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.claude/skills/cecilapp-cecil/SKILL.md| Test case | Without → With | Effect | Δ tokens | Δ turns |
|---|---|---|---|---|
| case-01 | ✗→✓ | ▲ Improved | 89% | 0% |
| case-02 | ✗→✓ | ▲ Improved | 95% | 0% |
| case-03 | ✗→✓ | ▲ Improved | 79% | 0% |
| case-08 | ✗→✓ | ▲ Improved | 53% | 0% |
| case-13 | ✗→✓ | ▲ Improved | 126% | 0% |
You are an expert Cecil developer capable of creating and generating static websites with Cecil, a PHP-based static site generator powered by Symfony components and Twig.
Use this skill when:
my-site/
├── cecil.yml # Main configuration file (or config.yml)
├── pages/ # Markdown pages
├── layouts/ # Twig templates
├── assets/ # Processed files (CSS, JS, images)
├── static/ # Static files copied as-is
└── data/ # Data collections (YAML/JSON/...)site.dataCecil follows a build pipeline:
Builder → Steps → Generators → Renderer → OutputStep/): Sequential build phasesGenerator/): Page generators executed via priority queueRenderer/): Twig-based rendering with custom extensions_site/ directory---, +++, or <!-- -->)pages/ (e.g. pages/blog/post-1.md -> section blog)pages/ define generated pathsA nested folder that explicitly contains an index.md file becomes a _sub-section_ of its parent _Section_. A nested folder without an index.md file is not a sub-section: its pages simply belong to the parent section.
plaintextpages/ └─ blog # Section "blog" ├─ index.md ├─ post-1.md # Page in "blog" └─ 2024 # Sub-section (contains an "index.md") ├─ index.md └─ post-2.md # Page in "blog" AND "blog/2024"
A sub-section:
type, variables, and layout resolution) available at its own URL (e.g. /blog/2024/)blog/2024/06/)Sub-sections support the same front matter variables as any section (sortby, pagination, cascade, circular). Use cascade on a parent index.md to propagate variables down to sub-sections and their pages.
Configuration is defined in cecil.yml or config.yml at project root:
title, baseurl, description, taxonomies, menussite variable access (for example site.title)config/default.php and base pipeline in config/base.phpDownload Cecil using curl:
bashcurl -LO https://cecil.app/cecil.phar chmod +x cecil.phar
Use the new:site command to scaffold a new website:
bashphp cecil.phar new:site
Edit cecil.yml:
yamltitle: My Site baseurl: https://example.com/ description: My awesome static site taxonomies: categories: category tags: tag
Create a page with:
bashphp cecil.phar new:page
Then edit the generated file in pages/:
markdown--- title: My First Post description: Welcome to my blog date: 2024-05-14 tags: [Welcome, "First post"] --- # My First Post This is my first post content.
Create Twig templates in layouts/ (for example layouts/page.html.twig):
twig<!DOCTYPE html> <html> <head> <title>{{ page.title }} - {{ site.title }}</title> </head> <body> <header> <h1>{{ site.title }}</h1> </header> <main> {{ page.content }} </main> <footer> <p>© {{ site.title }}</p> </footer> </body> </html>
bashphp cecil.phar build
Output is generated in _site/ directory.
| Command | Purpose | |------------------------------|-------------------------------------| | php cecil.phar new:site | Create a new website | | php cecil.phar new:page | Create a new page | | php cecil.phar build | Build the static site | | php cecil.phar serve | Start local server with live reload | | php cecil.phar show:config | Display effective configuration | | php cecil.phar cache:clear | Clear all cache files | | php cecil.phar clear | Remove generated files |
Twig templates live in layouts/ and follow Cecil naming conventions.
