Extension Point API Reference

Use this page when you know what you want to extend and need the exact contract, registration point, and fallback behavior. Start with Extension point chooser if you are still deciding.

Reading The Tables

Column	Meaning
API	Contract, registry, facade, or tag to use.
Register from	Where package code should usually register it.
Called by	Runtime surface that consumes the contribution.
Safe fallback	What should happen when the package is absent, disabled, or returns nothing.
Test recipe	Smallest useful proof.

Core And Package Runtime

Need	API	Register from	Called by	Safe fallback	Test recipe
Page subject type	CapellCore::registerPageType(new PageTypeData(...))	Runtime provider registeringPackage() or boot method	Blueprint/page type selection	Type is absent from selectors	Assert CapellCore::getPageTypes() contains the key.
Model morph alias	CapellCore::registerModel() / registerModels()	Runtime provider	Morph map and model resolution	Laravel default morph behavior	Assert morph map resolves the model alias.
Model behavior	CapellCore::registerModelInterceptor()	Runtime/admin provider	Capell model interceptor resolver	Base model behavior remains unchanged	Instantiate model and assert interceptor method affects only matching context.
Settings schema	SettingsSchemaRegistry::register() plus registerSettingsClass()	Runtime/admin provider or AdminBridge	Admin settings surfaces	Group/tab is absent	Resolve registry and assert schema/settings class for group.
Package settings page	CapellAdmin::registerExtensionPage()	AdminBridge or admin provider	Installed Extensions page and grouped Filament sub-navigation	No package control page	Assert ExtensionPageRegistry::get($packageName) returns the page and the sub-navigation contains accessible registered pages grouped by product group.
Content graph extraction	ContentGraphRegistry::TAG or registry registration	Runtime provider	Content graph builders	Content is not linked into graph	Build graph for fixture content and assert edge exists.
Link picker entries	LinkableContentRegistry::register(...)	Runtime/admin provider	Link picker/search UI	Item type is not searchable	Assert registry includes provider and search returns fixture.
Renderable definition	RenderableRegistry::register(...)	Runtime provider	Rendering/runtime builders	Definition is unavailable	Assert registry returns the definition key.
Tailwind assets	TailwindAssetsRegistry::registerSource() / registerImport()	Runtime/frontend provider	Frontend/admin asset commands	Package classes are not scanned	Assert toReport() includes source/import origin.
Vendor asset condition	VendorAssetConditionRegistry::register(...)	Runtime provider	Asset manifest builders	Asset is not conditionally loaded	Assert condition returns expected value for fixture context.
Developer maker	MakerRegistryInterface::register(...)	Runtime/dev provider	Maker commands	Maker command option is absent	Assert maker appears in registry.

Admin Runtime

Need	API	Register from	Called by	Safe fallback	Test recipe
Multiple admin surfaces	AdminBridge with AdminBridgeRegistrar	Runtime/admin provider	Admin bridge registry	Package contributes no admin surfaces	Assert bridge is registered for package name.
Single admin page/resource/widget	CapellAdmin::contributeToAdminSurface(AdminSurfaceContributionData::...)	Admin provider	CapellAdminPlugin	Surface is absent	Assert admin surface lookup contains the class.
Dashboard widget	CapellAdmin::registerDashboardWidget(...)	Admin provider or bridge	Dashboard widget resolver	Widget hidden	Assert widget appears in expected dashboard slot.
Overview stat	CapellAdmin::registerOverviewStat(...)	Admin provider	Dashboard stats	Stat hidden	Assert stat key appears for allowed user/context.
User menu item	CapellAdmin::registerUserMenuItem(...)	Admin provider	User menu registry	Menu item hidden	Assert user menu registry contains item.
Admin header tool	AdminToolItem::TAG	Tag class in provider	Admin tool registry	Tool hidden	Resolve app()->tagged(AdminToolItem::TAG).
Page form fields	PageSchemaExtender::TAG	Tag extender in provider or bridge	Page schema resolver	Base page form only	Build schema for fixture page and assert field exists.
Site form fields	SiteSchemaExtender::TAG	Tag extender in provider or bridge	Site schema resolver	Base site form only	Build schema for fixture site and assert field exists.
Layout form fields	LayoutSchemaExtender::TAG	Tag extender in provider or bridge	Layout schema resolver	Base layout form only	Build schema for fixture layout and assert field exists.
User form fields	UserSchemaExtender::TAG	Tag extender or user bridge	User schema resolver	Base user form only	Assert supports() and schema field for target user model.
Page table query	PageTableExtender::TAG	Tag extender in provider	Page tables and page selects	Base query	Assert modified query includes expected relation/filter.
Page table publish/workflow status	PageTableStatusResolver container binding	Admin provider	Pages table status column	Publish-date status resolver	Bind a fake resolver and assert the table renders its state.
User table query	UserTableExtender::TAG	Tag extender or user bridge	User resource table	Base query	Assert modified query behavior.
Header actions	PageHeaderActionExtender::TAG, SiteHeaderActionExtender::TAG, ResourceHeaderActionExtender::TAG	Tag extender in provider	Resource/page action resolvers	Action hidden	Render header actions and assert action key.
Site row actions	SiteRecordActionExtender::TAG	Tag extender in provider	Sites table	Action hidden	Render table actions for fixture site.
Publish panel content	PublishPanelExtender::TAG	Tag extender in provider	Page publish section	Panel remains unchanged	Assert view/html appears only for supported page.
Page edit content	PageEditExtender::TAG	Tag extender in provider	Edit page	Extra content hidden	Render edit page and assert component appears.
Page resource pages/widgets	PageResourcePageExtender::TAG, PageResourceWidgetExtender::TAG	Tag extender in provider	Page resource	Extra pages/widgets hidden	Assert PageResource includes class.
Page export fields	PageExportExtender::TAG	Tag extender in provider	Page/site export actions	Extra fields omitted	Run export action and assert payload contains field.
Media edit actions	MediaEditActionExtender::TAG	Tag extender in provider	Media edit page	Action hidden	Render media edit actions.
Extensions page content	ExtensionsPageExtender::TAG	Tag extender in provider	Installed Extensions page	No package alert/content	Render Extensions page and assert package section.
Extensions page actions	ExtensionsPageActionRegistry	afterResolving() or provider boot	Installed Extensions page	Action hidden	Resolve registry and assert header/table action key.
Admin panel customization	AdminPanelExtender::TAG	Tag extender in provider	CapellAdminPlugin	Base panel config	Build panel and assert plugin/middleware/theme change.
Validation gates	ValidationSubscriber or subscriber contracts	Runtime/admin provider	Subscriber manager/admin events	Validation not applied	Notify event with fixture and assert error/result.
Admin event handlers	AdminEventRegistry::register(...)	Admin provider	HasDynamicEventListeners	Event has no extra handler	Dispatch Livewire event and assert handler ran.
Activity display/revert	ActivityChangeSetBuilder::TAG, ActivityRevertHandler::TAG	Admin provider	Activity/revert actions	Default activity behavior	Run activity builder/revert fixture.
Site Health report	SiteHealthReportExtender::TAG	Admin provider	Site Health action/page	Report section absent	Build Site Health report and assert section.

