From 392a1fc42b9a91bd2d77f1e26b5bb9e9fbc5a973 Mon Sep 17 00:00:00 2001
From: Nate <sestinj@gmail.com>
Date: Thu, 5 Feb 2026 11:07:47 -0800
Subject: [PATCH] .continue/agents

---
 .continue/agents/anti-slop.md                 |   21 +
 .continue/agents/react-best-practices.md      | 2395 +++++++++++++++++
 .continue/agents/security-audit.md            |    6 +
 .continue/agents/update-agents-md.md          |   80 +
 .continue/agents/update-continue-docs.md      |   90 +
 .gitignore                                    |    1 -
 .../cli/.continue/agents/format-check.md      |    1 +
 7 files changed, 2593 insertions(+), 1 deletion(-)
 create mode 100644 .continue/agents/anti-slop.md
 create mode 100644 .continue/agents/react-best-practices.md
 create mode 100644 .continue/agents/security-audit.md
 create mode 100644 .continue/agents/update-agents-md.md
 create mode 100644 .continue/agents/update-continue-docs.md
 create mode 100644 extensions/cli/.continue/agents/format-check.md

diff --git a/.continue/agents/anti-slop.md b/.continue/agents/anti-slop.md
new file mode 100644
index 00000000000..3d72c4260df
--- /dev/null
+++ b/.continue/agents/anti-slop.md
@@ -0,0 +1,21 @@
+---
+name: Anti-slop
+description: Fix AI Slop
+---
+
+I want to follow the **Anti AI-slop rule**: clean up any AI-generated code patterns that harm readability and maintainability. Please look around at the files that were changed. If there are any with "AI slop" patterns, make targeted changes to clean them up. Stick to a single file maximum. If no changes are necessary, then do nothing.
+
+**What qualifies as AI slop in code:**
+
+1. **Overly verbose comments** - Comments that restate exactly what the code does (e.g., `// increment counter by 1` above `counter++`)
+2. **Excessive defensive programming** - Unnecessary null checks, try-catches, or validations that clutter the logic without providing real safety
+3. **Redundant type annotations** - Type declarations that are already inferred by the language/compiler
+4. **Boilerplate explosion** - Creating separate classes/functions/files for trivial operations that could be a simple expression
+5. **Over-abstraction** - Interfaces with single implementations, factories that create one thing, strategy patterns for two options
+6. **Verbose variable names that obscure intent** - e.g., `currentUserAuthenticationStatusBoolean` instead of `isAuthenticated`
+7. **Unnecessary intermediate variables** - Variables used exactly once on the next line purely to "document" a step
+8. **Repetitive error handling** - Copy-pasted try-catch blocks that could be consolidated
+9. **Filler documentation** - JSDoc/docstrings that add no information beyond the function signature
+10. **"Just in case" code** - Unused parameters, dead code paths, or features built for hypothetical future needs
+
+**The goal:** Code should be concise, readable, and no more complex than necessary. Remove ceremony, not functionality.
diff --git a/.continue/agents/react-best-practices.md b/.continue/agents/react-best-practices.md
new file mode 100644
index 00000000000..0553f842f58
--- /dev/null
+++ b/.continue/agents/react-best-practices.md
@@ -0,0 +1,2395 @@
+---
+name: React Best Practices
+description: React Best Practices
+---
+
+You are an agent responsible for evaluating a PR for adherence to the React best practices outlined below. Your goal is to identify any poor practices. If you find a poor practice, address it with a code change. Keep all of your changes constrained to a single commit. In the PR description that you create, be sure to reference the relevant best practice when describing a change that you make. If you do not find any poor practices, do not open a PR.
+
+Note: These best practices are pulled from https://github.com/vercel-labs/agent-skills/blob/main/skills/react-best-practices/AGENTS.md#1-eliminating-waterfalls
+
+# React Best Practices
+
+**Version 1.0.0**  
+Vercel Engineering  
+January 2026
+
+> **Note:**  
+> This document is mainly for agents and LLMs to follow when maintaining,  
+> generating, or refactoring React and Next.js codebases at Vercel. 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 and Next.js applications, designed for AI agents and LLMs. Contains 40+ rules across 8 categories, prioritized by impact from critical (eliminating waterfalls, reducing bundle size) to incremental (advanced patterns). 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. [Eliminating Waterfalls](#1-eliminating-waterfalls) — **CRITICAL**
+   - 1.1 [Defer Await Until Needed](#11-defer-await-until-needed)
+   - 1.2 [Dependency-Based Parallelization](#12-dependency-based-parallelization)
+   - 1.3 [Prevent Waterfall Chains in API Routes](#13-prevent-waterfall-chains-in-api-routes)
+   - 1.4 [Promise.all() for Independent Operations](#14-promiseall-for-independent-operations)
