From 3c068c98de1ffb59064b169675926819000b623b Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Fri, 8 Aug 2025 11:56:27 +0200
Subject: [PATCH 01/18] Refactor tombstone handling into Tombstone class

Moved all tombstone detection logic into a new Activitypub\Tombstone class, deprecating is_tombstone() and Http::is_tombstone(). Updated all usages to use Tombstone::check() and related methods. Added a tombstone JSON template and updated tests to reflect the new class. This centralizes and standardizes tombstone checks across the codebase.
---
 includes/class-activitypub.php                |   5 +
 includes/class-http.php                       |  22 +--
 includes/class-query.php                      |   2 +-
 includes/class-scheduler.php                  |   2 +-
 includes/class-tombstone.php                  | 170 ++++++++++++++++++
 includes/collection/class-followers.php       |   5 +-
 includes/functions.php                        |  10 +-
 includes/handler/class-delete.php             |   8 +-
 templates/tombstone-json.php                  |  27 +++
 ...test-http.php => class-test-tombstone.php} |   6 +-
 10 files changed, 218 insertions(+), 39 deletions(-)
 create mode 100644 includes/class-tombstone.php
 create mode 100644 templates/tombstone-json.php
 rename tests/includes/{class-test-http.php => class-test-tombstone.php} (91%)

diff --git a/includes/class-activitypub.php b/includes/class-activitypub.php
index 08deccc99..8711848ce 100644
--- a/includes/class-activitypub.php
+++ b/includes/class-activitypub.php
@@ -117,6 +117,11 @@ public static function render_activitypub_template( $template ) {
 			return $template;
 		}
 
+		if ( Tombstone::check_local_url( Query::get_instance()->get_request_url() ) ) {
+			\status_header( 410 );
+			return ACTIVITYPUB_PLUGIN_DIR . 'templates/tombstone-json.php';
+		}
+
 		$activitypub_template = false;
 		$activitypub_object   = Query::get_instance()->get_activitypub_object();
 
diff --git a/includes/class-http.php b/includes/class-http.php
index ecd25ec27..962cacada 100644
--- a/includes/class-http.php
+++ b/includes/class-http.php
@@ -182,27 +182,9 @@ public static function get( $url, $cached = false ) {
 	 * @return bool True if the URL is a tombstone.
 	 */
 	public static function is_tombstone( $url ) {
-		/**
-		 * Fires before checking if the URL is a tombstone.
-		 *
-		 * @param string $url The URL to check.
-		 */
-		\do_action( 'activitypub_pre_http_is_tombstone', $url );
-
-		$response = \wp_safe_remote_get( $url, array( 'headers' => array( 'Accept' => 'application/activity+json' ) ) );
-		$code     = \wp_remote_retrieve_response_code( $response );
-
-		if ( in_array( (int) $code, array( 404, 410 ), true ) ) {
-			return true;
-		}
-
-		$data = \wp_remote_retrieve_body( $response );
-		$data = \json_decode( $data, true );
-		if ( $data && isset( $data['type'] ) && 'Tombstone' === $data['type'] ) {
-			return true;
-		}
+		_deprecated_function( __METHOD__, 'unreleased', 'Activitypub\Tombstone::check_remote_url' );
 
-		return false;
+		return Tombstone::check_remote_url( $url );
 	}
 
 	/**
diff --git a/includes/class-query.php b/includes/class-query.php
index ea5eae870..7690d5e9c 100644
--- a/includes/class-query.php
+++ b/includes/class-query.php
@@ -248,7 +248,7 @@ protected function maybe_get_virtual_object() {
 	 *
 	 * @return string|null The request URL.
 	 */
-	protected function get_request_url() {
+	public function get_request_url() {
 		if ( ! isset( $_SERVER['REQUEST_URI'] ) ) {
 			return null;
 		}
diff --git a/includes/class-scheduler.php b/includes/class-scheduler.php
index b12632c5f..d4bbbbf39 100644
--- a/includes/class-scheduler.php
+++ b/includes/class-scheduler.php
@@ -194,7 +194,7 @@ public static function cleanup_remote_actors() {
 		foreach ( $actors as $actor ) {
 			$meta = get_remote_metadata_by_actor( $actor->guid, false );
 
-			if ( is_tombstone( $meta ) ) {
+			if ( Tombstone::check( $meta ) ) {
 				\wp_delete_post( $actor->ID );
 			} elseif ( empty( $meta ) || ! is_array( $meta ) || \is_wp_error( $meta ) ) {
 				if ( Actors::count_errors( $actor->ID ) >= 5 ) {
diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
new file mode 100644
index 000000000..bfabb540c
--- /dev/null
+++ b/includes/class-tombstone.php
@@ -0,0 +1,170 @@
+<?php
+/**
+ * Tombstone class file.
+ *
+ * @package Activitypub
+ */
+
+namespace Activitypub;
+
+use Activitypub\Activity\Base_Object;
+
+/**
+ * ActivityPub Tombstone Class.
+ */
+class Tombstone {
+	/**
+	 * HTTP codes that indicate a tombstone.
+	 *
+	 * @var array
+	 */
+	private static $codes = array( 404, 410 );
+
+	/**
+	 * Check for Tombstone.
+	 *
+	 * @param string|\WP_Error|array|object $various The various data to check.
+	 *
+	 * @return bool True if the various data is a tombstone.
+	 */
+	public static function check( $various ) {
+		if ( \is_wp_error( $various ) ) {
+			return self::check_wp_error( $various );
+		}
+
+		if ( \is_string( $various ) ) {
+			if ( is_same_domain( $various ) ) {
+				return self::check_local_url( $various );
+			}
+			return self::check_remote_url( $various );
+		}
+
+		if ( \is_array( $various ) ) {
+			return self::check_array( $various );
+		}
+
+		if ( \is_object( $various ) ) {
+			return self::check_object( $various );
+		}
+
+		return false;
+	}
+
+	/**
+	 * Check for remote URL for Tombstone.
+	 *
+	 * @param string $url The URL to check.
+	 *
+	 * @return bool True if the URL is a tombstone.
+	 */
+	public static function check_remote_url( $url ) {
+		/**
+		 * Fires before checking if the URL is a tombstone.
+		 *
+		 * @param string $url The URL to check.
+		 */
+		\do_action( 'activitypub_pre_http_is_tombstone', $url );
+
+		$response = \wp_safe_remote_get( $url, array( 'headers' => array( 'Accept' => 'application/activity+json' ) ) );
+		$code     = \wp_remote_retrieve_response_code( $response );
+
+		if ( in_array( (int) $code, self::$codes, true ) ) {
+			return true;
+		}
+
+		$data = \wp_remote_retrieve_body( $response );
+		$data = \json_decode( $data, true );
+		if ( $data && isset( $data['type'] ) && 'Tombstone' === $data['type'] ) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Check for local URL for Tombstone.
+	 *
+	 * @param string $url The URL to check.
+	 *
+	 * @return bool True if the URL is a tombstone.
+	 */
+	public static function check_local_url( $url ) {
+		$urls = get_option( 'activitypub_tombstone_urls', array() );
+
+		return in_array( normalize_url( $url ), $urls, true );
+	}
+
+	/**
+	 * Check if the response is a WP_Error.
+	 *
+	 * @param WP_Error $wp_error The response to check.
+	 *
+	 * @return bool True if the response is a WP_Error, false otherwise.
+	 */
+	public static function check_wp_error( $wp_error ) {
+		if ( ! \is_wp_error( $wp_error ) ) {
+			return false;
+		}
+
+		if ( in_array( (int) $wp_error->get_error_code(), self::$codes, true ) ) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Check if the response is a WP_Error.
+	 *
+	 * @param array $data The response to check.
+	 *
+	 * @return bool True if the response is a WP_Error, false otherwise.
+	 */
+	public static function check_array( $data ) {
+		if ( ! \is_array( $data ) ) {
+			return false;
+		}
+
+		if ( isset( $data['type'] ) && 'Tombstone' === $data['type'] ) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Check if the response is a WP_Error.
+	 *
+	 * @param object $data The response to check.
+	 *
+	 * @return bool True if the response is a WP_Error, false otherwise.
+	 */
+	public static function check_object( $data ) {
+		if ( ! \is_object( $data ) ) {
+			return false;
+		}
+
+		if ( isset( $data->type ) && 'Tombstone' === $data->type ) {
+			return true;
+		}
+
+		if ( $data instanceof Base_Object && 'Tombstone' === $data->get_type() ) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Bury a URL.
+	 *
+	 * @param string $url The URL to bury.
+	 */
+	public static function bury( $url ) {
+		$urls   = \get_option( 'activitypub_tombstone_urls', array() );
+		$urls[] = normalize_url( $url );
+		$urls   = \array_unique( $urls );
+
+		\update_option( 'activitypub_tombstone_urls', $urls );
+	}
+}
diff --git a/includes/collection/class-followers.php b/includes/collection/class-followers.php
index 287587b98..42239614f 100644
--- a/includes/collection/class-followers.php
+++ b/includes/collection/class-followers.php
@@ -7,7 +7,8 @@
 
