favicon

Generate a complete set of favicons from the source image at

$1

and update the project's HTML with the appropriate link tags.

Prerequisites

First, verify ImageMagick v7+ is installed by running:

bash

which magick

If not found, stop and instruct the user to install it:

macOS:
```
brew install imagemagick
```
Linux:
```
sudo apt install imagemagick
```

Step 1: Validate Source Image

Verify the source image exists at the provided path:
```
$1
```
Check the file extension is a supported format (PNG, JPG, JPEG, SVG, WEBP, GIF)
If the file doesn't exist or isn't a valid image format, report the error and stop

Note whether the source is an SVG file - if so, it will also be copied as

favicon.svg

Step 2: Detect Project Type and Static Assets Directory

Detect the project type and determine where static assets should be placed. Check in this order:

Framework	Detection	Static Assets Directory
Rails	`config/routes.rb` exists	`public/`
Next.js	`next.config.*` exists	`public/`
Gatsby	`gatsby-config.*` exists	`static/`
SvelteKit	`svelte.config.*` exists	`static/`
Astro	`astro.config.*` exists	`public/`
Hugo	`hugo.toml` or `config.toml` with Hugo markers	`static/`
Jekyll	`_config.yml` with Jekyll markers	Root directory (same as `index.html` )
Vite	`vite.config.*` exists	`public/`
Create React App	`package.json` has `react-scripts` dependency	`public/`
Vue CLI	`vue.config.*` exists	`public/`
Angular	`angular.json` exists	`src/assets/`
Eleventy	`.eleventy.js` or `eleventy.config.*` exists	Check `_site` output or root
Static HTML	`index.html` in root	Same directory as `index.html`

Important: If existing favicon files are found (e.g.,

favicon.ico

apple-touch-icon.png

), use their location as the target directory regardless of framework detection.

Report the detected project type and the static assets directory that will be used.

When in doubt, ask: If you are not 100% confident about where static assets should be placed (e.g., ambiguous project structure, multiple potential locations, unfamiliar framework), use

AskUserQuestionTool

to confirm the target directory before proceeding. It's better to ask than to put files in the wrong place.

Step 3: Determine App Name

Find the app name from these sources (in priority order):

Existing
site.webmanifest
- Check the detected static assets directory for an existing manifest and extract the
```
name
```
field
package.json
- Extract the
```
name
```
field if it exists
Rails
config/application.rb
- Extract the module name (e.g.,
```
module MyApp
```
→ "MyApp")
Directory name - Use the current working directory name as fallback

Convert the name to title case if needed (e.g., "my-app" → "My App").

Step 4: Ensure Static Assets Directory Exists

Check if the detected static assets directory exists. If not, create it.

Step 5: Generate Favicon Files

Run these ImageMagick commands to generate all favicon files. Replace

[STATIC_DIR]

with the detected static assets directory from Step 2.

favicon.ico (multi-resolution: 16x16, 32x32, 48x48)

bash

magick "$1" \
  \( -clone 0 -resize 16x16 \) \
  \( -clone 0 -resize 32x32 \) \
  \( -clone 0 -resize 48x48 \) \
  -delete 0 -alpha on -background none \
  [STATIC_DIR]/favicon.ico

favicon-96x96.png

bash

magick "$1" -resize 96x96 -background none -alpha on [STATIC_DIR]/favicon-96x96.png

apple-touch-icon.png (180x180)

bash

magick "$1" -resize 180x180 -background none -alpha on [STATIC_DIR]/apple-touch-icon.png

web-app-manifest-192x192.png

bash

magick "$1" -resize 192x192 -background none -alpha on [STATIC_DIR]/web-app-manifest-192x192.png

web-app-manifest-512x512.png

bash

magick "$1" -resize 512x512 -background none -alpha on [STATIC_DIR]/web-app-manifest-512x512.png

favicon.svg (only if source is SVG)

If the source file has a

.svg

extension, copy it:

bash

cp "$1" [STATIC_DIR]/favicon.svg

Step 6: Create/Update site.webmanifest

Create or update

[STATIC_DIR]/site.webmanifest

with this content (substitute the detected app name):

json

{
  "name": "[APP_NAME]",
  "short_name": "[APP_NAME]",
  "icons": [
    {
      "src": "/web-app-manifest-192x192.png",
      "sizes": "192x192",
      "type": "image/png",
      "purpose": "maskable"
    },
    {
      "src": "/web-app-manifest-512x512.png",
      "sizes": "512x512",
      "type": "image/png",
      "purpose": "maskable"
    }
  ],
  "theme_color": "#ffffff",
  "background_color": "#ffffff",
  "display": "standalone"
}

site.webmanifest

already exists in the static directory, preserve the existing

theme_color

background_color

, and

display

values while updating the

name

short_name

, and

icons

array.

