Agent skill

Cecil Theme

Create, structure and package themes for Cecil (visual themes and component themes), following the conventions of the official Cecilapp/theme- repositories.

EUPL-1.2Auto-check passedDevelopment

Install Cecil Theme

skills CLI

$ npx skills add Cecilapp/Cecil --skill cecil-theme -a claude-code

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

GitHub CLI

$ gh skill install Cecilapp/Cecil cecil-theme --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/Cecilapp/Cecil.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/cecil-theme .claude/skills/cecil-theme && 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/

Paste into Claude Code

Install the "cecil-theme" agent skill from https://github.com/Cecilapp/Cecil/tree/main/skills/cecil-theme into .claude/skills/cecil-theme/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cecil-theme", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/Cecilapp/Cecil/tree/main/skills/cecil-theme

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add Cecilapp/Cecil --skill cecil-theme -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install Cecilapp/Cecil cecil-theme --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Cecilapp/Cecil.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/cecil-theme .agents/skills/cecil-theme && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "cecil-theme" agent skill from https://github.com/Cecilapp/Cecil/tree/main/skills/cecil-theme into .agents/skills/cecil-theme/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cecil-theme", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add Cecilapp/Cecil --skill cecil-theme -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install Cecilapp/Cecil cecil-theme --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Cecilapp/Cecil.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/cecil-theme .cursor/skills/cecil-theme && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "cecil-theme" agent skill from https://github.com/Cecilapp/Cecil/tree/main/skills/cecil-theme into .cursor/skills/cecil-theme/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cecil-theme", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/Cecilapp/Cecil.git --path skills/cecil-theme

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add Cecilapp/Cecil --skill cecil-theme -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install Cecilapp/Cecil cecil-theme --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Cecilapp/Cecil.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/cecil-theme .gemini/skills/cecil-theme && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "cecil-theme" agent skill from https://github.com/Cecilapp/Cecil/tree/main/skills/cecil-theme into .gemini/skills/cecil-theme/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cecil-theme", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install Cecilapp/Cecil cecil-theme

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add Cecilapp/Cecil --skill cecil-theme -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/Cecilapp/Cecil.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/cecil-theme .github/skills/cecil-theme && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "cecil-theme" agent skill from https://github.com/Cecilapp/Cecil/tree/main/skills/cecil-theme into .github/skills/cecil-theme/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cecil-theme", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add Cecilapp/Cecil --skill cecil-theme -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install Cecilapp/Cecil cecil-theme --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Cecilapp/Cecil.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/cecil-theme .opencode/skills/cecil-theme && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "cecil-theme" agent skill from https://github.com/Cecilapp/Cecil/tree/main/skills/cecil-theme into .opencode/skills/cecil-theme/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "cecil-theme", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: cecil-theme
GitHub stars: 297
Token cost: ~4.6k tokens
SKILL.md length: 1,210 words
Files: 1
Skills in repo: 4
Repo updated: Oct 6, 2026
First seen: Oct 7, 2026
Licence: EUPL-1.2

At a glance

Create, structure and package themes for Cecil (visual themes and component themes), following the conventions of the official Cecilapp/theme- repositories.

Works in 8 steps: Scaffold a test site → Write config.yml → Write theme.yml (optional metadata) → …
Development work in your project
SKILL.md covers When to Use This Skill, How Cecil Loads Themes, Theme Structure and Step-by-Step: Create a Theme, plus 5 more sections
Calls php and curl; reaches cecil.app and github.com

What it does

Cecil Theme is an agent skill from Cecilapp/Cecil. Create, structure and package themes for Cecil (visual themes and component themes), following the conventions of the official Cecilapp/theme- repositories.

Its SKILL.md is about 4.6k 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 Development. The repository describes itself as: A simple and powerful content-driven static site generator.

When your agent uses it

Development work in your project

Example prompts

“/cecil-theme”

Workflow steps

8 steps, taken from the step headings in SKILL.md.

Scaffold a test site
Write config.yml
Write theme.yml (optional metadata)
Create the base layout
Create child layouts
Assets
Menus, URLs and collections
Translations

What it can do on your machine

Read from SKILL.md and the folder at commit d5c73ab. 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:
- php
- curl
From the folder's file list and the shell code blocks in SKILL.md.
Network
Hosts in commands or code, which the agent is likely to contact:
- cecil.app
- github.com
- author.tld
- cdn.jsdelivr.net
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

Cecil Theme loads about 4.6k tokens when it runs. Until then it costs about 42 tokens; SKILL.md has 1,210 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~42
When it runs · the whole SKILL.md, loaded when a task matches: ~4.6k

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

Its licence (EUPL-1.2) doesn't allow us to republish the file, so here is its outline and opening line. It has 1,210 words (~4,611 tokens).

“You are an expert Cecil theme developer. You create reusable themes for Cecil: full visual themes (layouts, styles, assets) and small component themes (a feature plugged into any site or theme), packaged for Composer like the official Cecilapp themes.”

