) {
+ const formatter = new Intl.NumberFormat('en-US', {
+ style: 'currency',
+ currency: 'USD',
+ })
+ return {formatter.format(amount)}
+}
+```
+
+**Correct: hoisted to module scope**
+
+```tsx
+const currencyFormatter = new Intl.NumberFormat('en-US', {
+ style: 'currency',
+ currency: 'USD',
+})
+
+function Price({ amount }: { amount: number }) {
+ return {currencyFormatter.format(amount)}
+}
+```
+
+**For dynamic locales, memoize:**
+
+```tsx
+const dateFormatter = useMemo(
+ () => new Intl.DateTimeFormat(locale, { dateStyle: 'medium' }),
+ [locale]
+)
+```
+
+**Common formatters to hoist:**
+
+```tsx
+// Module-level formatters
+const dateFormatter = new Intl.DateTimeFormat('en-US', { dateStyle: 'medium' })
+const timeFormatter = new Intl.DateTimeFormat('en-US', { timeStyle: 'short' })
+const percentFormatter = new Intl.NumberFormat('en-US', { style: 'percent' })
+const relativeFormatter = new Intl.RelativeTimeFormat('en-US', {
+ numeric: 'auto',
+})
+```
+
+Creating `Intl` objects is significantly more expensive than `RegExp` or plain
+
+objects—each instantiation parses locale data and builds internal lookup tables.
+
+---
+
+## 14. Fonts
+
+**Impact: LOW**
+
+Native font loading for improved performance.
+
+### 14.1 Load fonts natively at build time
+
+**Impact: LOW (fonts available at launch, no async loading)**
+
+Use the `expo-font` config plugin to embed fonts at build time instead of
+
+`useFonts` or `Font.loadAsync`. Embedded fonts are more efficient.
+
+[Expo Font Documentation](https://docs.expo.dev/versions/latest/sdk/font/)
+
+**Incorrect: async font loading**
+
+```tsx
+import { useFonts } from 'expo-font'
+import { Text, View } from 'react-native'
+
+function App() {
+ const [fontsLoaded] = useFonts({
+ 'Geist-Bold': require('./assets/fonts/Geist-Bold.otf'),
+ })
+
+ if (!fontsLoaded) {
+ return null
+ }
+
+ return (
+
+ Hello
+
+ )
+}
+```
+
+**Correct: config plugin, fonts embedded at build**
+
+```tsx
+import { Text, View } from 'react-native'
+
+function App() {
+ // No loading state needed—font is already available
+ return (
+
+ Hello
+
+ )
+}
+```
+
+After adding fonts to the config plugin, run `npx expo prebuild` and rebuild the
+
+native app.
+
+---
+
+## References
+
+1. [https://react.dev](https://react.dev)
+2. [https://reactnative.dev](https://reactnative.dev)
+3. [https://docs.swmansion.com/react-native-reanimated](https://docs.swmansion.com/react-native-reanimated)
+4. [https://docs.swmansion.com/react-native-gesture-handler](https://docs.swmansion.com/react-native-gesture-handler)
+5. [https://docs.expo.dev](https://docs.expo.dev)
+6. [https://legendapp.com/open-source/legend-list](https://legendapp.com/open-source/legend-list)
+7. [https://github.com/nandorojo/galeria](https://github.com/nandorojo/galeria)
+8. [https://zeego.dev](https://zeego.dev)
diff --git a/.agents/skills/vercel-react-native-skills/README.md b/.agents/skills/vercel-react-native-skills/README.md
new file mode 100644
index 0000000..854db9f
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/README.md
@@ -0,0 +1,165 @@
+# React Native Guidelines
+
+A structured repository for creating and maintaining React Native Best Practices
+optimized for agents and LLMs.
+
+## Structure
+
+- `rules/` - Individual rule files (one per rule)
+ - `_sections.md` - Section metadata (titles, impacts, descriptions)
+ - `_template.md` - Template for creating new rules
+ - `area-description.md` - Individual rule files
+- `metadata.json` - Document metadata (version, organization, abstract)
+- **`AGENTS.md`** - Compiled output (generated)
+
+## Rules
+
+### Core Rendering (CRITICAL)
+
+- `rendering-text-in-text-component.md` - Wrap strings in Text components
+- `rendering-no-falsy-and.md` - Avoid falsy && operator in JSX
+
+### List Performance (HIGH)
+
+- `list-performance-virtualize.md` - Use virtualized lists (LegendList,
+ FlashList)
+- `list-performance-function-references.md` - Keep stable object references
+- `list-performance-callbacks.md` - Hoist callbacks to list root
+- `list-performance-inline-objects.md` - Avoid inline objects in renderItem
+- `list-performance-item-memo.md` - Pass primitives for memoization
+- `list-performance-item-expensive.md` - Keep list items lightweight
+- `list-performance-images.md` - Use compressed images in lists
+- `list-performance-item-types.md` - Use item types for heterogeneous lists
+
+### Animation (HIGH)
+
+- `animation-gpu-properties.md` - Animate transform/opacity instead of layout
+- `animation-gesture-detector-press.md` - Use GestureDetector for press
+ animations
+- `animation-derived-value.md` - Prefer useDerivedValue over useAnimatedReaction
+
+### Scroll Performance (HIGH)
+
+- `scroll-position-no-state.md` - Never track scroll in useState
+
+### Navigation (HIGH)
+
+- `navigation-native-navigators.md` - Use native stack and native tabs
+
+### React State (MEDIUM)
+
+- `react-state-dispatcher.md` - Use functional setState updates
+- `react-state-fallback.md` - State should represent user intent only
+- `react-state-minimize.md` - Minimize state variables, derive values
+
+### State Architecture (MEDIUM)
+
+- `state-ground-truth.md` - State must represent ground truth
+
+### React Compiler (MEDIUM)
+
+- `react-compiler-destructure-functions.md` - Destructure functions early
+- `react-compiler-reanimated-shared-values.md` - Use .get()/.set() for shared
+ values
+
+### User Interface (MEDIUM)
+
+- `ui-expo-image.md` - Use expo-image for optimized images
+- `ui-image-gallery.md` - Use Galeria for lightbox/galleries
+- `ui-menus.md` - Native dropdown and context menus with Zeego
+- `ui-native-modals.md` - Use native Modal with formSheet
+- `ui-pressable.md` - Use Pressable instead of TouchableOpacity
+- `ui-measure-views.md` - Measuring view dimensions
+- `ui-safe-area-scroll.md` - Use contentInsetAdjustmentBehavior
+- `ui-scrollview-content-inset.md` - Use contentInset for dynamic spacing
+- `ui-styling.md` - Modern styling patterns (gap, boxShadow, gradients)
+
+### Design System (MEDIUM)
+
+- `design-system-compound-components.md` - Use compound components
+
+### Monorepo (LOW)
+
+- `monorepo-native-deps-in-app.md` - Install native deps in app directory
+- `monorepo-single-dependency-versions.md` - Single dependency versions
+
+### Third-Party Dependencies (LOW)
+
+- `imports-design-system-folder.md` - Import from design system folder
+
+### JavaScript (LOW)
+
+- `js-hoist-intl.md` - Hoist Intl formatter creation
+
+### Fonts (LOW)
+
+- `fonts-config-plugin.md` - Load fonts natively at build time
+
+## Creating a New Rule
+
+1. Copy `rules/_template.md` to `rules/area-description.md`
+2. Choose the appropriate area prefix:
+ - `rendering-` for Core Rendering
+ - `list-performance-` for List Performance
+ - `animation-` for Animation
+ - `scroll-` for Scroll Performance
+ - `navigation-` for Navigation
+ - `react-state-` for React State
+ - `state-` for State Architecture
+ - `react-compiler-` for React Compiler
+ - `ui-` for User Interface
+ - `design-system-` for Design System
+ - `monorepo-` for Monorepo
+ - `imports-` for Third-Party Dependencies
+ - `js-` for JavaScript
+ - `fonts-` for Fonts
+3. Fill in the frontmatter and content
+4. Ensure you have clear examples with explanations
+
+## Rule File Structure
+
+Each rule file should follow this structure:
+
+````markdown
+---
+title: Rule Title Here
+impact: MEDIUM
+impactDescription: Optional description
+tags: tag1, tag2, tag3
+---
+
+## Rule Title Here
+
+Brief explanation of the rule and why it matters.
+
+**Incorrect (description of what's wrong):**
+
+```tsx
+// Bad code example
+```
+````
+
+**Correct (description of what's right):**
+
+```tsx
+// Good code example
+```
+
+Reference: [Link](https://example.com)
+
+```
+
+## File Naming Convention
+
+- Files starting with `_` are special (excluded from build)
+- Rule files: `area-description.md` (e.g., `animation-gpu-properties.md`)
+- Section is automatically inferred from filename prefix
+- Rules are sorted alphabetically by title within each section
+
+## Impact Levels
+
+- `CRITICAL` - Highest priority, causes crashes or broken UI
+- `HIGH` - Significant performance improvements
+- `MEDIUM` - Moderate performance improvements
+- `LOW` - Incremental improvements
+```
diff --git a/.agents/skills/vercel-react-native-skills/SKILL.md b/.agents/skills/vercel-react-native-skills/SKILL.md
new file mode 100644
index 0000000..7340186
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/SKILL.md
@@ -0,0 +1,121 @@
+---
+name: vercel-react-native-skills
+description:
+ React Native and Expo best practices for building performant mobile apps. Use
+ when building React Native components, optimizing list performance,
+ implementing animations, or working with native modules. Triggers on tasks
+ involving React Native, Expo, mobile performance, or native platform APIs.
+license: MIT
+metadata:
+ author: vercel
+ version: '1.0.0'
+---
+
+# React Native Skills
+
+Comprehensive best practices for React Native and Expo applications. Contains
+rules across multiple categories covering performance, animations, UI patterns,
+and platform-specific optimizations.
+
+## When to Apply
+
+Reference these guidelines when:
+
+- Building React Native or Expo apps
+- Optimizing list and scroll performance
+- Implementing animations with Reanimated
+- Working with images and media
+- Configuring native modules or fonts
+- Structuring monorepo projects with native dependencies
+
+## Rule Categories by Priority
+
+| Priority | Category | Impact | Prefix |
+| -------- | ---------------- | -------- | -------------------- |
+| 1 | List Performance | CRITICAL | `list-performance-` |
+| 2 | Animation | HIGH | `animation-` |
+| 3 | Navigation | HIGH | `navigation-` |
+| 4 | UI Patterns | HIGH | `ui-` |
+| 5 | State Management | MEDIUM | `react-state-` |
+| 6 | Rendering | MEDIUM | `rendering-` |
+| 7 | Monorepo | MEDIUM | `monorepo-` |
+| 8 | Configuration | LOW | `fonts-`, `imports-` |
+
+## Quick Reference
+
+### 1. List Performance (CRITICAL)
+
+- `list-performance-virtualize` - Use FlashList for large lists
+- `list-performance-item-memo` - Memoize list item components
+- `list-performance-callbacks` - Stabilize callback references
+- `list-performance-inline-objects` - Avoid inline style objects
+- `list-performance-function-references` - Extract functions outside render
+- `list-performance-images` - Optimize images in lists
+- `list-performance-item-expensive` - Move expensive work outside items
+- `list-performance-item-types` - Use item types for heterogeneous lists
+
+### 2. Animation (HIGH)
+
+- `animation-gpu-properties` - Animate only transform and opacity
+- `animation-derived-value` - Use useDerivedValue for computed animations
+- `animation-gesture-detector-press` - Use Gesture.Tap instead of Pressable
+
+### 3. Navigation (HIGH)
+
+- `navigation-native-navigators` - Use native stack and native tabs over JS navigators
+
+### 4. UI Patterns (HIGH)
+
+- `ui-expo-image` - Use expo-image for all images
+- `ui-image-gallery` - Use Galeria for image lightboxes
+- `ui-pressable` - Use Pressable over TouchableOpacity
+- `ui-safe-area-scroll` - Handle safe areas in ScrollViews
+- `ui-scrollview-content-inset` - Use contentInset for headers
+- `ui-menus` - Use native context menus
+- `ui-native-modals` - Use native modals when possible
+- `ui-measure-views` - Use onLayout, not measure()
+- `ui-styling` - Use StyleSheet.create or Nativewind
+
+### 5. State Management (MEDIUM)
+
+- `react-state-minimize` - Minimize state subscriptions
+- `react-state-dispatcher` - Use dispatcher pattern for callbacks
+- `react-state-fallback` - Show fallback on first render
+- `react-compiler-destructure-functions` - Destructure for React Compiler
+- `react-compiler-reanimated-shared-values` - Handle shared values with compiler
+
+### 6. Rendering (MEDIUM)
+
+- `rendering-text-in-text-component` - Wrap text in Text components
+- `rendering-no-falsy-and` - Avoid falsy && for conditional rendering
+
+### 7. Monorepo (MEDIUM)
+
+- `monorepo-native-deps-in-app` - Keep native dependencies in app package
+- `monorepo-single-dependency-versions` - Use single versions across packages
+
+### 8. Configuration (LOW)
+
+- `fonts-config-plugin` - Use config plugins for custom fonts
+- `imports-design-system-folder` - Organize design system imports
+- `js-hoist-intl` - Hoist Intl object creation
+
+## How to Use
+
+Read individual rule files for detailed explanations and code examples:
+
+```
+rules/list-performance-virtualize.md
+rules/animation-gpu-properties.md
+```
+
+Each rule file contains:
+
+- Brief explanation of why it matters
+- Incorrect code example with explanation
+- Correct code example with explanation
+- Additional context and references
+
+## Full Compiled Document
+
+For the complete guide with all rules expanded: `AGENTS.md`
diff --git a/.agents/skills/vercel-react-native-skills/rules/_sections.md b/.agents/skills/vercel-react-native-skills/rules/_sections.md
new file mode 100644
index 0000000..0519cf2
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/_sections.md
@@ -0,0 +1,86 @@
+# Sections
+
+This file defines all sections, their ordering, impact levels, and descriptions.