+   - 1.5 [Strategic Suspense Boundaries](#15-strategic-suspense-boundaries)
+2. [Bundle Size Optimization](#2-bundle-size-optimization) — **CRITICAL**
+   - 2.1 [Avoid Barrel File Imports](#21-avoid-barrel-file-imports)
+   - 2.2 [Conditional Module Loading](#22-conditional-module-loading)
+   - 2.3 [Defer Non-Critical Third-Party Libraries](#23-defer-non-critical-third-party-libraries)
+   - 2.4 [Dynamic Imports for Heavy Components](#24-dynamic-imports-for-heavy-components)
+   - 2.5 [Preload Based on User Intent](#25-preload-based-on-user-intent)
+3. [Server-Side Performance](#3-server-side-performance) — **HIGH**
+   - 3.1 [Cross-Request LRU Caching](#31-cross-request-lru-caching)
+   - 3.2 [Minimize Serialization at RSC Boundaries](#32-minimize-serialization-at-rsc-boundaries)
+   - 3.3 [Parallel Data Fetching with Component Composition](#33-parallel-data-fetching-with-component-composition)
+   - 3.4 [Per-Request Deduplication with React.cache()](#34-per-request-deduplication-with-reactcache)
+   - 3.5 [Use after() for Non-Blocking Operations](#35-use-after-for-non-blocking-operations)
+4. [Client-Side Data Fetching](#4-client-side-data-fetching) — **MEDIUM-HIGH**
+   - 4.1 [Deduplicate Global Event Listeners](#41-deduplicate-global-event-listeners)
+   - 4.2 [Use Passive Event Listeners for Scrolling Performance](#42-use-passive-event-listeners-for-scrolling-performance)
+   - 4.3 [Use SWR for Automatic Deduplication](#43-use-swr-for-automatic-deduplication)
+   - 4.4 [Version and Minimize localStorage Data](#44-version-and-minimize-localstorage-data)
+5. [Re-render Optimization](#5-re-render-optimization) — **MEDIUM**
+   - 5.1 [Defer State Reads to Usage Point](#51-defer-state-reads-to-usage-point)
+   - 5.2 [Extract to Memoized Components](#52-extract-to-memoized-components)
+   - 5.3 [Narrow Effect Dependencies](#53-narrow-effect-dependencies)
+   - 5.4 [Subscribe to Derived State](#54-subscribe-to-derived-state)
+   - 5.5 [Use Functional setState Updates](#55-use-functional-setstate-updates)
+   - 5.6 [Use Lazy State Initialization](#56-use-lazy-state-initialization)
+   - 5.7 [Use Transitions for Non-Urgent Updates](#57-use-transitions-for-non-urgent-updates)
+6. [Rendering Performance](#6-rendering-performance) — **MEDIUM**
+   - 6.1 [Animate SVG Wrapper Instead of SVG Element](#61-animate-svg-wrapper-instead-of-svg-element)
+   - 6.2 [CSS content-visibility for Long Lists](#62-css-content-visibility-for-long-lists)
+   - 6.3 [Hoist Static JSX Elements](#63-hoist-static-jsx-elements)
+   - 6.4 [Optimize SVG Precision](#64-optimize-svg-precision)
+   - 6.5 [Prevent Hydration Mismatch Without Flickering](#65-prevent-hydration-mismatch-without-flickering)
+   - 6.6 [Use Activity Component for Show/Hide](#66-use-activity-component-for-showhide)
+   - 6.7 [Use Explicit Conditional Rendering](#67-use-explicit-conditional-rendering)
+7. [JavaScript Performance](#7-javascript-performance) — **LOW-MEDIUM**
+   - 7.1 [Batch DOM CSS Changes](#71-batch-dom-css-changes)
+   - 7.2 [Build Index Maps for Repeated Lookups](#72-build-index-maps-for-repeated-lookups)
+   - 7.3 [Cache Property Access in Loops](#73-cache-property-access-in-loops)
+   - 7.4 [Cache Repeated Function Calls](#74-cache-repeated-function-calls)
+   - 7.5 [Cache Storage API Calls](#75-cache-storage-api-calls)
+   - 7.6 [Combine Multiple Array Iterations](#76-combine-multiple-array-iterations)
+   - 7.7 [Early Length Check for Array Comparisons](#77-early-length-check-for-array-comparisons)
+   - 7.8 [Early Return from Functions](#78-early-return-from-functions)
+   - 7.9 [Hoist RegExp Creation](#79-hoist-regexp-creation)
+   - 7.10 [Use Loop for Min/Max Instead of Sort](#710-use-loop-for-minmax-instead-of-sort)
+   - 7.11 [Use Set/Map for O(1) Lookups](#711-use-setmap-for-o1-lookups)
+   - 7.12 [Use toSorted() Instead of sort() for Immutability](#712-use-tosorted-instead-of-sort-for-immutability)
+8. [Advanced Patterns](#8-advanced-patterns) — **LOW**
+   - 8.1 [Store Event Handlers in Refs](#81-store-event-handlers-in-refs)
+   - 8.2 [useLatest for Stable Callback Refs](#82-uselatest-for-stable-callback-refs)
+
+---
+
+## 1. Eliminating Waterfalls
+
+**Impact: CRITICAL**
+
+Waterfalls are the #1 performance killer. Each sequential await adds full network latency. Eliminating them yields the largest gains.
+
+### 1.1 Defer Await Until Needed
+
+**Impact: HIGH (avoids blocking unused code paths)**
+
+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.
+
+### 1.2 Dependency-Based Parallelization
+
+**Impact: CRITICAL (2-10× improvement)**
+
+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);
+  },
+});
+```
+
+Reference: [https://github.com/shuding/better-all](https://github.com/shuding/better-all)
+
+### 1.3 Prevent Waterfall Chains in API Routes
+
+**Impact: CRITICAL (2-10× improvement)**
+
+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).
