Stop Cursor from Hallucinating: The Ultimate Context Setup for Next.js 15

If you are using Cursor, Windsurf, or GitHub Copilot to build a Next.js application, you have probably experienced The Hallucination Loop.

You ask the AI to add a new feature. It writes the code. You hit save, and your terminal explodes with errors. You paste the error back to the AI. It apologizes, writes more code, and creates three new errors.

Why does this happen? Because your AI does not have the right context.

Why AI Hallucinates Code

LLMs are trained on billions of lines of code. When you ask them to write a Next.js component, they have to choose between the Next.js 12 (Pages Router) syntax they learned in 2021, or the Next.js 15 (App Router) syntax they learned recently.

If your codebase is messy, or if you haven't explicitly told the AI what rules to follow, it will guess. And it usually guesses wrong.

How to Fix It: The .cursorrules File

The secret to stopping hallucinations is forcing the AI to read a set of strict guidelines before it writes a single line of code. In Cursor, this is done using a .cursorrules file in the root of your project.

Here is a snippet of what a good rule file looks like:

You are an expert full-stack developer using Next.js 15 (App Router), React 19, Tailwind CSS, and Drizzle ORM.

Strict Rules:
1. ALWAYS use the App Router (`app/` directory). Never use the Pages Router.
2. ALWAYS use server components by default. Only add `"use client"` when hooks (useState, useEffect) or event listeners are required.
3. For database queries, ALWAYS use Drizzle ORM syntax. Never write raw SQL strings.
4. For authentication, ALWAYS reference the Better-Auth session object.

By placing this file in your project, the AI reads it every time you hit Cmd+K. The hallucinations stop instantly.

The Ultimate AI-Native Boilerplate

Writing good context rules and structuring your files perfectly takes hours. If you want to skip the setup and start building immediately, you should use AgentStart.

AgentStart is a Next.js 15 boilerplate built specifically for the AI era. It comes out of the box with:

• A hyper-optimized .cursorrules file.
• Clean, modular architecture that AI can easily read.
• Drizzle ORM, Better-Auth, and Tailwind CSS already wired up.

Stop fighting with your AI. Get AgentStart here.