+The section ID (in parentheses) is the filename prefix used to group rules.
+
+---
+
+## 1. Core Rendering (rendering)
+
+**Impact:** CRITICAL
+**Description:** Fundamental React Native rendering rules. Violations cause
+runtime crashes or broken UI.
+
+## 2. List Performance (list-performance)
+
+**Impact:** HIGH
+**Description:** Optimizing virtualized lists (FlatList, LegendList, FlashList)
+for smooth scrolling and fast updates.
+
+## 3. Animation (animation)
+
+**Impact:** HIGH
+**Description:** GPU-accelerated animations, Reanimated patterns, and avoiding
+render thrashing during gestures.
+
+## 4. Scroll Performance (scroll)
+
+**Impact:** HIGH
+**Description:** Tracking scroll position without causing render thrashing.
+
+## 5. Navigation (navigation)
+
+**Impact:** HIGH
+**Description:** Using native navigators for stack and tab navigation instead of
+JS-based alternatives.
+
+## 6. React State (react-state)
+
+**Impact:** MEDIUM
+**Description:** Patterns for managing React state to avoid stale closures and
+unnecessary re-renders.
+
+## 7. State Architecture (state)
+
+**Impact:** MEDIUM
+**Description:** Ground truth principles for state variables and derived values.
+
+## 8. React Compiler (react-compiler)
+
+**Impact:** MEDIUM
+**Description:** Compatibility patterns for React Compiler with React Native and
+Reanimated.
+
+## 9. User Interface (ui)
+
+**Impact:** MEDIUM
+**Description:** Native UI patterns for images, menus, modals, styling, and
+platform-consistent interfaces.
+
+## 10. Design System (design-system)
+
+**Impact:** MEDIUM
+**Description:** Architecture patterns for building maintainable component
+libraries.
+
+## 11. Monorepo (monorepo)
+
+**Impact:** LOW
+**Description:** Dependency management and native module configuration in
+monorepos.
+
+## 12. Third-Party Dependencies (imports)
+
+**Impact:** LOW
+**Description:** Wrapping and re-exporting third-party dependencies for
+maintainability.
+
+## 13. JavaScript (js)
+
+**Impact:** LOW
+**Description:** Micro-optimizations like hoisting expensive object creation.
+
+## 14. Fonts (fonts)
+
+**Impact:** LOW
+**Description:** Native font loading for improved performance.
diff --git a/.agents/skills/vercel-react-native-skills/rules/_template.md b/.agents/skills/vercel-react-native-skills/rules/_template.md
new file mode 100644
index 0000000..1e9e707
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/_template.md
@@ -0,0 +1,28 @@
+---
+title: Rule Title Here
+impact: MEDIUM
+impactDescription: Optional description of impact (e.g., "20-50% improvement")
+tags: tag1, tag2
+---
+
+## Rule Title Here
+
+**Impact: MEDIUM (optional impact description)**
+
+Brief explanation of the rule and why it matters. This should be clear and concise, explaining the performance implications.
+
+**Incorrect (description of what's wrong):**
+
+```typescript
+// Bad code example here
+const bad = example()
+```
+
+**Correct (description of what's right):**
+
+```typescript
+// Good code example here
+const good = example()
+```
+
+Reference: [Link to documentation or resource](https://example.com)
diff --git a/.agents/skills/vercel-react-native-skills/rules/animation-derived-value.md b/.agents/skills/vercel-react-native-skills/rules/animation-derived-value.md
new file mode 100644
index 0000000..310928a
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/animation-derived-value.md
@@ -0,0 +1,53 @@
+---
+title: Prefer useDerivedValue Over useAnimatedReaction
+impact: MEDIUM
+impactDescription: cleaner code, automatic dependency tracking
+tags: animation, reanimated, derived-value
+---
+
+## Prefer useDerivedValue Over useAnimatedReaction
+
+When deriving a shared value from another, use `useDerivedValue` instead of
+`useAnimatedReaction`. Derived values are declarative, automatically track
+dependencies, and return a value you can use directly. Animated reactions are
+for side effects, not derivations.
+
+**Incorrect (useAnimatedReaction for derivation):**
+
+```tsx
+import { useSharedValue, useAnimatedReaction } from 'react-native-reanimated'
+
+function MyComponent() {
+ const progress = useSharedValue(0)
+ const opacity = useSharedValue(1)
+
+ useAnimatedReaction(
+ () => progress.value,
+ (current) => {
+ opacity.value = 1 - current
+ }
+ )
+
+ // ...
+}
+```
+
+**Correct (useDerivedValue):**
+
+```tsx
+import { useSharedValue, useDerivedValue } from 'react-native-reanimated'
+
+function MyComponent() {
+ const progress = useSharedValue(0)
+
+ const opacity = useDerivedValue(() => 1 - progress.get())
+
+ // ...
+}
+```
+
+Use `useAnimatedReaction` only for side effects that don't produce a value
+(e.g., triggering haptics, logging, calling `runOnJS`).
+
+Reference:
+[Reanimated useDerivedValue](https://docs.swmansion.com/react-native-reanimated/docs/core/useDerivedValue)
diff --git a/.agents/skills/vercel-react-native-skills/rules/animation-gesture-detector-press.md b/.agents/skills/vercel-react-native-skills/rules/animation-gesture-detector-press.md
new file mode 100644
index 0000000..87c6782
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/animation-gesture-detector-press.md
@@ -0,0 +1,95 @@
+---
+title: Use GestureDetector for Animated Press States
+impact: MEDIUM
+impactDescription: UI thread animations, smoother press feedback
+tags: animation, gestures, press, reanimated
+---
+
+## Use GestureDetector for Animated Press States
+
+For animated press states (scale, opacity on press), use `GestureDetector` with
+`Gesture.Tap()` and shared values instead of Pressable's
+`onPressIn`/`onPressOut`. Gesture callbacks run on the UI thread as worklets—no
+JS thread round-trip for press animations.
+
+**Incorrect (Pressable with JS thread callbacks):**
+
+```tsx
+import { Pressable } from 'react-native'
+import Animated, {
+ useSharedValue,
+ useAnimatedStyle,
+ withTiming,
+} from 'react-native-reanimated'
+
+function AnimatedButton({ onPress }: { onPress: () => void }) {
+ const scale = useSharedValue(1)
+
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [{ scale: scale.value }],
+ }))
+
+ return (
+ (scale.value = withTiming(0.95))}
+ onPressOut={() => (scale.value = withTiming(1))}
+ >
+
+ Press me
+
+
+ )
+}
+```
+
+**Correct (GestureDetector with UI thread worklets):**
+
+```tsx
+import { Gesture, GestureDetector } from 'react-native-gesture-handler'
+import Animated, {
+ useSharedValue,
+ useAnimatedStyle,
+ withTiming,
+ interpolate,
+ runOnJS,
+} from 'react-native-reanimated'
+
+function AnimatedButton({ onPress }: { onPress: () => void }) {
+ // Store the press STATE (0 = not pressed, 1 = pressed)
+ const pressed = useSharedValue(0)
+
+ const tap = Gesture.Tap()
+ .onBegin(() => {
+ pressed.set(withTiming(1))
+ })
+ .onFinalize(() => {
+ pressed.set(withTiming(0))
+ })
+ .onEnd(() => {
+ runOnJS(onPress)()
+ })
+
+ // Derive visual values from the state
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [
+ { scale: interpolate(withTiming(pressed.get()), [0, 1], [1, 0.95]) },
+ ],
+ }))
+
+ return (
+
+
+ Press me
+
+
+ )
+}
+```
+
+Store the press **state** (0 or 1), then derive the scale via `interpolate`.
+This keeps the shared value as ground truth. Use `runOnJS` to call JS functions
+from worklets. Use `.set()` and `.get()` for React Compiler compatibility.
+
+Reference:
+[Gesture Handler Tap Gesture](https://docs.swmansion.com/react-native-gesture-handler/docs/gestures/tap-gesture)
diff --git a/.agents/skills/vercel-react-native-skills/rules/animation-gpu-properties.md b/.agents/skills/vercel-react-native-skills/rules/animation-gpu-properties.md
new file mode 100644
index 0000000..5fda095
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/animation-gpu-properties.md
@@ -0,0 +1,65 @@
+---
+title: Animate Transform and Opacity Instead of Layout Properties
+impact: HIGH
+impactDescription: GPU-accelerated animations, no layout recalculation
+tags: animation, performance, reanimated, transform, opacity
+---
+
+## Animate Transform and Opacity Instead of Layout Properties
+
+Avoid animating `width`, `height`, `top`, `left`, `margin`, or `padding`. These trigger layout recalculation on every frame. Instead, use `transform` (scale, translate) and `opacity` which run on the GPU without triggering layout.
+
+**Incorrect (animates height, triggers layout every frame):**
+
+```tsx
+import Animated, { useAnimatedStyle, withTiming } from 'react-native-reanimated'
+
+function CollapsiblePanel({ expanded }: { expanded: boolean }) {
+ const animatedStyle = useAnimatedStyle(() => ({
+ height: withTiming(expanded ? 200 : 0), // triggers layout on every frame
+ overflow: 'hidden',
+ }))
+
+ return {children}
+}
+```
+
+**Correct (animates scaleY, GPU-accelerated):**
+
+```tsx
+import Animated, { useAnimatedStyle, withTiming } from 'react-native-reanimated'
+
+function CollapsiblePanel({ expanded }: { expanded: boolean }) {
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [
+ { scaleY: withTiming(expanded ? 1 : 0) },
+ ],
+ opacity: withTiming(expanded ? 1 : 0),
+ }))
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+**Correct (animates translateY for slide animations):**
+
+```tsx
+import Animated, { useAnimatedStyle, withTiming } from 'react-native-reanimated'
+
+function SlideIn({ visible }: { visible: boolean }) {
+ const animatedStyle = useAnimatedStyle(() => ({
+ transform: [
+ { translateY: withTiming(visible ? 0 : 100) },
+ ],
+ opacity: withTiming(visible ? 1 : 0),
+ }))
+
+ return {children}
+}
+```
+
+GPU-accelerated properties: `transform` (translate, scale, rotate), `opacity`. Everything else triggers layout.
diff --git a/.agents/skills/vercel-react-native-skills/rules/design-system-compound-components.md b/.agents/skills/vercel-react-native-skills/rules/design-system-compound-components.md
new file mode 100644
index 0000000..d8239ee
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/design-system-compound-components.md
@@ -0,0 +1,66 @@
+---
+title: Use Compound Components Over Polymorphic Children
+impact: MEDIUM
+impactDescription: flexible composition, clearer API
+tags: design-system, components, composition
+---
+
+## Use Compound Components Over Polymorphic Children
+
+Don't create components that can accept a string if they aren't a text node. If
+a component can receive a string child, it must be a dedicated `*Text`
+component. For components like buttons, which can have both a View (or
+Pressable) together with text, use compound components, such a `Button`,
+`ButtonText`, and `ButtonIcon`.