 namespace Activitypub\Collection;
 
-use function Activitypub\is_tombstone;
+use Activitypub\Tombstone;
+
 use function Activitypub\get_remote_metadata_by_actor;
 
 /**
@@ -42,7 +43,7 @@ class Followers {
 	public static function add_follower( $user_id, $actor ) {
 		$meta = get_remote_metadata_by_actor( $actor );
 
-		if ( is_tombstone( $meta ) ) {
+		if ( Tombstone::check( $meta ) ) {
 			return $meta;
 		}
 
diff --git a/includes/functions.php b/includes/functions.php
index fa8319576..18c67930c 100644
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -204,15 +204,9 @@ function is_comment() {
  * @return boolean True if HTTP-Code is 410 or 404.
  */
 function is_tombstone( $wp_error ) {
-	if ( ! is_wp_error( $wp_error ) ) {
-		return false;
-	}
-
-	if ( in_array( (int) $wp_error->get_error_code(), array( 404, 410 ), true ) ) {
-		return true;
-	}
+	_deprecated_function( __FUNCTION__, 'unreleased', 'Activitypub\Tombstone::check_wp_error' );
 
-	return false;
+	return Tombstone::check_wp_error( $wp_error );
 }
 
 /**
diff --git a/includes/handler/class-delete.php b/includes/handler/class-delete.php
index 8f04d5cd1..fb887fd8c 100644
--- a/includes/handler/class-delete.php
+++ b/includes/handler/class-delete.php
@@ -7,7 +7,7 @@
 
 namespace Activitypub\Handler;
 
-use Activitypub\Http;
+use Activitypub\Tombstone;
 use Activitypub\Collection\Actors;
 use Activitypub\Collection\Interactions;
 
@@ -104,7 +104,7 @@ public static function maybe_delete_follower( $activity ) {
 		$follower = Actors::get_remote_by_uri( $activity['actor'] );
 
 		// Verify that Actor is deleted.
-		if ( ! is_wp_error( $follower ) && Http::is_tombstone( $activity['actor'] ) ) {
+		if ( ! is_wp_error( $follower ) && Tombstone::check( $activity['actor'] ) ) {
 			Actors::delete( $follower->ID );
 			self::maybe_delete_interactions( $activity );
 		}
@@ -117,7 +117,7 @@ public static function maybe_delete_follower( $activity ) {
 	 */
 	public static function maybe_delete_interactions( $activity ) {
 		// Verify that Actor is deleted.
-		if ( Http::is_tombstone( $activity['actor'] ) ) {
+		if ( Tombstone::check( $activity['actor'] ) ) {
 			\wp_schedule_single_event(
 				\time(),
 				'activitypub_delete_actor_interactions',
@@ -153,7 +153,7 @@ public static function maybe_delete_interaction( $activity ) {
 
 		$comments = Interactions::get_interaction_by_id( $id );
 
-		if ( $comments && Http::is_tombstone( $id ) ) {
+		if ( $comments && Tombstone::check( $id ) ) {
 			foreach ( $comments as $comment ) {
 				wp_delete_comment( $comment->comment_ID, true );
 			}
diff --git a/templates/tombstone-json.php b/templates/tombstone-json.php
new file mode 100644
index 000000000..85944b08c
--- /dev/null
+++ b/templates/tombstone-json.php
@@ -0,0 +1,27 @@
+<?php
+/**
+ * Tombstone JSON template.
+ *
+ * @package Activitypub
+ */
+
+$object = new \Activitypub\Activity\Base_Object();
+$object->set_id( \Activitypub\Query::get_instance()->get_request_url() );
+$object->set_type( 'Tombstone' );
+
+/**
+ * Fires before an ActivityPub object is generated and sent to the client.
+ *
+ * @param object $object The ActivityPub object.
+ */
+\do_action( 'activitypub_json_pre', $object );
+
+\header( 'Content-Type: application/activity+json' );
+echo $object->to_json(); // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+
+/**
+ * Fires after an ActivityPub object is generated and sent to the client.
+ *
+ * @param object $object The ActivityPub object.
+ */
+\do_action( 'activitypub_json_post', $object );
diff --git a/tests/includes/class-test-http.php b/tests/includes/class-test-tombstone.php
similarity index 91%
rename from tests/includes/class-test-http.php
rename to tests/includes/class-test-tombstone.php
index 5d3f57b36..1d74afb36 100644
--- a/tests/includes/class-test-http.php
+++ b/tests/includes/class-test-tombstone.php
@@ -7,14 +7,14 @@
 
 namespace Activitypub\Tests;
 
-use Activitypub\Http;
+use Activitypub\Tombstone;
 
 /**
  * Test class for ActivityPub HTTP Class
  *
  * @coversDefaultClass \Activitypub\Http
  */
-class Test_Http extends \WP_UnitTestCase {
+class Test_Tombstone extends \WP_UnitTestCase {
 
 	/**
 	 * Response code is 404 -> is_tombstone returns true
@@ -31,7 +31,7 @@ public function test_is_tombstone( $request, $result ) {
 			return $request;
 		};
 		add_filter( 'pre_http_request', $fake_request, 10, 3 );
-		$response = Http::is_tombstone( 'https://fake.test/object/123' );
+		$response = Tombstone::is_tombstone( 'https://fake.test/object/123' );
 		$this->assertEquals( $result, $response );
 		remove_filter( 'pre_http_request', $fake_request, 10 );
 	}

From 7193a64379dc31238febb43af3990553132900cb Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Fri, 8 Aug 2025 11:58:49 +0200
Subject: [PATCH 02/18] Refactor Tombstone type check logic

Replaces inline array check in the is_tombstone() method with a call to self::check_array() for improved code reuse and maintainability.
---
 includes/class-tombstone.php | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index bfabb540c..0a7a215dd 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -74,11 +74,8 @@ public static function check_remote_url( $url ) {
 
 		$data = \wp_remote_retrieve_body( $response );
 		$data = \json_decode( $data, true );
-		if ( $data && isset( $data['type'] ) && 'Tombstone' === $data['type'] ) {
-			return true;
-		}
 
