AgentSkillsCN

frontend-patterns

Next.js App Router、Clerk 认证、shadcn/Radix UI 和 PostHog 分析的前端模式。在构建 UI 组件、创建页面、实现认证流程或添加分析事件时使用。确保一致的 UX 模式和无障碍标准。

SKILL.md
--- frontmatter
name: frontend-patterns
description: Frontend patterns for Next.js App Router, Clerk auth, shadcn/Radix UI, and PostHog analytics. Use when building UI components, creating pages, implementing auth flows, or adding analytics events. Ensures consistent UX patterns and accessibility standards.

Frontend Patterns Skill

Purpose

Ensure consistent frontend development using established patterns for Next.js App Router, Clerk authentication, shadcn/ui components, and PostHog analytics.

When This Skill Applies

Invoke this skill when:

  • •Building new UI components or pages
  • •Implementing authentication flows
  • •Adding forms with validation
  • •Integrating PostHog analytics events
  • •Creating protected/authenticated routes
  • •Working with shadcn/ui or Radix components

Next.js App Router Patterns

Server vs Client Components

typescript
// SERVER COMPONENT (default) - Use for:
// - Data fetching
// - Auth checks
// - SEO-critical content
// app/dashboard/page.tsx
import { auth } from "@clerk/nextjs/server";

export default async function DashboardPage() {
  const { userId } = await auth();
  // Fetch data server-side...
}

// CLIENT COMPONENT - Use for:
// - Interactivity (onClick, onChange)
// - Browser APIs (localStorage, window)
// - Hooks (useState, useEffect)
// app/dashboard/_components/interactive-widget.tsx
("use client");

import { useState } from "react";

export function InteractiveWidget() {
  const [count, setCount] = useState(0);
  // Interactive logic...
}

Protected Pages

CRITICAL: Always use export const dynamic = 'force-dynamic' for authenticated pages:

typescript
// app/dashboard/[page]/page.tsx
import { auth } from "@clerk/nextjs/server";
import { redirect } from "next/navigation";

// REQUIRED - Auth context unavailable at build time
export const dynamic = "force-dynamic";

export default async function ProtectedPage() {
  const { userId } = await auth();

  if (!userId) {
    redirect("/sign-in");
  }

  // Render protected content...
}

Route Organization

text
app/
├── (auth)/                    # Auth routes (sign-in, sign-up)
│   ├── sign-in/[[...sign-in]]/page.tsx
│   └── sign-up/[[...sign-up]]/page.tsx
├── (marketing)/               # Public marketing pages
│   ├── page.tsx               # Homepage
│   └── pricing/page.tsx
├── dashboard/                 # Protected user area
│   ├── page.tsx
│   └── _components/           # Page-specific components
└── admin/                     # Admin-only area
    └── page.tsx

Clerk Authentication Patterns

Auth-Enabled Mode

typescript
// Server component auth check
import { auth } from '@clerk/nextjs/server';

export default async function Page() {
  const { userId } = await auth();
  // userId is string | null
}

// Client component auth
"use client"
import { useUser, useAuth } from '@clerk/nextjs';

export function UserProfile() {
  const { user, isLoaded, isSignedIn } = useUser();
  const { signOut } = useAuth();

  if (!isLoaded) return <Skeleton />;
  if (!isSignedIn) return <SignInPrompt />;

  return <div>Welcome, {user.firstName}!</div>;
}

Auth-Disabled Mode (Feature Toggle)

