shinyseo

June 8, 2026 · View on GitHub

shinyseo is a small helper package for Shiny apps that need social, search, and PWA metadata.

It builds one shiny::tags$head() fragment containing:

canonical URL and description
Open Graph tags for Facebook, LinkedIn, Slack, and similar previews
Twitter Card tags
favicon, apple-touch-icon, theme-color, and web app manifest links
optional schema.org JSON-LD
optional Bing, Google, Yandex, Baidu, Naver, Facebook, and Pinterest verification
arbitrary custom meta tags

The package accepts either a YAML file path or a named list.

Six exported functions:

init_meta(path) — interactively answer a few questions at the console and write the result to a YAML file, so you can get started without reading the field reference below
social_meta(meta) — inject metadata into the UI at startup
update_meta(session, ...) — update title, description, url, or image reactively from the server
write_manifest(meta, ...) — generate www/manifest.json for PWA support
generate_assets(meta, generator, ...) — fill in a missing favicon, Apple touch icon, or share image by calling your own LLM/image-generation function, or one of the built-in generators below
openai_image_generator(api_key, model) — a ready-made generator for generate_assets() that calls OpenAI's image API

Getting started

Run shinyseo::init_meta() in the console. It will ask for your title, description, URL, image, and a handful of optional fields (favicon, theme colour, home screen shortcut support, and so on), then write the answers to meta.yml. Pass that file straight to social_meta():

shinyseo::social_meta("meta.yml")

What it does

When you call social_meta(), the package:

Reads metadata from YAML or uses the list you pass in.
Fills in safe defaults for common fields like locale, robots, and Twitter card type.
Checks that the required fields exist.
Builds HTML tags for Shiny UI.
Adds JSON-LD unless you turn schema off.
Registers a JavaScript handler so update_meta() can update tags at runtime.

API in short

social_meta(meta):

meta may be a YAML path or a named list
title, description, url, and image are required
if meta is a character string, it is read with yaml::read_yaml()
missing keys use package defaults where provided
schema = FALSE disables JSON-LD output
any other value of schema keeps JSON-LD enabled

update_meta(session, title, description, url, image):

call from the server to update metadata without a page reload
only the fields you supply are changed
requires social_meta() to be present in the UI

write_manifest(meta, path, display, start_url, background_color):

generates www/manifest.json for PWA support
call once in global.R before the app starts
reference the result with manifest = "/manifest.json" in social_meta()

generate_assets(meta, generator, path, assets):

fills in a missing favicon, apple_touch_icon, or image by calling a generator function — either one you write yourself, or a built-in one such as openai_image_generator()
generator is function(prompt, kind); it talks to whatever LLM/image API it's written against, and returns either raw image bytes or a path to a file on disk
only missing fields are generated; existing values are left untouched
run it once at setup time (e.g. from the console), then persist the updated meta with yaml::write_yaml()

meta <- shinyseo::generate_assets(meta,
  generator = shinyseo::openai_image_generator()
)
yaml::write_yaml(meta, "meta.yml")

Or supply your own, against whatever service you already have access to:

meta <- shinyseo::generate_assets(meta, generator = function(prompt, kind) {
  # your own call to Adobe Firefly, a local model, ...
})
yaml::write_yaml(meta, "meta.yml")

openai_image_generator(api_key, model):

builds a ready-made generator for generate_assets() that calls OpenAI's image API (gpt-image-1 by default) and returns the generated image bytes
api_key defaults to the OPENAI_API_KEY environment variable
requires the httr package, but only loads it (via requireNamespace()) when you call this constructor — it costs nothing if you never use it
shinyseo ships only this one built-in generator. OpenAI's image API is a straightforward fit for the job; most other LLM vendors either don't generate images at all (e.g. Claude/Anthropic, which can see images but not generate them) or need enough vendor-specific glue that they're better suited to a community-contributed generator — see LLM.md for the shape a contribution should take

meta <- shinyseo::generate_assets(meta,
  generator = shinyseo::openai_image_generator(api_key = "sk-...")
)