-		return false;
+		return self::check_array( $data );
 	}
 
 	/**

From 48f196f208a217f26a41c50b8d04d2cc1d7d82ec Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Fri, 8 Aug 2025 12:06:15 +0200
Subject: [PATCH 03/18] Add tests for new Tombstone check methods

Expanded the test suite in class-test-tombstone.php to cover Tombstone::check_wp_error, check_array, check_object, and check_local_url methods. Updated existing tests and data providers to reflect method renaming from is_tombstone to check_remote_url.
---
 tests/includes/class-test-tombstone.php | 71 +++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 5 deletions(-)

diff --git a/tests/includes/class-test-tombstone.php b/tests/includes/class-test-tombstone.php
index 1d74afb36..4708594ee 100644
--- a/tests/includes/class-test-tombstone.php
+++ b/tests/includes/class-test-tombstone.php
@@ -19,19 +19,19 @@ class Test_Tombstone extends \WP_UnitTestCase {
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::is_tombstone
+	 * @covers ::check_remote_url
 	 *
-	 * @dataProvider data_is_tombstone
+	 * @dataProvider data_check_remote_url
 	 *
 	 * @param array $request The request array.
 	 * @param bool  $result  The expected result.
 	 */
-	public function test_is_tombstone( $request, $result ) {
+	public function test_check_remote_url( $request, $result ) {
 		$fake_request = function () use ( $request ) {
 			return $request;
 		};
 		add_filter( 'pre_http_request', $fake_request, 10, 3 );
-		$response = Tombstone::is_tombstone( 'https://fake.test/object/123' );
+		$response = Tombstone::check_remote_url( 'https://fake.test/object/123' );
 		$this->assertEquals( $result, $response );
 		remove_filter( 'pre_http_request', $fake_request, 10 );
 	}
@@ -41,7 +41,7 @@ public function test_is_tombstone( $request, $result ) {
 	 *
 	 * @return array
 	 */
-	public function data_is_tombstone() {
+	public function data_check_remote_url() {
 		return array(
 			array( array( 'response' => array( 'code' => 404 ) ), true ),
 			array( array( 'response' => array( 'code' => 410 ) ), true ),
@@ -82,4 +82,65 @@ public function data_is_tombstone() {
 			),
 		);
 	}
+
+	/**
+	 * Response code is 404 -> is_tombstone returns true
+	 *
+	 * @covers ::check_wp_error
+	 */
+	public function test_check_wp_error() {
+		$response = Tombstone::check_wp_error( new \WP_Error( 404 ) );
+		$this->assertTrue( $response );
+
+		$response = Tombstone::check_wp_error( new \WP_Error( 410 ) );
+		$this->assertTrue( $response );
+
+		$response = Tombstone::check_wp_error( new \WP_Error( 200 ) );
+		$this->assertFalse( $response );
+	}
+
+	/**
+	 * Response code is 404 -> is_tombstone returns true
+	 *
+	 * @covers ::check_array
+	 */
+	public function test_check_array() {
+		$response = Tombstone::check_array( array( 'type' => 'Tombstone' ) );
+		$this->assertTrue( $response );
+
+		$response = Tombstone::check_array( array( 'type' => 'Note' ) );
+		$this->assertFalse( $response );
+	}
+
+	/**
+	 * Response code is 404 -> is_tombstone returns true
+	 *
+	 * @covers ::check_object
+	 */
+	public function test_check_object() {
+		$response = Tombstone::check_object( (object) array( 'type' => 'Tombstone' ) );
+		$this->assertTrue( $response );
+
+		$response = Tombstone::check_object( (object) array( 'type' => 'Note' ) );
+		$this->assertFalse( $response );
+	}
+
+	/**
+	 * Response code is 404 -> is_tombstone returns true
+	 *
+	 * @covers ::check_local_url
+	 */
+	public function test_check_local_url() {
+		$url = 'https://fake.test/object/123';
+
+		$response = Tombstone::check_local_url( $url );
+		$this->assertFalse( $response );
+
+		Tombstone::bury( $url );
+
+		$response = Tombstone::check_local_url( $url );
+		$this->assertTrue( $response );
+
+		\delete_option( 'activitypub_tombstone_urls' );
+	}
 }

From 37ae91c8b5571c9060a70c0374a32ebce824edec Mon Sep 17 00:00:00 2001
From: Automattic Bot <sysops+ghmatticbot@automattic.com>
Date: Fri, 8 Aug 2025 20:10:48 +0200
Subject: [PATCH 04/18] Add changelog

---
 .github/changelog/2066-from-description | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 .github/changelog/2066-from-description

diff --git a/.github/changelog/2066-from-description b/.github/changelog/2066-from-description
new file mode 100644
index 000000000..344b8c0f6
--- /dev/null
+++ b/.github/changelog/2066-from-description
@@ -0,0 +1,4 @@
+Significance: minor
+Type: added
+
+Improved handling of deleted content with a new unified system for better tracking and compatibility.

From 7ea9925a9291e4f248af5e2348b9ea9ce9d044ea Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Fri, 8 Aug 2025 20:11:58 +0200
Subject: [PATCH 05/18] Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 includes/class-tombstone.php | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index 0a7a215dd..ba452dba2 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -111,11 +111,11 @@ public static function check_wp_error( $wp_error ) {
 	}
 
 	/**
-	 * Check if the response is a WP_Error.
+	 * Check if the given array represents a tombstone.
 	 *
-	 * @param array $data The response to check.
+	 * @param array $data The array to check.
 	 *
-	 * @return bool True if the response is a WP_Error, false otherwise.
+	 * @return bool True if the array represents a tombstone, false otherwise.
 	 */
 	public static function check_array( $data ) {
 		if ( ! \is_array( $data ) ) {

From f6722aa523eab498e28e2b1f8fadc32c12121804 Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Fri, 8 Aug 2025 20:12:13 +0200
Subject: [PATCH 06/18] Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 includes/class-tombstone.php | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index ba452dba2..1f01d9c9a 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -130,11 +130,11 @@ public static function check_array( $data ) {
 	}
 
 	/**
-	 * Check if the response is a WP_Error.
+	 * Check if the given object represents a tombstone.
 	 *
-	 * @param object $data The response to check.
+	 * @param object $data The object to check.
 	 *
-	 * @return bool True if the response is a WP_Error, false otherwise.
+	 * @return bool True if the object represents a tombstone, false otherwise.
 	 */
 	public static function check_object( $data ) {
 		if ( ! \is_object( $data ) ) {

From 3831be167eee2a096d6ac68ee90e1c807b5424ea Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Fri, 8 Aug 2025 20:12:39 +0200
Subject: [PATCH 07/18] Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 tests/includes/class-test-tombstone.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/includes/class-test-tombstone.php b/tests/includes/class-test-tombstone.php
index 4708594ee..c54dea211 100644
--- a/tests/includes/class-test-tombstone.php
+++ b/tests/includes/class-test-tombstone.php
@@ -10,9 +10,9 @@
 use Activitypub\Tombstone;
 
 /**
- * Test class for ActivityPub HTTP Class
+ * Test class for ActivityPub Tombstone Class
  *
- * @coversDefaultClass \Activitypub\Http
+ * @coversDefaultClass \Activitypub\Tombstone
  */
 class Test_Tombstone extends \WP_UnitTestCase {
 

From c8b85ee15fd1b43d93d52f8ab4a8c8e7413478e6 Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Fri, 8 Aug 2025 20:12:52 +0200
Subject: [PATCH 08/18] Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 tests/includes/class-test-tombstone.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/includes/class-test-tombstone.php b/tests/includes/class-test-tombstone.php
index c54dea211..098491824 100644
--- a/tests/includes/class-test-tombstone.php
+++ b/tests/includes/class-test-tombstone.php
@@ -1,6 +1,6 @@
 <?php
 /**
- * Test file for Activitypub HTTP Class
+ * Test file for Activitypub Tombstone Class
  *
  * @package Activitypub
  */

