Hooks and extension points

Filters and actions found in current includes/ PHP. For use case registration, see use-cases-and-output-profiles.md.

Actions

Action	Source	Purpose
coverkit_init	coverkit.php (fire_coverkit_init on init priority 15)	Register use case types (priority < 10); registry boots at priority 10
coverkit_generate_image	REST::__construct()	Async fetch of queued generation URLs
coverkit_retry_screenshots	includes/functions.php	Retries templates flagged _coverkit_needs_retry
coverkit_fs_loaded	includes/freemius.php	Fires when Freemius SDK is loaded

Register custom use cases on coverkit_init:

add_action(
  'coverkit_init',
  static function (): void {
    \CoverKit\coverkit_register_use_case( 'my_slug', array(
      'label' => 'My use case',
      'class' => \MyPlugin\My_Use_Case::class,
    ) );
  },
  5
);

Filters — generation and images

Filter	Source	Purpose
coverkit_pre_generate	Renderer::generate()	Return non-null to short-circuit generation
coverkit_after_generate	Renderer::generate()	Adjust generation result array
coverkit_generation_options	Generator (canvas process)	Merge options before render
coverkit_max_canvas_dimension	Generator	Max canvas edge (default 12000)
coverkit_responsive_sizes	get_coverkit_responsive_sizes()	Canvas hash derivative widths (non-use-case routes)
coverkit_use_case_allowed_widths	coverkit_get_use_case_allowed_widths()	Public ?width= per use case (null = canonical only)
coverkit_user_can_resize_images	coverkit_user_can_resize_images()	Whether the current user may request arbitrary REST ?width=
coverkit_rest_generation_max_width	coverkit_get_rest_generation_max_width()	Max width for privileged resize requests
coverkit_post_list_preview_width	coverkit_get_post_list_preview_width()	Posts list thumbnail width (privileged)
coverkit_template_list_preview_width	coverkit_get_template_list_preview_width()	Templates list Preview column thumbnail width (default 150px)
coverkit_post_list_popover_preview_width	coverkit_get_post_list_popover_preview_width()	Posts list popover image max layout width (default 500px)
coverkit_rest_use_case_image_srcset_densities	coverkit_rest_use_case_image_srcset()	Multipliers for posts list thumbnail srcset (default 1, 2)
coverkit_rest_template_preview_srcset_densities	coverkit_rest_template_preview_srcset()	Multipliers for templates list thumbnail srcset (default 1, 2)
coverkit_canvas_image_cache_time	REST::serve_canvas_image()	Cache-Control max-age (default 31536000)
coverkit_allow_image_browser_cache	REST::should_allow_browser_cache_for_image()	Whether use-case image responses may send browser cache headers (ETag, 304, long max-age); template preview routes always bypass this
coverkit_autocompleter_options	REST::get_autocompleters()	Editor placeholder tags

Filters — fields and use cases

Filter	Source	Purpose
coverkit_collect_field_raw	Field_Resolver::collect_raw()	Adjust raw field value after built-in resolution
coverkit_preview_data	Field_Resolver::collect_preview_data()	Placeholder data when no post context
coverkit_format_field_value	Use_Case::format_field_value()	Global formatter pass
coverkit_use_case_{$slug}_format_field_value	Use_Case::format_field_value()	Per use case (also registered when subclass implements filter_format_field_value())
coverkit_use_case_settings_schema	Use_Case::get_settings_schema()	Settings fields for editor
coverkit_use_case_{$slug}_settings_schema	same	Per-slug settings schema
coverkit_use_case_mapping_sources	Use_Case::get_mapping_sources()	Mapping picker catalog
coverkit_use_case_{$slug}_mapping_sources	same	Per-slug mapping sources
coverkit_block_bindings_enabled	Block_Bindings::is_enabled()	Enable native metadata.bindings on coverkit/layer (default true; requires WP 7.0+)

Filters — Open Graph

Filter	Source	Purpose
coverkit_opengraph_meta_enabled	Open_Graph_Image_Use_Case	Disable meta output for a request context
coverkit_opengraph_request_post_id	same	Post ID embedded in image URL
coverkit_opengraph_template_id	same	Template ID used for OG image

Filters — Featured image

Filter	Source	Purpose
coverkit_featured_image_template_id	Featured_Image_Use_Case	Template ID resolved for a post
coverkit_featured_image_url	same	REST image URL for front-end or editor preview
coverkit_featured_image_html_enabled	same	Disable <img> replacement for a post

Filters — REST and Site Health

Filter	Source	Purpose
coverkit_use_case_public_image_permission	REST::get_use_case_image_permission()	Whether a use-case image route allows anonymous access
coverkit_site_health_check_methods	Site_Health	Async Site Health test method list
coverkit_site_health_async_transient_ttl	Site_Health	TTL for async Site Health transients (default one hour)

Filters — cache

Filter	Source	Purpose
coverkit_cache_unique_id	coverkit_get_cache_unique_id() in includes/functions.php	Override the six-character hex id in the cache directory name coverkit-{id} (must match /^[a-f0-9]{6}$/ after lowercasing; invalid values fall back to the AUTH_KEY-derived default)

Default id: substr( hash_hmac( 'sha256', 'coverkit-cache-directory', AUTH_KEY ), 0, 6 ), or wp_salt( 'coverkit_cache' ) when AUTH_KEY is missing or empty. Helpers: coverkit_get_cache_unique_id(), coverkit_get_cache_unique_id_default(), coverkit_get_cache_directory_basename(), get_coverkit_path().

Other integration filters

Filter	Source	Purpose
coverkit_screenshot_request_args	get_screenshot() in functions.php	mShots / screenshot HTTP args
coverkit_freemius_args	includes/freemius.php	Freemius SDK initialization args

Block and pattern extension

• Block category: Post_Type::block_categories() — coverkit
• Patterns: patterns/*.php via Patterns, category coverkit, postTypes → coverkit

Internal WordPress hooks (selected)

• plugins_loaded — plugin init()
• rest_api_init — REST routes
• allowed_block_types_all — restrict template editor to coverkit/*
• updated_post_meta / added_post_meta / deleted_post_meta — rebuild loader manifest when _coverkit_use_cases changes
• wp_head — Open Graph tags from Open_Graph_Image_Use_Case