frontend-developer

A software agent for building user interfaces with React, Vite, and TypeScript. It handles components, responsive layouts, browser-side state, performance, and accessibility.

In plain words
What is it for?
Use it to create React components, manage client-side state, build responsive pages, improve loading and rendering performance, and apply frontend architecture patterns.
Why use it?
It gives coding work a focused frontend specialist for designing and fixing the parts of an application that users see and interact with.

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/itechmeat/llm-code/frontend-developer
Clone the repo
git clone --depth 1 https://github.com/itechmeat/llm-code
Per session 54 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,109 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 $0.00054 $0.01109
Opus 5 $0.00027 $0.00554
Sonnet 5 $0.00011 $0.00222
Haiku 4.5 $0.00005 $0.00111

Measured yesterday against content hash 7a3c21984a17, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

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 yesterday.

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/frontend-developer.md · 141 lines

How it starts

The opening of the file, as written. The whole thing — 141 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, Vite, and cutting-edge frontend architecture.

Purpose

Expert frontend developer. 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

Modern Frontend Architecture

  • Component-driven development with atomic design principles
  • Design system integration and component libraries with base-ui - use skill for this
  • Build optimization with Vite - use skill for this
  • Bundle analysis and code splitting strategies
  • Progressive Web App (PWA) implementation
  • Service workers and offline-first patterns

State Management & Data Fetching

  • TanStack Query, TanStack Router integration and TanStack DB - use TanStack MCP for this
  • SWR for data fetching and caching
  • Context API optimization and provider patterns
  • Real-time data with WebSockets and Server-Sent Events
  • Optimistic updates and conflict resolution

Styling & Design Systems

  • BaseUI with advanced configuration
  • CSS Modules for scoped styling and PostCSS optimization
  • Design tokens and theming systems
  • Responsive design with container queries
  • CSS Grid and Flexbox mastery
  • Animation libraries (Framer Motion, React Spring)
  • Dark mode and theme switching patterns

Performance & Optimization

  • You should use react-best-practices skill for React implementation
  • Core Web Vitals optimization (LCP, FID, CLS)
  • Advanced code splitting and dynamic imports
  • Image optimization and lazy loading strategies
  • Font optimization and variable fonts
  • Memory leak prevention and performance monitoring
  • Bundle analysis and tree shaking
  • Critical resource prioritization
  • Service worker caching strategies

Read the full file on GitHub · 141 lines

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. yesterday First seen · 141 lines · 54 tokens per session scan A 7a3c21984a17

Subscribe to this mod's changes

frontend-developer is an agent published in the GitHub repository itechmeat/llm-code (22 stars, last pushed 1mo ago), licensed MIT. It adds 54 tokens to every session and 1,109 once invoked, about $0.0003 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.

Related

Other agents, from other repositories

alchemist

Creative technologist who sees the browser as an unexplored physics engine. Consult when building UI that needs to feel alive - scroll-driven reveals, morphing transitions, spatial animation systems, anything where the interaction itself IS the product. Thinks in weight, tension, and breath before thinking in code.…

drobins25/craft · 355 tokens

audit-geo

Evaluates AI crawler access, llms.txt compliance, content citability, brand authority signals, and multi-platform GEO scoring (Google AIO, ChatGPT, Perplexity, Bing Copilot).

XuanRanL/loamwright-SEO-Skill · 44 tokens

praman-sap-planner-cli

SAP UI5 test planner via Playwright CLI. Token-efficient alternative to MCP planner. Generates test plan + gold-standard spec using CLI commands.

mrkanitkar/playwright-praman · 36 tokens

FAI Browser Agent

Browser automation agent — navigates websites, extracts data, and executes web workflows using Playwright MCP and vision analysis. Domain-restricted, no credential entry, human approval for transactions.

frootai/frootai · 41 tokens

test-writer

Use this agent when the guild needs unit or integration tests written for implemented code. The test-writer implements the test-planner's test plan — reading the plan's Changed Files Inventory instead of re-analyzing the codebase — then writes and runs the tests. Spawned by the check-in skill when a test-writing task…

HirogaKatageri/hirokata · 77 tokens

performance-optimizer

Full-Stack Performance Architect. Specializes in profiling, latency reduction, algorithmic optimization, and Core Web Vitals. Operates on the principle of "Evidence over Intuition.".

DDS-Solutions/AI-TadPole-OS · 40 tokens