From b5505799005b40c899a67c88fd71934b75731f6e Mon Sep 17 00:00:00 2001
From: Konstantin Obenland <obenland@gmx.de>
Date: Tue, 19 Aug 2025 08:36:36 -0500
Subject: [PATCH 09/18] Update WP_Error type hint in docblock

Changed the docblock parameter type from WP_Error to \WP_Error for improved clarity and namespacing consistency.
---
 includes/class-tombstone.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index 1f01d9c9a..271c522bb 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -94,7 +94,7 @@ public static function check_local_url( $url ) {
 	/**
 	 * Check if the response is a WP_Error.
 	 *
-	 * @param WP_Error $wp_error The response to check.
+	 * @param \WP_Error $wp_error The response to check.
 	 *
 	 * @return bool True if the response is a WP_Error, false otherwise.
 	 */

From 56c8d14a05a1c2cd1bff53402c08fa67fe503a83 Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Sun, 24 Aug 2025 19:32:57 +0200
Subject: [PATCH 10/18] Update templates/tombstone-json.php

Co-authored-by: Konstantin Obenland <obenland@gmx.de>
---
 templates/tombstone-json.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/templates/tombstone-json.php b/templates/tombstone-json.php
index 85944b08c..156ff1948 100644
--- a/templates/tombstone-json.php
+++ b/templates/tombstone-json.php
@@ -22,6 +22,6 @@
 /**
  * Fires after an ActivityPub object is generated and sent to the client.
  *
- * @param object $object The ActivityPub object.
+ * @param Activitypub\Activity\Base_Object $object The ActivityPub object.
  */
 \do_action( 'activitypub_json_post', $object );

From 823c8cac82c69554ba12bbeff3d133d1315a11d2 Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Sun, 24 Aug 2025 19:33:35 +0200
Subject: [PATCH 11/18] Update templates/tombstone-json.php

Co-authored-by: Konstantin Obenland <obenland@gmx.de>
---
 templates/tombstone-json.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/templates/tombstone-json.php b/templates/tombstone-json.php
index 156ff1948..0f826de3d 100644
--- a/templates/tombstone-json.php
+++ b/templates/tombstone-json.php
@@ -12,7 +12,7 @@
 /**
  * Fires before an ActivityPub object is generated and sent to the client.
  *
- * @param object $object The ActivityPub object.
+ * @param Activitypub\Activity\Base_Object $object The ActivityPub object.
  */
 \do_action( 'activitypub_json_pre', $object );
 

From 05315c1618c55469d1f47dea83dcf4a72956c0a8 Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Sun, 24 Aug 2025 19:44:57 +0200
Subject: [PATCH 12/18] change to `is_gone`

@obenland what about `is_gone`? because the tombstone check is for `410 gone`.
---
 includes/class-activitypub.php          |  2 +-
 includes/class-http.php                 |  4 +--
 includes/class-scheduler.php            |  2 +-
 includes/class-tombstone.php            | 24 +++++++-------
 includes/collection/class-followers.php |  2 +-
 includes/functions.php                  |  4 +--
 includes/handler/class-delete.php       |  6 ++--
 tests/includes/class-test-tombstone.php | 44 ++++++++++++-------------
 8 files changed, 44 insertions(+), 44 deletions(-)

diff --git a/includes/class-activitypub.php b/includes/class-activitypub.php
index b59a91e76..38eb93a5c 100644
--- a/includes/class-activitypub.php
+++ b/includes/class-activitypub.php
@@ -117,7 +117,7 @@ public static function render_activitypub_template( $template ) {
 			return $template;
 		}
 
-		if ( Tombstone::check_local_url( Query::get_instance()->get_request_url() ) ) {
+		if ( Tombstone::is_local_url_gone( Query::get_instance()->get_request_url() ) ) {
 			\status_header( 410 );
 			return ACTIVITYPUB_PLUGIN_DIR . 'templates/tombstone-json.php';
 		}
diff --git a/includes/class-http.php b/includes/class-http.php
index 962cacada..fcf7ec1e8 100644
--- a/includes/class-http.php
+++ b/includes/class-http.php
@@ -182,9 +182,9 @@ public static function get( $url, $cached = false ) {
 	 * @return bool True if the URL is a tombstone.
 	 */
 	public static function is_tombstone( $url ) {
-		_deprecated_function( __METHOD__, 'unreleased', 'Activitypub\Tombstone::check_remote_url' );
+		_deprecated_function( __METHOD__, 'unreleased', 'Activitypub\Tombstone::is_remote_url_gone' );
 
-		return Tombstone::check_remote_url( $url );
+		return Tombstone::is_remote_url_gone( $url );
 	}
 
 	/**
diff --git a/includes/class-scheduler.php b/includes/class-scheduler.php
index d4bbbbf39..7243f1b2f 100644
--- a/includes/class-scheduler.php
+++ b/includes/class-scheduler.php
@@ -194,7 +194,7 @@ public static function cleanup_remote_actors() {
 		foreach ( $actors as $actor ) {
 			$meta = get_remote_metadata_by_actor( $actor->guid, false );
 
-			if ( Tombstone::check( $meta ) ) {
+			if ( Tombstone::is_gone( $meta ) ) {
 				\wp_delete_post( $actor->ID );
 			} elseif ( empty( $meta ) || ! is_array( $meta ) || \is_wp_error( $meta ) ) {
 				if ( Actors::count_errors( $actor->ID ) >= 5 ) {
diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index 271c522bb..93e8a6f5e 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -27,24 +27,24 @@ class Tombstone {
 	 *
 	 * @return bool True if the various data is a tombstone.
 	 */
-	public static function check( $various ) {
+	public static function is_gone( $various ) {
 		if ( \is_wp_error( $various ) ) {
-			return self::check_wp_error( $various );
+			return self::is_wp_error( $various );
 		}
 
 		if ( \is_string( $various ) ) {
 			if ( is_same_domain( $various ) ) {
-				return self::check_local_url( $various );
+				return self::is_local_url_gone( $various );
 			}
-			return self::check_remote_url( $various );
+			return self::is_remote_url_gone( $various );
 		}
 
 		if ( \is_array( $various ) ) {
-			return self::check_array( $various );
+			return self::is_array_gone( $various );
 		}
 
 		if ( \is_object( $various ) ) {
-			return self::check_object( $various );
+			return self::is_object_gone( $various );
 		}
 
 		return false;
@@ -57,7 +57,7 @@ public static function check( $various ) {
 	 *
 	 * @return bool True if the URL is a tombstone.
 	 */
-	public static function check_remote_url( $url ) {
+	public static function is_remote_url_gone( $url ) {
 		/**
 		 * Fires before checking if the URL is a tombstone.
 		 *
@@ -75,7 +75,7 @@ public static function check_remote_url( $url ) {
 		$data = \wp_remote_retrieve_body( $response );
 		$data = \json_decode( $data, true );
 
-		return self::check_array( $data );
+		return self::is_array_gone( $data );
 	}
 