+
+### 1.4 Promise.all() for Independent Operations
+
+**Impact: CRITICAL (2-10× improvement)**
+
+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(),
+]);
+```
+
+### 1.5 Strategic Suspense Boundaries
+
+**Impact: HIGH (faster initial paint)**
+
+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 (
+    <div>
+      <div>Sidebar</div>
+      <div>Header</div>
+      <div>
+        <DataDisplay data={data} />
+      </div>
+      <div>Footer</div>
+    </div>
+  );
+}
+```
+
+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 (
+    <div>
+      <div>Sidebar</div>
+      <div>Header</div>
+      <div>
+        <Suspense fallback={<Skeleton />}>
+          <DataDisplay />
+        </Suspense>
+      </div>
+      <div>Footer</div>
+    </div>
+  );
+}
+
+async function DataDisplay() {
+  const data = await fetchData(); // Only blocks this component
+  return <div>{data.content}</div>;
+}
+```
+
+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 (
+    <div>
+      <div>Sidebar</div>
+      <div>Header</div>
+      <Suspense fallback={<Skeleton />}>
+        <DataDisplay dataPromise={dataPromise} />
+        <DataSummary dataPromise={dataPromise} />
+      </Suspense>
+      <div>Footer</div>
+    </div>
+  );
+}
+
+function DataDisplay({ dataPromise }: { dataPromise: Promise<Data> }) {
+  const data = use(dataPromise); // Unwraps the promise
+  return <div>{data.content}</div>;
+}
+
+function DataSummary({ dataPromise }: { dataPromise: Promise<Data> }) {
+  const data = use(dataPromise); // Reuses the same promise
+  return <div>{data.summary}</div>;
+}
+```
+
+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.
+
+---
+
+## 2. Bundle Size Optimization
+
+**Impact: CRITICAL**
+
+Reducing initial bundle size improves Time to Interactive and Largest Contentful Paint.
+
+### 2.1 Avoid Barrel File Imports
+
+**Impact: CRITICAL (200-800ms import cost, slow builds)**
+
+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: imports only what you need**
+
+```tsx
+import Check from "lucide-react/dist/esm/icons/check";
+import X from "lucide-react/dist/esm/icons/x";
+import Menu from "lucide-react/dist/esm/icons/menu";
+// Loads only 3 modules (~2KB vs ~1MB)
+
+import Button from "@mui/material/Button";
+import TextField from "@mui/material/TextField";
+// Loads only what you use
+```
+
+**Alternative: Next.js 13.5+**
+
+```js
+// next.config.js - use optimizePackageImports
+module.exports = {
+  experimental: {
+    optimizePackageImports: ["lucide-react", "@mui/material"],
+  },
+};
+
+// Then you can keep the ergonomic barrel imports:
+import { Check, X, Menu } from "lucide-react";
+// Automatically transformed to direct imports at build time
+```
+
+Direct imports 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: [https://vercel.com/blog/how-we-optimized-package-imports-in-next-js](https://vercel.com/blog/how-we-optimized-package-imports-in-next-js)
+
+### 2.2 Conditional Module Loading
+
+**Impact: HIGH (loads large data only when needed)**
+
+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.Dispatch<React.SetStateAction<boolean>>;
+}) {
+  const [frames, setFrames] = useState<Frame[] | null>(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 <Skeleton />;
+  return <Canvas frames={frames} />;
+}
+```
+
+The `typeof window !== 'undefined'` check prevents bundling this module for SSR, optimizing server bundle size and build speed.
+
+### 2.3 Defer Non-Critical Third-Party Libraries
+
+**Impact: MEDIUM (loads after hydration)**
+
+Analytics, logging, and error tracking don't block user interaction. Load them after hydration.
+
+**Incorrect: blocks initial bundle**
+
+```tsx
+import { Analytics } from "@vercel/analytics/react";
+
+export default function RootLayout({ children }) {
+  return (
+    <html>
+      <body>
+        {children}
+        <Analytics />
+      </body>
+    </html>
+  );
+}
+```
+
+**Correct: loads after hydration**
+
+```tsx
+import dynamic from "next/dynamic";
+
+const Analytics = dynamic(
+  () => import("@vercel/analytics/react").then((m) => m.Analytics),
+  { ssr: false },
+);
+
+export default function RootLayout({ children }) {
+  return (
+    <html>
+      <body>
+        {children}
+        <Analytics />
+      </body>
+    </html>
+  );
+}
+```
+
+### 2.4 Dynamic Imports for Heavy Components
+
+**Impact: CRITICAL (directly affects TTI and LCP)**
+
+Use `next/dynamic` to lazy-load large components not needed on initial render.
+
+**Incorrect: Monaco bundles with main chunk ~300KB**
+
+```tsx
+import { MonacoEditor } from "./monaco-editor";
+
+function CodePanel({ code }: { code: string }) {
+  return <MonacoEditor value={code} />;
+}
+```
+
+**Correct: Monaco loads on demand**
+
+```tsx
+import dynamic from "next/dynamic";
+
+const MonacoEditor = dynamic(
+  () => import("./monaco-editor").then((m) => m.MonacoEditor),
+  { ssr: false },
+);
+
+function CodePanel({ code }: { code: string }) {
+  return <MonacoEditor value={code} />;
+}
+```
+
+### 2.5 Preload Based on User Intent
+
+**Impact: MEDIUM (reduces perceived latency)**
+
+Preload heavy bundles before they're needed to reduce perceived latency.
