CoverKit codebase reference

Developer documentation aligned with the current plugin source. For architecture of use cases and output profiles, start with use-cases-and-output-profiles.md. For site-owner workflows, see the plugin README on GitHub and the user guide.

What the plugin does

CoverKit is a WordPress plugin for designing template-based images in the block editor and rendering them to image files on the server (Imagick). Built-in use cases route those images to the front end (social link previews including Open Graph, featured images), the editor sidebar, and custom integrations—each configured per coverkit template.

The codebase splits into:

• PHP — includes/, bootstrapped by coverkit.php
• Editor — src/, compiled to build/ via webpack (npm run build)

Boot sequence

1. coverkit.php loads autoloaders and includes/functions.php.
2. CoverKit\init() runs on plugins_loaded priority 1 and constructs:
   • Settings
   • REST
   • Post_Type
   • Use_Case_Registry
   • Use_Case_Storage
   • Post_List_Preview_Columns
   • Patterns
   • Examples (unless COVERKIT_LOAD_EXAMPLES is false)
3. init priority 15: fire_coverkit_init() runs do_action( 'coverkit_init' ).
4. coverkit_init priority 5: built-in and third-party code call coverkit_register_use_case().
5. coverkit_init priority 10: Use_Case_Registry::boot() loads coverkit_usecases and calls Use_Case::maybe_init() on each active class.
6. Activation runs Post_Type::activate() and Settings::activate() (starter templates from assets/templates/ when missing).

Primary entry points

Area	Source	Role
Bootstrap	coverkit.php	Constants, autoload, init(), activation
Template CPT	includes/class-coverkit-post-type.php	coverkit post type, meta, blocks, list preview, cache actions
REST	includes/class-coverkit-rest.php	coverkit/v1 routes (images, preview, use cases)
Rendering	includes/class-coverkit-renderer.php	generate(), generate_from_content()
Generator	includes/class-coverkit-generator.php, includes/generator/	Imagick canvas pipeline and cache
Template parsing	includes/class-coverkit-template.php	Block → canvas/elements; field placeholders and mappings
Field pipeline	includes/class-coverkit-field-resolver.php, class-coverkit-field-formatter.php, class-coverkit-mapping-applicator.php, class-coverkit-block-bindings.php, class-coverkit-block-bindings-applicator.php	Collect, format, apply use-case mappings and native block bindings
Use cases	includes/class-coverkit-use-case.php, class-coverkit-use-case-registry.php, class-coverkit-use-case-storage.php, includes/use-cases/	Registration, boot, assignments, Open Graph / sidebar
Settings	includes/class-coverkit-settings.php, src/settings/	Settings → CoverKit (coverkit_options, coverkit_presets); CoverKit → Settings links here when the CPT uses the top-level menu
Editor	src/editor/, src/blocks/, src/editor/use-cases/	Gutenberg UI, mapping sidebar, previews

Data model

coverkit post type

Private UI post type; admin menu is top-level CoverKit by default, or nested under Media when menu_in_media is enabled in Settings (coverkit_options). Supports title, editor, revisions, page-attributes, custom-fields.

Template post meta

Meta key	Type	Purpose
width	integer	Canvas width (default 500)
height	integer	Canvas height
background	string	Canvas background color
gradient	string	Canvas gradient
_coverkit_use_cases	object	Per–use-case assignments (active, settings, mappings, optional instances) — Use_Case_Storage::META_KEY
_coverkit_active_use_cases	array	Derived slug list for editor/debug — Use_Case_Storage::SUMMARY_META_KEY

Options

Option	Purpose
coverkit_options	Global settings (e.g. image_format, menu_in_media) — schema in schemas/options.php; read via coverkit_option()
coverkit_presets	Dimension presets for new templates — schemas/templates.php
coverkit_usecases	List of active use case slugs to boot — Use_Case_Registry::LOADER_MANIFEST_OPTION

When _coverkit_use_cases changes, Use_Case_Storage rebuilds coverkit_usecases.

Rendering flow (summary)

1. Edit — User designs coverkit/canvas + coverkit/layer blocks; use cases and mappings are saved in _coverkit_use_cases.
2. Generate — Renderer::generate( $use_case_slug, $template_id, $post_id, $options ) builds a Template, runs apply_data() (placeholders + block bindings + apply_use_case_mappings()), then Generator::generate().
3. Open Graph — Open_Graph_Image_Use_Case::init() hooks wp_head and points og:image at GET /wp-json/coverkit/v1/use-case/opengraph/{template_id}/{post_id}.{ext}.
4. Serve — Cached files are exposed via /coverkit/v1/canvas/{filename} or /coverkit/v1/use-case/{use_case}/... routes.

Good first files to read

Backend

1. coverkit.php
2. includes/class-coverkit-post-type.php
3. includes/class-coverkit-rest.php
4. includes/class-coverkit-template.php
5. includes/class-coverkit-renderer.php
6. includes/class-coverkit-use-case-registry.php
7. use-cases-and-output-profiles.md

Frontend

1. src/blocks/canvas/, src/blocks/layer/
2. src/editor/index.js
3. src/editor/use-cases/ (UseCasePanel, UseCaseAssignment, mapping components)

More reference

• Use cases and output profiles
• PHP backend
• REST API
• Blocks and editor
• Native block bindings (experiment)
• Hooks and extension points
• PHP examples
• Documentation maintenance