A set of guidance for designing and improving frontend interfaces, such as websites, dashboards, forms, and app screens. Frontend means the part of software people see and use.

Creating, redesigning, reviewing, polishing, or adapting working frontend code.

It gives the agent a defined process for making interface changes and checking the project's existing design rules.

impeccable — Skill by steve-magne

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/steve-magne/hookstack/impeccable

Any agent

npx skills add steve-magne/hookstack --skill impeccable

Clone the repo

git clone --depth 1 https://github.com/steve-magne/hookstack

Made for: Claude Code, Codex.

Per session 189 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,586 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin 91% copy Near-identical to another mod 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	$0.00189	$0.04586
Opus 5	$0.00095	$0.02293
Sonnet 5	$0.00038	$0.00917
Haiku 4.5	$0.00019	$0.00459

Measured 2d ago against content hash 4128333148c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

impeccable 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.

The scan reads SKILL.md. This mod also ships 32 executable files (scripts/context-signals.mjs, scripts/context.mjs, scripts/critique-storage.mjs, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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

This is a copy

91% identical to impeccable — 26 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/impeccable/SKILL.md · 164 lines

How it starts

The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Designs and iterates production-grade frontend interfaces. Real working code, committed design choices, exceptional craft.

Setup

You MUST do these steps before proceeding:

Run node .claude/skills/impeccable/scripts/context.mjs once per session. If you've already seen its output in this conversation, do not re-run it. The script either prints the project's PRODUCT.md (and DESIGN.md when present) as a markdown block, or tells you it's missing. Follow whatever it prints. If it reports NO_PRODUCT_MD, stop and follow reference/init.md before doing anything else. If the output ends with an UPDATE_AVAILABLE directive, follow it (ask the user once about updating, then continue). It never blocks the current task.
If the user invoked a sub-command (craft, shape, audit, polish, ...), you MUST read reference/<command>.md next. Non-optional. The reference defines the command's flow; without it you will skip steps the user expects.
Familiarize yourself with any existing design system, conventions, and components in the code. Read at least one project file (CSS / tokens / theme / a representative component or page). Required even when you've loaded a sub-command reference in step 2. Don't reinvent the wheel; use what's there when it works, branch out when the UX wins.
Read the matching register reference. This is non-optional; skipping it produces generic output. If the project is marketing, a landing page, a campaign, long-form content, or a portfolio (design IS the product), read reference/brand.md. If it is app UI, admin, a dashboard, or a tool (design SERVES the product), read reference/product.md. Pick by first match: (1) task cue ("landing page" vs "dashboard"); (2) surface in focus (the page, file, or route being worked on); (3) register field in PRODUCT.md.
If the project is brand-new (no existing CSS tokens / theme / committed brand colors found in step 3), run node .claude/skills/impeccable/scripts/palette.mjs to receive a brand seed color and composition guidance. This is the anchor for your primary brand color. Compose the rest of the palette (bg, surface, ink, accent, muted) around it per the script's instructions. Use OKLCH throughout. Skip this step only if step 3 found committed brand colors in existing tokens; in that case identity-preservation wins.

Read the full file on GitHub · 164 lines

Files

What ships with it

60 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.

2d ago First seen · 164 lines · 189 tokens per session scan A 4128333148c9

Subscribe to this mod's changes

impeccable is a skill published in the GitHub repository steve-magne/hookstack (7 stars, last pushed 8d ago), licensed MIT. It adds 189 tokens to every session and 4,586 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to impeccable, differing in 26 lines, and is treated as a copy.

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