 	/**
@@ -85,7 +85,7 @@ public static function check_remote_url( $url ) {
 	 *
 	 * @return bool True if the URL is a tombstone.
 	 */
-	public static function check_local_url( $url ) {
+	public static function is_local_url_gone( $url ) {
 		$urls = get_option( 'activitypub_tombstone_urls', array() );
 
 		return in_array( normalize_url( $url ), $urls, true );
@@ -98,7 +98,7 @@ public static function check_local_url( $url ) {
 	 *
 	 * @return bool True if the response is a WP_Error, false otherwise.
 	 */
-	public static function check_wp_error( $wp_error ) {
+	public static function is_wp_error( $wp_error ) {
 		if ( ! \is_wp_error( $wp_error ) ) {
 			return false;
 		}
@@ -117,7 +117,7 @@ public static function check_wp_error( $wp_error ) {
 	 *
 	 * @return bool True if the array represents a tombstone, false otherwise.
 	 */
-	public static function check_array( $data ) {
+	public static function is_array_gone( $data ) {
 		if ( ! \is_array( $data ) ) {
 			return false;
 		}
@@ -136,7 +136,7 @@ public static function check_array( $data ) {
 	 *
 	 * @return bool True if the object represents a tombstone, false otherwise.
 	 */
-	public static function check_object( $data ) {
+	public static function is_object_gone( $data ) {
 		if ( ! \is_object( $data ) ) {
 			return false;
 		}
diff --git a/includes/collection/class-followers.php b/includes/collection/class-followers.php
index 42239614f..0e6315f6c 100644
--- a/includes/collection/class-followers.php
+++ b/includes/collection/class-followers.php
@@ -43,7 +43,7 @@ class Followers {
 	public static function add_follower( $user_id, $actor ) {
 		$meta = get_remote_metadata_by_actor( $actor );
 
-		if ( Tombstone::check( $meta ) ) {
+		if ( Tombstone::is_gone( $meta ) ) {
 			return $meta;
 		}
 
diff --git a/includes/functions.php b/includes/functions.php
index 18c67930c..bd35420b6 100644
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -204,9 +204,9 @@ function is_comment() {
  * @return boolean True if HTTP-Code is 410 or 404.
  */
 function is_tombstone( $wp_error ) {
-	_deprecated_function( __FUNCTION__, 'unreleased', 'Activitypub\Tombstone::check_wp_error' );
+	_deprecated_function( __FUNCTION__, 'unreleased', 'Activitypub\Tombstone::is_wp_error' );
 
-	return Tombstone::check_wp_error( $wp_error );
+	return Tombstone::is_wp_error( $wp_error );
 }
 
 /**
diff --git a/includes/handler/class-delete.php b/includes/handler/class-delete.php
index fb887fd8c..a9306b49e 100644
--- a/includes/handler/class-delete.php
+++ b/includes/handler/class-delete.php
@@ -104,7 +104,7 @@ public static function maybe_delete_follower( $activity ) {
 		$follower = Actors::get_remote_by_uri( $activity['actor'] );
 
 		// Verify that Actor is deleted.
-		if ( ! is_wp_error( $follower ) && Tombstone::check( $activity['actor'] ) ) {
+		if ( ! is_wp_error( $follower ) && Tombstone::is_gone( $activity['actor'] ) ) {
 			Actors::delete( $follower->ID );
 			self::maybe_delete_interactions( $activity );
 		}
@@ -117,7 +117,7 @@ public static function maybe_delete_follower( $activity ) {
 	 */
 	public static function maybe_delete_interactions( $activity ) {
 		// Verify that Actor is deleted.
-		if ( Tombstone::check( $activity['actor'] ) ) {
+		if ( Tombstone::is_gone( $activity['actor'] ) ) {
 			\wp_schedule_single_event(
 				\time(),
 				'activitypub_delete_actor_interactions',
@@ -153,7 +153,7 @@ public static function maybe_delete_interaction( $activity ) {
 
 		$comments = Interactions::get_interaction_by_id( $id );
 
-		if ( $comments && Tombstone::check( $id ) ) {
+		if ( $comments && Tombstone::is_gone( $id ) ) {
 			foreach ( $comments as $comment ) {
 				wp_delete_comment( $comment->comment_ID, true );
 			}
diff --git a/tests/includes/class-test-tombstone.php b/tests/includes/class-test-tombstone.php
index 098491824..9ca7526fb 100644
--- a/tests/includes/class-test-tombstone.php
+++ b/tests/includes/class-test-tombstone.php
@@ -19,19 +19,19 @@ class Test_Tombstone extends \WP_UnitTestCase {
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::check_remote_url
+	 * @covers ::is_remote_url_gone
 	 *
-	 * @dataProvider data_check_remote_url
+	 * @dataProvider data_is_remote_url_gone
 	 *
 	 * @param array $request The request array.
 	 * @param bool  $result  The expected result.
 	 */
-	public function test_check_remote_url( $request, $result ) {
+	public function test_is_remote_url_gone( $request, $result ) {
 		$fake_request = function () use ( $request ) {
 			return $request;
 		};
 		add_filter( 'pre_http_request', $fake_request, 10, 3 );
-		$response = Tombstone::check_remote_url( 'https://fake.test/object/123' );
+		$response = Tombstone::is_remote_url_gone( 'https://fake.test/object/123' );
 		$this->assertEquals( $result, $response );
 		remove_filter( 'pre_http_request', $fake_request, 10 );
 	}
@@ -41,7 +41,7 @@ public function test_check_remote_url( $request, $result ) {
 	 *
 	 * @return array
 	 */
-	public function data_check_remote_url() {
+	public function data_is_remote_url_gone() {
 		return array(
 			array( array( 'response' => array( 'code' => 404 ) ), true ),
 			array( array( 'response' => array( 'code' => 410 ) ), true ),
@@ -86,59 +86,59 @@ public function data_check_remote_url() {
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::check_wp_error
+	 * @covers ::is_wp_error
 	 */
-	public function test_check_wp_error() {
-		$response = Tombstone::check_wp_error( new \WP_Error( 404 ) );
+	public function test_is_wp_error() {
+		$response = Tombstone::is_wp_error( new \WP_Error( 404 ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::check_wp_error( new \WP_Error( 410 ) );
+		$response = Tombstone::is_wp_error( new \WP_Error( 410 ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::check_wp_error( new \WP_Error( 200 ) );
+		$response = Tombstone::is_wp_error( new \WP_Error( 200 ) );
 		$this->assertFalse( $response );
 	}
 
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::check_array
+	 * @covers ::is_array_gone
 	 */
-	public function test_check_array() {
-		$response = Tombstone::check_array( array( 'type' => 'Tombstone' ) );
+	public function test_is_array_gone() {
+		$response = Tombstone::is_array_gone( array( 'type' => 'Tombstone' ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::check_array( array( 'type' => 'Note' ) );
+		$response = Tombstone::is_array_gone( array( 'type' => 'Note' ) );
 		$this->assertFalse( $response );
 	}
 
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::check_object
+	 * @covers ::is_object_gone
 	 */
-	public function test_check_object() {
-		$response = Tombstone::check_object( (object) array( 'type' => 'Tombstone' ) );
+	public function test_is_object_gone() {
+		$response = Tombstone::is_object_gone( (object) array( 'type' => 'Tombstone' ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::check_object( (object) array( 'type' => 'Note' ) );
+		$response = Tombstone::is_object_gone( (object) array( 'type' => 'Note' ) );
 		$this->assertFalse( $response );
 	}
 
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::check_local_url
+	 * @covers ::is_local_url_gone
 	 */
-	public function test_check_local_url() {
+	public function test_is_local_url_gone() {
 		$url = 'https://fake.test/object/123';
 
-		$response = Tombstone::check_local_url( $url );
+		$response = Tombstone::is_local_url_gone( $url );
 		$this->assertFalse( $response );
 
 		Tombstone::bury( $url );
 
-		$response = Tombstone::check_local_url( $url );
+		$response = Tombstone::is_local_url_gone( $url );
 		$this->assertTrue( $response );
 
