What is frontend-coding-standards?

A starting guide for frontend development covering HTML rules, progressive enhancement, asset handling, and performance requirements.

It helps build and review websites with standards-based HTML, support for simpler browsers where practical, registered assets, and performance requirements.

It gives developers a common set of frontend practices and directs language-specific questions to the relevant JavaScript and CSS guides.

frontend-coding-standards — Skill for Claude Code by systempromptio

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 systempromptio/systemprompt-marketplace --skill frontend-coding-standards

Clone the repo

git clone --depth 1 https://github.com/systempromptio/systemprompt-marketplace

Made for: Claude Code.

Or install development, the plugin that ships this one along with the rest of its 20 skills.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/systempromptio/systemprompt-marketplace/frontend-coding-standards/github.svg)](https://agentmods.dev/skills/systempromptio/systemprompt-marketplace/frontend-coding-standards)

Your own site

<a href="https://agentmods.dev/skills/systempromptio/systemprompt-marketplace/frontend-coding-standards"><img src="https://agentmods.dev/badge/skills/systempromptio/systemprompt-marketplace/frontend-coding-standards/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/systempromptio/systemprompt-marketplace/frontend-coding-standards"><img src="https://agentmods.dev/badge/skills/systempromptio/systemprompt-marketplace/frontend-coding-standards.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,524 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 unknown 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.

Model	Per session	Once invoked
Fable 5.1	$0.00053	$0.02524
Opus 5.5	$0.00021	$0.01010
Sonnet 5.5	$0.00011	$0.00505
Haiku 4.5	$0.00005	$0.00252

Measured 2mo ago against content hash 9c98c7ad7e11, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

frontend-coding-standards 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 2mo 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/development/skills/frontend-coding-standards/SKILL.md · 247 lines

The source is not reproduced here

No licence file

Read it on GitHub

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.

2mo ago First seen · 247 lines · 53 tokens per session scan A 9c98c7ad7e11

Subscribe to this mod's changes

frontend-coding-standards is a skill published in the GitHub repository systempromptio/systemprompt-marketplace (2 stars, last pushed 1mo ago), with no licence file. It adds 53 tokens to every session and 2,524 once invoked, about $0.0002 per session on Opus 5.5. 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.

CSS and styling Claude Code Frontend agents ai-development marketplace mcp plugins

frontend-coding-standards next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
frontend-coding-standardssystempromptio/systemprompt-marketplace	Skill	2	1mo ago	none	A	53	Claude Code
usemelodic-software/claude-code-plugins	Skill	30	today	MIT	A	183	Claude Code
figma-design-handoffyonatangross/orchestkit	Skill	301	yesterday	MIT	A	76	Claude Code
accessibilityyonatangross/orchestkit	Skill	301	yesterday	MIT	A	65	Claude Code
animation-motion-designyonatangross/orchestkit	Skill	301	yesterday	MIT	A	52	Claude Code
responsive-patternsyonatangross/orchestkit	Skill	301	yesterday	MIT	A	46	Claude Code
morning-briefmelodic-software/claude-code-plugins	Skill	30	today	MIT	A	152	Claude Code