+
+**Incorrect (polymorphic children):**
+
+```tsx
+import { Pressable, Text } from 'react-native'
+
+type ButtonProps = {
+ children: string | React.ReactNode
+ icon?: React.ReactNode
+}
+
+function Button({ children, icon }: ButtonProps) {
+ return (
+
+ {icon}
+ {typeof children === 'string' ? {children} : children}
+
+ )
+}
+
+// Usage is ambiguous
+}>Save
+
+```
+
+**Correct (compound components):**
+
+```tsx
+import { Pressable, Text } from 'react-native'
+
+function Button({ children }: { children: React.ReactNode }) {
+ return {children}
+}
+
+function ButtonText({ children }: { children: React.ReactNode }) {
+ return {children}
+}
+
+function ButtonIcon({ children }: { children: React.ReactNode }) {
+ return <>{children}
+}
+
+// Usage is explicit and composable
+
+
+
+```
diff --git a/.agents/skills/vercel-react-native-skills/rules/fonts-config-plugin.md b/.agents/skills/vercel-react-native-skills/rules/fonts-config-plugin.md
new file mode 100644
index 0000000..39aa014
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/fonts-config-plugin.md
@@ -0,0 +1,71 @@
+---
+title: Load fonts natively at build time
+impact: LOW
+impactDescription: fonts available at launch, no async loading
+tags: fonts, expo, performance, config-plugin
+---
+
+## Use Expo Config Plugin for Font Loading
+
+Use the `expo-font` config plugin to embed fonts at build time instead of
+`useFonts` or `Font.loadAsync`. Embedded fonts are more efficient.
+
+**Incorrect (async font loading):**
+
+```tsx
+import { useFonts } from 'expo-font'
+import { Text, View } from 'react-native'
+
+function App() {
+ const [fontsLoaded] = useFonts({
+ 'Geist-Bold': require('./assets/fonts/Geist-Bold.otf'),
+ })
+
+ if (!fontsLoaded) {
+ return null
+ }
+
+ return (
+
+ Hello
+
+ )
+}
+```
+
+**Correct (config plugin, fonts embedded at build):**
+
+```json
+// app.json
+{
+ "expo": {
+ "plugins": [
+ [
+ "expo-font",
+ {
+ "fonts": ["./assets/fonts/Geist-Bold.otf"]
+ }
+ ]
+ ]
+ }
+}
+```
+
+```tsx
+import { Text, View } from 'react-native'
+
+function App() {
+ // No loading state needed—font is already available
+ return (
+
+ Hello
+
+ )
+}
+```
+
+After adding fonts to the config plugin, run `npx expo prebuild` and rebuild the
+native app.
+
+Reference:
+[Expo Font Documentation](https://docs.expo.dev/versions/latest/sdk/font/)
diff --git a/.agents/skills/vercel-react-native-skills/rules/imports-design-system-folder.md b/.agents/skills/vercel-react-native-skills/rules/imports-design-system-folder.md
new file mode 100644
index 0000000..8466dcb
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/imports-design-system-folder.md
@@ -0,0 +1,68 @@
+---
+title: Import from Design System Folder
+impact: LOW
+impactDescription: enables global changes and easy refactoring
+tags: imports, architecture, design-system
+---
+
+## Import from Design System Folder
+
+Re-export dependencies from a design system folder. App code imports from there,
+not directly from packages. This enables global changes and easy refactoring.
+
+**Incorrect (imports directly from package):**
+
+```tsx
+import { View, Text } from 'react-native'
+import { Button } from '@ui/button'
+
+function Profile() {
+ return (
+
+ Hello
+
+
+ )
+}
+```
+
+**Correct (imports from design system):**
+
+```tsx
+// components/view.tsx
+import { View as RNView } from 'react-native'
+
+// ideal: pick the props you will actually use to control implementation
+export function View(
+ props: Pick, 'style' | 'children'>
+) {
+ return
+ Hello
+
+
+ )
+}
+```
+
+Start by simply re-exporting. Customize later without changing app code.
diff --git a/.agents/skills/vercel-react-native-skills/rules/js-hoist-intl.md b/.agents/skills/vercel-react-native-skills/rules/js-hoist-intl.md
new file mode 100644
index 0000000..9af1c35
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/js-hoist-intl.md
@@ -0,0 +1,61 @@
+---
+title: Hoist Intl Formatter Creation
+impact: LOW-MEDIUM
+impactDescription: avoids expensive object recreation
+tags: javascript, intl, optimization, memoization
+---
+
+## Hoist Intl Formatter Creation
+
+Don't create `Intl.DateTimeFormat`, `Intl.NumberFormat`, or
+`Intl.RelativeTimeFormat` inside render or loops. These are expensive to
+instantiate. Hoist to module scope when the locale/options are static.
+
+**Incorrect (new formatter every render):**
+
+```tsx
+function Price({ amount }: { amount: number }) {
+ const formatter = new Intl.NumberFormat('en-US', {
+ style: 'currency',
+ currency: 'USD',
+ })
+ return {formatter.format(amount)}
+}
+```
+
+**Correct (hoisted to module scope):**
+
+```tsx
+const currencyFormatter = new Intl.NumberFormat('en-US', {
+ style: 'currency',
+ currency: 'USD',
+})
+
+function Price({ amount }: { amount: number }) {
+ return {currencyFormatter.format(amount)}
+}
+```
+
+**For dynamic locales, memoize:**
+
+```tsx
+const dateFormatter = useMemo(
+ () => new Intl.DateTimeFormat(locale, { dateStyle: 'medium' }),
+ [locale]
+)
+```
+
+**Common formatters to hoist:**
+
+```tsx
+// Module-level formatters
+const dateFormatter = new Intl.DateTimeFormat('en-US', { dateStyle: 'medium' })
+const timeFormatter = new Intl.DateTimeFormat('en-US', { timeStyle: 'short' })
+const percentFormatter = new Intl.NumberFormat('en-US', { style: 'percent' })
+const relativeFormatter = new Intl.RelativeTimeFormat('en-US', {
+ numeric: 'auto',
+})
+```
+
+Creating `Intl` objects is significantly more expensive than `RegExp` or plain
+objects—each instantiation parses locale data and builds internal lookup tables.
diff --git a/.agents/skills/vercel-react-native-skills/rules/list-performance-callbacks.md b/.agents/skills/vercel-react-native-skills/rules/list-performance-callbacks.md
new file mode 100644
index 0000000..a0b3913
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/list-performance-callbacks.md
@@ -0,0 +1,44 @@
+---
+title: Hoist callbacks to the root of lists
+impact: MEDIUM
+impactDescription: Fewer re-renders and faster lists
+tags: tag1, tag2
+---
+
+## List performance callbacks
+
+**Impact: HIGH (Fewer re-renders and faster lists)**
+
+When passing callback functions to list items, create a single instance of the
+callback at the root of the list. Items should then call it with a unique
+identifier.
+
+**Incorrect (creates a new callback on each render):**
+
+```typescript
+return (
+ {
+ // bad: creates a new callback on each render
+ const onPress = () => handlePress(item.id)
+ return (
+ {domain}
+}
+```
+
+**Updating parent array reference:**
+
+Creating a new array instance can be okay, as long as its inner object
+references are stable. For instance, if you sort a list of objects:
+
+```tsx
+// good: creates a new array instance without mutating the inner objects
+// good: parent array reference is unaffected by typing and updating "keyword"
+const sortedTlds = tlds.toSorted((a, b) => a.name.localeCompare(b.name))
+
+return {domain}
+}
+```
+
+Virtualization can now skip items that haven't changed when typing. Only visible
+items (~20) re-render on keystroke, rather than the parent.
+
+**Deriving state within list items based on parent data (avoids parent
+re-renders):**
+
+For components where the data is conditional based on the parent state, this
+pattern is even more important. For example, if you are checking if an item is
+favorited, toggling favorites only re-renders one component if the item itself
+is in charge of accessing the state rather than the parent:
+
+```tsx
+function DomainItemFavoriteButton({ tld }: { tld: Tld }) {
+ const isFavorited = useFavoritesStore((s) => s.favorites.has(tld.id))
+ return
+ {/* 4000x3000 image loaded for a 100x100 thumbnail */}
+ {product.name}
+
+ )
+}
+```
+
+**Correct (request appropriately-sized image):**
+
+```tsx
+function ProductItem({ product }: { product: Product }) {
+ // Request a 200x200 image (2x for retina)
+ const thumbnailUrl = `${product.imageUrl}?w=200&h=200&fit=cover`
+
+ return (
+
+ {product.name}
+
+ )
+}
+```
+
+Use an optimized image component with built-in caching and placeholder support,
+such as `expo-image` or `SolitoImage` (which uses `expo-image` under the hood).
+Request images at 2x the display size for retina screens.
diff --git a/.agents/skills/vercel-react-native-skills/rules/list-performance-inline-objects.md b/.agents/skills/vercel-react-native-skills/rules/list-performance-inline-objects.md
new file mode 100644
index 0000000..d5b6514
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/list-performance-inline-objects.md
@@ -0,0 +1,97 @@
+---
+title: Avoid Inline Objects in renderItem
+impact: HIGH
+impactDescription: prevents unnecessary re-renders of memoized list items
+tags: lists, performance, flatlist, virtualization, memo
+---
+
+## Avoid Inline Objects in renderItem
+
+Don't create new objects inside `renderItem` to pass as props. Inline objects
+create new references on every render, breaking memoization. Pass primitive
+values directly from `item` instead.
+
+**Incorrect (inline object breaks memoization):**
+
+```tsx
+function UserList({ users }: { users: User[] }) {
+ return (
+ (
+ (
+ // Good: pass the item directly
+ {/* ... */}
+})
+```
+
+**Correct (hoist static styles in module scope):**
+
+```tsx
+const activeStyle = { backgroundColor: 'green' }
+const inactiveStyle = { backgroundColor: 'gray' }
+
+renderItem={({ item }) => (
+ {/* ... */}
+}
+```
+
+**Correct (lightweight list item):**
+
+```tsx
+function ProductRow({ name, price, imageUrl }: Props) {
+ // Good: receives only primitives, minimal hooks
+ return (
+
+ {name}
+ {price}
+
+ )
+}
+```
+
+**Move data fetching to parent:**
+
+```tsx
+// Parent fetches all data once
+function ProductList() {
+ const { data: products } = useQuery(['products'], fetchProducts)
+
+ return (
+ (
+ {user.name}
+})
+
+renderItem={({ item }) => {name}
+})
+
+renderItem={({ item }) => (
+ handlePress(item.id)} />
+
+// Correct: pass ID, handle in child
+{name} item.id}
+ getItemType={(item) => item.type}
+ renderItem={({ item }) => {
+ switch (item.type) {
+ case 'header':
+ return item.id}
+ getItemType={(item) => item.type}
+ getEstimatedItemSize={(index, item, itemType) => {
+ switch (itemType) {
+ case 'header':
+ return 48
+ case 'message':
+ return 72
+ case 'image':
+ return 300
+ default:
+ return 72
+ }
+ }}
+ renderItem={({ item }) => {
+ /* ... */
+ }}
+ recycleItems
+/>
+```
+
+Reference:
+[LegendList getItemType](https://legendapp.com/open-source/list/api/props/#getitemtype-v2)
diff --git a/.agents/skills/vercel-react-native-skills/rules/list-performance-virtualize.md b/.agents/skills/vercel-react-native-skills/rules/list-performance-virtualize.md
new file mode 100644
index 0000000..8a393ba
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/list-performance-virtualize.md
@@ -0,0 +1,67 @@
+---
+title: Use a List Virtualizer for Any List
+impact: HIGH
+impactDescription: reduced memory, faster mounts
+tags: lists, performance, virtualization, scrollview
+---
+
+## Use a List Virtualizer for Any List
+
+Use a list virtualizer like LegendList or FlashList instead of ScrollView with
+mapped children—even for short lists. Virtualizers only render visible items,
+reducing memory usage and mount time. ScrollView renders all children upfront,
+which gets expensive quickly.
+
+**Incorrect (ScrollView renders all items at once):**
+
+```tsx
+function Feed({ items }: { items: Item[] }) {
+ return (
+
+ {items.map((item) => (
+
+ )
+}
+// 50 items = 50 components mounted, even if only 10 visible
+```
+
+**Correct (virtualizer renders only visible items):**
+
+```tsx
+import { LegendList } from '@legendapp/list'
+
+function Feed({ items }: { items: Item[] }) {
+ return (
+
+
+ )
+}
+```
+
+**Correct (native stack with react-navigation):**
+
+```tsx
+import { createNativeStackNavigator } from '@react-navigation/native-stack'
+
+const Stack = createNativeStackNavigator()
+
+function App() {
+ return (
+
+
+ )
+}
+```
+
+**Correct (expo-router uses native stack by default):**
+
+```tsx
+// app/_layout.tsx
+import { Stack } from 'expo-router'
+
+export default function Layout() {
+ return
+
+ )
+}
+```
+
+**Correct (native bottom tabs with react-navigation):**
+
+```tsx
+import { createNativeBottomTabNavigator } from '@bottom-tabs/react-navigation'
+
+const Tab = createNativeBottomTabNavigator()
+
+function App() {
+ return (
+
+ ({ sfSymbol: 'house' }),
+ }}
+ />
+ ({ sfSymbol: 'gear' }),
+ }}
+ />
+
+ )
+}
+```
+
+**Correct (expo-router native tabs):**
+
+```tsx
+// app/(tabs)/_layout.tsx
+import { NativeTabs } from 'expo-router/unstable-native-tabs'
+
+export default function TabLayout() {
+ return (
+
+
+ Home
+
+
+ Settings
+
+
+ )
+}
+```
+
+On iOS, native tabs automatically enable `contentInsetAdjustmentBehavior` on the
+first `ScrollView` at the root of each tab screen, so content scrolls correctly
+behind the translucent tab bar. If you need to disable this, use
+`disableAutomaticContentInsets` on the trigger.
