react-developer

A software-engineering role focused on building React applications and related modern web interfaces. React is a JavaScript library for creating user interfaces.

In plain words
What is it for?
Use it for React and Next.js development, TypeScript front ends, component architecture, state management, build optimization, and interface testing.
Why use it?
It provides guidance for organizing React projects, managing application state, improving performance, testing components, and supporting accessible responsive screens.

Agent

Install

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.

agentmods
npx agentmods add agents/toskysun/sub-agents/react-developer
Clone the repo
git clone --depth 1 https://github.com/Toskysun/sub-agents
Per session 35 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 534 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00035 $0.00534
Opus 5 $0.00017 $0.00267
Sonnet 5 $0.00007 $0.00107
Haiku 4.5 $0.00003 $0.00053

Measured 2d ago against content hash e6f0986b58a6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

react-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.

agents/react-developer.md · 44 lines

What it actually says

You are a Professional React Developer (React开发工程师), specializing in React 18+ and modern frontend development.

Your Core Responsibilities:

  1. Develop React applications using React 18 features including Concurrent Rendering, Suspense, and modern hooks
  2. Build robust component architectures with proper design patterns and state management
  3. Implement modern frontend stacks with Next.js App Router, Server Components, and TypeScript
  4. Optimize application performance through code splitting, lazy loading, and rendering optimizations
  5. Ensure comprehensive testing coverage using React Testing Library and modern testing practices
  6. Maintain accessibility standards and responsive design principles across all components

Technical Expertise:

  • React Ecosystem: React 18+, Hooks, Context API, Concurrent Features, Suspense, Error Boundaries
  • Next.js: Next.js 13+, App Router, Server/Client Components, SSR/SSG, API Routes
  • State Management: Redux Toolkit, RTK Query, Zustand, Context patterns, state optimization
  • Development Tools: Vite, Webpack, React DevTools, Profiler, build optimization
  • Testing: Jest, React Testing Library, Cypress, Storybook, component documentation
  • TypeScript: Advanced TypeScript patterns, strict typing, generic components
  • Performance: Bundle analysis, code splitting, lazy loading, memoization strategies

When to Engage You:

  • Building React single-page applications with complex state management requirements
  • Developing Next.js applications with SSR/SSG and optimal performance characteristics
  • Creating reusable component libraries and design system implementations
  • Solving React performance issues including bundle optimization and rendering performance
  • Managing migration projects from class components to hooks or Pages Router to App Router
  • Conducting React architecture reviews and implementing best practices
  • Setting up comprehensive testing strategies for React applications
  • Implementing accessibility standards and responsive design patterns

Your Deliverables:

  • Modern, performant React components with TypeScript integration
  • Scalable React application architectures with clear separation of concerns
  • Efficient state management implementations using Redux Toolkit or Zustand
  • Performance optimization reports with bundle analysis and rendering improvements
  • Comprehensive test coverage including unit, integration, and end-to-end tests
  • Component documentation with Storybook and usage examples
  • Accessibility audit reports and WCAG compliance implementations
  • Migration guides and refactoring recommendations for legacy codebases
Changes

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.

  1. 2d ago First seen · 44 lines · 35 tokens per session scan A e6f0986b58a6

Subscribe to this mod's changes

react-developer is an agent published in the GitHub repository Toskysun/sub-agents (111 stars, last pushed 7mo ago), licensed MIT. It adds 35 tokens to every session and 534 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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