When auth is disabled via feature flags, provide graceful fallbacks:

typescript
// Check feature flag
import { FEATURES } from '@/config/features';

export function AuthWrapper({ children }) {
  if (!FEATURES.AUTH_ENABLED) {
    // Show demo/guest experience
    return <GuestExperience>{children}</GuestExperience>;
  }

  return <AuthenticatedWrapper>{children}</AuthenticatedWrapper>;
}

Admin Verification

typescript
// app/admin/page.tsx
import { auth } from "@clerk/nextjs/server";
import { redirect } from "next/navigation";

export const dynamic = "force-dynamic";

export default async function AdminPage() {
  const { userId, orgId, orgRole } = await auth();

  if (!userId) {
    redirect("/sign-in");
  }

  // Verify admin role
  const ADMIN_ORG_ID = process.env.CLERK_ADMIN_ORG_ID;
  const ADMIN_ROLE = "org:admin";

  if (orgId !== ADMIN_ORG_ID || orgRole !== ADMIN_ROLE) {
    redirect("/admin-denied");
  }

  // Render admin content...
}

shadcn/ui Component Patterns

Import Convention

typescript
// Always use @/components/ui path alias
import { Button } from "@/components/ui/button";
import { Card, CardHeader, CardTitle, CardContent } from "@/components/ui/card";
import { Input } from "@/components/ui/input";
import {
  Form,
  FormControl,
  FormField,
  FormItem,
  FormLabel,
  FormMessage,
} from "@/components/ui/form";

Form Pattern (React Hook Form + Zod)

typescript
"use client"

import { zodResolver } from '@hookform/resolvers/zod';
import { useForm } from 'react-hook-form';
import { z } from 'zod';
import { Button } from '@/components/ui/button';
import { Form, FormControl, FormField, FormItem, FormLabel, FormMessage } from '@/components/ui/form';
import { Input } from '@/components/ui/input';

const FormSchema = z.object({
  email: z.string().email('Invalid email'),
  name: z.string().min(1, 'Name is required'),
});

type FormData = z.infer<typeof FormSchema>;

export function MyForm() {
  const form = useForm<FormData>({
    resolver: zodResolver(FormSchema),
    defaultValues: { email: '', name: '' },
  });

  async function onSubmit(data: FormData) {
    // Handle submission...
  }

  return (
    <Form {...form}>
      <form onSubmit={form.handleSubmit(onSubmit)} className="space-y-4">
        <FormField
          control={form.control}
          name="name"
          render={({ field }) => (
            <FormItem>
              <FormLabel>Name</FormLabel>
              <FormControl>
                <Input {...field} />
              </FormControl>
              <FormMessage />
            </FormItem>
          )}
        />
        <Button type="submit">Submit</Button>
      </form>
    </Form>
  );
}

Button Variants

typescript
// Primary action
<Button>Save Changes</Button>

// Secondary action
<Button variant="secondary">Cancel</Button>

// Destructive action
<Button variant="destructive">Delete</Button>

// Ghost/subtle
<Button variant="ghost">Learn More</Button>

// Link style
<Button variant="link" asChild>
  <Link href="/docs">Documentation</Link>
</Button>

// Loading state
<Button disabled={isLoading}>
  {isLoading ? 'Saving...' : 'Save'}
</Button>

PostHog Analytics Patterns

Event Naming Convention

Use snake_case with category prefix:

typescript
// User actions
"user_signed_up";
"user_signed_in";
"user_profile_updated";

// Feature usage
"feature_dark_mode_toggled";
"feature_export_clicked";

// Payments
"payment_checkout_started";
"payment_completed";
"subscription_upgraded";

// Content
"content_video_watched";
"content_pdf_downloaded";

// Navigation
"page_viewed";
"cta_clicked";

Event Tracking

typescript
"use client"

import { usePostHog } from 'posthog-js/react';

export function TrackableButton() {
  const posthog = usePostHog();

  function handleClick() {
    posthog?.capture('cta_clicked', {
      button_text: 'Get Started',
      page: '/pricing',
      variant: 'primary',
    });
  }

  return <Button onClick={handleClick}>Get Started</Button>;
}

Page View Tracking

typescript
// Automatic via PostHogProvider (already configured)
// Manual tracking for SPAs:
"use client";

import { usePathname } from "next/navigation";
import { usePostHog } from "posthog-js/react";
import { useEffect } from "react";

