frontend

A frontend development guide with an authoring mode for building user interfaces and a read-only critique mode for reviewing them against set criteria.

In plain words
What is it for?
Use it to plan visual direction, create or update DESIGN.md files, handle loading and error states, improve responsive layouts and performance, or score an existing interface.
Why use it?
It helps avoid inaccessible, poorly adapted, slow, or generic-looking interfaces, and makes review findings more consistent.

Skill for Claude CodeCodex

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 skills/romiluz13/cc10x/frontend
Any agent
npx skills add romiluz13/cc10x --skill frontend
Clone the repo
git clone --depth 1 https://github.com/romiluz13/cc10x

Made for: Claude Code, Codex.

Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,912 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 $0.00063 $0.01912
Opus 5 $0.00032 $0.00956
Sonnet 5 $0.00013 $0.00382
Haiku 4.5 $0.00006 $0.00191

Measured 2d ago against content hash b0a7e20c52f3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend 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.

plugins/cc10x/skills/frontend/SKILL.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Frontend (Authoring + Critique)

Two modes: authoring (build UI with patterns) and critique (score built UI). Both share the visual-direction rules below.

Reference Files

Read only what's needed:

  • references/ui-state-and-feedback.md — loading/error/empty/success ordering, skeleton vs spinner
  • references/accessibility-and-forms.md — WCAG, keyboard/focus, labels, form patterns, mobile
  • references/performance-and-layout.md — responsive, motion, overflow, URL state, light/dark mode
  • references/design-md-authoring.md — creating/updating DESIGN.md from screenshots, existing UI, preferences
  • references/design-md-inspiration-index.md — style references when user asks for direction

Shared Visual Direction Rules

Two-Altitude Reflex Check

Before committing a visual direction, run both tests:

  1. First-order: Could you guess the theme/palette from the category alone? ("Fintech → blue + sans-serif.") If yes → generic. Reject.
  2. Second-order: Could you guess it from category + anti-references? Once everyone "avoids the purple gradient," the avoidance becomes a reflex — fintech dodging blue lands on the same off-black + lime. If predictable given what people flee toward → still generic. Reject.

The cure: derive direction from the specific product, audience, and content — not from the category or what the category is fleeing.

Reflex-Reject Lists (maintained, pruned as families saturate)

Reflex-reject fonts Reflex-reject aesthetic lanes
Inter, Roboto, Arial, system-ui defaults Purple/violet gradient on white (AI-tool reflex #1)
Geist / Geist Mono (over-saturated) Off-black + acid-lime "anti-corporate" (reflex #2)
Space Grotesk as default "modern" pick Warm-beige + serif "anti-AI" editorial (reflex #2)
Generic Google-Fonts pairing of the month Glassmorphism cards on gradient mesh

Prune a lane out once it stops being a reflex; add new families as they saturate. A stale blocklist becomes its own reflex.

Read the full file on GitHub · 158 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. 2d ago First seen · 158 lines · 63 tokens per session scan A b0a7e20c52f3

Subscribe to this mod's changes

frontend is a skill published in the GitHub repository romiluz13/cc10x (164 stars, last pushed 29d ago), licensed MIT. It adds 63 tokens to every session and 1,912 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.

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