— opening of SKILL.md by Cecilapp, EUPL-1.2

name: cecil-theme
license: EUPL-1.2

Outline of SKILL.md

Cecil Theme Builder
When to Use This Skill
How Cecil Loads Themes
Theme Structure
Visual theme
Component theme
Step-by-Step: Create a Theme
Step 1: Scaffold a test site
Step 2: Write config.yml
Step 3: Write theme.yml (optional metadata)
Step 4: Create the base layout
Step 5: Create child layouts
Step 6: Assets
Step 7: Menus, URLs and collections
Step 8: Translations
Component Themes Patterns
Packaging
composer.json
.editorconfig
README.md
Demo on GitHub Pages (optional)
Conventions Checklist
Troubleshooting
Useful Resources

Read the full SKILL.md on GitHub

Files

Just SKILL.md in skills/cecil-theme of Cecilapp/Cecil.

Open the folder on GitHubat commit d5c73ab

Compare with similar skills

Cecil Theme 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.

Cecil Theme compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Cecil Theme this skillCecilapp/Cecil	297	—	~4.6k	Automated safety check: Pass	EUPL-1.2	yesterday
Finishing a Development Branchobra/superpowers	296k	5 repos	~1.9k	Automated safety check: Pass	MIT	yesterday
Typescript Advanced Typesrolling-scopes/rsschool-app	10k	24 repos	~4.2k	Automated safety check: Pass	MPL-2.0	3 days ago
PR Babysitteropeninterpreter/openinterpreter	69k	3 repos	~4.2k	Automated safety check: Pass	Apache-2.0	yesterday
Code Review ChecklistshareAI-lab/learn-claude-code	78k	5 repos	~1.1k	Automated safety check: Pass	MIT	9 days ago
Greplooponyx-dot-app/onyx	32k	4 repos	~3.3k	Automated safety check: Pass	MIT	today

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Questions about Cecil Theme

What does Cecil Theme do?

Create, structure and package themes for Cecil (visual themes and component themes), following the conventions of the official Cecilapp/theme- repositories. Cecil Theme is an agent skill from Cecilapp/Cecil. Create, structure and package themes for Cecil (visual themes and component themes), following the conventions of the official Cecilapp/theme- repositories.

When should I use Cecil Theme?

Cecil Theme fits situations like: development work in your project.

How do I install Cecil Theme in Claude Code?

Run `npx skills add Cecilapp/Cecil --skill cecil-theme -a claude-code`. Or copy the skill folder (skills/cecil-theme in Cecilapp/Cecil) into .claude/skills/cecil-theme in your project. Claude Code loads it when a task matches its description.

How do I install Cecil Theme in Codex?

Run `npx skills add Cecilapp/Cecil --skill cecil-theme -a codex`. Or copy the skill folder (skills/cecil-theme in Cecilapp/Cecil) into .agents/skills/cecil-theme in your project. Codex loads it when a task matches its description.

Can I use Cecil Theme 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 Cecilapp/Cecil --skill cecil-theme -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/cecil-theme, .gemini/skills/cecil-theme, .github/skills/cecil-theme and .opencode/skills/cecil-theme in your project.

What does Cecil Theme need to run?

Going by SKILL.md and its folder, Cecil Theme needs the command-line tools its instructions call (php and curl).

Does Cecil Theme access the network?

SKILL.md names 4 domains. In commands or code: cecil.app, github.com, author.tld and cdn.jsdelivr.net; the agent is likely to contact these when it follows the instructions. This is read from the text; nothing was executed.

Is Cecil Theme 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 Cecil Theme use?

Cecil Theme is published under the EUPL-1.2 licence (declared in SKILL.md).

How many tokens does Cecil Theme use?

About 4.6k tokens (SKILL.md is roughly 18k 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 Cecil Theme?

Skills that share tags, products or a category with Cecil Theme: Finishing a Development Branch (obra/superpowers, 296k stars), Typescript Advanced Types (rolling-scopes/rsschool-app, 10k stars), PR Babysitter (openinterpreter/openinterpreter, 69k stars) and Code Review Checklist (shareAI-lab/learn-claude-code, 78k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Cecil Theme?

Cecilapp (a GitHub organization) maintains it in Cecilapp/Cecil, which has 297 GitHub stars. The repository holds 4 skills in this directory. The repository was last updated on October 6, 2026.

Source: Cecilapp/Cecil on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Cecil Theme

Install Cecil Theme

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Files

Compare with similar skills

Similar skills

Finishing a Development Branch

Typescript Advanced Types

PR Babysitter

Code Review Checklist

Greploop

Guidelines

More from Cecilapp/Cecil

Address PR Comments Cecil

Cecil

Php Development

Questions about Cecil Theme

Install Cecil Theme

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Files

Compare with similar skills

Similar skills

More from Cecilapp/Cecil

Related

Questions about Cecil Theme