 		\delete_option( 'activitypub_tombstone_urls' );

From 57718e49be85e7ec932df08c645c3ae7b1c36fce Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Sun, 24 Aug 2025 19:48:14 +0200
Subject: [PATCH 13/18] Check for `get_error_data`

---
 includes/class-tombstone.php            | 5 +++++
 tests/includes/class-test-tombstone.php | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index 93e8a6f5e..06a5a7ee6 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -107,6 +107,11 @@ public static function is_wp_error( $wp_error ) {
 			return true;
 		}
 
+		$data = $wp_error->get_error_data();
+		if ( isset( $data['status'] ) && in_array( (int) $data['status'], self::$codes, true ) ) {
+			return true;
+		}
+
 		return false;
 	}
 
diff --git a/tests/includes/class-test-tombstone.php b/tests/includes/class-test-tombstone.php
index 9ca7526fb..0e978a714 100644
--- a/tests/includes/class-test-tombstone.php
+++ b/tests/includes/class-test-tombstone.php
@@ -97,6 +97,15 @@ public function test_is_wp_error() {
 
 		$response = Tombstone::is_wp_error( new \WP_Error( 200 ) );
 		$this->assertFalse( $response );
+
+		$response = Tombstone::is_wp_error( new \WP_Error( 'foo', '', array( 'status' => 404 ) ) );
+		$this->assertTrue( $response );
+
+		$response = Tombstone::is_wp_error( new \WP_Error( 'bar', '', array( 'status' => 410 ) ) );
+		$this->assertTrue( $response );
+
+		$response = Tombstone::is_wp_error( new \WP_Error( 'baz', '', array( 'status' => 200 ) ) );
+		$this->assertFalse( $response );
 	}
 
 	/**

From 546cfabb7e73c246ea07d980e884e4487a078abf Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Mon, 25 Aug 2025 23:09:22 +0200
Subject: [PATCH 14/18] Send `Delete` Activity on User-Delete (#2035)

---
 .github/changelog/2035-from-description       |  4 +
 includes/class-dispatcher.php                 |  6 +-
 includes/class-http.php                       |  2 +-
 includes/collection/class-actors.php          | 33 +++++++
 includes/collection/class-followers.php       | 21 ++--
 includes/collection/class-outbox.php          | 13 ++-
 includes/scheduler/class-actor.php            | 49 ++++++++++
 .../collection/class-test-followers.php       |  7 +-
 tests/includes/scheduler/class-test-actor.php | 96 +++++++++++++++++++
 9 files changed, 213 insertions(+), 18 deletions(-)
 create mode 100644 .github/changelog/2035-from-description

diff --git a/.github/changelog/2035-from-description b/.github/changelog/2035-from-description
new file mode 100644
index 000000000..a09d5c4a7
--- /dev/null
+++ b/.github/changelog/2035-from-description
@@ -0,0 +1,4 @@
+Significance: minor
+Type: added
+
+Adds support for sending Delete activities when a user is removed.
diff --git a/includes/class-dispatcher.php b/includes/class-dispatcher.php
index d5c37b59d..5b4686de6 100644
--- a/includes/class-dispatcher.php
+++ b/includes/class-dispatcher.php
@@ -60,8 +60,9 @@ public static function process_outbox( $id ) {
 			return;
 		}
 
+		$type  = \get_post_meta( $outbox_item->ID, '_activitypub_activity_type', true );
 		$actor = Outbox::get_actor( $outbox_item );
-		if ( \is_wp_error( $actor ) ) {
+		if ( \is_wp_error( $actor ) && 'Delete' !== $type ) {
 			// If the actor is not found, publish the post and don't try again.
 			\wp_publish_post( $outbox_item );
 			return;
@@ -99,8 +100,7 @@ public static function send_to_followers( $outbox_item_id, $batch_size = ACTIVIT
 		$outbox_item = \get_post( $outbox_item_id );
 		$json        = Outbox::get_activity( $outbox_item_id )->to_json();
 		$inboxes     = Followers::get_inboxes_for_activity( $json, $outbox_item->post_author, $batch_size, $offset );
-
-		$retries = self::send_to_inboxes( $inboxes, $outbox_item_id );
+		$retries     = self::send_to_inboxes( $inboxes, $outbox_item_id );
 
 		// Retry failed inboxes.
 		if ( ! empty( $retries ) ) {
diff --git a/includes/class-http.php b/includes/class-http.php
index fcf7ec1e8..ba23e97fa 100644
--- a/includes/class-http.php
+++ b/includes/class-http.php
@@ -52,7 +52,7 @@ public static function post( $url, $body, $user_id ) {
 				'Date'         => \gmdate( 'D, d M Y H:i:s T' ),
 			),
 			'body'                => $body,
-			'key_id'              => Actors::get_by_id( $user_id )->get_id() . '#main-key',
+			'key_id'              => \json_decode( $body )->actor . '#main-key',
 			'private_key'         => Actors::get_private_key( $user_id ),
 		);
 
diff --git a/includes/collection/class-actors.php b/includes/collection/class-actors.php
index af78ae99f..7147692a1 100644
--- a/includes/collection/class-actors.php
+++ b/includes/collection/class-actors.php
@@ -49,6 +49,13 @@ class Actors {
 	 */
 	const POST_TYPE = 'ap_actor';
 
+	/**
+	 * Cache key for the followers inbox.
+	 *
+	 * @var string
+	 */
+	const CACHE_KEY_INBOXES = 'actor_inboxes';
+
 	/**
 	 * Get the Actor by ID.
 	 *
@@ -421,6 +428,32 @@ public static function get_all() {
 		return $return;
 	}
 
+	/**
+	 * Returns all Inboxes for all known remote Actors.
+	 *
+	 * @return array The list of Inboxes.
+	 */
+	public static function get_inboxes() {
+		$inboxes = \wp_cache_get( self::CACHE_KEY_INBOXES, 'activitypub' );
+
+		if ( $inboxes ) {
+			return $inboxes;
+		}
+
+		global $wpdb;
+		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery
+		$results = $wpdb->get_col(
+			"SELECT DISTINCT meta_value FROM {$wpdb->postmeta}
+			WHERE meta_key = '_activitypub_inbox'
+			AND meta_value IS NOT NULL"
+		);
+
+		$inboxes = \array_filter( $results );
+		\wp_cache_set( self::CACHE_KEY_INBOXES, $inboxes, 'activitypub' );
+
+		return $inboxes;
+	}
+
 	/**
 	 * Returns the actor type based on the user ID.
 	 *
diff --git a/includes/collection/class-followers.php b/includes/collection/class-followers.php
index 0e6315f6c..944eb81a9 100644
--- a/includes/collection/class-followers.php
+++ b/includes/collection/class-followers.php
@@ -60,6 +60,7 @@ public static function add_follower( $user_id, $actor ) {
 		if ( \is_array( $post_meta ) && ! \in_array( (string) $user_id, $post_meta, true ) ) {
 			\add_post_meta( $post_id, self::FOLLOWER_META_KEY, $user_id );
 			\wp_cache_delete( \sprintf( self::CACHE_KEY_INBOXES, $user_id ), 'activitypub' );
+			\wp_cache_delete( Actors::CACHE_KEY_INBOXES, 'activitypub' );
 		}
 
 		return $post_id;
@@ -81,6 +82,7 @@ public static function remove( $post_id, $user_id ) {
 		}
 
 		\wp_cache_delete( \sprintf( self::CACHE_KEY_INBOXES, $user_id ), 'activitypub' );
+		\wp_cache_delete( Actors::CACHE_KEY_INBOXES, 'activitypub' );
 