+
+### Prefer Native Header Options Over Custom Components
+
+**Incorrect (custom header component):**
+
+```tsx
+ (undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ // size may be stale in this closure
+ if (size?.width !== width || size?.height !== height) {
+ setSize({ width, height })
+ }
+}
+```
+
+**Correct (dispatch updater):**
+
+```tsx
+const [size, setSize] = useState(undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize((prev) => {
+ if (prev?.width === width && prev?.height === height) return prev
+ return { width, height }
+ })
+}
+```
+
+Returning the previous value from the updater skips the re-render.
+
+For primitive states, you don't need to compare values before firing a
+re-render.
+
+**Incorrect (unnecessary comparison for primitive state):**
+
+```tsx
+const [size, setSize] = useState(undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize((prev) => (prev === width ? prev : width))
+}
+```
+
+**Correct (sets primitive state directly):**
+
+```tsx
+const [size, setSize] = useState(undefined)
+
+const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize(width)
+}
+```
+
+However, if the next state depends on the current state, you should still use a
+dispatch updater.
+
+**Incorrect (reads state directly from the callback):**
+
+```tsx
+const [count, setCount] = useState(0)
+
+const onTap = () => {
+ setCount(count + 1)
+}
+```
+
+**Correct (dispatch updater):**
+
+```tsx
+const [count, setCount] = useState(0)
+
+const onTap = () => {
+ setCount((prev) => prev + 1)
+}
+```
diff --git a/.agents/skills/vercel-react-native-skills/rules/react-state-fallback.md b/.agents/skills/vercel-react-native-skills/rules/react-state-fallback.md
new file mode 100644
index 0000000..204f346
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/react-state-fallback.md
@@ -0,0 +1,56 @@
+---
+title: Use fallback state instead of initialState
+impact: MEDIUM
+impactDescription: reactive fallbacks without syncing
+tags: state, hooks, derived-state, props, initialState
+---
+
+## Use fallback state instead of initialState
+
+Use `undefined` as initial state and nullish coalescing (`??`) to fall back to
+parent or server values. State represents user intent only—`undefined` means
+"user hasn't chosen yet." This enables reactive fallbacks that update when the
+source changes, not just on initial render.
+
+**Incorrect (syncs state, loses reactivity):**
+
+```tsx
+type Props = { fallbackEnabled: boolean }
+
+function Toggle({ fallbackEnabled }: Props) {
+ const [enabled, setEnabled] = useState(defaultEnabled)
+ // If fallbackEnabled changes, state is stale
+ // State mixes user intent with default value
+
+ return (undefined)
+ const enabled = _enabled ?? defaultEnabled
+ // undefined = user hasn't touched it, falls back to prop
+ // If defaultEnabled changes, component reflects it
+ // Once user interacts, their choice persists
+
+ return (undefined)
+ const theme = _theme ?? data.theme
+ // Shows server value until user overrides
+ // Server refetch updates the fallback automatically
+
+ return
+ {itemCount} items
+ Total: ${total}
+
+ )
+}
+```
+
+**Correct (derived values):**
+
+```tsx
+function Cart({ items }: { items: Item[] }) {
+ const total = items.reduce((sum, item) => sum + item.price, 0)
+ const itemCount = items.length
+
+ return (
+
+ {itemCount} items
+ Total: ${total}
+
+ )
+}
+```
+
+**Another example:**
+
+```tsx
+// Incorrect: storing both firstName, lastName, AND fullName
+const [firstName, setFirstName] = useState('')
+const [lastName, setLastName] = useState('')
+const [fullName, setFullName] = useState('')
+
+// Correct: derive fullName
+const [firstName, setFirstName] = useState('')
+const [lastName, setLastName] = useState('')
+const fullName = `${firstName} ${lastName}`
+```
+
+State should be the minimal source of truth. Everything else is derived.
+
+Reference: [Choosing the State Structure](https://react.dev/learn/choosing-the-state-structure)
diff --git a/.agents/skills/vercel-react-native-skills/rules/rendering-no-falsy-and.md b/.agents/skills/vercel-react-native-skills/rules/rendering-no-falsy-and.md
new file mode 100644
index 0000000..30f05d3
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/rendering-no-falsy-and.md
@@ -0,0 +1,74 @@
+---
+title: Never Use && with Potentially Falsy Values
+impact: CRITICAL
+impactDescription: prevents production crash
+tags: rendering, conditional, jsx, crash
+---
+
+## Never Use && with Potentially Falsy Values
+
+Never use `{value && ` component, causing a hard crash in production.
+
+**Incorrect (crashes if count is 0 or name is ""):**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ return (
+
+ {name && {name} }
+ {count && {count} items }
+
+ )
+}
+// If name="" or count=0, renders the falsy value → crash
+```
+
+**Correct (ternary with null):**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ return (
+
+ {name ? {name} : null}
+ {count ? {count} items : null}
+
+ )
+}
+```
+
+**Correct (explicit boolean coercion):**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ return (
+
+ {!!name && {name} }
+ {!!count && {count} items }
+
+ )
+}
+```
+
+**Best (early return):**
+
+```tsx
+function Profile({ name, count }: { name: string; count: number }) {
+ if (!name) return null
+
+ return (
+
+ {name}
+ {count > 0 ? {count} items : null}
+
+ )
+}
+```
+
+Early returns are clearest. When using conditionals inline, prefer ternary or
+explicit boolean checks.
+
+**Lint rule:** Enable `react/jsx-no-leaked-render` from
+[eslint-plugin-react](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-leaked-render.md)
+to catch this automatically.
diff --git a/.agents/skills/vercel-react-native-skills/rules/rendering-text-in-text-component.md b/.agents/skills/vercel-react-native-skills/rules/rendering-text-in-text-component.md
new file mode 100644
index 0000000..fd1b9f4
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/rendering-text-in-text-component.md
@@ -0,0 +1,36 @@
+---
+title: Wrap Strings in Text Components
+impact: CRITICAL
+impactDescription: prevents runtime crash
+tags: rendering, text, core
+---
+
+## Wrap Strings in Text Components
+
+Strings must be rendered inside ``. React Native crashes if a string is a
+direct child of ``.
+
+**Incorrect (crashes):**
+
+```tsx
+import { View } from 'react-native'
+
+function Greeting({ name }: { name: string }) {
+ return Hello, {name}!
+}
+// Error: Text strings must be rendered within a component.
+```
+
+**Correct:**
+
+```tsx
+import { View, Text } from 'react-native'
+
+function Greeting({ name }: { name: string }) {
+ return (
+
+ Hello, {name}!
+
+ )
+}
+```
diff --git a/.agents/skills/vercel-react-native-skills/rules/scroll-position-no-state.md b/.agents/skills/vercel-react-native-skills/rules/scroll-position-no-state.md
new file mode 100644
index 0000000..a5760cd
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/scroll-position-no-state.md
@@ -0,0 +1,82 @@
+---
+title: Never Track Scroll Position in useState
+impact: HIGH
+impactDescription: prevents render thrashing during scroll
+tags: scroll, performance, reanimated, useRef
+---
+
+## Never Track Scroll Position in useState
+
+Never store scroll position in `useState`. Scroll events fire rapidly—state
+updates cause render thrashing and dropped frames. Use a Reanimated shared value
+for animations or a ref for non-reactive tracking.
+
+**Incorrect (useState causes jank):**
+
+```tsx
+import { useState } from 'react'
+import {
+ ScrollView,
+ NativeSyntheticEvent,
+ NativeScrollEvent,
+} from 'react-native'
+
+function Feed() {
+ const [scrollY, setScrollY] = useState(0)
+
+ const onScroll = (e: NativeSyntheticEvent) => {
+ setScrollY(e.nativeEvent.contentOffset.y) // re-renders on every frame
+ }
+
+ return ) => {
+ scrollY.current = e.nativeEvent.contentOffset.y // no re-render
+ }
+
+ return (null)
+
+ return (
+ <>
+ {urls.map((url) => (
+ setSelected(url)}>
+
+ ))}
+ setSelected(null)}>
+
+
+ )
+}
+```
+
+**Correct (Galeria with expo-image):**
+
+```tsx
+import { Galeria } from '@nandorojo/galeria'
+import { Image } from 'expo-image'
+
+function ImageGallery({ urls }: { urls: string[] }) {
+ return (
+
+ {urls.map((url, index) => (
+
+
+ ))}
+
+ )
+}
+```
+
+**Single image:**
+
+```tsx
+import { Galeria } from '@nandorojo/galeria'
+import { Image } from 'expo-image'
+
+function Avatar({ url }: { url: string }) {
+ return (
+
+
+
+
+ )
+}
+```
+
+**With low-res thumbnails and high-res fullscreen:**
+
+```tsx
+
+ {lowResUrls.map((url, index) => (
+
+
+ ))}
+
+```
+
+**With FlashList:**
+
+```tsx
+
+ (
+
+
+ )}
+ numColumns={3}
+ estimatedItemSize={100}
+ />
+
+```
+
+Works with `expo-image`, `SolitoImage`, `react-native` Image, or any image
+component.
+
+Reference: [Galeria](https://github.com/nandorojo/galeria)
diff --git a/.agents/skills/vercel-react-native-skills/rules/ui-measure-views.md b/.agents/skills/vercel-react-native-skills/rules/ui-measure-views.md
new file mode 100644
index 0000000..8b783fe
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/ui-measure-views.md
@@ -0,0 +1,78 @@
+---
+title: Measuring View Dimensions
+impact: MEDIUM
+impactDescription: synchronous measurement, avoid unnecessary re-renders
+tags: layout, measurement, onLayout, useLayoutEffect
+---
+
+## Measuring View Dimensions
+
+Use both `useLayoutEffect` (synchronous) and `onLayout` (for updates). The sync
+measurement gives you the initial size immediately; `onLayout` keeps it current
+when the view changes. For non-primitive states, use a dispatch updater to
+compare values and avoid unnecessary re-renders.
+
+**Height only:**
+
+```tsx
+import { useLayoutEffect, useRef, useState } from 'react'
+import { View, LayoutChangeEvent } from 'react-native'
+
+function MeasuredBox({ children }: { children: React.ReactNode }) {
+ const ref = useRef(null)
+ const [height, setHeight] = useState(undefined)
+
+ useLayoutEffect(() => {
+ // Sync measurement on mount (RN 0.82+)
+ const rect = ref.current?.getBoundingClientRect()
+ if (rect) setHeight(rect.height)
+ // Pre-0.82: ref.current?.measure((x, y, w, h) => setHeight(h))
+ }, [])
+
+ const onLayout = (e: LayoutChangeEvent) => {
+ setHeight(e.nativeEvent.layout.height)
+ }
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+**Both dimensions:**
+
+```tsx
+import { useLayoutEffect, useRef, useState } from 'react'
+import { View, LayoutChangeEvent } from 'react-native'
+
+type Size = { width: number; height: number }
+
+function MeasuredBox({ children }: { children: React.ReactNode }) {
+ const ref = useRef(null)
+ const [size, setSize] = useState(undefined)
+
+ useLayoutEffect(() => {
+ const rect = ref.current?.getBoundingClientRect()
+ if (rect) setSize({ width: rect.width, height: rect.height })
+ }, [])
+
+ const onLayout = (e: LayoutChangeEvent) => {
+ const { width, height } = e.nativeEvent.layout
+ setSize((prev) => {
+ // for non-primitive states, compare values before firing a re-render
+ if (prev?.width === width && prev?.height === height) return prev
+ return { width, height }
+ })
+ }
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+Use functional setState to compare—don't read state directly in the callback.
diff --git a/.agents/skills/vercel-react-native-skills/rules/ui-menus.md b/.agents/skills/vercel-react-native-skills/rules/ui-menus.md
new file mode 100644
index 0000000..5168bc2
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/ui-menus.md
@@ -0,0 +1,174 @@
+---
+title: Use Native Menus for Dropdowns and Context Menus
+impact: HIGH
+impactDescription: native accessibility, platform-consistent UX
+tags: user-interface, menus, context-menus, zeego, accessibility
+---
+
+## Use Native Menus for Dropdowns and Context Menus
+
+Use native platform menus instead of custom JS implementations. Native menus
+provide built-in accessibility, consistent platform UX, and better performance.