Use this pattern:
plaintextlayouts/(<section>/)<type>|<layout>.<format>(.<language>).twig
Examples:
layouts/page.html.twig - default page templatelayouts/list.html.twig - section/home/term listing templatelayouts/blog/list.rss.twig - RSS template for blog sectionlayouts/page.html.fr.twig - French page templatelayouts/_default/page.html.twig - fallback templatelayout templates first.| Page Kind | Step 1 | Step 2 | Step 3 | Step 4 | |---------------|--------------------------------------------------|-------------------|--------------|--------------| | Homepage | index.* | home.* | list.* | _default/* | | Standard page | page.* | _default/page.* | - | - | | Section page | section-specific list.* or explicit layout.* | list.* | _default/* | - | | Taxonomy page | taxonomy template or explicit layout.* | list.* | _default/* | - |
In practice, you usually need only:
layouts/page.html.twiglayouts/list.html.twiglayouts/_default/ or per sectionMost useful variables in Twig:
site.title, site.baseurl, site.descriptionsite.pages - pages collection (current language)site.allpages - pages in all languagessite.taxonomies - vocabularies and termssite.menus.<name> - menu entriespage.title, page.date, page.content, page.path, page.type, page.sectionConfigure languages in cecil.yml:
yamllanguage: en languages: - code: en name: English locale: en_US - code: fr name: Français locale: fr_FR
Use suffixed filenames for translations:
plaintextpages/about.md pages/about.fr.md
You can render a language switcher in templates with:
twig{% include 'partials/languages.html.twig' %}
Useful collection helpers:
site.pages.showable to skip draft/virtual/excluded pagessort_by_weight filter for menu entriestwig{# layouts/page.html.twig #} <!DOCTYPE html> <html lang="{{ site.language }}"> <head> <meta charset="utf-8"> <title>{{ page.title }} - {{ site.title }}</title> {{ include('partials/metatags.html.twig') }} </head> <body> <header> <h1><a href="{{ url('/') }}">{{ site.title }}</a></h1> {% if site.menus.main is defined %} <nav> <ul> {% for entry in site.menus.main|sort_by_weight %} <li><a href="{{ url(entry.url) }}">{{ entry.name }}</a></li> {% endfor %} </ul> </nav> {% endif %} </header> <main> <article> <h2>{{ page.title }}</h2> {% if page.date %} <time datetime="{{ page.date|date('c') }}">{{ page.date|date('Y-m-d') }}</time> {% endif %} {{ page.content }} </article> </main> </body> </html>
partials/metatags.html.twig - SEO/social tagspartials/navigation.html.twig - navigation helperpartials/paginator.html.twig - pagination linkspartials/languages.html.twig - language switcherIf needed, extract built-in templates to customize them:
bashphp cecil.phar util:templates:extract
Pagination is configured globally under pages.pagination, and can be overridden in section front matter.
yamlpages: pagination: max: 5 path: page
In list templates, include paginator links with:
twig{% include 'partials/paginator.html.twig' %}
Core Twig helpers commonly used in Cecil templates:
url() - generate internal/absolute URLs depending on configasset() - reference and process assetsinclude() - compose templates with partials/componentsConfigure asset optimization:
yamlassets: minify: true fingerprint: true compile: style: compressed images: optimize: true
draft: true to exclude non-published content from buildsExtend Cecil by creating custom generators:
php<?php namespace MyProject\Generator; use Cecil\Generator\AbstractGenerator; class CustomGenerator extends AbstractGenerator { public function generate(): void { // Custom generation logic } }
Then register it in configuration with pages.generators.
yamlpages: generators: 100: MyProject\Generator\CustomGenerator
> Note: use single backslashes in YAML. Double backslashes (\\) are only needed inside JSON or PHP strings.
Create CLI commands by extending AbstractCommand:
php<?php namespace MyProject\Command; use Cecil\Command\AbstractCommand; class MyCommand extends AbstractCommand { // Implementation }
You can also extend Twig (via layouts.extensions) and post-process output (via output.postprocessors).
yamllayouts: extensions: MyExtension: MyProject\Twig\MyExtension
The Twig extension class should implement Twig\Extension\ExtensionInterface (or extend Twig\Extension\AbstractExtension).
yamloutput: postprocessors: MyProcessor: MyProject\Renderer\PostProcessor\MyProcessor
Post-processors should implement Cecil\Renderer\PostProcessor\PostProcessorInterface.
Cecil generates pure static HTML, compatible with:
bash# Build php cecil.phar build # Deploy output directory (_site/) # to your hosting platform
bashphp cecil.phar build # Commit _site/ directory and push to gh-pages branch
When extending or contributing to Cecil:
declare(strict_types=1); in all PHP files\ (e.g., \count())pages/blog/index.md for blog sectionpages/blog/post-*.mdphp cecil.phar buildpages/ directorylayouts/pages/search.json.md with front matter output: jsonlayouts/search.json.twig that iterates site.pages.showable and emits a JSON array of {title, url, content} objectsWhen a user reports unexpected behavior or asks about a specific feature, ask them to run php cecil.phar doctor and include the output. If you are uncertain whether a feature is available in the user's Cecil version, say so explicitly and direct them to the official documentation at https://cecil.app/documentation/ rather than guessing version ranges.
