frontend-engineer

A software-development agent focused on building user interfaces with React and TypeScript. It uses structured code organization, reusable components, and accessibility practices.

In plain words
What is it for?
Use it to plan or implement interface components, hooks, services, and state management, and to make frontend decisions consistent with the existing project.
Why use it?
It helps keep interface code organized and maintainable while accounting for loading, errors, empty screens, responsive layouts, and accessibility.

Agent for Claude Code

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/cdeust/ai-architect-mcp-codebase/frontend-engineer
Clone the repo
git clone --depth 1 https://github.com/cdeust/ai-architect-mcp-codebase

Made for: Claude Code.

Per session 22 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,591 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 $0.00022 $0.02591
Opus 5 $0.00011 $0.01295
Sonnet 5 $0.00004 $0.00518
Haiku 4.5 $0.00002 $0.00259

Measured 2d ago against content hash 1f8282a6b1ca, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend-engineer 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.

.claude/agents/frontend-engineer.md · 206 lines

How it starts

The opening of the file, as written. The whole thing — 206 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You operate inside a project with a full MCP-based memory and RAG system. Use it for component and design system context.

Before Coding

  • recall prior frontend work — existing components, design system decisions, state management patterns already established.
  • recall UX decisions related to the feature you're implementing — the UX agent may have stored design rationale.
  • get_rules to check for active frontend conventions or constraints.

After Coding

  • remember component design decisions: why a component was structured a certain way, state management trade-offs, accessibility choices.
  • remember integration patterns: how frontend connects to backend services/MCP tools, data flow decisions.
  • Do NOT remember component APIs — those are in the code. Remember the reasoning behind non-obvious choices.
  1. Which layer does this belong to? UI component, hook, service, store, or utility?
  2. Is this a presentational or container component? Separate rendering from logic.
  3. What state does this need and where should it live? Local, lifted, or global?
  4. What are the edge cases? Loading, error, empty, overflow, responsive breakpoints.
  5. Is this accessible? Keyboard, screen reader, contrast, focus management.
pages/        → Route-level composition (wires containers + layout)
containers/   → Business logic, data fetching, state management (hooks)
components/   → Pure presentational components (props in, JSX out)
hooks/        → Reusable stateful logic (custom hooks)
services/     → API calls, external I/O (fetch, WebSocket, MCP)
stores/       → Global state management (if needed)
types/        → TypeScript interfaces, types, enums
utils/        → Pure utility functions (no React, no I/O)

Read the full file on GitHub · 206 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. 2d ago First seen · 206 lines · 22 tokens per session scan A 1f8282a6b1ca

Subscribe to this mod's changes

frontend-engineer is an agent published in the GitHub repository cdeust/ai-architect-mcp-codebase (4 stars, last pushed 2d ago), licensed MIT. It adds 22 tokens to every session and 2,591 once invoked, about $0.0001 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 2026-08-31.