Step 7: Update HTML/Layout Files

Based on the detected project type, update the appropriate file. Adjust the

href

paths based on where the static assets directory is relative to the web root:

If static files are in
```
public/
```
or
```
static/
```
and served from root → use
```
/favicon.ico
```
If static files are in
```
src/assets/
```
→ use
```
/assets/favicon.ico
```
If static files are in the same directory as HTML → use
```
./favicon.ico
```
or just
```
favicon.ico
```

For Rails Projects

Edit

app/views/layouts/application.html.erb

. Find the

<head>

section and add/replace favicon-related tags with:

html

<link rel="icon" type="image/png" href="/favicon-96x96.png" sizes="96x96" />
<link rel="icon" type="image/svg+xml" href="/favicon.svg" />
<link rel="shortcut icon" href="/favicon.ico" />
<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png" />
<meta name="apple-mobile-web-app-title" content="[APP_NAME]" />
<link rel="manifest" href="/site.webmanifest" />

Important:

If the source was NOT an SVG, omit the

<link rel="icon" type="image/svg+xml" href="/favicon.svg" />

line

Remove any existing

<link rel="icon"

<link rel="shortcut icon"

<link rel="apple-touch-icon"

, or

<link rel="manifest"

tags before adding the new ones

Place these tags near the top of the
```
<head>
```
section, after
```
<meta charset>
```
and
```
<meta name="viewport">
```
if present

For Next.js Projects

Edit the detected layout file (

app/layout.tsx

src/app/layout.tsx

). Update or add the

metadata

export to include icons configuration:

typescript

export const metadata: Metadata = {
  // ... keep existing metadata fields
  icons: {
    icon: [
      { url: '/favicon.ico' },
      { url: '/favicon-96x96.png', sizes: '96x96', type: 'image/png' },
      { url: '/favicon.svg', type: 'image/svg+xml' },
    ],
    shortcut: '/favicon.ico',
    apple: '/apple-touch-icon.png',
  },
  manifest: '/site.webmanifest',
  appleWebApp: {
    title: '[APP_NAME]',
  },
};

Important:

If the source was NOT an SVG, omit the
```
{ url: '/favicon.svg', type: 'image/svg+xml' }
```
entry from the icon array
If metadata export doesn't exist, create it with just the icons-related fields
If metadata export exists, merge the icons configuration with existing fields

For Static HTML Projects

Edit the detected

index.html

file. Add the same HTML as Rails within the

<head>

section.

If No Project Detected

Skip HTML updates and inform the user they need to manually add the following to their HTML

<head>

html

<link rel="icon" type="image/png" href="/favicon-96x96.png" sizes="96x96" />
<link rel="icon" type="image/svg+xml" href="/favicon.svg" />
<link rel="shortcut icon" href="/favicon.ico" />
<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png" />
<meta name="apple-mobile-web-app-title" content="[APP_NAME]" />
<link rel="manifest" href="/site.webmanifest" />

Step 8: Summary

Report completion with:

Detected project type and framework
Static assets directory used
List of files generated
App name used in manifest and HTML
Layout file updated (or note if manual update is needed)
Note if any existing files were overwritten

Error Handling

If ImageMagick is not installed, provide installation instructions and stop
If the source image doesn't exist, report the exact path that was tried and stop
If ImageMagick commands fail, report the specific error message
If the layout file cannot be found for HTML updates, generate files anyway and instruct on manual HTML addition

favicon

NPX Install

Tags

SKILL.md Content

Prerequisites

Step 1: Validate Source Image

Step 2: Detect Project Type and Static Assets Directory

Step 3: Determine App Name

Step 4: Ensure Static Assets Directory Exists

Step 5: Generate Favicon Files

favicon.ico (multi-resolution: 16x16, 32x32, 48x48)

favicon-96x96.png

apple-touch-icon.png (180x180)

web-app-manifest-192x192.png

web-app-manifest-512x512.png

favicon.svg (only if source is SVG)

Step 6: Create/Update site.webmanifest

Step 7: Update HTML/Layout Files

For Rails Projects

For Next.js Projects

For Static HTML Projects

If No Project Detected

Step 8: Summary

Error Handling