cecil.yml syntax and configurationpages/ directoryphp cecil.phar build -vv for verbose outputphp cecil.phar cache:clearGet detailed build information:
bashphp cecil.phar build -v # Verbose php cecil.phar build -vv # Very verbose php cecil.phar build -vvv # Debug
| Case | Status | Duration (ms) | Turns | Tokens | Tool calls | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Without | With | Δ | Without | With | Δ | Without | With | Δ | Without | With | Δ | ||
case-01 | fail→pass | 19,264 | 18,356 | -5% | 1 | 1 | 0% | 3,423 | 6,477 | +89% | 0 | 0 | — |
case-02 | fail→pass | 25,604 | 15,914 | -38% | 1 | 1 | 0% | 3,654 | 7,135 | +95% | 0 | 0 | — |
case-03 | fail→pass | 17,021 | 11,186 | -34% | 1 | 1 | 0% | 3,276 | 5,851 | +79% | 0 | 0 | — |
case-04 | pass→pass | 4,178 | 2,701 | -35% | 1 | 1 | 0% | 675 | 4,338 | +543% | 0 | 0 | — |
case-05 | pass→pass | 4,695 | 3,087 | -34% | 1 | 1 | 0% | 796 | 4,426 | +456% | 0 | 0 | — |
case-06 | pass→pass | 11,368 | 8,582 | -25% | 1 | 1 | 0% | 1,221 | 4,551 | +273% | 0 | 0 | — |
case-07 | pass→pass | 5,109 | 2,980 | -42% | 1 | 1 | 0% | 871 | 4,429 | +408% | 0 | 0 | — |
case-08 | fail→pass | 17,120 | 9,052 | -47% | 1 | 1 | 0% | 3,054 | 4,661 | +53% | 0 | 0 | — |
case-09 | pass→pass | 26,352 | 10,343 | -61% | 1 | 1 | 0% | 4,146 | 5,003 | +21% | 0 | 0 | — |
case-10 | pass→pass | 11,875 | 7,841 | -34% | 1 | 1 | 0% | 1,123 | 4,477 | +299% | 0 | 0 | — |
case-11 | pass→pass | 12,421 | 4,021 | -68% | 1 | 1 | 0% | 1,276 | 4,621 | +262% | 0 | 0 | — |
case-12 | pass→pass | 3,999 | 7,368 | +84% | 1 | 1 | 0% | 662 | 4,292 | +548% | 0 | 0 | — |
case-13 | fail→pass | 10,404 | 2,596 | -75% | 1 | 1 | 0% | 1,936 | 4,380 | +126% | 0 | 0 | — |
case-14 | pass→pass | 12,689 | 6,681 | -47% | 1 | 1 | 0% | 1,305 | 4,190 | +221% | 0 | 0 | — |
case-15 | pass→pass | 16,239 | 12,217 | -25% | 1 | 1 | 0% | 1,942 | 5,266 | +171% | 0 | 0 | — |
case-16 | fail→pass | 13,273 | 7,489 | -44% | 1 | 1 | 0% | 946 | 4,294 | +354% | 0 | 0 | — |
case-17 | pass→pass | 14,136 | 3,914 | -72% | 1 | 1 | 0% | 2,512 | 4,683 | +86% | 0 | 0 | — |
case-18 | pass→pass | 8,202 | 3,512 | -57% | 1 | 1 | 0% | 1,361 | 4,547 | +234% | 0 | 0 | — |
case-19 | pass→pass | 11,004 | 2,219 | -80% | 1 | 1 | 0% | 971 | 4,271 | +340% | 0 | 0 | — |
case-20 | pass→pass | 9,216 | 3,035 | -67% | 1 | 1 | 0% | 500 | 4,455 | +791% | 0 | 0 | — |
case-21 | pass→pass | 3,613 | 7,339 | +103% | 1 | 1 | 0% | 598 | 4,349 | +627% | 0 | 0 | — |
case-22 | pass→pass | 9,028 | 2,329 | -74% | 1 | 1 | 0% | 621 | 4,255 | +585% | 0 | 0 | — |
case-23 | pass→pass | 7,596 | 8,207 | +8% | 1 | 1 | 0% | 1,409 | 4,453 | +216% | 0 | 0 | — |
DecimalAI ran this skill against gemini-3.6-flash twice over the same eval suite — once with the skill loaded and once without — and compared the two runs case by case. 23 cases were attempted. The headline lift of +26 percentage points is the difference between those two pass rates over the 23 comparable cases.
Without the skill loaded, the model failed this case. With it loaded, the same prompt on the same model passed. This is one improved case from the latest verified run; every case, including any that regressed, is in the table above.
| Model | Method | Date | Lift |
|---|---|---|---|
| gemini-3.6-flash | verified | 8/23/2026 | +50% |
Other measured skills in the registry, with their headline benchmark lift.