Plugins ship as Django apps with a PluginConfig-style class declaring version bounds, middleware, optional django_apps merged into INSTALLED_APPS, django-rq queue names, and an events_pipeline list merged globally.
Default resource hooks (by conventional import paths) include:
The extras app area hosts cross-model constructs: webhooks, export templates, custom fields, relationships (where applicable in this version lineage), job-like script storage, and similar—pattern aligns with Source A’s “platform services” idea but concrete models differ by release.
Administrators can define validation and deletion protection rules so business policy is enforced at save/delete time.
A process-wide registry tracks installed plugins and contributions (menus, GraphQL fragments, template hooks)—supporting introspection in the UI.