frontend-engineering

frontend-engineering is a skill for Claude Code, Codex from magnus919/hermes-profiles. It costs 39 tokens per session (842 once invoked), scanned A, original, MIT.

A framework-neutral method for building the user-facing part of web applications. It covers reusable interface components, browser-side data and state, responsive layouts, API connections, performance, and frontend tests.

In plain words
What is it for?
Use it to build components, manage client-side state, connect interfaces to APIs, implement authentication and live updates, support different screen sizes, improve loading and rendering, and test frontend code.
Why use it?
Frontend work can become difficult to maintain when interface structure, data flow, mobile layouts, and performance are handled inconsistently. This provides guidance for organizing those implementation decisions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to build components, manage client-side state, connect interfaces to APIs, implement authentication and live updates, support different screen sizes, improve loading and rendering, and test frontend code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/magnus919/hermes-profiles/frontend-engineering
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.

Any agent
npx skills add magnus919/hermes-profiles --skill frontend-engineering
Clone the repo
git clone --depth 1 https://github.com/magnus919/hermes-profiles

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for frontend-engineering

README.md
[![agentmods](https://agentmods.dev/badge/skills/magnus919/hermes-profiles/frontend-engineering/github.svg)](https://agentmods.dev/skills/magnus919/hermes-profiles/frontend-engineering)
Your own site
<a href="https://agentmods.dev/skills/magnus919/hermes-profiles/frontend-engineering"><img src="https://agentmods.dev/badge/skills/magnus919/hermes-profiles/frontend-engineering/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for frontend-engineering

Your own site · 80×15
<a href="https://agentmods.dev/skills/magnus919/hermes-profiles/frontend-engineering"><img src="https://agentmods.dev/badge/skills/magnus919/hermes-profiles/frontend-engineering.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 842 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00039 $0.00842
Opus 5 $0.00019 $0.00421
Sonnet 5 $0.00008 $0.00168
Haiku 4.5 $0.00004 $0.00084

Measured 9d ago against content hash 4e2280641037, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

frontend-engineering 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 9d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/frontend-engineering/SKILL.md · 50 lines

How it starts

The opening of the file, as written. The whole thing — 50 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Frontend Engineering Methodology

Frontend engineering is the craft of building the user-facing layer of applications — components, state management, API integration, responsive layout, and client-side performance. This methodology bridges UX design (user journeys, wireframes, accessibility standards) and the reviewer (code quality gate).

The Frontend Engineer's Domain

You own You don't own
Component implementation — UI component composition, props/state interfaces, rendering patterns, lifecycle User journeys, wireframes, accessibility standards, interaction design — that's the ux-designer
State management — client-side state architecture, data fetching patterns, caching, optimistic updates API contract design — that's the technical-architect
API integration — frontend-to-backend data flow, auth flows (OAuth, JWT), real-time updates Test strategy and automation — that's the QA-engineer
Responsive design implementation — layout systems, breakpoints, cross-device testing Visual identity and brand guidelines — that's the brand-designer
Client-side performance — bundle optimization, lazy loading, Core Web Vitals, render optimization Editorial content and copy — that's the writer
Frontend testing — component tests, integration tests, visual regression, accessibility tests Code review and quality gates — that's the reviewer
Build tooling — bundler config, TypeScript config, linting, formatting, dev environment CI/CD pipeline infrastructure — that's the platform-engineer

Reference Files

Reference When to load
references/component-architecture.md Designing component trees — composition patterns, props/state interfaces, lifecycle, accessibility fundamentals
references/state-management.md Choosing and implementing state management — client vs server state, data fetching, caching, optimistic updates
references/api-integration.md Connecting frontend to backend — API client design, auth token flow, error handling in the UI, real-time subscriptions
references/responsive-layout-testing.md Implementing responsive designs (layout system selection — Grid vs Flexbox vs Container Queries, breakpoint strategies, cross-device testing methodology) and testing frontend code (component testing with Testing Library, integration testing with Playwright/Cypress, visual regression, accessibility testing with axe-core and Lighthouse CI, test data management)
references/performance.md Optimizing client-side performance — Core Web Vitals, bundle analysis, code splitting, render optimization

Read the full file on GitHub · 50 lines

Files

What ships with it

5 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.

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. 9d ago First seen · 50 lines · 39 tokens per session scan A 4e2280641037

Subscribe to this mod's changes

frontend-engineering is a skill published in the GitHub repository magnus919/hermes-profiles (152 stars, last pushed 2mo ago), licensed MIT. It adds 39 tokens to every session and 842 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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