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Agent skill

Cls

by LiberatedPixelCup in LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator

Measure lab CLS with profile:cls, debug layout shift from loading shells and first-paint jump, and keep budgets tied to a CI artifact.

GPL-3.0Auto-check passedFrontend & Design

Install Cls

skills CLI
$ npx skills add LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator --skill cls -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator cls --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/cls .claude/skills/cls && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
cls
GitHub stars
1.8k
Token cost
~822 tokens
SKILL.md length
316 words
Files
1
Skills in repo
11
Repo updated
First seen
Licence
GPL-3.0

At a glance

Measure lab CLS with profile:cls, debug layout shift from loading shells and first-paint jump, and keep budgets tied to a CI artifact.

  • Works in 3 steps: Hydrate floor: layout-shifts nodes in… → Dump the matching viewport: CLS mobile → → Dumps are post-hydrate. A hydrate-only…
  • Editing first-paint CSS
  • SKILL.md covers Measure and Debug
  • Calls npm

What it does

Cls is an agent skill from LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator. Measure lab CLS with profile:cls, debug layout shift from loading shells and first-paint jump, and keep budgets tied to a CI artifact. Use when editing first-paint CSS, loading shells, critical-shell, or when the user mentions CLS, layout shift, or Lighthouse.

Its SKILL.md is about 820 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Frontend & Design, covering Web performance. The repository describes itself as: Character Generator based on Universal-LPC-Spritesheet. The licence is GPL-3.0.

When your agent uses it

  • Editing first-paint CSS
  • The user mentions CLS

Example prompts

  • “/cls”

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

  1. Hydrate floor: layout-shifts nodes in tmp/cls-profile.json. Jump
  2. Dump the matching viewport: CLS mobile →
  3. Dumps are post-hydrate. A hydrate-only jump will not show as a single-URL

What it can do on your machine

Read from SKILL.md and the folder at commit 58ce1aa. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • npm

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use npm, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Cls loads about 822 tokens when it runs. Until then it costs about 66 tokens; SKILL.md has 316 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~66
When it runs · the whole SKILL.md, loaded when a task matches
~822

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator at commit 58ce1aa, republished under its GPL-3.0 licence (© LiberatedPixelCup). 316 words, ~822 tokens.

Download SKILL.mdSave it as .claude/skills/cls/SKILL.md (or your agent's skills folder).
name
cls
description
Measure lab CLS with profile:cls, debug layout shift from loading shells and first-paint jump, and keep budgets tied to a CI artifact. Use when editing first-paint CSS, loading shells, critical-shell, or when the user mentions CLS, layout shift, or Lighthouse.

Lab CLS

Load CLS.md before touching critical CSS for shift. Measure with npm run profile:cls rather than asking the user for DevTools.

This is not Argos and not window.profiler:

  • Argos is post-hydrate screenshots at 390 / 834 / 1440. CLS mobile is 412×823. Visual checks: visual-test.
  • profile:app / profile:load are timing. Layout shift is this skill. performance-profiling.

Measure

bash
npm run profile:cls
npm run profile:cls -- --preset mobile
npm run profile:cls:check
npm run profile:cls:delayed
npm run profile:cls:baseline:delayed
npm run profile:cls:check:delayed

Production vite preview with ?debug=false. Default port 4179. Culprits are in the JSON layout-shifts nodes, not the CLS audit debugdata.

Two labs:

  • Un-delayed profile:cls:check is the hydrate floor (cls-budgets.json).
  • Delayed profile:cls:check:delayed (--delay-css-ms 3000) is the jump gate (cls-budgets-delayed.json). A delayed run with delayedStylesheetHits 0 is a broken proxy, not a green jump. --check --preset gates only that viewport. Do not paste delayed medians into cls-budgets.json.

diff:cls-profile always exits 0. A hostUserAgent warning is Chrome-build churn (chrome-version: latest), not a layout regression.

Both budget files are slack around a CI median, never Google's 0.1. Delayed tablet sits above 0.1 today; green there means the jump has not grown, not that it is fixed.

See CLS.md.

Do not hand-edit scripts/profile/cls-budgets.json or delayed budgets without the matching CI cls-profile artifact. Local macOS medians will not match Linux CI.

