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). Primary outputs are Open Graph / social preview images and editor sidebar previews, driven by use cases 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_active_use_case_classes 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	Collect, format, apply use-case mappings
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)
Editor	src/editor/, src/blocks/, src/editor/use-cases/	Gutenberg UI, mapping sidebar, previews

Data model

coverkit post type

Private UI post type under Media (show_in_menu → upload.php). 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. default image_format) — schema in schemas/options.php
coverkit_presets	Dimension presets for new templates — schemas/templates.php
coverkit_active_use_case_classes	Loader manifest: slug → FQCN for classes to boot — Use_Case_Registry::LOADER_MANIFEST_OPTION

When _coverkit_use_cases changes, Use_Case_Storage rebuilds coverkit_active_use_case_classes.

Rendering flow (summary)

1. Edit — User designs coverkit/canvas + coverkit/shape 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 + 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/opengraph/{template_id}/{post_id}.{ext}.
4. Serve — Cached files are exposed via /coverkit/v1/canvas/{filename} or use-case/opengraph 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/shape/
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
• Hooks and extension points
• PHP examples
• Documentation maintenance