Frontend Runtime

Need	API	Register from	Called by	Safe fallback	Test recipe
Small public HTML injection	RenderHookRegistry::register(...)	Frontend/runtime provider	Public Blade hook calls	Hook outputs nothing	Render anonymous page and assert safe HTML.
Frontend component alias	FrontendComponentRegistryInterface::register(...)	Frontend provider	Runtime component resolver	Alias is unavailable	Assert has() and hasReference() for key/alias.
Builder block rendering	WidgetRegistry::register(...) with frontend target	Runtime/frontend provider	Content renderer	Block is skipped/unrenderable	Render fixture block and assert output.
Reserved public path	ReservedFrontendPathRegistry::reserveExact() / reservePrefix()	Frontend provider before fallback routes	Frontend route resolver	Path falls through to page lookup	Assert package route responds and page fallback does not catch it.
Public route middleware	FrontendRouteMiddlewareRegistry	Frontend provider	Public page route	Base middleware order	Assert all() order or request side effect.
Frontend rule condition	FrontendRuleConditionRegistry::register(...)	Frontend provider	Runtime rules	Rule never matches	Directly evaluate condition against fixture context.
Response renderer	FrontendResponseRendererRegistry::register() / registerClass()	Frontend provider	Runtime response pipeline	Default renderer	Resolve renderer for runtime and assert response class/content.
Cache invalidation	CacheInvalidationRegistry::registerDependency(...)	Frontend/runtime provider	Model observers/cache invalidator	Cache remains until TTL/manual clear	Save fixture model and assert invalidation plan.
Critical/deferred assets	CriticalAssetRegistry::registerCritical() / registerDeferred()	Frontend provider	Frontend asset rendering	Asset not emitted	Render page and assert handle/url in expected section.
Runtime manifest contributors	FrontendRuntimeManifestContributor::TAG	Frontend provider	Frontend runtime builder	Manifest lacks package data	Build runtime manifest and assert contribution.
Asset contributors	FrontendAssetContributor::TAG	Frontend provider	Frontend asset manifest builder	Asset absent	Build asset manifest and assert package handle.

Installer And Marketplace Runtime

Need	API	Register from	Called by	Safe fallback	Test recipe
Browser install guide patch	Patch plus PatchRegistry::register(...)	Installer provider registerPatches()	Install guide page/action	Patch absent	Probe/apply fixture host file and assert idempotence.
Installer default packages	CAPELL_SETUP_DEFAULT_PACKAGES plus package metadata	Host env/config	Browser installer page data	Package not preselected	Build installer page data and assert default list.
Extension dashboard widget	CapellAdmin::registerDashboardWidget($widget, DashboardEnum::Extensions) or $registrar->extensionDashboardWidget($widget)	Admin provider or admin bridge	Extensions dashboard	Widget absent	Register fixture widget and assert it appears in DashboardEnum::Extensions.
Marketplace installed extensions content	ExtensionsPageExtender::TAG	Marketplace/provider	Extensions dashboard actions area	No Marketplace alert	Render Extensions page in connected/unconnected states.
Marketplace theme header action	ResourceHeaderActionExtender::TAG	Marketplace/provider	Theme resource header	Action hidden	Render theme resource action list.
Marketplace activation verification	Container binding capell.marketplace.activation-verifier	Marketplace provider	Install/activation flow	Signed activation unavailable	Resolve binding and verify signed fixture payload.

Rules

• Register in the package that owns the behavior.
• Return null, an empty array, or no-op output when the package does not support the current context.
• Test both the expected contribution and the safe fallback.
• Public frontend extensions must pass public HTML safety.

Next

• Build an extension end to end
• Admin extensions
• Frontend extensions
• Extension troubleshooting