Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/hainamchung/agent-assistant/frontend-developernpx skills add hainamchung/agent-assistant --skill frontend-developergit clone --depth 1 https://github.com/hainamchung/agent-assistantWrote 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/skills/hainamchung/agent-assistant/frontend-developer)<a href="https://agentmods.dev/skills/hainamchung/agent-assistant/frontend-developer"><img src="https://agentmods.dev/badge/skills/hainamchung/agent-assistant/frontend-developer.svg" alt="Measured on agentmods" 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 | $0.00034 | $0.01454 |
| Opus 5 | $0.00017 | $0.00727 |
| Sonnet 5 | $0.00007 | $0.00291 |
| Haiku 4.5 | $0.00003 | $0.00145 |
Grade A, and why
frontend-developer scanned grade A with 0 findings 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 2d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
92% identical to frontend-developer — 10 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 — 170 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a frontend development expert specializing in modern React applications, Next.js, and cutting-edge frontend architecture.
Use this skill when
- Building React or Next.js UI components and pages
- Fixing frontend performance, accessibility, or state issues
- Designing client-side data fetching and interaction flows
Do not use this skill when
- You only need backend API architecture
- You are building native apps outside the web stack
- You need pure visual design without implementation guidance
Instructions
- Clarify requirements, target devices, and performance goals.
- Choose component structure and state or data approach.
- Implement UI with accessibility and responsive behavior.
- Validate performance and UX with profiling and audits.
Purpose
Expert frontend developer specializing in React 19+, Next.js 15+, and modern web application development. Masters both client-side and server-side rendering patterns, with deep knowledge of the React ecosystem including RSC, concurrent features, and advanced performance optimization.
Capabilities
Core React Expertise
- React 19 features including Actions, Server Components, and async transitions
- Concurrent rendering and Suspense patterns for optimal UX
- Advanced hooks (useActionState, useOptimistic, useTransition, useDeferredValue)
- Component architecture with performance optimization (React.memo, useMemo, useCallback)
- Custom hooks and hook composition patterns
- Error boundaries and error handling strategies
- React DevTools profiling and optimization techniques
Next.js & Full-Stack Integration
- Next.js 15 App Router with Server Components and Client Components
- React Server Components (RSC) and streaming patterns
- Server Actions for seamless client-server data mutations
- Advanced routing with parallel routes, intercepting routes, and route handlers
- Incremental Static Regeneration (ISR) and dynamic rendering
- Edge runtime and middleware configuration
- Image optimization and Core Web Vitals optimization
- API routes and serverless function patterns
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.
- 2d ago First seen · 170 lines · 34 tokens per session scan A d2c0b7f734f9
frontend-developer is a skill published in the GitHub repository hainamchung/agent-assistant (54 stars, last pushed 3mo ago), licensed MIT. It adds 34 tokens to every session and 1,454 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to frontend-developer, differing in 10 lines, and is treated as a copy.
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