Custom purge plugins

Purge plugins decide which messages to delete for a template during cron. Built- in plugins are quota and days.

Plugin annotation

Place classes under src/Plugin/MessagePurge in your module (or follow the discovery path used by MessagePurgePluginManager):

/**
 * @MessagePurge(
 *   id = "my_purge",
 *   label = @Translation("My purge", context = "MessagePurge"),
 *   description = @Translation("Deletes messages matching custom rules."),
 * )
 */
class MyPurge extends MessagePurgeBase {
  // ...
}

Interface contract

Implement Drupal\message\MessagePurgeInterface (or extend MessagePurgeBase):

Method	Responsibility
`fetch(MessageTemplateInterface $template)`	Return message IDs to purge
`process(array $ids)`	Act on those IDs (base class queues deletes)
Form methods	Collect plugin configuration

MessagePurgeBase::process() chunks IDs into sets of MessagePurgeInterface::MESSAGE_DELETE_SIZE (100) and enqueues them on the message_delete queue.

Extending the base class

Use baseQuery($template) from MessagePurgeBase for an access-unchecked query scoped to the template, sorted by created and mid descending. Add your own conditions in fetch().

Inject the message entity query and message_delete queue in create(), following Quota or Days as examples.

Orchestration

You do not call plugins directly from cron. message_cron() invokes message.purge_orchestrator, which:

Splits templates into global vs override
Instantiates configured plugins
Calls fetch() then process() for each

Global purge must be enabled (purge_enable) for non-overriding templates. Overriding templates use their own purge_methods settings.

Altering plugin definitions

Use hook_message_purge_alter() if you need to change discovered purge plugin definitions.