+
+**Example: preload on hover/focus**
+
+```tsx
+function EditorButton({ onClick }: { onClick: () => void }) {
+  const preload = () => {
+    if (typeof window !== "undefined") {
+      void import("./monaco-editor");
+    }
+  };
+
+  return (
+    <button onMouseEnter={preload} onFocus={preload} onClick={onClick}>
+      Open Editor
+    </button>
+  );
+}
+```
+
+**Example: preload when feature flag is enabled**
+
+```tsx
+function FlagsProvider({ children, flags }: Props) {
+  useEffect(() => {
+    if (flags.editorEnabled && typeof window !== "undefined") {
+      void import("./monaco-editor").then((mod) => mod.init());
+    }
+  }, [flags.editorEnabled]);
+
+  return (
+    <FlagsContext.Provider value={flags}>{children}</FlagsContext.Provider>
+  );
+}
+```
+
+The `typeof window !== 'undefined'` check prevents bundling preloaded modules for SSR, optimizing server bundle size and build speed.
+
+---
+
+## 3. Server-Side Performance
+
+**Impact: HIGH**
+
+Optimizing server-side rendering and data fetching eliminates server-side waterfalls and reduces response times.
+
+### 3.1 Cross-Request LRU Caching
+
+**Impact: HIGH (caches across requests)**
+
+`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<string, any>({
+  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)
+
+### 3.2 Minimize Serialization at RSC Boundaries
+
+**Impact: HIGH (reduces data transfer size)**
+
+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 <Profile user={user} />;
+}
+
+("use client");
+function Profile({ user }: { user: User }) {
+  return <div>{user.name}</div>; // uses 1 field
+}
+```
+
+**Correct: serializes only 1 field**
+
+```tsx
+async function Page() {
+  const user = await fetchUser();
+  return <Profile name={user.name} />;
+}
+
+("use client");
+function Profile({ name }: { name: string }) {
+  return <div>{name}</div>;
+}
+```
+
+### 3.3 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 (
+    <div>
+      <div>{header}</div>
+      <Sidebar />
+    </div>
+  );
+}
+
+async function Sidebar() {
+  const items = await fetchSidebarItems();
+  return <nav>{items.map(renderItem)}</nav>;
+}
+```
+
+**Correct: both fetch simultaneously**
+
+```tsx
+async function Header() {
+  const data = await fetchHeader();
+  return <div>{data}</div>;
+}
+
+async function Sidebar() {
+  const items = await fetchSidebarItems();
+  return <nav>{items.map(renderItem)}</nav>;
+}
+
+export default function Page() {
+  return (
+    <div>
+      <Header />
+      <Sidebar />
+    </div>
+  );
+}
+```
+
+**Alternative with children prop:**
+
+```tsx
+async function Header() {
+  const data = await fetchHeader();
+  return <div>{data}</div>;
+}
+
+async function Sidebar() {
+  const items = await fetchSidebarItems();
+  return <nav>{items.map(renderItem)}</nav>;
+}
+
+function Layout({ children }: { children: ReactNode }) {
+  return (
+    <div>
+      <Header />
+      {children}
+    </div>
+  );
+}
+
+export default function Page() {
+  return (
+    <Layout>
+      <Sidebar />
+    </Layout>
+  );
+}
+```
+
+### 3.4 Per-Request Deduplication with React.cache()
+
+**Impact: MEDIUM (deduplicates within request)**
+
+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 params = { uid: 1 };
+getUser(params); // Query runs
+getUser(params); // Cache hit (same reference)
+```
+
+If you must pass objects, pass the 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: [https://react.dev/reference/react/cache](https://react.dev/reference/react/cache)
+
+### 3.5 Use after() for Non-Blocking Operations
+
+**Impact: MEDIUM (faster response times)**
+
+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)
+
+---
+
+## 4. Client-Side Data Fetching
+
+**Impact: MEDIUM-HIGH**
+
+Automatic deduplication and efficient data fetching patterns reduce redundant network requests.
+
+### 4.1 Deduplicate Global Event Listeners
+
+**Impact: LOW (single listener for N components)**
+
+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<string, Set<() => 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", () => {
+    /* ... */
+  });
+  // ...
+}
+```
+
+### 4.2 Use Passive Event Listeners for Scrolling Performance
+
+**Impact: MEDIUM (eliminates scroll delay caused by event listeners)**
+
+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()`.
+
+### 4.3 Use SWR for Automatic Deduplication
+
+**Impact: MEDIUM-HIGH (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 <button onClick={() => trigger()}>Update</button>;
+}
+```
+
+Reference: [https://swr.vercel.app](https://swr.vercel.app)
+
+### 4.4 Version and Minimize localStorage Data
+
+**Impact: MEDIUM (prevents schema conflicts, reduces storage size)**
+
+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.
+
+---
+
+## 5. Re-render Optimization
+
+**Impact: MEDIUM**
+
+Reducing unnecessary re-renders minimizes wasted computation and improves UI responsiveness.
+
+### 5.1 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 <button onClick={handleShare}>Share</button>;
+}
+```
+
+**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 <button onClick={handleShare}>Share</button>;
+}
+```
+
+### 5.2 Extract to Memoized Components
+
+**Impact: MEDIUM (enables early returns)**
+
+Extract expensive work into memoized components to enable early returns before computation.
