llms.txt is an open proposal for a short Markdown file that lists a project's key docs and links, so AI tools can find them without crawling every page.

Where should llms.txt be deployed?

At /llms.txt on your documentation site, or in your repository root. Tools read it when they fetch it; nothing loads it automatically.

# Next.js 16 App Router & Server Actions Specialist

> Production guidelines for Next.js App Router. Enforces React Server Components (RSC) by default, Server Actions for mutations with Zod validation, and Tailwind CSS v4 styling.

## Quick Reference

- **Framework**: Next.js 16 (App Router)

- **Language**: TypeScript

- **Styling & UI**: Tailwind CSS v4

- **Database / Persistence**: PostgreSQL / Prisma / Drizzle

- **Architectural Philosophy**: pragmatic

## Core Architectural Invariants

- **Server Components (RSC) First**: Default to React Server Components; keep client components confined to leaves.

- **Feature-Colocated Structure**: Group components, hooks, tests, and utils inside domain feature folders.

- **Guard Clauses & Early Returns**: Exit early from functions to eliminate deeply nested if-else pyramids.

- **Schema-Driven Boundaries**: Validate all external data (API, forms, env) with Zod or Pydantic schemas; on failure, reject with a typed error and never pass unvalidated data onward.

- **Accessible UI by Default**: Enforce semantic HTML, keyboard navigability, and proper ARIA roles.

## Operational Guardrails & Prohibited Patterns

- **Inspect Before Acting**: Always read and understand existing code and imports before suggesting changes.

- **Minimal Surgical Diffs**: Touch only lines relevant to prompt. Preserve existing comments and formatting.

- **Concise & Direct Tone**: Skip conversational pleasantries. Deliver focused diffs and a short rationale.

- **Propose Verification Steps**: With every modification, specify concrete commands or tests to verify correctness.

- **Preserve Codebase Idioms**: Match existing naming conventions, indentation, and directory patterns.

## Mandatory Project Directives

- Banned: Do not use pages/ router conventions or old getServerSideProps.

- Request interception lives in proxy.ts (export function proxy); middleware.ts is deprecated.

- Keep client bundles minimal; never import server libraries into client components.

- Use Next/Image for optimized media with explicit width/height or fill.

## Implementation Reference

### Preferred Patterns

```typescript

// Good: Server Action with Zod validation and safe error return

"use server";

import { z } from "zod";

import { db } from "@/lib/db";

const Schema = z.object({ email: z.string().email(), name: z.string().min(2) });

export async function createUserAction(formData: FormData) {

const parsed = Schema.safeParse(Object.fromEntries(formData));

if (!parsed.success) return { ok: false, errors: parsed.error.flatten().fieldErrors };

await db.user.create({ data: parsed.data });

return { ok: true };

}

```

### Discouraged Anti-Patterns

```typescript

// Discouraged: Unvalidated client-side mutation with inline API call

"use client";

export function SubmitUser() {

const submit = async (data: any) => {

await fetch("/api/users", { method: "POST", body: JSON.stringify(data) });

};

return <button onClick={submit}>Save</button>;

}

```

## Verification Commands & Workflows

1. Fetch data directly in React Server Components; never introduce 'use client' for purely read-only views.

2. Isolate client interactivity to leaf components (buttons, dropdowns, forms) with strict props interfaces.

3. Encapsulate data mutations inside Server Actions, validating input with Zod schemas before running database queries.

4. Await request APIs: params and searchParams props, cookies(), headers() and draftMode() are async in Next.js 16 and have no sync form.

5. Caching is opt-in: mark cached functions and components with "use cache" (cacheComponents: true). After a mutation call updateTag(tag) in the Server Action, or revalidateTag(tag, "max") for stale-while-revalidate.

6. Manage transient UI state with React 19 hooks (useActionState, useOptimistic) and searchParams for URL sync.

7. Provide dedicated loading.tsx skeletons and error.tsx error boundaries for all dynamic route segments.

## Context Documents & Specs

- [System Architecture](ARCHITECTURE.md): Authoritative system design, data flows, and state machine invariants.

- [AI Multi-Agent Spec](AGENTS.md): Universal specification for autonomous coding agent operations.

Frontend · Any LLM tool that fetches it

Next.js 16 App Router llms.txt

An llms.txt for a Next.js 16 App Router project: a short Markdown map of what it is and where the key docs and code live.

Path: llms.txt
Loads: Fetched on request
Format: Markdown index (.txt)
Used by: Any LLM tool that fetches it

All llms.txt presets and how llms.txt works

What this file tells the agent

An llms.txt gives language models and agents a short Markdown map of your Next.js 16 App Router project: what it is and where the key docs and code live, so a tool that fetches it can go straight to the right files.

Enforce React Server Components (RSC) by default; restrict 'use client' strictly to interactive leaf components.
Mutate state exclusively via Server Actions with Zod safeParse validation.
Await the async request APIs (cookies(), headers(), params, searchParams); Next.js 16 removed the sync forms.
Avoid pages/ directory conventions or legacy getServerSideProps.
Colocate loading.tsx and error.tsx for dynamic route segments.

Code to avoid, and what to write instead

The rule steers the agent away from the left and toward the right.

avoid

"use client";
export function SaveItem() {
  const submit = async (e: any) => {
    e.preventDefault();
    await fetch("/api/items", { method: "POST", body: JSON.stringify({ title: "Test" }) });
  };
  return <button onClick={submit}>Save</button>;
}

write instead

"use server";
import { z } from "zod";
import { db } from "@/lib/db";

const Schema = z.object({ title: z.string().min(3) });

export async function createItem(formData: FormData) {
  const parsed = Schema.safeParse(Object.fromEntries(formData));
  if (!parsed.success) return { ok: false, errors: parsed.error.flatten().fieldErrors };
  await db.item.create({ data: parsed.data });
  return { ok: true };
}

Install it in one command

01
Go to your project root
The file goes at llms.txt, relative to the root.
02
Download the file
Run the command on the right. It downloads this preset and writes the file.
03
Make sure it gets used
Nothing loads llms.txt automatically. Serve it at your site root, or point agents to it from CLAUDE.md or AGENTS.md.

$ curl -fsSL "https://www.devscratchpad.tech/api/raw/llms-txt/nextjs-16" -o "llms.txt"

writes llms.txt

path

llms.txt

To write the file from your own code instead, use Read your code or Convert Legacy Rules in the editor above.

More for Next.js 16 App Router

Other formats

Other llms.txt presets

Questions

What is llms.txt?: llms.txt is an open proposal for a short Markdown file that lists a project's key docs and links, so AI tools can find them without crawling every page.
Where should llms.txt be deployed?: At /llms.txt on your documentation site, or in your repository root. Tools read it when they fetch it; nothing loads it automatically.

Target Standard & File Format

Identity & Activation Rules

Technology Stack Context

Engineering Philosophy

Architectural & Code Quality Conventions

Agent Behavioral Guardrails

Step-by-Step Workflow Procedures

Target File Location