SEO Extras Plugin

The seo-extras plugin provides Yoast-like per-content SEO overrides. After activation, content edit pages receive an optional SEO panel with fields for SEO title, SEO description, Open Graph image, and robots directives.

Why It Exists

Core SEO metadata is inferred from content fields:

SEO field	Default source
Description and Open Graph description	`Content.Excerpt`, truncated when needed.
Open Graph image	`Content.ImageURL`.
Title and Open Graph title	`Content.Title`.
Robots	`index, follow`.

Some editorial workflows need a separate SEO title, custom description, special share image, or noindex directive without changing the visible page content.

Activate seo-extras from Admin > Plugins. The four editor fields are optional and can be mixed: a filled value overrides its corresponding field, while an empty value continues to use core output.

Storage

The plugin stores values in gp_content_meta with _seo_ keys:

Field	Meta key
SEO Title	`_seo_title`
SEO Description	`_seo_description`
Open Graph Image	`_seo_image`
Robots	`_seo_robots`

Empty fields are deleted rather than stored as empty strings. This keeps the meaning clear: missing metadata means use the default SEO output.

Hooks

The plugin is implemented without core schema changes. It subscribes to:

admin.content_form.fields  -> render SEO panel
admin.content.saved        -> persist submitted values
seo.content.meta           -> patch SEOMeta

BaseTheme-based themes receive the SEO patch automatically, and so do typed themes that embed coreTheme.SEOPageService — its BuildContentSEO already calls coreTheme.ApplyContentMetaSEO. Only themes that build SEOMeta entirely by hand (not via SEOPageService) must call coreTheme.ApplyContentMetaSEO themselves when building page SEO.

The complete rendering path is:

SEOBuilder.ForContent
  -> request-aware site option overrides
  -> ApplyContentMetaSEO
     -> seo.content.meta filter chain
  -> PageData.SEO / data["SEO"]
  -> {{seoHeadFor .}}

Activation Behavior

State	Result
Inactive	No panel or filter; core title, excerpt, image, and robots values render.
Active, fields empty	Panel is visible, but SEO output remains unchanged.
Active, some fields set	Only supplied fields override core output.
Deactivated after use	Hook output disappears; stored `_seo_*` values remain but are not read.

The plugin owns no custom table or route. It reuses gp_content_meta, and deactivation removes all three hook handles.

Custom SEO Plugins

Additional SEO plugins can subscribe to the same seo.content.meta filter. Priority order controls how multiple plugins compose their changes.

Keep custom plugins additive: use the shared metadata filter for new schema or Open Graph behavior rather than importing a theme or replacing its complete HTML response.