+
+**Incorrect: computes avatar even when loading**
+
+```tsx
+function Profile({ user, loading }: Props) {
+  const avatar = useMemo(() => {
+    const id = computeAvatarId(user);
+    return <Avatar id={id} />;
+  }, [user]);
+
+  if (loading) return <Skeleton />;
+  return <div>{avatar}</div>;
+}
+```
+
+**Correct: skips computation when loading**
+
+```tsx
+const UserAvatar = memo(function UserAvatar({ user }: { user: User }) {
+  const id = useMemo(() => computeAvatarId(user), [user]);
+  return <Avatar id={id} />;
+});
+
+function Profile({ user, loading }: Props) {
+  if (loading) return <Skeleton />;
+  return (
+    <div>
+      <UserAvatar user={user} />
+    </div>
+  );
+}
+```
+
+**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.
+
+### 5.3 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]);
+```
+
+### 5.4 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 <nav className={isMobile ? "mobile" : "desktop"} />;
+}
+```
+
+**Correct: re-renders only when boolean changes**
+
+```tsx
+function Sidebar() {
+  const isMobile = useMediaQuery("(max-width: 767px)");
+  return <nav className={isMobile ? "mobile" : "desktop"} />;
+}
+```
+
+### 5.5 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 <ItemsEditor items={items} onAdd={addItems} onRemove={removeItem} />;
+}
+```
+
+The first callback is recreated every time `items` changes, which can cause child components to re-render unnecessarily. The second callback has a stale closure bug—it will always reference the initial `items` value.
+
+**Correct: stable callbacks, no stale closures**
+
+```tsx
+function TodoList() {
+  const [items, setItems] = useState(initialItems);
+
+  // Stable callback, never recreated
+  const addItems = useCallback((newItems: Item[]) => {
+    setItems((curr) => [...curr, ...newItems]);
+  }, []); // ✅ No dependencies needed
+
+  // Always uses latest state, no stale closure risk
+  const removeItem = useCallback((id: string) => {
+    setItems((curr) => curr.filter((item) => item.id !== id));
+  }, []); // ✅ Safe and stable
+
+  return <ItemsEditor items={items} onAdd={addItems} onRemove={removeItem} />;
+}
+```
+
+**Benefits:**
+
+1. **Stable callback references** - Callbacks don't need to be recreated when state changes
+
+2. **No stale closures** - Always operates on the latest state value
+
+3. **Fewer dependencies** - Simplifies dependency arrays and reduces memory leaks
+
+4. **Prevents bugs** - Eliminates the most common source of React closure bugs
+
+**When to use functional updates:**
+
+- Any setState that depends on the current state value
+
+- Inside useCallback/useMemo when state is needed
+
+- Event handlers that reference state
+
+- Async operations that update state
+
+**When direct updates are fine:**
+
+- Setting state to a static value: `setCount(0)`
+
+- Setting state from props/arguments only: `setName(newName)`
+
+- State doesn't depend on previous value
+
+**Note:** If your project has [React Compiler](https://react.dev/learn/react-compiler) enabled, the compiler can automatically optimize some cases, but functional updates are still recommended for correctness and to prevent stale closure bugs.
+
+### 5.6 Use Lazy State Initialization
+
+**Impact: MEDIUM (wasted computation on every render)**
+
+Pass a function to `useState` for expensive initial values. Without the function form, the initializer runs on every render even though the value is only used once.
+
+**Incorrect: runs on every render**
+
+```tsx
+function FilteredList({ items }: { items: Item[] }) {
+  // buildSearchIndex() runs on EVERY render, even after initialization
+  const [searchIndex, setSearchIndex] = useState(buildSearchIndex(items));
+  const [query, setQuery] = useState("");
+
+  // When query changes, buildSearchIndex runs again unnecessarily
+  return <SearchResults index={searchIndex} query={query} />;
+}
+
+function UserProfile() {
+  // JSON.parse runs on every render
+  const [settings, setSettings] = useState(
+    JSON.parse(localStorage.getItem("settings") || "{}"),
+  );
+
+  return <SettingsForm settings={settings} onChange={setSettings} />;
+}
+```
+
+**Correct: runs only once**
+
+```tsx
+function FilteredList({ items }: { items: Item[] }) {
+  // buildSearchIndex() runs ONLY on initial render
+  const [searchIndex, setSearchIndex] = useState(() => buildSearchIndex(items));
+  const [query, setQuery] = useState("");
+
+  return <SearchResults index={searchIndex} query={query} />;
+}
+
+function UserProfile() {
+  // JSON.parse runs only on initial render
+  const [settings, setSettings] = useState(() => {
+    const stored = localStorage.getItem("settings");
+    return stored ? JSON.parse(stored) : {};
+  });
+
+  return <SettingsForm settings={settings} onChange={setSettings} />;
+}
+```
+
+Use lazy initialization when computing initial values from localStorage/sessionStorage, building data structures (indexes, maps), reading from the DOM, or performing heavy transformations.
+
+For simple primitives (`useState(0)`), direct references (`useState(props.value)`), or cheap literals (`useState({})`), the function form is unnecessary.
+
+### 5.7 Use Transitions for Non-Urgent Updates
+
+**Impact: MEDIUM (maintains UI responsiveness)**
+
+Mark frequent, non-urgent state updates as transitions to maintain UI responsiveness.