+Use [zeego](https://zeego.dev) for cross-platform native menus.
+
+**Incorrect (custom JS menu):**
+
+```tsx
+import { useState } from 'react'
+import { View, Pressable, Text } from 'react-native'
+
+function MyMenu() {
+ const [open, setOpen] = useState(false)
+
+ return (
+
+ setOpen(!open)}>
+ Open Menu
+
+ {open && (
+
+ console.log('edit')}>
+ Edit
+
+ console.log('delete')}>
+ Delete
+
+
+ )}
+
+ )
+}
+```
+
+**Correct (native menu with zeego):**
+
+```tsx
+import * as DropdownMenu from 'zeego/dropdown-menu'
+
+function MyMenu() {
+ return (
+
+
+
+ Open Menu
+
+
+
+
+ console.log('edit')}>
+ Edit
+
+
+ console.log('delete')}
+ >
+ Delete
+
+
+
+ )
+}
+```
+
+**Context menu (long-press):**
+
+```tsx
+import * as ContextMenu from 'zeego/context-menu'
+
+function MyContextMenu() {
+ return (
+
+
+
+ Long press me
+
+
+
+
+ console.log('copy')}>
+ Copy
+
+
+ console.log('paste')}>
+ Paste
+
+
+
+ )
+}
+```
+
+**Checkbox items:**
+
+```tsx
+import * as DropdownMenu from 'zeego/dropdown-menu'
+
+function SettingsMenu() {
+ const [notifications, setNotifications] = useState(true)
+
+ return (
+
+
+
+ Settings
+
+
+
+
+ setNotifications((prev) => !prev)}
+ >
+ Notifications
+
+
+
+ )
+}
+```
+
+**Submenus:**
+
+```tsx
+import * as DropdownMenu from 'zeego/dropdown-menu'
+
+function MenuWithSubmenu() {
+ return (
+
+
+
+ Options
+
+
+
+
+ console.log('home')}>
+ Home
+
+
+
+
+ More Options
+
+
+
+
+ Settings
+
+
+
+ Help
+
+
+
+
+
+ )
+}
+```
+
+Reference: [Zeego Documentation](https://zeego.dev/components/dropdown-menu)
diff --git a/.agents/skills/vercel-react-native-skills/rules/ui-native-modals.md b/.agents/skills/vercel-react-native-skills/rules/ui-native-modals.md
new file mode 100644
index 0000000..f560e11
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/ui-native-modals.md
@@ -0,0 +1,77 @@
+---
+title: Use Native Modals Over JS-Based Bottom Sheets
+impact: HIGH
+impactDescription: native performance, gestures, accessibility
+tags: modals, bottom-sheet, native, react-navigation
+---
+
+## Use Native Modals Over JS-Based Bottom Sheets
+
+Use native `` with `presentationStyle="formSheet"` or React Navigation
+v7's native form sheet instead of JS-based bottom sheet libraries. Native modals
+have built-in gestures, accessibility, and better performance. Rely on native UI
+for low-level primitives.
+
+**Incorrect (JS-based bottom sheet):**
+
+```tsx
+import BottomSheet from 'custom-js-bottom-sheet'
+
+function MyScreen() {
+ const sheetRef = useRef(null)
+
+ return (
+
+
+ )
+}
+```
+
+**Correct (native Modal with formSheet):**
+
+```tsx
+import { Modal, View, Text, Button } from 'react-native'
+
+function MyScreen() {
+ const [visible, setVisible] = useState(false)
+
+ return (
+
+
+ )
+}
+```
+
+**Correct (React Navigation v7 native form sheet):**
+
+```tsx
+// In your navigator
+
+ Press me
+
+ )
+}
+```
+
+**Correct (Pressable):**
+
+```tsx
+import { Pressable } from 'react-native'
+
+function MyButton({ onPress }: { onPress: () => void }) {
+ return (
+
+ Press me
+
+ )
+}
+```
+
+**Correct (Pressable from gesture handler for lists):**
+
+```tsx
+import { Pressable } from 'react-native-gesture-handler'
+
+function ListItem({ onPress }: { onPress: () => void }) {
+ return (
+
+ Item
+
+ )
+}
+```
+
+Use `react-native-gesture-handler` Pressable inside scrollable lists for better
+gesture coordination, as long as you are using the ScrollView from
+`react-native-gesture-handler` as well.
+
+**For animated press states (scale, opacity changes):** Use `GestureDetector`
+with Reanimated shared values instead of Pressable's style callback. See the
+`animation-gesture-detector-press` rule.
diff --git a/.agents/skills/vercel-react-native-skills/rules/ui-safe-area-scroll.md b/.agents/skills/vercel-react-native-skills/rules/ui-safe-area-scroll.md
new file mode 100644
index 0000000..79812bc
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/ui-safe-area-scroll.md
@@ -0,0 +1,65 @@
+---
+title: Use contentInsetAdjustmentBehavior for Safe Areas
+impact: MEDIUM
+impactDescription: native safe area handling, no layout shifts
+tags: safe-area, scrollview, layout
+---
+
+## Use contentInsetAdjustmentBehavior for Safe Areas
+
+Use `contentInsetAdjustmentBehavior="automatic"` on the root ScrollView instead of wrapping content in SafeAreaView or manual padding. This lets iOS handle safe area insets natively with proper scroll behavior.
+
+**Incorrect (SafeAreaView wrapper):**
+
+```tsx
+import { SafeAreaView, ScrollView, View, Text } from 'react-native'
+
+function MyScreen() {
+ return (
+
+
+
+ Content
+
+
+
+ )
+}
+```
+
+**Incorrect (manual safe area padding):**
+
+```tsx
+import { ScrollView, View, Text } from 'react-native'
+import { useSafeAreaInsets } from 'react-native-safe-area-context'
+
+function MyScreen() {
+ const insets = useSafeAreaInsets()
+
+ return (
+
+
+ Content
+
+
+ )
+}
+```
+
+**Correct (native content inset adjustment):**
+
+```tsx
+import { ScrollView, View, Text } from 'react-native'
+
+function MyScreen() {
+ return (
+
+
+ Content
+
+
+ )
+}
+```
+
+The native approach handles dynamic safe areas (keyboard, toolbars) and allows content to scroll behind the status bar naturally.
diff --git a/.agents/skills/vercel-react-native-skills/rules/ui-scrollview-content-inset.md b/.agents/skills/vercel-react-native-skills/rules/ui-scrollview-content-inset.md
new file mode 100644
index 0000000..bbebc3b
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/ui-scrollview-content-inset.md
@@ -0,0 +1,45 @@
+---
+title: Use contentInset for Dynamic ScrollView Spacing
+impact: LOW
+impactDescription: smoother updates, no layout recalculation
+tags: scrollview, layout, contentInset, performance
+---
+
+## Use contentInset for Dynamic ScrollView Spacing
+
+When adding space to the top or bottom of a ScrollView that may change
+(keyboard, toolbars, dynamic content), use `contentInset` instead of padding.
+Changing `contentInset` doesn't trigger layout recalculation—it adjusts the
+scroll area without re-rendering content.
+
+**Incorrect (padding causes layout recalculation):**
+
+```tsx
+function Feed({ bottomOffset }: { bottomOffset: number }) {
+ return (
+
+ {children}
+
+ )
+}
+// Changing bottomOffset triggers full layout recalculation
+```
+
+**Correct (contentInset for dynamic spacing):**
+
+```tsx
+function Feed({ bottomOffset }: { bottomOffset: number }) {
+ return (
+
+ {children}
+
+ )
+}
+// Changing bottomOffset only adjusts scroll bounds
+```
+
+Use `scrollIndicatorInsets` alongside `contentInset` to keep the scroll
+indicator aligned. For static spacing that never changes, padding is fine.
diff --git a/.agents/skills/vercel-react-native-skills/rules/ui-styling.md b/.agents/skills/vercel-react-native-skills/rules/ui-styling.md
new file mode 100644
index 0000000..3908de3
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/rules/ui-styling.md
@@ -0,0 +1,87 @@
+---
+title: Modern React Native Styling Patterns
+impact: MEDIUM
+impactDescription: consistent design, smoother borders, cleaner layouts
+tags: styling, css, layout, shadows, gradients
+---
+
+## Modern React Native Styling Patterns
+
+Follow these styling patterns for cleaner, more consistent React Native code.
+
+**Always use `borderCurve: 'continuous'` with `borderRadius`:**
+
+```tsx
+// Incorrect
+{ borderRadius: 12 }
+
+// Correct – smoother iOS-style corners
+{ borderRadius: 12, borderCurve: 'continuous' }
+```
+
+**Use `gap` instead of margin for spacing between elements:**
+
+```tsx
+// Incorrect – margin on children
+
+ Title
+ Subtitle
+
+
+// Correct – gap on parent
+
+ Title
+ Subtitle
+
+```
+
+**Use `padding` for space within, `gap` for space between:**
+
+```tsx
+
+ First
+ Second
+
+```
+
+**Use `experimental_backgroundImage` for linear gradients:**
+
+```tsx
+// Incorrect – third-party gradient library
+Title
+Subtitle
+Caption
+
+// Correct – consistent size, vary weight and color
+Title
+Subtitle
+Caption
+```
+
+Limiting font sizes creates visual consistency. Use `fontWeight` (bold/semibold)
+and grayscale colors for hierarchy instead.
diff --git a/skills-lock.json b/skills-lock.json
index 01564b4..576996d 100644
--- a/skills-lock.json
+++ b/skills-lock.json
@@ -5,6 +5,11 @@
"source": "vercel-labs/agent-skills",
"sourceType": "github",
"computedHash": "bbc31a48537b473ff4feea6360ef0de3bfdcbef26c14f4967a5deefe8ca801d3"
+ },
+ "vercel-react-native-skills": {
+ "source": "vercel-labs/agent-skills",
+ "sourceType": "github",
+ "computedHash": "2e9088a7333666d8c2833b8ff58bd51b955501c42b4c7244f72b4cbf22dafcc4"
}
}
}
From 520408b5f61afec395205b6f558f799a479880f0 Mon Sep 17 00:00:00 2001
From: Mattia Panzeri <1754457+panz3r@users.noreply.github.com>
Date: Sat, 28 Mar 2026 00:02:41 +0100
Subject: [PATCH 4/4] chore(agents): add "Orchestrator" agent documentation for
coordinating development cycles
---
.github/agents/orchestrator.agent.md | 159 +++++++++++++++++++++++++++
1 file changed, 159 insertions(+)
create mode 100644 .github/agents/orchestrator.agent.md
diff --git a/.github/agents/orchestrator.agent.md b/.github/agents/orchestrator.agent.md
new file mode 100644
index 0000000..584afd3
--- /dev/null
+++ b/.github/agents/orchestrator.agent.md
@@ -0,0 +1,159 @@
+---
+name: 'Beppe - Orchestrator'
+description: "Use when: coordinating a full development cycle across planning, implementation, review, and refinement in this monorepo by delegating to the Developer and Reviewer agents."
+tools: [agent, vscode/askQuestions, vscode/memory, execute, read, edit, search, web, todo]
+agents: ['Cesco - React Software Engineer', 'Mattia - Code Reviewer']
+argument-hint: 'Describe the goal, target package, constraints, and whether you want planning, implementation, review, or the full cycle.'
+handoffs:
+ - label: Hand Off To Cesco
+ agent: 'Cesco - React Software Engineer'
+ prompt: 'Implement the agreed change, including focused tests and package-scoped verification.'
+ send: false
+ - label: Hand Off To Mattia
+ agent: 'Mattia - Code Reviewer'
+ prompt: 'Review the latest implementation for regressions, missing tests, auth lifecycle risks, and release readiness.'
+ send: false
+---
+
+## Identity
+
+You are a delivery orchestrator for this repository. You coordinate the right specialist at the right moment, keep the workflow moving, and make the current phase explicit.
+
+You are **Beppe**: a pragmatic orchestrator inspired by BMAD-style coordination, adapted to VS Code custom agents and this monorepo's existing specialist agents. You do not pretend to be every specialist at once. You decide when to delegate, capture the result, and drive the next step.
+
+Work in a concise, operational style. Prefer clear phase transitions, explicit decisions, and minimal context loading. Keep the user aware of what phase is active and why a handoff or subagent run is happening.
+
+## Project Scope
+
+This repository is the React Auth monorepo. Coordinate work across:
+
+- Core auth primitives in `lib/`
+- Google Sign-In adapter in `packages/google-signin/`
+- Example applications in `examples/`
+
+Default to the existing architecture, package boundaries, testing approach, and security constraints already documented in the repository.
+
+## Available Specialists
+
+- **Cesco - React Software Engineer**
+ - Use for implementation, debugging, targeted refactors, tests, and package-scoped verification.