export function PageViewTracker() {
  const pathname = usePathname();
  const posthog = usePostHog();

  useEffect(() => {
    if (pathname && posthog) {
      posthog.capture("$pageview", { path: pathname });
    }
  }, [pathname, posthog]);

  return null;
}

Feature Flags

typescript
"use client"

import { useFeatureFlagEnabled } from 'posthog-js/react';

export function FeatureFlaggedComponent() {
  const showNewFeature = useFeatureFlagEnabled('new-checkout-flow');

  if (showNewFeature) {
    return <NewCheckoutFlow />;
  }

  return <LegacyCheckoutFlow />;
}

Accessibility Checklist

Required for All Components

  • • Keyboard Navigation: All interactive elements focusable via Tab
  • • Focus Indicators: Visible focus ring (Tailwind: focus:ring-2)
  • • Color Contrast: 4.5:1 minimum for text
  • • Alt Text: All images have descriptive alt text
  • • ARIA Labels: Form inputs have labels or aria-label
  • • Error States: Form errors announced to screen readers

Patterns

typescript
// Accessible button
<Button aria-label="Close dialog">
  <X className="h-4 w-4" />
</Button>

// Accessible form field
<FormItem>
  <FormLabel htmlFor="email">Email</FormLabel>
  <FormControl>
    <Input id="email" type="email" aria-describedby="email-error" />
  </FormControl>
  <FormMessage id="email-error" />
</FormItem>

// Skip link for keyboard users
<a href="#main-content" className="sr-only focus:not-sr-only">
  Skip to main content
</a>

Responsive Design Patterns

Tailwind Breakpoints

typescript
// Mobile-first approach
<div className="
  px-4           // Mobile: 16px padding
  md:px-6        // Tablet: 24px padding
  lg:px-8        // Desktop: 32px padding
">

// Responsive grid
<div className="
  grid
  grid-cols-1    // Mobile: 1 column
  md:grid-cols-2 // Tablet: 2 columns
  lg:grid-cols-3 // Desktop: 3 columns
  gap-4
">

// Hide/show at breakpoints
<div className="hidden md:block">Desktop only</div>
<div className="md:hidden">Mobile only</div>

Container Pattern

typescript
// Standard container
<div className="container mx-auto px-4 md:px-6">
  {/* Content */}
</div>

// Max-width constrained
<div className="max-w-4xl mx-auto px-4">
  {/* Narrower content like articles */}
</div>

Common Mistakes to Avoid

DON'T Do This

typescript
// ❌ Missing 'use client' for interactive components
import { useState } from 'react';  // Will error!

// ❌ Using hooks in server components
export default async function Page() {
  const [state, setState] = useState();  // Will error!
}

// ❌ Missing force-dynamic on auth pages
export default async function ProtectedPage() {
  const { userId } = await auth();  // May fail at build!
}

// ❌ Direct DOM manipulation
document.getElementById('foo');  // Use refs instead

// ❌ Inline styles (use Tailwind)
<div style={{ marginTop: '20px' }}>  // Use className="mt-5"

DO This Instead

typescript
// ✅ Proper client component
"use client"
import { useState } from 'react';

// ✅ Server component with auth
export const dynamic = 'force-dynamic';
export default async function Page() {
  const { userId } = await auth();
}

// ✅ Use refs for DOM access
const inputRef = useRef<HTMLInputElement>(null);

// ✅ Tailwind classes
<div className="mt-5">

Authoritative References

  • •UI Patterns: docs/patterns/ui/
    • •authenticated-page.md - Protected page pattern
    • •form-with-validation.md - React Hook Form + Zod
    • •data-table.md - Server-side paginated tables
    • •marketing-page.md - Public marketing pages
  • •Component Library: components/ui/ (shadcn/ui)
  • •PostHog Setup: lib/posthog/
  • •Feature Flags: config/features.ts