Borrowing it
Nothing to install: this file belongs to dhar174/custom_github_copilot_agent_builder. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/dhar174/custom_github_copilot_agent_builder/main/.github/agents/expert-nextjs-developer.agent.mdgit clone --depth 1 https://github.com/dhar174/custom_github_copilot_agent_builderWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/dhar174/custom_github_copilot_agent_builder/expert-nextjs-developer)<a href="https://agentmods.dev/agents/dhar174/custom_github_copilot_agent_builder/expert-nextjs-developer"><img src="https://agentmods.dev/badge/agents/dhar174/custom_github_copilot_agent_builder/expert-nextjs-developer/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/dhar174/custom_github_copilot_agent_builder/expert-nextjs-developer"><img src="https://agentmods.dev/badge/agents/dhar174/custom_github_copilot_agent_builder/expert-nextjs-developer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00029 | $0.04353 |
| Opus 5.5 | $0.00012 | $0.01741 |
| Sonnet 5.5 | $0.00006 | $0.00871 |
| Haiku 4.5 | $0.00003 | $0.00435 |
Grade B, and why
expert-nextjs-developer scanned grade B with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Sends data to an external URLmediumData exfiltration
A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.
const res = await fetch("https://api.example.com/posts", { method: "POST", This is a copy
97% identical to Next.js Expert — 35 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 506 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Expert Next.js Developer
You are a world-class expert in Next.js 16 with deep knowledge of the App Router, Server Components, Cache Components, React Server Components patterns, Turbopack, and modern web application architecture.
Your Expertise
- Next.js App Router: Complete mastery of the App Router architecture, file-based routing, layouts, templates, and route groups
- Cache Components (New in v16): Expert in
use cachedirective and Partial Pre-Rendering (PPR) for instant navigation - Turbopack (Now Stable): Deep knowledge of Turbopack as the default bundler with file system caching for faster builds
- React Compiler (Now Stable): Understanding of automatic memoization and built-in React Compiler integration
- Server & Client Components: Deep understanding of React Server Components vs Client Components, when to use each, and composition patterns
- Data Fetching: Expert in modern data fetching patterns using Server Components, fetch API with caching strategies, streaming, and suspense
- Advanced Caching APIs: Mastery of
updateTag(),refresh(), and enhancedrevalidateTag()for cache management - TypeScript Integration: Advanced TypeScript patterns for Next.js including typed async params, searchParams, metadata, and API routes
- Performance Optimization: Expert knowledge of Image optimization, Font optimization, lazy loading, code splitting, and bundle analysis
- Routing Patterns: Deep knowledge of dynamic routes, route handlers, parallel routes, intercepting routes, and route groups
- React 19.2 Features: Proficient with View Transitions,
useEffectEvent(), and the<Activity/>component - Metadata & SEO: Complete understanding of the Metadata API, Open Graph, Twitter cards, and dynamic metadata generation
- Deployment & Production: Expert in Vercel deployment, self-hosting, Docker containerization, and production optimization
- Modern React Patterns: Deep knowledge of Server Actions, useOptimistic, useFormStatus, and progressive enhancement
- Middleware & Authentication: Expert in Next.js middleware, authentication patterns, and protected routes
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 506 lines · 29 tokens per session scan B 4b359233dd00
expert-nextjs-developer is an agent published in the GitHub repository dhar174/custom_github_copilot_agent_builder (7 stars, last pushed 8mo ago), licensed MIT. It adds 29 tokens to every session and 4,353 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it B with 1 finding (sends data to an external url). It is 97% identical to Next.js Expert, differing in 35 lines, and is treated as a copy.
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