+- **Mattia - Code Reviewer**
+ - Use for review, regression analysis, QA validation, release-readiness assessment, and identifying missing tests or risks.
+
+## Required References
+
+- Architecture and conventions: [AGENTS.md](../../AGENTS.md)
+- Repo-wide behavior requirements: [copilot-instructions.md](../copilot-instructions.md)
+- Developer specialist: [developer.agent.md](./developer.agent.md)
+- Reviewer specialist: [reviewer.agent.md](./reviewer.agent.md)
+
+## Operating Rules
+
+The system shall treat orchestration as an explicit workflow with named phases: `Intake`, `Plan`, `Implement`, `Review`, `Refine`, and `Closeout`.
+
+The system shall prefer delegating specialized implementation work to Cesco and specialized review work to Mattia instead of mixing both roles in one pass.
+
+The system shall use the `agent` tool when a subtask benefits from context isolation, specialized instructions, or an independent judgment pass.
+
+The system shall keep only the relevant specialists available as subagents and avoid broad, ambiguous delegation.
+
+The system shall make the active phase explicit before significant work, and after each delegated step summarize: what was requested, what came back, and what happens next.
+
+The system shall iterate between implementation and review until the result converges or a blocker requires user input.
+
+The system shall favor minimal, codebase-aligned changes over broad rewrites, even when coordinating multiple steps.
+
+When requirements are unclear, the system shall ask focused questions before kicking off irreversible work.
+
+When a specialist result conflicts with repository conventions or the user's stated constraints, the system shall reconcile that conflict before proceeding.
+
+Before closing out, the system shall state what was implemented, what was reviewed, what verification ran, and any remaining risk or follow-up.
+
+## Delegation Strategy
+
+Use the following default workflow unless the user asks for a narrower slice:
+
+1. `Intake`
+ - Clarify objective, scope, constraints, and definition of done.
+ - Identify target package and likely test surface.
+
+2. `Plan`
+ - Read the minimum necessary code and docs.
+ - Produce a short plan and call out likely risk areas.
+ - If the task is simple, keep planning lightweight and move on.
+
+3. `Implement`
+ - Invoke **Cesco - React Software Engineer** as a subagent for any non-trivial implementation, debugging, or refactor task.
+ - Ask Cesco for focused code changes, tests, and package-scoped validation.
+
+4. `Review`
+ - Invoke **Mattia - Code Reviewer** as a subagent after meaningful code changes or when the user asks for QA/review.
+ - Ask Mattia to prioritize defects, regressions, missing tests, auth lifecycle risks, and release readiness.
+
+5. `Refine`
+ - If Mattia reports issues, send a targeted fix request back through **Cesco - React Software Engineer**.
+ - Repeat the implement/review loop until issues are resolved, accepted, or blocked by the user.
+
+6. `Closeout`
+ - Summarize the final state, verification, residual risks, and next action.
+ - Keep the user-facing summary concise and outcome-focused.
+
+## When To Delegate vs Work Directly
+
+Delegate by default when:
+
+- The task needs substantial code changes.
+- A clean independent review is valuable.
+- Different tool scopes or mental models improve quality.
+- You want a fresh pass on correctness after implementation.
+
+Work directly only when:
+
+- The task is trivial and delegation would add overhead.
+- You are synthesizing specialist output into a final answer.
+- You are making very small glue changes after a delegated step.
+
+## BMAD-Inspired Behavior, Adapted
+
+- Act as the workflow coordinator, not a generic catch-all coder.
+- Keep the current role and phase visible.
+- Recommend the next best specialist or step when the path is obvious.
+- Load only the context needed for the current phase.
+- Use numbered steps when presenting options or workflow stages.
+- Prefer explicit transitions over silent context switches.
+- Preserve user control: escalate when trade-offs or unresolved findings matter.
+
+## Tooling Strategy
+
+- Use `todo` to track the active phase and open work.
+- Use `search` and `read` to establish context before delegation.
+- Use `agent` for specialist execution and independent review passes.
+- Use `edit` and `execute` only when direct intervention is faster or necessary.
+- Use `vscode/askQuestions` when scope, acceptance criteria, or trade-offs are unclear.
+- Use `vscode/memory` to retain reusable repo-specific orchestration patterns.
+
+## Output Format
+
+For substantial tasks, structure responses in this order:
+
+1. Active phase and objective.
+2. What was delegated or done directly.
+3. Key result or finding.
+4. Next phase or blocking decision.
+
+When presenting workflow choices, use numbered lists.
+
+When review findings exist, surface them before summaries.
+
+When no delegation was needed, say so briefly and explain why.
+
+## VERIFY
+
+Before responding:
+
+1. The current phase is explicit.
+2. Delegation was used where it adds real value.
+3. Cesco handled implementation-oriented work and Mattia handled review-oriented work when applicable.
+4. Specialist outputs were synthesized, not pasted back blindly.
+5. Any review feedback was either addressed, accepted as risk, or escalated.
+6. Final verification status and residual risk are stated clearly.
+
+
+ )
+}
+```
+
+This applies to all CSS transforms and transitions (`transform`, `opacity`, `translate`, `scale`, `rotate`). The wrapper div allows browsers to use GPU acceleration for smoother animations.
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-conditional-render.md b/.agents/skills/vercel-react-best-practices/rules/rendering-conditional-render.md
new file mode 100644
index 0000000..7e866f5
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-conditional-render.md
@@ -0,0 +1,40 @@
+---
+title: Use Explicit Conditional Rendering
+impact: LOW
+impactDescription: prevents rendering 0 or NaN
+tags: rendering, conditional, jsx, falsy-values
+---
+
+## Use Explicit Conditional Rendering
+
+Use explicit ternary operators (`? :`) instead of `&&` for conditional rendering when the condition can be `0`, `NaN`, or other falsy values that render.
+
+**Incorrect (renders "0" when count is 0):**
+
+```tsx
+function Badge({ count }: { count: number }) {
+ return (
+
+ {count && {count}}
+
+ )
+}
+
+// When count = 0, renders: 0
+// When count = 5, renders: 5
+```
+
+**Correct (renders nothing when count is 0):**
+
+```tsx
+function Badge({ count }: { count: number }) {
+ return (
+
+ {count > 0 ? {count} : null}
+
+ )
+}
+
+// When count = 0, renders:
+// When count = 5, renders: 5
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-content-visibility.md b/.agents/skills/vercel-react-best-practices/rules/rendering-content-visibility.md
new file mode 100644
index 0000000..aa66563
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-content-visibility.md
@@ -0,0 +1,38 @@
+---
+title: CSS content-visibility for Long Lists
+impact: HIGH
+impactDescription: faster initial render
+tags: rendering, css, content-visibility, long-lists
+---
+
+## CSS content-visibility for Long Lists
+
+Apply `content-visibility: auto` to defer off-screen rendering.
+
+**CSS:**
+
+```css
+.message-item {
+ content-visibility: auto;
+ contain-intrinsic-size: 0 80px;
+}
+```
+
+**Example:**
+
+```tsx
+function MessageList({ messages }: { messages: Message[] }) {
+ return (
+
+ {messages.map(msg => (
+
+ )
+}
+```
+
+For 1000 messages, browser skips layout/paint for ~990 off-screen items (10× faster initial render).
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-hoist-jsx.md b/.agents/skills/vercel-react-best-practices/rules/rendering-hoist-jsx.md
new file mode 100644
index 0000000..32d2f3f
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-hoist-jsx.md
@@ -0,0 +1,46 @@
+---
+title: Hoist Static JSX Elements
+impact: LOW
+impactDescription: avoids re-creation
+tags: rendering, jsx, static, optimization
+---
+
+## Hoist Static JSX Elements
+
+Extract static JSX outside components to avoid re-creation.
+
+**Incorrect (recreates element every render):**
+
+```tsx
+function LoadingSkeleton() {
+ return
+}
+
+function Container() {
+ return (
+
+
+ ))}
+ {msg.content}
+
+ {loading &&
+ )
+}
+```
+
+**Correct (reuses same element):**
+
+```tsx
+const loadingSkeleton = (
+
+)
+
+function Container() {
+ return (
+
+ {loading && loadingSkeleton}
+
+ )
+}
+```
+
+This is especially helpful for large and static SVG nodes, which can be expensive to recreate on every render.
+
+**Note:** If your project has [React Compiler](https://react.dev/learn/react-compiler) enabled, the compiler automatically hoists static JSX elements and optimizes component re-renders, making manual hoisting unnecessary.
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-hydration-no-flicker.md b/.agents/skills/vercel-react-best-practices/rules/rendering-hydration-no-flicker.md
new file mode 100644
index 0000000..5cf0e79
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-hydration-no-flicker.md
@@ -0,0 +1,82 @@
+---
+title: Prevent Hydration Mismatch Without Flickering
+impact: MEDIUM
+impactDescription: avoids visual flicker and hydration errors
+tags: rendering, ssr, hydration, localStorage, flicker
+---
+
+## Prevent Hydration Mismatch Without Flickering
+
+When rendering content that depends on client-side storage (localStorage, cookies), avoid both SSR breakage and post-hydration flickering by injecting a synchronous script that updates the DOM before React hydrates.
+
+**Incorrect (breaks SSR):**
+
+```tsx
+function ThemeWrapper({ children }: { children: ReactNode }) {
+ // localStorage is not available on server - throws error
+ const theme = localStorage.getItem('theme') || 'light'
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+Server-side rendering will fail because `localStorage` is undefined.
+
+**Incorrect (visual flickering):**
+
+```tsx
+function ThemeWrapper({ children }: { children: ReactNode }) {
+ const [theme, setTheme] = useState('light')
+
+ useEffect(() => {
+ // Runs after hydration - causes visible flash
+ const stored = localStorage.getItem('theme')
+ if (stored) {
+ setTheme(stored)
+ }
+ }, [])
+
+ return (
+
+ {children}
+
+ )
+}
+```
+
+Component first renders with default value (`light`), then updates after hydration, causing a visible flash of incorrect content.
+
+**Correct (no flicker, no hydration mismatch):**
+
+```tsx
+function ThemeWrapper({ children }: { children: ReactNode }) {
+ return (
+ <>
+
+ {children}
+
+
+
+ )
+}
+```
+
+The inline script executes synchronously before showing the element, ensuring the DOM already has the correct value. No flickering, no hydration mismatch.
+
+This pattern is especially useful for theme toggles, user preferences, authentication states, and any client-only data that should render immediately without flashing default values.
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-hydration-suppress-warning.md b/.agents/skills/vercel-react-best-practices/rules/rendering-hydration-suppress-warning.md
new file mode 100644
index 0000000..24ba251
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-hydration-suppress-warning.md
@@ -0,0 +1,30 @@
+---
+title: Suppress Expected Hydration Mismatches
+impact: LOW-MEDIUM
+impactDescription: avoids noisy hydration warnings for known differences
+tags: rendering, hydration, ssr, nextjs
+---
+
+## Suppress Expected Hydration Mismatches
+
+In SSR frameworks (e.g., Next.js), some values are intentionally different on server vs client (random IDs, dates, locale/timezone formatting). For these *expected* mismatches, wrap the dynamic text in an element with `suppressHydrationWarning` to prevent noisy warnings. Do not use this to hide real bugs. Don’t overuse it.
+
+**Incorrect (known mismatch warnings):**
+
+```tsx
+function Timestamp() {
+ return {new Date().toLocaleString()}
+}
+```
+
+**Correct (suppress expected mismatch only):**
+
+```tsx
+function Timestamp() {
+ return (
+
+ {new Date().toLocaleString()}
+
+ )
+}
+```
diff --git a/.agents/skills/vercel-react-best-practices/rules/rendering-resource-hints.md b/.agents/skills/vercel-react-best-practices/rules/rendering-resource-hints.md
new file mode 100644
index 0000000..1290bef
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rendering-resource-hints.md
@@ -0,0 +1,85 @@
+---
+title: Use React DOM Resource Hints
+impact: HIGH
+impactDescription: reduces load time for critical resources
+tags: rendering, preload, preconnect, prefetch, resource-hints
+---
+
+## Use React DOM Resource Hints
+
+**Impact: HIGH (reduces load time for critical resources)**
+
+React DOM provides APIs to hint the browser about resources it will need. These are especially useful in server components to start loading resources before the client even receives the HTML.
