Add Feature

Add Feature Skill

You are helping add a new feature to a Next.js 15 application with TypeScript, Tailwind CSS, BetterAuth, and Drizzle ORM.

Context

This is a Next.js 15 App Router project with:

• Server Components by default
• Drizzle ORM for database (PostgreSQL)
• BetterAuth for authentication
• TypeScript strict mode
• Tailwind CSS v4 + shadcn/ui

Your Task

When the user asks to add a feature, follow this workflow:

1. Understand Requirements

Ask clarifying questions:

• What routes are needed?
• Is authentication required?
• Does it need database tables?
• What data needs to be displayed?
• What user interactions are needed?

2. Plan Architecture

Before coding, outline:

Route Structure:
- app/[feature-name]/page.tsx (main page)
- app/[feature-name]/layout.tsx (if needed)
- app/[feature-name]/loading.tsx (loading state)
- app/[feature-name]/error.tsx (error boundary)

Database Schema:
- lib/server/db/schema/[feature].ts (if new tables needed)

Server Actions:
- lib/actions/[feature].ts (for mutations)

Components:
- components/[feature]/ (feature-specific components)

3. Implementation Order

Always implement in this order:

Step 1: Database Schema (if needed)

Create schema file:

// lib/server/db/schema/[feature].ts
import { pgTable, text, timestamp, uuid, boolean } from "drizzle-orm/pg-core"
import { createInsertSchema, createSelectSchema } from "drizzle-zod"

export const [tableName] = pgTable("[table_name]", {
  id: uuid("id").primaryKey().defaultRandom(),
  // Add fields here
  createdAt: timestamp("createdAt").notNull().defaultNow(),
  updatedAt: timestamp("updatedAt").notNull().defaultNow(),
})

export const insert[TableName]Schema = createInsertSchema([tableName])
export const select[TableName]Schema = createSelectSchema([tableName])

export type [TableName] = typeof [tableName].$inferSelect
export type New[TableName] = typeof [tableName].$inferInsert

Export from schema/index.ts:

export * from "./[feature]"

Run migration:

npm run db:push

Step 2: Server Actions (if mutations needed)

Create server actions:

// lib/actions/[feature].ts
"use server"

import { db } from "@/lib/server/db"
import { [tableName], insert[TableName]Schema } from "@/lib/server/db/schema"
import { revalidatePath } from "next/cache"
import { z } from "zod"

export async function create[Resource](data: z.infer<typeof insert[TableName]Schema>) {
  try {
    const validated = insert[TableName]Schema.parse(data)
    const [created] = await db.insert([tableName]).values(validated).returning()
    revalidatePath("/[feature-path]")
    return { success: true, data: created }
  } catch (error) {
    return {
      success: false,
      error: error instanceof Error ? error.message : "Unknown error"
    }
  }
}

Step 3: Page Components

Create the main page (Server Component):

// app/[feature]/page.tsx
import { db } from "@/lib/server/db"
import { [tableName] } from "@/lib/server/db/schema"

export const metadata = {
  title: "[Feature Title]",
  description: "[Feature description]",
}

export default async function [Feature]Page() {
  // Fetch data in Server Component
  const data = await db.query.[tableName].findMany()

  return (
    <div className="container mx-auto p-8">
      <h1 className="text-3xl font-bold">[Feature Title]</h1>
      {/* Render data */}
    </div>
  )
}

Step 4: Interactive Components (Client Components)

Only create Client Components when needed:

// components/[feature]/[component-name].tsx
"use client"

import { useState } from "react"
import { create[Resource] } from "@/lib/actions/[feature]"
import { Button } from "@/components/ui/button"

export function [ComponentName]() {
  const [isLoading, setIsLoading] = useState(false)

  async function handleAction() {
    setIsLoading(true)
    const result = await create[Resource](data)
    setIsLoading(false)
  }

  return (
    <div>
      <Button disabled={isLoading}>
        {isLoading ? "Loading..." : "Action"}
      </Button>
    </div>
  )
}

Step 5: Loading & Error States

Create loading.tsx:

// app/[feature]/loading.tsx
export default function Loading() {
  return (
    <div className="container mx-auto p-8">
      <div className="h-8 w-64 animate-pulse rounded bg-muted" />
    </div>
  )
}

Create error.tsx:

// app/[feature]/error.tsx
"use client"

export default function Error({ error, reset }: {
  error: Error
  reset: () => void
}) {
  return (
    <div className="container mx-auto p-8">
      <h2>Something went wrong!</h2>
      <button => reset()}>Try again</button>
    </div>
  )
}

Step 6: Authentication (if needed)

⚠️ Always use server layouts for auth, NOT middleware.

Add auth layout with forced dynamic rendering:

// app/[feature]/layout.tsx
import { redirect } from "next/navigation"
import { auth } from "@/lib/server/auth"
import { headers } from "next/headers"

// ⚠️ CRITICAL: Force dynamic rendering for fresh auth checks
export const dynamic = "force-dynamic"

export default async function [Feature]Layout({
  children,
}: {
  children: React.ReactNode
}) {
  const session = await auth.api.getSession({
    headers: await headers(),
  })

  if (!session) {
    redirect("/auth/signin")
  }

  return <>{children}</>
}

Why server layouts for auth:

• ✅ Execute on the same request (no extra hops)
• ✅ Full TypeScript support and type inference
• ✅ Can render UI and compose with data fetching
• ✅ Co-located with protected routes

Do NOT use middleware for auth gates - middleware should only be used for session refresh and cross-cutting concerns like i18n.

4. Best Practices Checklist

Before completing, verify:

• Server Components by default
• Client Components only when needed
• Type safety (TypeScript + Zod validation)
• Error handling in server actions
• Loading states (loading.tsx)
• Error boundaries (error.tsx)
• Metadata for SEO
• Revalidation after mutations
• Mobile-responsive design
• Accessibility (ARIA attributes, semantic HTML)

5. Testing

After implementation:

1. Test the feature manually
2. Verify TypeScript compilation: npm run type-check
3. Check for lint errors: npm run lint
4. Test all user flows
5. Verify error states
6. Test loading states

Key Principles

1. Server-First: Always start with Server Components
2. Type Safety: Use TypeScript and Zod everywhere
3. Co-location: Keep related code together
4. Performance: Minimize client-side JavaScript
5. User Experience: Always show loading and error states
6. Security: Validate all inputs, check permissions

Common Patterns

Data Fetching Pattern

// In Server Component
const data = await db.query.table.findMany()

Mutation Pattern

// In Server Action
"use server"
const validated = schema.parse(data)
await db.insert(table).values(validated)
revalidatePath("/path")

Form Pattern

// Client Component
const result = await serverAction(formData)
if (result.success) {
  router.push("/success")
}

Now, help the user implement their feature following these guidelines!