 		/**
 		 * Fires before a Follower is removed.
@@ -310,14 +312,12 @@ public static function get_inboxes( $user_id ) {
 	 * @return array The list of Inboxes.
 	 */
 	public static function get_inboxes_for_activity( $json, $actor_id, $batch_size = 50, $offset = 0 ) {
-		$inboxes = self::get_inboxes( $actor_id );
-
-		if ( self::maybe_add_inboxes_of_blog_user( $json, $actor_id ) ) {
-			$inboxes = \array_fill_keys( $inboxes, 1 );
-			foreach ( self::get_inboxes( Actors::BLOG_USER_ID ) as $inbox ) {
-				$inboxes[ $inbox ] = 1;
-			}
-			$inboxes = \array_keys( $inboxes );
+		$activity = \json_decode( $json, true );
+		// Only if this is a Delete. Create handles its own "Announce" in dual user mode.
+		if ( 'Delete' === ( $activity['type'] ?? null ) ) {
+			$inboxes = Actors::get_inboxes();
+		} else {
+			$inboxes = self::get_inboxes( $actor_id );
 		}
 
 		return \array_slice( $inboxes, $offset, $batch_size );
@@ -326,11 +326,16 @@ public static function get_inboxes_for_activity( $json, $actor_id, $batch_size =
 	/**
 	 * Maybe add Inboxes of the Blog User.
 	 *
+	 * @deprecated unreleased
+	 *
 	 * @param string $json     The ActivityPub Activity JSON.
 	 * @param int    $actor_id The WordPress Actor ID.
+	 *
 	 * @return bool True if the Inboxes of the Blog User should be added, false otherwise.
 	 */
 	public static function maybe_add_inboxes_of_blog_user( $json, $actor_id ) {
+		\_deprecated_function( __METHOD__, 'unreleased' );
+
 		// Only if we're in both Blog and User modes.
 		if ( ACTIVITYPUB_ACTOR_AND_BLOG_MODE !== \get_option( 'activitypub_actor_mode', ACTIVITYPUB_ACTOR_MODE ) ) {
 			return false;
diff --git a/includes/collection/class-outbox.php b/includes/collection/class-outbox.php
index 6c575e882..e83e44587 100644
--- a/includes/collection/class-outbox.php
+++ b/includes/collection/class-outbox.php
@@ -242,10 +242,6 @@ public static function reschedule( $outbox_item ) {
 	 */
 	public static function get_activity( $outbox_item ) {
 		$outbox_item = \get_post( $outbox_item );
-		$actor       = self::get_actor( $outbox_item );
-		if ( is_wp_error( $actor ) ) {
-			return $actor;
-		}
 
 		$activity_object = \json_decode( $outbox_item->post_content, true );
 		$type            = \get_post_meta( $outbox_item->ID, '_activitypub_activity_type', true );
@@ -253,9 +249,18 @@ public static function get_activity( $outbox_item ) {
 		if ( $activity_object['type'] === $type ) {
 			$activity = Activity::init_from_array( $activity_object );
 			if ( ! $activity->get_actor() ) {
+				$actor = self::get_actor( $outbox_item );
+				if ( \is_wp_error( $actor ) ) {
+					return $actor;
+				}
 				$activity->set_actor( $actor->get_id() );
 			}
 		} else {
+			$actor = self::get_actor( $outbox_item );
+			if ( \is_wp_error( $actor ) ) {
+				return $actor;
+			}
+
 			$activity = new Activity();
 			$activity->set_type( $type );
 			$activity->set_id( $outbox_item->guid );
diff --git a/includes/scheduler/class-actor.php b/includes/scheduler/class-actor.php
index 58e670c46..6fa09272f 100644
--- a/includes/scheduler/class-actor.php
+++ b/includes/scheduler/class-actor.php
@@ -7,8 +7,11 @@
 
 namespace Activitypub\Scheduler;
 
+use Activitypub\Activity\Activity;
 use Activitypub\Collection\Actors;
 use Activitypub\Collection\Extra_Fields;
+use Activitypub\Collection\Outbox;
+use Activitypub\Tombstone;
 
 use function Activitypub\add_to_outbox;
 use function Activitypub\is_user_type_disabled;
@@ -51,6 +54,10 @@ public static function init() {
 
 		\add_action( 'post_stuck', array( self::class, 'sticky_post_update' ) );
 		\add_action( 'post_unstuck', array( self::class, 'sticky_post_update' ) );
+
+		// User deletion handling.
+		\add_action( 'delete_user', array( self::class, 'schedule_user_delete' ), 10, 3 );
+		\add_filter( 'post_types_to_delete_with_user', array( self::class, 'post_types_to_delete_with_user' ) );
 	}
 
 	/**
@@ -161,4 +168,46 @@ public static function sticky_post_update( $post_id ) {
 
 		self::schedule_profile_update( $post->post_author );
 	}
+
+	/**
+	 * Schedule a Delete activity when a user is deleted.
+	 *
+	 * @param int $user_id The user ID being deleted.
+	 */
+	public static function schedule_user_delete( $user_id ) {
+		// Don't bother if the user can't publish ActivityPub content.
+		if ( ! \user_can( $user_id, 'activitypub' ) ) {
+			return;
+		}
+
+		// Get the actor before deletion to ensure we have the data.
+		$actor = Actors::get_by_id( $user_id );
+		if ( \is_wp_error( $actor ) ) {
+			return;
+		}
+
+		Tombstone::bury( $actor->get_id() );
+		Tombstone::bury( $actor->get_url() );
+
+		$activity = new Activity();
+		$activity->set_actor( $actor->get_id() );
+		$activity->set_object( $actor->get_id() );
+		$activity->set_type( 'Delete' );
+
+		add_to_outbox( $activity, null, $user_id );
+	}
+
+	/**
+	 * Remove outbox from post types to delete with user.
+	 *
+	 * Outbox items should not be deleted with the user, because we
+	 * need to federate the `Delete` Activities.
+	 *
+	 * @param array $post_types The post types to delete with user.
+	 *
+	 * @return array The post types to delete with user without outbox.
+	 */
+	public static function post_types_to_delete_with_user( $post_types ) {
+		return \array_diff( $post_types, array( Outbox::POST_TYPE ) );
+	}
 }
diff --git a/tests/includes/collection/class-test-followers.php b/tests/includes/collection/class-test-followers.php
index a7887ac4e..1a4ffc935 100644
--- a/tests/includes/collection/class-test-followers.php
+++ b/tests/includes/collection/class-test-followers.php
@@ -479,6 +479,7 @@ public function test_get_inboxes() {
 		$this->assertCount( 30, $inboxes );
 
 		wp_cache_delete( sprintf( Followers::CACHE_KEY_INBOXES, 1 ), 'activitypub' );
+		wp_cache_delete( Actors::CACHE_KEY_INBOXES, 'activitypub' );
 
 		for ( $j = 0; $j < 5; $j++ ) {
 			$k    = $j + 100;
@@ -589,6 +590,8 @@ public function data_maybe_add_inboxes_of_blog_user() {
 	 * @covers ::maybe_add_inboxes_of_blog_user
 	 * @dataProvider data_maybe_add_inboxes_of_blog_user
 	 *
+	 * @expectedDeprecated Activitypub\Collection\Followers::maybe_add_inboxes_of_blog_user
+	 *
 	 * @param string  $actor_mode The actor mode to test with.
 	 * @param string  $json       The JSON to test with.
 	 * @param int     $actor_id   The actor ID to test with.
@@ -632,7 +635,7 @@ public function test_get_inboxes_for_activity() {
 		);
 