+
+- **`prefetchDNS(href)`**: Resolve DNS for a domain you expect to connect to
+- **`preconnect(href)`**: Establish connection (DNS + TCP + TLS) to a server
+- **`preload(href, options)`**: Fetch a resource (stylesheet, font, script, image) you'll use soon
+- **`preloadModule(href)`**: Fetch an ES module you'll use soon
+- **`preinit(href, options)`**: Fetch and evaluate a stylesheet or script
+- **`preinitModule(href)`**: Fetch and evaluate an ES module
+
+**Example (preconnect to third-party APIs):**
+
+```tsx
+import { preconnect, prefetchDNS } from 'react-dom'
+
+export default function App() {
+ prefetchDNS('https://analytics.example.com')
+ preconnect('https://api.example.com')
+
+ return {fullName}
+} +``` + +**Correct (derive during render):** + +```tsx +function Form() { + const [firstName, setFirstName] = useState('First') + const [lastName, setLastName] = useState('Last') + const fullName = firstName + ' ' + lastName + + return{fullName}
+} +``` + +References: [You Might Not Need an Effect](https://react.dev/learn/you-might-not-need-an-effect) diff --git a/.agents/skills/vercel-react-best-practices/rules/rerender-derived-state.md b/.agents/skills/vercel-react-best-practices/rules/rerender-derived-state.md new file mode 100644 index 0000000..e5c899f --- /dev/null +++ b/.agents/skills/vercel-react-best-practices/rules/rerender-derived-state.md @@ -0,0 +1,29 @@ +--- +title: Subscribe to Derived State +impact: MEDIUM +impactDescription: reduces re-render frequency +tags: rerender, derived-state, media-query, optimization +--- + +## Subscribe to Derived State + +Subscribe to derived boolean state instead of continuous values to reduce re-render frequency. + +**Incorrect (re-renders on every pixel change):** + +```tsx +function Sidebar() { + const width = useWindowWidth() // updates continuously + const isMobile = width < 768 + return +} +``` + +**Correct (re-renders only when boolean changes):** + +```tsx +function Sidebar() { + const isMobile = useMediaQuery('(max-width: 767px)') + return +} +``` diff --git a/.agents/skills/vercel-react-best-practices/rules/rerender-functional-setstate.md b/.agents/skills/vercel-react-best-practices/rules/rerender-functional-setstate.md new file mode 100644 index 0000000..b004ef4 --- /dev/null +++ b/.agents/skills/vercel-react-best-practices/rules/rerender-functional-setstate.md @@ -0,0 +1,74 @@ +--- +title: Use Functional setState Updates +impact: MEDIUM +impactDescription: prevents stale closures and unnecessary callback recreations +tags: react, hooks, useState, useCallback, callbacks, closures +--- + +## Use Functional setState Updates + +When updating state based on the current state value, use the functional update form of setState instead of directly referencing the state variable. This prevents stale closures, eliminates unnecessary dependencies, and creates stable callback references. + +**Incorrect (requires state as dependency):** + +```tsx +function TodoList() { + const [items, setItems] = useState(initialItems) + + // Callback must depend on items, recreated on every items change + const addItems = useCallback((newItems: Item[]) => { + setItems([...items, ...newItems]) + }, [items]) // ❌ items dependency causes recreations + + // Risk of stale closure if dependency is forgotten + const removeItem = useCallback((id: string) => { + setItems(items.filter(item => item.id !== id)) + }, []) // ❌ Missing items dependency - will use stale items! + + return{avatar}
+}
+```
+
+**Correct (skips computation when loading):**
+
+```tsx
+const UserAvatar = memo(function UserAvatar({ user }: { user: User }) {
+ const id = useMemo(() => computeAvatarId(user), [user])
+ return
+
+ )
+}
+```
+
+**Note:** If your project has [React Compiler](https://react.dev/learn/react-compiler) enabled, manual memoization with `memo()` and `useMemo()` is not necessary. The compiler automatically optimizes re-renders.
diff --git a/.agents/skills/vercel-react-best-practices/rules/rerender-move-effect-to-event.md b/.agents/skills/vercel-react-best-practices/rules/rerender-move-effect-to-event.md
new file mode 100644
index 0000000..dd58a1a
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rerender-move-effect-to-event.md
@@ -0,0 +1,45 @@
+---
+title: Put Interaction Logic in Event Handlers
+impact: MEDIUM
+impactDescription: avoids effect re-runs and duplicate side effects
+tags: rerender, useEffect, events, side-effects, dependencies
+---
+
+## Put Interaction Logic in Event Handlers
+
+If a side effect is triggered by a specific user action (submit, click, drag), run it in that event handler. Do not model the action as state + effect; it makes effects re-run on unrelated changes and can duplicate the action.
+
+**Incorrect (event modeled as state + effect):**
+
+```tsx
+function Form() {
+ const [submitted, setSubmitted] = useState(false)
+ const theme = useContext(ThemeContext)
+
+ useEffect(() => {
+ if (submitted) {
+ post('/api/register')
+ showToast('Registered', theme)
+ }
+ }, [submitted, theme])
+
+ return
+}
+```
+
+**Correct (do it in the handler):**
+
+```tsx
+function Form() {
+ const theme = useContext(ThemeContext)
+
+ function handleSubmit() {
+ post('/api/register')
+ showToast('Registered', theme)
+ }
+
+ return
+}
+```
+
+Reference: [Should this code move to an event handler?](https://react.dev/learn/removing-effect-dependencies#should-this-code-move-to-an-event-handler)
diff --git a/.agents/skills/vercel-react-best-practices/rules/rerender-no-inline-components.md b/.agents/skills/vercel-react-best-practices/rules/rerender-no-inline-components.md
new file mode 100644
index 0000000..d97592a
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rerender-no-inline-components.md
@@ -0,0 +1,82 @@
+---
+title: Don't Define Components Inside Components
+impact: HIGH
+impactDescription: prevents remount on every render
+tags: rerender, components, remount, performance
+---
+
+## Don't Define Components Inside Components
+
+**Impact: HIGH (prevents remount on every render)**
+
+Defining a component inside another component creates a new component type on every render. React sees a different component each time and fully remounts it, destroying all state and DOM.
+
+A common reason developers do this is to access parent variables without passing props. Always pass props instead.
+
+**Incorrect (remounts on every render):**
+
+```tsx
+function UserProfile({ user, theme }) {
+ // Defined inside to access `theme` - BAD
+ const Avatar = () => (
+
+ {user.followers} followers
+ {user.posts} posts
+
+ )
+
+ return (
+
+
+ )
+}
+```
+
+Every time `UserProfile` renders, `Avatar` and `Stats` are new component types. React unmounts the old instances and mounts new ones, losing any internal state, running effects again, and recreating DOM nodes.
+
+**Correct (pass props instead):**
+
+```tsx
+function Avatar({ src, theme }: { src: string; theme: string }) {
+ return (
+
+ {followers} followers
+ {posts} posts
+
+ )
+}
+
+function UserProfile({ user, theme }) {
+ return (
+
+
+ )
+}
+```
+
+**Symptoms of this bug:**
+- Input fields lose focus on every keystroke
+- Animations restart unexpectedly
+- `useEffect` cleanup/setup runs on every parent render
+- Scroll position resets inside the component
diff --git a/.agents/skills/vercel-react-best-practices/rules/rerender-simple-expression-in-memo.md b/.agents/skills/vercel-react-best-practices/rules/rerender-simple-expression-in-memo.md
new file mode 100644
index 0000000..59dfab0
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rerender-simple-expression-in-memo.md
@@ -0,0 +1,35 @@
+---
+title: Do not wrap a simple expression with a primitive result type in useMemo
+impact: LOW-MEDIUM
+impactDescription: wasted computation on every render
+tags: rerender, useMemo, optimization
+---
+
+## Do not wrap a simple expression with a primitive result type in useMemo
+
+When an expression is simple (few logical or arithmetical operators) and has a primitive result type (boolean, number, string), do not wrap it in `useMemo`.
+Calling `useMemo` and comparing hook dependencies may consume more resources than the expression itself.
+
+**Incorrect:**
+
+```tsx
+function Header({ user, notifications }: Props) {
+ const isLoading = useMemo(() => {
+ return user.isLoading || notifications.isLoading
+ }, [user.isLoading, notifications.isLoading])
+
+ if (isLoading) return
+
+
+ )
+}
+```
+
+**When to use:**
+
+- Filtering/searching large lists
+- Expensive visualizations (charts, graphs) reacting to input
+- Any derived state that causes noticeable render delays
+
+**Note:** Wrap the expensive computation in `useMemo` with the deferred value as a dependency, otherwise it still runs on every render.
+
+Reference: [React useDeferredValue](https://react.dev/reference/react/useDeferredValue)
diff --git a/.agents/skills/vercel-react-best-practices/rules/rerender-use-ref-transient-values.md b/.agents/skills/vercel-react-best-practices/rules/rerender-use-ref-transient-values.md
new file mode 100644
index 0000000..cf04b81
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/rerender-use-ref-transient-values.md
@@ -0,0 +1,73 @@
+---
+title: Use useRef for Transient Values
+impact: MEDIUM
+impactDescription: avoids unnecessary re-renders on frequent updates
+tags: rerender, useref, state, performance
+---
+
+## Use useRef for Transient Values
+
+When a value changes frequently and you don't want a re-render on every update (e.g., mouse trackers, intervals, transient flags), store it in `useRef` instead of `useState`. Keep component state for UI; use refs for temporary DOM-adjacent values. Updating a ref does not trigger a re-render.
+
+**Incorrect (renders every update):**
+
+```tsx
+function Tracker() {
+ const [lastX, setLastX] = useState(0)
+
+ useEffect(() => {
+ const onMove = (e: MouseEvent) => setLastX(e.clientX)
+ window.addEventListener('mousemove', onMove)
+ return () => window.removeEventListener('mousemove', onMove)
+ }, [])
+
+ return (
+
+ )
+}
+```
+
+**Correct (no re-render for tracking):**
+
+```tsx
+function Tracker() {
+ const lastXRef = useRef(0)
+ const dotRef = useRef
+ 
+ Hello World
+
,
+ { fonts: [{ name: 'Inter', data: fontData }] }
+ )
+}
+```
+
+**Correct: loads once at module initialization**
+
+```typescript
+// app/api/og/route.tsx
+import { ImageResponse } from 'next/og'
+
+// Module-level: runs ONCE when module is first imported
+const fontData = fetch(
+ new URL('./fonts/Inter.ttf', import.meta.url)
+).then(res => res.arrayBuffer())
+
+const logoData = fetch(
+ new URL('./images/logo.png', import.meta.url)
+).then(res => res.arrayBuffer())
+
+export async function GET(request: Request) {
+ // Await the already-started promises
+ const [font, logo] = await Promise.all([fontData, logoData])
+
+ return new ImageResponse(
+
+ 
+ Hello World
+
,
+ { fonts: [{ name: 'Inter', data: font }] }
+ )
+}
+```
+
+**Alternative: synchronous file reads with Node.js fs**
+
+```typescript
+// app/api/og/route.tsx
+import { ImageResponse } from 'next/og'
+import { readFileSync } from 'fs'
+import { join } from 'path'
+
+// Synchronous read at module level - blocks only during module init
+const fontData = readFileSync(
+ join(process.cwd(), 'public/fonts/Inter.ttf')
+)
+
+const logoData = readFileSync(
+ join(process.cwd(), 'public/images/logo.png')
+)
+
+export async function GET(request: Request) {
+ return new ImageResponse(
+
+
+ Hello World
+
,
+ { fonts: [{ name: 'Inter', data: fontData }] }
+ )
+}
+```
+
+**General Node.js example: loading config or templates**
+
+```typescript
+// Incorrect: reads config on every call
+export async function processRequest(data: Data) {
+ const config = JSON.parse(
+ await fs.readFile('./config.json', 'utf-8')
+ )
+ const template = await fs.readFile('./template.html', 'utf-8')
+
+ return render(template, data, config)
+}
+
+// Correct: loads once at module level
+const configPromise = fs.readFile('./config.json', 'utf-8')
+ .then(JSON.parse)
+const templatePromise = fs.readFile('./template.html', 'utf-8')
+
+export async function processRequest(data: Data) {
+ const [config, template] = await Promise.all([
+ configPromise,
+ templatePromise
+ ])
+
+ return render(template, data, config)
+}
+```
+
+**When to use this pattern:**
+
+- Loading fonts for OG image generation
+- Loading static logos, icons, or watermarks
+- Reading configuration files that don't change at runtime
+- Loading email templates or other static templates
+- Any static asset that's the same across all requests
+
+**When NOT to use this pattern:**
+
+- Assets that vary per request or user
+- Files that may change during runtime (use caching with TTL instead)
+- Large files that would consume too much memory if kept loaded
+- Sensitive data that shouldn't persist in memory
+
+**With Vercel's [Fluid Compute](https://vercel.com/docs/fluid-compute):** Module-level caching is especially effective because multiple concurrent requests share the same function instance. The static assets stay loaded in memory across requests without cold start penalties.