After a Lighthouse bump, refresh tests/fixtures/lighthouse/lhr-delayed.json via the recipe in CLS.md (trimmed --save-lhr dump). Do not reshape the JSON by eye.

Debug

  1. Hydrate floor: layout-shifts nodes in tmp/cls-profile.json. Jump: tmp/cls-profile-delayed.json or profile:cls:delayed at the same --preset. If culprits are empty or you need the raw audits, --save-lhr locally with the same delay as that lab — the GitHub artifact is not an LHR. CLS.md section 6.
  2. Dump the matching viewport: CLS mobile → npm run compute-style-dump:lighthouse-mobile (412×823), not compute-style-dump:mobile (Argos 390). Tablet / mediumDesktop use the same-named dump presets.
  3. Dumps are post-hydrate. A hydrate-only jump will not show as a single-URL dump diff.

After a CSS change run un-delayed and delayed profile:cls and npm run test:visual. New skill folder: npm run skills:link so .claude/skills/cls exists (gitignored).

© LiberatedPixelCup, GPL-3.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/cls of LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator.

Open the folder on GitHubat commit 58ce1aa

Compare with similar skills

Cls next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Cls compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Cls this skillLiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator1.8k—~822Automated safety check: PassGPL-3.0
React Doctormakeplane/plane61k12 repos~657Automated safety check: PassAGPL-3.0
Fixing Motion Performanceibelick/ui-skills9.5k5 repos~1.4kAutomated safety check: PassMIT
GSAP Performance Tuninggreensock/gsap-skills16k4 repos~1kAutomated safety check: PassMIT
React Frontend Development Guidelinesdiet103/claude-code-infrastructure-showcase10k2 repos~2.9kAutomated safety check: PassMIT
Web Quality Auditaddyosmani/web-quality-skills2.9k—~2.6kAutomated safety check: PassMIT

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  • Fixing Motion Performance

    ibelick/ui-skills

    Audits and fixes web animation performance: layout thrashing, work that belongs on the compositor, scroll-linked motion and costly blur effects.

    9.5k GitHub starsUsed in 5 repos~1.4k tokens
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  • Performance Profiling

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  • Typescript

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Categories

Questions about Cls

What does Cls do?

Measure lab CLS with profile:cls, debug layout shift from loading shells and first-paint jump, and keep budgets tied to a CI artifact. Cls is an agent skill from LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator. Measure lab CLS with profile:cls, debug layout shift from loading shells and first-paint jump, and keep budgets tied to a CI artifact.

When should I use Cls?

Cls fits situations like: editing first-paint CSS; the user mentions CLS.

How do I install Cls in Claude Code?

Run `npx skills add LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator --skill cls -a claude-code`. Or copy the skill folder (.agents/skills/cls in LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator) into .claude/skills/cls in your project. Claude Code loads it when a task matches its description.

How do I install Cls in Codex?

Run `npx skills add LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator --skill cls -a codex`. Or copy the skill folder (.agents/skills/cls in LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator) into .agents/skills/cls in your project. Codex loads it when a task matches its description.

Can I use Cls in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator --skill cls -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/cls, .gemini/skills/cls, .github/skills/cls and .opencode/skills/cls in your project.

What does Cls need to run?

Going by SKILL.md and its folder, Cls needs the command-line tools its instructions call (npm).

Does Cls access the network?

SKILL.md contains no URLs. Its commands use npm, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Cls safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Cls use?

Cls is published under the GPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Cls use?

About 822 tokens (SKILL.md is roughly 3.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Cls?

Skills that share tags, products or a category with Cls: React Doctor (makeplane/plane, 61k stars), Fixing Motion Performance (ibelick/ui-skills, 9.5k stars), GSAP Performance Tuning (greensock/gsap-skills, 16k stars) and React Frontend Development Guidelines (diet103/claude-code-infrastructure-showcase, 10k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Cls?

LiberatedPixelCup (a GitHub organization) maintains it in LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator, which has 1,829 GitHub stars. The repository holds 11 skills in this directory. The repository was last updated on October 7, 2026.

Source: LiberatedPixelCup/Universal-LPC-Spritesheet-Character-Generator on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.