Config cheat sheet

Minimal configuration:

title: "Example app"
description: "A short app description."
url: "https://example.no"
image: "https://example.no/share.png"

Common extras:

Field	What it does
`locale`	Sets Open Graph locale and schema language default
`robots`	Controls the robots meta tag
`twitter_card`	Sets the Twitter card type
`site_name`	Sets `og:site_name`
`twitter_site`	Sets `twitter:site`
`twitter_creator`	Sets `twitter:creator`
`image_alt`	Sets `og:image:alt`
`twitter_image_alt`	Sets `twitter:image:alt`
`favicon`	Sets `<link rel="icon">` with auto-detected MIME type
`favicon_type`	Overrides the MIME type inferred from `favicon`
`favicon_png`	Adds a PNG `<link rel="icon">` fallback — set this when `favicon` is an SVG; Chromium address bars don't render SVG favicons and show a generic globe icon without a PNG fallback
`favicon_png_sizes`	Overrides the `sizes` attribute on `favicon_png` (defaults to `"32x32"`)
`apple_touch_icon`	Sets `<link rel="apple-touch-icon">`
`theme_color`	Sets `<meta name="theme-color">`
`manifest`	Sets `<link rel="manifest">`
`short_name`	Used by `write_manifest()` for the manifest short name
`apple_mobile_web_app_capable`	Set to `TRUE` to run standalone when added to a phone's home screen (`apple-mobile-web-app-capable` and `mobile-web-app-capable`)
`apple_mobile_web_app_title`	Sets the name shown under the home screen icon (`apple-mobile-web-app-title`)
`apple_mobile_web_app_status_bar_style`	Sets the iOS status bar style (`apple-mobile-web-app-status-bar-style`)
`custom`	List of lists — each becomes an arbitrary `<meta>` tag
`bing_site_verification`	Sets Bing verification
`google_site_verification`	Sets Google Search Console verification
`yandex_site_verification`	Sets Yandex Webmaster verification
`baidu_site_verification`	Sets Baidu Webmaster verification
`naver_site_verification`	Sets Naver Webmaster verification
`facebook_domain_verification`	Sets Facebook domain verification
`pinterest_domain_verification`	Sets Pinterest domain verification
`schema`	Set to `FALSE` to disable JSON-LD

If you want shared defaults across several apps, you can set these in .Renviron and let app-level YAML override them when needed:

SHINYSEO_BING_SITE_VERIFICATION
SHINYSEO_TWITTER_SITE
SHINYSEO_TWITTER_CREATOR

What belongs where

Use .Renviron for values that are shared across many apps on the same machine or deployment:

SHINYSEO_BING_SITE_VERIFICATION
SHINYSEO_TWITTER_SITE
SHINYSEO_TWITTER_CREATOR

Keep per-app values in each app's meta.yml:

title
description
url
image
locale if one app differs from the shared default
site_name if one app needs a different display name
twitter_site or twitter_creator if one app should override the shared default
bing_site_verification if one app needs a different Bing token

SHINYSEO_GOOGLE_ANALYTICS_MEASUREMENT_ID is not used by shinyseo itself. If you use GA4, keep that in your server or deployment config instead of in meta.yml.

Quick use

# global.R — generate manifest once at startup
shinyseo::write_manifest("meta.yml")

# ui.R
ui <- fluidPage(
  shinyseo::social_meta("meta.yml"),
  h1("My app")
)

# server.R — update metadata when the user navigates
server <- function(input, output, session) {
  observeEvent(input$tabs, {
    shinyseo::update_meta(session, title = paste(input$tabs, "– My App"))
  })
}

You can also pass a list directly instead of a YAML file:

shinyseo::social_meta(list(
  title       = "Example app",
  description = "A short app description.",
  url         = "https://example.no",
  image       = "https://example.no/share.png",
  favicon     = "/favicon.png",
  theme_color = "#1a73e8"
))

Vignettes

The long-form package docs live in vignettes:

If the package is installed, you can also open them with browseVignettes("shinyseo").

For LLM use, see LLM.md.