+
+**In traditional serverless:** Each cold start re-executes module-level code, but subsequent warm invocations reuse the loaded assets until the instance is recycled.
diff --git a/.agents/skills/vercel-react-best-practices/rules/server-parallel-fetching.md b/.agents/skills/vercel-react-best-practices/rules/server-parallel-fetching.md
new file mode 100644
index 0000000..1affc83
--- /dev/null
+++ b/.agents/skills/vercel-react-best-practices/rules/server-parallel-fetching.md
@@ -0,0 +1,83 @@
+---
+title: Parallel Data Fetching with Component Composition
+impact: CRITICAL
+impactDescription: eliminates server-side waterfalls
+tags: server, rsc, parallel-fetching, composition
+---
+
+## Parallel Data Fetching with Component Composition
+
+React Server Components execute sequentially within a tree. Restructure with composition to parallelize data fetching.
+
+**Incorrect (Sidebar waits for Page's fetch to complete):**
+
+```tsx
+export default async function Page() {
+ const header = await fetchHeader()
+ return (
+
+
+ )
+}
+
+async function Sidebar() {
+ const items = await fetchSidebarItems()
+ return
+}
+```
+
+**Correct (both fetch simultaneously):**
+
+```tsx
+async function Header() {
+ const data = await fetchHeader()
+ return {header}
+ {data}
+}
+
+async function Sidebar() {
+ const items = await fetchSidebarItems()
+ return
+}
+
+export default function Page() {
+ return (
+
+
+ )
+}
+```
+
+**Alternative with children prop:**
+
+```tsx
+async function Header() {
+ const data = await fetchHeader()
+ return {data}
+}
+
+async function Sidebar() {
+ const items = await fetchSidebarItems()
+ return
+}
+
+function Layout({ children }: { children: ReactNode }) {
+ return (
+
+
+ )
+}
+
+export default function Page() {
+ return (
+ {user.name}
// uses 1 field
+}
+```
+
+**Correct (serializes only 1 field):**
+
+```tsx
+async function Page() {
+ const user = await fetchUser()
+ return {name}
+}
+```
diff --git a/skills-lock.json b/skills-lock.json
new file mode 100644
index 0000000..01564b4
--- /dev/null
+++ b/skills-lock.json
@@ -0,0 +1,10 @@
+{
+ "version": 1,
+ "skills": {
+ "vercel-react-best-practices": {
+ "source": "vercel-labs/agent-skills",
+ "sourceType": "github",
+ "computedHash": "bbc31a48537b473ff4feea6360ef0de3bfdcbef26c14f4967a5deefe8ca801d3"
+ }
+ }
+}
From a081246dd3f620c00ebf4d64ce8e7a8a3205815d Mon Sep 17 00:00:00 2001
From: Mattia Panzeri <1754457+panz3r@users.noreply.github.com>
Date: Fri, 27 Mar 2026 23:39:51 +0100
Subject: [PATCH 3/4] chore(skills): add `vercel-react-native-skills` skill
---
.../vercel-react-native-skills/AGENTS.md | 2897 +++++++++++++++++
.../vercel-react-native-skills/README.md | 165 +
.../vercel-react-native-skills/SKILL.md | 121 +
.../rules/_sections.md | 86 +
.../rules/_template.md | 28 +
.../rules/animation-derived-value.md | 53 +
.../rules/animation-gesture-detector-press.md | 95 +
.../rules/animation-gpu-properties.md | 65 +
.../design-system-compound-components.md | 66 +
.../rules/fonts-config-plugin.md | 71 +
.../rules/imports-design-system-folder.md | 68 +
.../rules/js-hoist-intl.md | 61 +
.../rules/list-performance-callbacks.md | 44 +
.../list-performance-function-references.md | 132 +
.../rules/list-performance-images.md | 53 +
.../rules/list-performance-inline-objects.md | 97 +
.../rules/list-performance-item-expensive.md | 94 +
.../rules/list-performance-item-memo.md | 82 +
.../rules/list-performance-item-types.md | 104 +
.../rules/list-performance-virtualize.md | 67 +
.../rules/monorepo-native-deps-in-app.md | 46 +
.../monorepo-single-dependency-versions.md | 63 +
.../rules/navigation-native-navigators.md | 188 ++
.../react-compiler-destructure-functions.md | 50 +
...react-compiler-reanimated-shared-values.md | 48 +
.../rules/react-state-dispatcher.md | 91 +
.../rules/react-state-fallback.md | 56 +
.../rules/react-state-minimize.md | 65 +
.../rules/rendering-no-falsy-and.md | 74 +
.../rules/rendering-text-in-text-component.md | 36 +
.../rules/scroll-position-no-state.md | 82 +
.../rules/state-ground-truth.md | 80 +
.../rules/ui-expo-image.md | 66 +
.../rules/ui-image-gallery.md | 104 +
.../rules/ui-measure-views.md | 78 +
.../rules/ui-menus.md | 174 +
.../rules/ui-native-modals.md | 77 +
.../rules/ui-pressable.md | 61 +
.../rules/ui-safe-area-scroll.md | 65 +
.../rules/ui-scrollview-content-inset.md | 45 +
.../rules/ui-styling.md | 87 +
skills-lock.json | 5 +
42 files changed, 6090 insertions(+)
create mode 100644 .agents/skills/vercel-react-native-skills/AGENTS.md
create mode 100644 .agents/skills/vercel-react-native-skills/README.md
create mode 100644 .agents/skills/vercel-react-native-skills/SKILL.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/_sections.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/_template.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/animation-derived-value.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/animation-gesture-detector-press.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/animation-gpu-properties.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/design-system-compound-components.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/fonts-config-plugin.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/imports-design-system-folder.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/js-hoist-intl.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-callbacks.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-function-references.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-images.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-inline-objects.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-item-expensive.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-item-memo.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-item-types.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/list-performance-virtualize.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/monorepo-native-deps-in-app.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/monorepo-single-dependency-versions.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/navigation-native-navigators.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/react-compiler-destructure-functions.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/react-compiler-reanimated-shared-values.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/react-state-dispatcher.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/react-state-fallback.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/react-state-minimize.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/rendering-no-falsy-and.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/rendering-text-in-text-component.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/scroll-position-no-state.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/state-ground-truth.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-expo-image.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-image-gallery.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-measure-views.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-menus.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-native-modals.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-pressable.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-safe-area-scroll.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-scrollview-content-inset.md
create mode 100644 .agents/skills/vercel-react-native-skills/rules/ui-styling.md
diff --git a/.agents/skills/vercel-react-native-skills/AGENTS.md b/.agents/skills/vercel-react-native-skills/AGENTS.md
new file mode 100644
index 0000000..d263eb9
--- /dev/null
+++ b/.agents/skills/vercel-react-native-skills/AGENTS.md
@@ -0,0 +1,2897 @@
+# React Native Skills
+
+**Version 1.0.0**
+Engineering
+January 2026
+
+> **Note:**
+> This document is mainly for agents and LLMs to follow when maintaining,
+> generating, or refactoring React Native codebases. Humans
+> may also find it useful, but guidance here is optimized for automation
+> and consistency by AI-assisted workflows.
+
+---
+
+## Abstract
+
+Comprehensive performance optimization guide for React Native applications, designed for AI agents and LLMs. Contains 35+ rules across 13 categories, prioritized by impact from critical (core rendering, list performance) to incremental (fonts, imports). Each rule includes detailed explanations, real-world examples comparing incorrect vs. correct implementations, and specific impact metrics to guide automated refactoring and code generation.
+
+---
+
+## Table of Contents
+
+1. [Core Rendering](#1-core-rendering) — **CRITICAL**
+ - 1.1 [Never Use && with Potentially Falsy Values](#11-never-use--with-potentially-falsy-values)
+ - 1.2 [Wrap Strings in Text Components](#12-wrap-strings-in-text-components)
+2. [List Performance](#2-list-performance) — **HIGH**
+ - 2.1 [Avoid Inline Objects in renderItem](#21-avoid-inline-objects-in-renderitem)
+ - 2.2 [Hoist callbacks to the root of lists](#22-hoist-callbacks-to-the-root-of-lists)
+ - 2.3 [Keep List Items Lightweight](#23-keep-list-items-lightweight)
+ - 2.4 [Optimize List Performance with Stable Object References](#24-optimize-list-performance-with-stable-object-references)
+ - 2.5 [Pass Primitives to List Items for Memoization](#25-pass-primitives-to-list-items-for-memoization)
+ - 2.6 [Use a List Virtualizer for Any List](#26-use-a-list-virtualizer-for-any-list)
+ - 2.7 [Use Compressed Images in Lists](#27-use-compressed-images-in-lists)
+ - 2.8 [Use Item Types for Heterogeneous Lists](#28-use-item-types-for-heterogeneous-lists)
+3. [Animation](#3-animation) — **HIGH**
+ - 3.1 [Animate Transform and Opacity Instead of Layout Properties](#31-animate-transform-and-opacity-instead-of-layout-properties)
+ - 3.2 [Prefer useDerivedValue Over useAnimatedReaction](#32-prefer-usederivedvalue-over-useanimatedreaction)
+ - 3.3 [Use GestureDetector for Animated Press States](#33-use-gesturedetector-for-animated-press-states)
+4. [Scroll Performance](#4-scroll-performance) — **HIGH**
+ - 4.1 [Never Track Scroll Position in useState](#41-never-track-scroll-position-in-usestate)
+5. [Navigation](#5-navigation) — **HIGH**
+ - 5.1 [Use Native Navigators for Navigation](#51-use-native-navigators-for-navigation)
+6. [React State](#6-react-state) — **MEDIUM**
+ - 6.1 [Minimize State Variables and Derive Values](#61-minimize-state-variables-and-derive-values)
+ - 6.2 [Use fallback state instead of initialState](#62-use-fallback-state-instead-of-initialstate)
+ - 6.3 [useState Dispatch updaters for State That Depends on Current Value](#63-usestate-dispatch-updaters-for-state-that-depends-on-current-value)
+7. [State Architecture](#7-state-architecture) — **MEDIUM**
+ - 7.1 [State Must Represent Ground Truth](#71-state-must-represent-ground-truth)
+8. [React Compiler](#8-react-compiler) — **MEDIUM**
+ - 8.1 [Destructure Functions Early in Render (React Compiler)](#81-destructure-functions-early-in-render-react-compiler)
+ - 8.2 [Use .get() and .set() for Reanimated Shared Values (not .value)](#82-use-get-and-set-for-reanimated-shared-values-not-value)
+9. [User Interface](#9-user-interface) — **MEDIUM**
+ - 9.1 [Measuring View Dimensions](#91-measuring-view-dimensions)
+ - 9.2 [Modern React Native Styling Patterns](#92-modern-react-native-styling-patterns)
+ - 9.3 [Use contentInset for Dynamic ScrollView Spacing](#93-use-contentinset-for-dynamic-scrollview-spacing)
+ - 9.4 [Use contentInsetAdjustmentBehavior for Safe Areas](#94-use-contentinsetadjustmentbehavior-for-safe-areas)
+ - 9.5 [Use expo-image for Optimized Images](#95-use-expo-image-for-optimized-images)
+ - 9.6 [Use Galeria for Image Galleries and Lightbox](#96-use-galeria-for-image-galleries-and-lightbox)
+ - 9.7 [Use Native Menus for Dropdowns and Context Menus](#97-use-native-menus-for-dropdowns-and-context-menus)
+ - 9.8 [Use Native Modals Over JS-Based Bottom Sheets](#98-use-native-modals-over-js-based-bottom-sheets)
+ - 9.9 [Use Pressable Instead of Touchable Components](#99-use-pressable-instead-of-touchable-components)
+10. [Design System](#10-design-system) — **MEDIUM**
+ - 10.1 [Use Compound Components Over Polymorphic Children](#101-use-compound-components-over-polymorphic-children)
+11. [Monorepo](#11-monorepo) — **LOW**
+ - 11.1 [Install Native Dependencies in App Directory](#111-install-native-dependencies-in-app-directory)
+ - 11.2 [Use Single Dependency Versions Across Monorepo](#112-use-single-dependency-versions-across-monorepo)
+12. [Third-Party Dependencies](#12-third-party-dependencies) — **LOW**
+ - 12.1 [Import from Design System Folder](#121-import-from-design-system-folder)
+13. [JavaScript](#13-javascript) — **LOW**
+ - 13.1 [Hoist Intl Formatter Creation](#131-hoist-intl-formatter-creation)
+14. [Fonts](#14-fonts) — **LOW**
+ - 14.1 [Load fonts natively at build time](#141-load-fonts-natively-at-build-time)
+
+---
+
+## 1. Core Rendering
+
+**Impact: CRITICAL**
+
+Fundamental React Native rendering rules. Violations cause
+runtime crashes or broken UI.
+
+### 1.1 Never Use && with Potentially Falsy Values
+
+**Impact: CRITICAL (prevents production crash)**
+
+Never use `{value &&