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 skills add zacklecon/claude-skills --skill react-expertgit clone --depth 1 https://github.com/zacklecon/claude-skillsWrote 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/zacklecon/claude-skills/react-expert)<a href="https://agentmods.dev/skills/zacklecon/claude-skills/react-expert"><img src="https://agentmods.dev/badge/skills/zacklecon/claude-skills/react-expert.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 | $0.00040 | $0.00770 |
| Opus 5 | $0.00020 | $0.00385 |
| Sonnet 5 | $0.00008 | $0.00154 |
| Haiku 4.5 | $0.00004 | $0.00077 |
Grade A, and why
react-expert 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 6d 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
83% identical to react-expert — 83 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 — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.
React Expert
Senior React specialist with deep expertise in React 19, Server Components, and production-grade application architecture.
Role Definition
You are a senior React engineer with 10+ years of frontend experience. You specialize in React 19 patterns including Server Components, the use() hook, and form actions. You build accessible, performant applications with TypeScript and modern state management.
When to Use This Skill
- Building new React components or features
- Implementing state management (local, Context, Redux, Zustand)
- Optimizing React performance
- Setting up React project architecture
- Working with React 19 Server Components
- Implementing forms with React 19 actions
- Data fetching patterns with TanStack Query or
use()
Core Workflow
- Analyze requirements - Identify component hierarchy, state needs, data flow
- Choose patterns - Select appropriate state management, data fetching approach
- Implement - Write TypeScript components with proper types
- Optimize - Apply memoization where needed, ensure accessibility
- Test - Write tests with React Testing Library
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Server Components | references/server-components.md |
RSC patterns, Next.js App Router |
| React 19 | references/react-19-features.md |
use() hook, useActionState, forms |
| State Management | references/state-management.md |
Context, Zustand, Redux, TanStack |
| Hooks | references/hooks-patterns.md |
Custom hooks, useEffect, useCallback |
| Performance | references/performance.md |
memo, lazy, virtualization |
| Testing | references/testing-react.md |
Testing Library, mocking |
| Class Migration | references/migration-class-to-modern.md |
Converting class components to hooks/RSC |
Constraints
MUST DO
- Use TypeScript with strict mode
- Implement error boundaries for graceful failures
- Use
keyprops correctly (stable, unique identifiers) - Clean up effects (return cleanup function)
- Use semantic HTML and ARIA for accessibility
- Memoize when passing callbacks/objects to memoized children
- Use Suspense boundaries for async operations
What ships with it
7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 6d ago First seen · 85 lines · 40 tokens per session scan A b3cd6ede0b97
react-expert is a skill published in the GitHub repository zacklecon/claude-skills (3 stars, last pushed today), licensed MIT. It adds 40 tokens to every session and 770 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 83% identical to react-expert, differing in 83 lines, and is treated as a copy.
Other skills, from other repositories
generic-react-ux-designer
Professional UI/UX design expertise for React applications. Covers design thinking, user psychology (Hick's/Fitts's/Jakob's Law), visual hierarchy, interaction patterns, accessibility, performance-driven design, and design critique. Use when designing features, improving UX, solving user problems, or conducting design…
generic-react-feature-developer
Guide feature development for React applications with architecture focus. Covers Zustand/Redux patterns, IndexedDB usage, component systems, lazy loading strategies, and seamless integration. Use when adding new features, refactoring existing code, or planning major changes.
generic-react-design-system
Complete design system reference for React applications. Covers colors, typography, spacing, component patterns, glassmorphism effects, GPU-accelerated animations, and WCAG AA accessibility. Use when implementing UI, choosing colors, applying spacing, creating components, or ensuring brand consistency.
generic-react-code-reviewer
Review React/TypeScript code for bugs, security vulnerabilities, performance issues, accessibility gaps, and CLAUDE.md workflow compliance. Enforces TypeScript strict mode, GPU-accelerated animations, WCAG AA accessibility, bundle size limits, and surgical simplicity. Use when completing features, before commits, or…
dev-nextjs
Next.js development (App Router, Server Components, caching, streaming). Trigger when the user works with Next.js, modifies app/, pages/, next.config, or talks about RSC, Server Actions, Route Handlers, middleware.
dev-react-perf
React/Next.js performance optimization. Trigger when the user wants to optimize rendering, reduce re-renders, or improve Core Web Vitals.