+
+**Incorrect: blocks UI on every scroll**
+
+```tsx
+function ScrollTracker() {
+  const [scrollY, setScrollY] = useState(0);
+  useEffect(() => {
+    const handler = () => setScrollY(window.scrollY);
+    window.addEventListener("scroll", handler, { passive: true });
+    return () => window.removeEventListener("scroll", handler);
+  }, []);
+}
+```
+
+**Correct: non-blocking updates**
+
+```tsx
+import { startTransition } from "react";
+
+function ScrollTracker() {
+  const [scrollY, setScrollY] = useState(0);
+  useEffect(() => {
+    const handler = () => {
+      startTransition(() => setScrollY(window.scrollY));
+    };
+    window.addEventListener("scroll", handler, { passive: true });
+    return () => window.removeEventListener("scroll", handler);
+  }, []);
+}
+```
+
+---
+
+## 6. Rendering Performance
+
+**Impact: MEDIUM**
+
+Optimizing the rendering process reduces the work the browser needs to do.
+
+### 6.1 Animate SVG Wrapper Instead of SVG Element
+
+**Impact: LOW (enables hardware acceleration)**
+
+Many browsers don't have hardware acceleration for CSS3 animations on SVG elements. Wrap SVG in a `<div>` and animate the wrapper instead.
+
+**Incorrect: animating SVG directly - no hardware acceleration**
+
+```tsx
+function LoadingSpinner() {
+  return (
+    <svg className="animate-spin" width="24" height="24" viewBox="0 0 24 24">
+      <circle cx="12" cy="12" r="10" stroke="currentColor" />
+    </svg>
+  );
+}
+```
+
+**Correct: animating wrapper div - hardware accelerated**
+
+```tsx
+function LoadingSpinner() {
+  return (
+    <div className="animate-spin">
+      <svg width="24" height="24" viewBox="0 0 24 24">
+        <circle cx="12" cy="12" r="10" stroke="currentColor" />
+      </svg>
+    </div>
+  );
+}
+```
+
+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 (
+    <div className="h-screen overflow-y-auto">
+      {messages.map((msg) => (
+        <div key={msg.id} className="message-item">
+          <Avatar user={msg.author} />
+          <div>{msg.content}</div>
+        </div>
+      ))}
+    </div>
+  );
+}
+```
+
+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 <div className="h-20 animate-pulse bg-gray-200" />;
+}
+
+function Container() {
+  return <div>{loading && <LoadingSkeleton />}</div>;
+}
+```
+
+**Correct: reuses same element**
+
+```tsx
+const loadingSkeleton = <div className="h-20 animate-pulse bg-gray-200" />;
+
+function Container() {
+  return <div>{loading && loadingSkeleton}</div>;
+}
+```
+
+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
+<path d="M 10.293847 20.847362 L 30.938472 40.192837" />
+```
+
+**Correct: 1 decimal place**
+
+```svg
+<path d="M 10.3 20.8 L 30.9 40.2" />
+```
+
+**Automate with SVGO:**
+
+```bash
+npx svgo --precision=1 --multipass icon.svg
+```
+
+### 6.5 Prevent Hydration Mismatch Without Flickering
+
+**Impact: MEDIUM (avoids visual flicker and hydration errors)**
+
+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 <div className={theme}>{children}</div>;
+}
+```
+
+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 <div className={theme}>{children}</div>;
+}
+```
+
+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 (
+    <>
+      <div id="theme-wrapper">{children}</div>
+      <script
+        dangerouslySetInnerHTML={{
+          __html: `
+            (function() {
+              try {
+                var theme = localStorage.getItem('theme') || 'light';
+                var el = document.getElementById('theme-wrapper');
+                if (el) el.className = theme;
+              } catch (e) {}
+            })();
+          `,
+        }}
+      />
+    </>
+  );
+}
+```
+
+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 Use Activity Component for Show/Hide
+
+**Impact: MEDIUM (preserves state/DOM)**
+
+Use React's `<Activity>` to preserve state/DOM for expensive components that frequently toggle visibility.
+
+**Usage:**
+
+```tsx
+import { Activity } from "react";
+
+function Dropdown({ isOpen }: Props) {
+  return (
+    <Activity mode={isOpen ? "visible" : "hidden"}>
+      <ExpensiveMenu />
+    </Activity>
+  );
+}
+```
+
+Avoids expensive re-renders and state loss.
+
+### 6.7 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 <div>{count && <span className="badge">{count}</span>}</div>;
+}
+
+// When count = 0, renders: <div>0</div>
+// When count = 5, renders: <div><span class="badge">5</span></div>
+```
+
+**Correct: renders nothing when count is 0**
+
+```tsx
+function Badge({ count }: { count: number }) {
+  return <div>{count > 0 ? <span className="badge">{count}</span> : null}</div>;
+}
+
+// When count = 0, renders: <div></div>
+// When count = 5, renders: <div><span class="badge">5</span></div>
+```
+
+---
+
+## 7. JavaScript Performance
+
+**Impact: LOW-MEDIUM**
+
+Micro-optimizations for hot paths can add up to meaningful improvements.
+
+### 7.1 Batch DOM CSS Changes
+
+**Impact: MEDIUM (reduces reflows/repaints)**
+
+Avoid changing styles one property at a time. Group multiple CSS changes together via classes or `cssText` to minimize browser reflows.
+
+**Incorrect: multiple reflows**
+
+```typescript
+function updateElementStyles(element: HTMLElement) {
+  // Each line triggers a reflow
+  element.style.width = "100px";
+  element.style.height = "200px";
+  element.style.backgroundColor = "blue";
+  element.style.border = "1px solid black";
+}
+```
+
+**Correct: add class - single reflow**
+
+```typescript
+// CSS file
+.highlighted-box {
+  width: 100px;
+  height: 200px;
+  background-color: blue;
+  border: 1px solid black;
+}
+
+// JavaScript
+function updateElementStyles(element: HTMLElement) {
+  element.classList.add('highlighted-box')
+}
+```
+
+**Correct: change cssText - single reflow**
+
+```typescript
+function updateElementStyles(element: HTMLElement) {
+  element.style.cssText = `
+    width: 100px;
+    height: 200px;
+    background-color: blue;
+    border: 1px solid black;
+  `;
+}
+```
+
+**React example:**
+
+```tsx
+// Incorrect: changing styles one by one
+function Box({ isHighlighted }: { isHighlighted: boolean }) {
+  const ref = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    if (ref.current && isHighlighted) {
+      ref.current.style.width = "100px";
+      ref.current.style.height = "200px";
+      ref.current.style.backgroundColor = "blue";
+    }
+  }, [isHighlighted]);
+
+  return <div ref={ref}>Content</div>;
+}
+
+// Correct: toggle class
+function Box({ isHighlighted }: { isHighlighted: boolean }) {
+  return <div className={isHighlighted ? "highlighted-box" : ""}>Content</div>;
+}
+```
+
+Prefer CSS classes over inline styles when possible. Classes are cached by the browser and provide better separation of concerns.
+
+### 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 (
+    <div>
+      {projects.map(project => {
+        // slugify() called 100+ times for same project names
+        const slug = slugify(project.name)
+
+        return <ProjectCard key={project.id} slug={slug} />
+      })}
+    </div>
+  )
+}
+```
+
+**Correct: cached results**
+
+```typescript
+// Module-level cache
+const slugifyCache = new Map<string, string>()
+
+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 (
+    <div>
+      {projects.map(project => {
+        // Computed only once per unique project name
+        const slug = cachedSlugify(project.name)
+
+        return <ProjectCard key={project.id} slug={slug} />
+      })}
+    </div>
+  )
+}
+```
+
+**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<string, string | null>();
+
+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<string, string> | 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 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/join 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
+
+### 7.8 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 };
+}
+```
+
+### 7.9 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:
+
+### 7.10 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 for very large arrays due to spread operator limitations. Use the loop approach for reliability.
+
+### 7.11 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))
+```
+
+### 7.12 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 <div>{sorted.map(renderUser)}</div>
+}
+```
+
+**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 <div>{sorted.map(renderUser)}</div>
+}
+```
+
+**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 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: () => 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: () => 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.
+
+### 8.2 useLatest 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.
+
+**Implementation:**
+
+```typescript
+function useLatest<T>(value: T) {
+  const ref = useRef(value);
+  useEffect(() => {
+    ref.current = value;
+  }, [value]);
+  return ref;
+}
+```
+
+**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: stable effect, fresh callback**
+
+```tsx
+function SearchInput({ onSearch }: { onSearch: (q: string) => void }) {
+  const [query, setQuery] = useState("");
+  const onSearchRef = useLatest(onSearch);
+
+  useEffect(() => {
+    const timeout = setTimeout(() => onSearchRef.current(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/.continue/agents/security-audit.md b/.continue/agents/security-audit.md
new file mode 100644
index 00000000000..6fddd39fb71
--- /dev/null
+++ b/.continue/agents/security-audit.md
@@ -0,0 +1,6 @@
+---
+name: Security Audit
+description: Security Audit
+---
+
+Please audit this pull request for any security vulnerabilities that were introduced. In particular you should look for new sources of potential prompt injections, or other vulnerabilities caused by the fact that this extension / CLI run locally on a user's machine. Do NOT look into anything unless it was changed in the pull request. When you are done, please make the required changes.
diff --git a/.continue/agents/update-agents-md.md b/.continue/agents/update-agents-md.md
new file mode 100644
index 00000000000..fd38abd0964
--- /dev/null
+++ b/.continue/agents/update-agents-md.md
@@ -0,0 +1,80 @@
+---
+name: Update AGENTS.md
+description: Update AGENTS.md
+---
+
+# Intent Layer Sync Agent
+
+You are an Intent Layer maintenance agent. Your job is to keep the codebase's intent documentation (AGENTS.md, CLAUDE.md, or similar files) synchronized with code changes.
+
+## Your Task
+
+Analyze the PR changes and determine if any intent layer files need updates. If yes, make edits in a stacked PR.
+
+## What is an Intent Layer?
+
+Intent layer files capture **institutional knowledge** that isn't visible in code:
+
+- System boundaries and ownership
+- Invariants and contracts that must hold
+- Patterns to follow / anti-patterns to avoid
+- Pitfalls and edge cases engineers encounter
+
+## Process
+
+### Step 1: Analyze Changed Files
+
+- List all files modified in this PR
+- Understand the semantic nature of changes (new feature, refactor, bug fix, API change, etc.)
+
+### Step 2: Identify Affected Intent Nodes
+
+- Find intent files (AGENTS.md, CLAUDE.md, etc.) that cover the changed directories
+- Check both the immediate directory and ancestor directories (intent is hierarchical)
+
+### Step 3: Evaluate Need for Updates
+
+An intent layer update is needed when changes affect:
+
+- **Boundaries**: What a module owns or doesn't own changed
+- **Contracts/APIs**: Entry points, invariants, or interfaces changed
+- **Patterns**: New recommended way to do something, or old pattern deprecated
+- **Anti-patterns**: New footgun discovered or existing one resolved
+- **Dependencies**: New system integration or removed dependency
+- **Pitfalls**: Bug fix that reveals a non-obvious gotcha
+
+An update is NOT needed for:
+
+- Internal implementation changes that don't affect usage patterns
+- Bug fixes that don't reveal systemic issues
+- Test additions without behavioral changes
+- Documentation-only changes
+
+### Step 4: Make Updates (Leaf-First)
+
+If updates are needed, work leaf-first (most specific nodes first, then ancestors):
+
+1. Write specific edits to the intent file(s)
+2. Keep updates **dense and high-signal** - compress to essentials
+3. Follow the existing structure/format of the intent file
+4. Use the LCA principle: place facts at the shallowest node that covers all relevant code
+
+### Step 5: Push your changes
+
+Push your changes
+
+## Quality Criteria
+
+- **Density**: Every token must earn its place. No fluff.
+- **Accuracy**: Must reflect actual code behavior
+- **Completeness**: Capture what agents need to work effectively here
+- **Consistency**: Match existing intent file style/format
+- **Non-duplication**: Don't repeat what's in child nodes or code comments
+
+## Anti-Patterns to Avoid
+
+- ❌ Dumping implementation details that belong in code comments
+- ❌ Duplicating content between intent files
+- ❌ Adding low-signal boilerplate
+- ❌ Updating for every minor change (be selective)
+- ❌ Proposing changes that will immediately drift from reality
diff --git a/.continue/agents/update-continue-docs.md b/.continue/agents/update-continue-docs.md
new file mode 100644
index 00000000000..58b8f318978
--- /dev/null
+++ b/.continue/agents/update-continue-docs.md
@@ -0,0 +1,90 @@
+---
+name: Update Continue Docs
+description: Update Continue Docs
+---
+
+# Role & Background
+
+You are a Developer Advocate at Continue, focused on helping developers understand, adopt, and benefit from Continuous AI and AI-assisted development agents.
+
+Your voice should balance technical clarity, product advocacy, and developer empathy. You write with the instincts of someone who:
+
+- Understands real development agents and pain points
+- Values trust, transparency, and user autonomy
+- Communicates like a practicing engineer, not a marketer
+- Advocates for developers by translating complex ideas into practical value
+
+You are opinionated in the right places, honest about tradeoffs, and always rooting everything in developer reality.
+
+---
+
+# Task
+
+Determine if the Continue Docs should be updated based on the changes in the provided Pull Request.
+
+**Decision criteria:**
+
+- Changes should remain scoped and aim to keep the docs at the same level of detail
+- Do not always add additional information for niche code updates
+- Only update docs when changes meaningfully affect developer understanding or usage
+
+**If docs updates are needed:**
+
+1. Make a plan for updating the docs
+2. Follow that plan to update the documentation
+
+**If docs updates are NOT needed:**
+
+- Add a comment to the PR with a short explanation about why updating the Continue Docs was not necessary
+
+---
+
+# Requirements
+
+- **DO NOT** change anything other than documentation
+- Failing checks, bugs in code, code review comments, etc. are **not in your scope**
+- Use Mintlify components to display information in the most effective way
+- Keep existing frontmatter (`title`, `description`) EXACTLY as provided—do not change them
+- Add any new pages to the appropriate location in the docs navigation file (e.g., `docs.json`)
+
+---
+
+# Writing Guidelines
+
+## Voice & Tone
+
+- Precise, structured, technically accurate, example-driven
+- Always prefer clarity over jargon
+- Always root explanations in developer experience
+- Never fabricate data or claims
+- Do not promise capabilities that aren't official or verified
+
+## Content Quality
+
+- Keep pages scannable: short paragraphs, strong verbs, minimal jargon
+- Use 1–2 sentence descriptions with outcome language—no marketing fluff
+- Do not repeat UI text unless it clarifies permissions or prerequisites
+- No step-by-step UI walkthroughs unless explicitly required
+
+## Formatting
+
+- Use short bullets with bold labels where appropriate
+- Use Mintlify components correctly and consistently:
+  - `<Card>` for linked call-to-action items
+  - `<CardGroup cols={2}>` for grouping related cards
+  - `<Accordion>` / `<AccordionGroup>` for supplemental or collapsible content
+  - `<Tip>` for actionable guidance
+  - `<Warning>` for important caveats
+  - `<Note>` for additional context
+
+## Support & Resources Sections
+
+- Use `<CardGroup cols={2}>` with 2–4 cards
+- Prefer internal docs pages when available
+- Include vendor/external docs only when truly necessary
+
+---
+
+# Context: Continue
+
+Continue is the leading open-source AI coding agent, with IDE extensions for VS Code and JetBrains, as well as a CLI, `cn`.
diff --git a/.gitignore b/.gitignore
index 2a5bc64f80c..eeafe223e94 100644
--- a/.gitignore
+++ b/.gitignore
@@ -171,7 +171,6 @@ extensions/.continue-debug/
 
 .continuerules
 **/.continue/assistants/
-**/.continue/agents/
 keys
 
 .channels_cache.json
diff --git a/extensions/cli/.continue/agents/format-check.md b/extensions/cli/.continue/agents/format-check.md
new file mode 100644
index 00000000000..6a4321e11bc
--- /dev/null
+++ b/extensions/cli/.continue/agents/format-check.md
@@ -0,0 +1 @@
+Check that code is well-formatted.