 		// username and jon have sharedInbox endpoints.
-		$this->assertCount( 2, $inboxes, 'Should retrieve exactly 3 inboxes.' );
+		$this->assertCount( 2, $inboxes, 'Should retrieve exactly 2 inboxes.' );
 		$this->assertContains( self::$actors['username@example.org']['endpoints']['sharedInbox'], $inboxes, 'Should contain first inbox.' );
 		$this->assertContains( self::$actors['doe@example.org']['inbox'], $inboxes, 'Should contain second inbox.' );
 
@@ -650,7 +653,7 @@ public function test_get_inboxes_for_activity() {
 		Followers::add_follower( Actors::BLOG_USER_ID, self::$actors['sally@example.org']['id'] );
 
 		$inboxes = Followers::get_inboxes_for_activity(
-			'{"type":"Update"}',
+			'{"type":"Delete"}',
 			$actor_id,
 			50,
 			0
diff --git a/tests/includes/scheduler/class-test-actor.php b/tests/includes/scheduler/class-test-actor.php
index a4f3eee25..051329559 100644
--- a/tests/includes/scheduler/class-test-actor.php
+++ b/tests/includes/scheduler/class-test-actor.php
@@ -351,4 +351,100 @@ public function test_sticky_post_update() {
 		\wp_delete_post( $post_id );
 		\wp_delete_user( $user_id );
 	}
+
+	/**
+	 * Test that user deletion creates a Delete activity.
+	 *
+	 * @covers ::schedule_user_delete
+	 */
+	public function test_schedule_user_delete() {
+		// Create a user with ActivityPub capability.
+		$user_id = self::factory()->user->create( array( 'role' => 'author' ) );
+
+		// Verify the user has ActivityPub capability.
+		$this->assertTrue( \user_can( $user_id, 'activitypub' ) );
+
+		// Get the actor before deletion.
+		$actor = Actors::get_by_id( $user_id );
+		$this->assertNotNull( $actor );
+		$this->assertFalse( \is_wp_error( $actor ) );
+
+		// Get the current outbox count.
+		$outbox_before = $this->get_latest_outbox_item();
+		$this->assertNull( $outbox_before );
+
+		// Call the method directly to test it.
+		Actor::schedule_user_delete( $user_id );
+
+		// Check that a Delete activity was added to the outbox.
+		$outbox_after = $this->get_latest_outbox_item();
+		$this->assertNotNull( $outbox_after );
+
+		// Verify it's a Delete activity.
+		$activity_type = \get_post_meta( $outbox_after->ID, '_activitypub_activity_type', true );
+		$this->assertEquals( 'Delete', $activity_type, 'Activity type should be Delete' );
+
+		// Verify the activity content.
+		$activity = \json_decode( $outbox_after->post_content, true );
+		$this->assertIsArray( $activity, 'Activity content should be valid JSON' );
+		$this->assertEquals( 'Delete', $activity['type'], 'Activity type in content should be Delete' );
+		$this->assertEquals( $actor->get_id(), $activity['actor'], 'Actor should match' );
+		$this->assertEquals( $actor->get_id(), $activity['object'], 'Object should be the actor being deleted' );
+
+		// Clean up.
+		\wp_delete_user( $user_id );
+	}
+
+	/**
+	 * Test that user deletion is skipped for users without ActivityPub capability.
+	 *
+	 * @covers ::schedule_user_delete
+	 */
+	public function test_schedule_user_delete_skips_non_activitypub_users() {
+		// Create a user without ActivityPub capability (subscriber role).
+		$user_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+
+		// Verify the user doesn't have ActivityPub capability.
+		$this->assertFalse( \user_can( $user_id, 'activitypub' ) );
+
+		// Get the current total outbox items across all users.
+		$total_before = \wp_count_posts( 'ap_outbox' )->publish;
+
+		// Call the method directly to test it.
+		Actor::schedule_user_delete( $user_id );
+
+		// Check that no Delete activity was added.
+		$total_after = \wp_count_posts( 'ap_outbox' )->publish;
+		$this->assertEquals( $total_before, $total_after, 'No Delete activity should be added for non-ActivityPub users' );
+
+		// Clean up.
+		\wp_delete_user( $user_id );
+	}
+
+	/**
+	 * Test that user deletion handles invalid actor gracefully.
+	 *
+	 * @covers ::schedule_user_delete
+	 */
+	public function test_schedule_user_delete_handles_invalid_actor() {
+		// Create a user with ActivityPub capability.
+		$user_id = self::factory()->user->create( array( 'role' => 'author' ) );
+
+		// Verify the user has ActivityPub capability.
+		$this->assertTrue( \user_can( $user_id, 'activitypub' ) );
+
+		// We'll use a filter to mock the response instead since we can't easily mock static methods.
+		// For this test, we'll delete the user first to make the actor invalid.
+		\wp_delete_user( $user_id );
+
+		// Get the current total outbox items.
+		$total_before = \wp_count_posts( 'ap_outbox' )->publish;
+
+		// Call the method with the deleted user ID.
+		Actor::schedule_user_delete( $user_id );
+
+		// Check that no Delete activity was added since the actor is invalid.
+		$total_after = \wp_count_posts( 'ap_outbox' )->publish;
+		$this->assertEquals( $total_before, $total_after, 'No Delete activity should be added for invalid actors' );
+	}
 }

From 28804b22431a349527d8756327a1f6d106dc2efc Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Tue, 26 Aug 2025 08:39:33 +0200
Subject: [PATCH 15/18] Remove redundant error code check in Tombstone class

Eliminated a duplicate check for error codes in the Tombstone class. The logic now relies solely on the error data's status field for validation.
---
 includes/class-tombstone.php | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index 06a5a7ee6..4e69a3a30 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -103,10 +103,6 @@ public static function is_wp_error( $wp_error ) {
 			return false;
 		}
 
-		if ( in_array( (int) $wp_error->get_error_code(), self::$codes, true ) ) {
-			return true;
-		}
-
 		$data = $wp_error->get_error_data();
 		if ( isset( $data['status'] ) && in_array( (int) $data['status'], self::$codes, true ) ) {
 			return true;

From 1d00bebb31e1cbbe8d7eac964a54c1f87f042b98 Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Tue, 26 Aug 2025 09:07:39 +0200
Subject: [PATCH 16/18] Refactor Tombstone API to use 'exists' naming

Renamed Tombstone methods from 'is_gone', 'is_remote_url_gone', 'is_local_url_gone', 'is_wp_error', 'is_array_gone', and 'is_object_gone' to 'exists', 'exists_remote', 'exists_local', 'exists_in_error', 'check_array', and 'check_object' for clarity and consistency. Updated all usages and related tests to match the new method names. Improves code readability and better reflects the purpose of the methods.
---
 includes/class-activitypub.php          |  2 +-
 includes/class-http.php                 |  4 +-
 includes/class-scheduler.php            |  2 +-
 includes/class-tombstone.php            | 39 +++++++++------
 includes/collection/class-followers.php |  2 +-
 includes/handler/class-delete.php       |  6 +--
 tests/includes/class-test-tombstone.php | 66 ++++++++++++++-----------
 7 files changed, 69 insertions(+), 52 deletions(-)

diff --git a/includes/class-activitypub.php b/includes/class-activitypub.php
index 515e8eb04..6cb119b01 100644
--- a/includes/class-activitypub.php
+++ b/includes/class-activitypub.php
@@ -110,7 +110,7 @@ public static function render_activitypub_template( $template ) {
 			return $template;
 		}
 
-		if ( Tombstone::is_local_url_gone( Query::get_instance()->get_request_url() ) ) {
+		if ( Tombstone::exists_local( Query::get_instance()->get_request_url() ) ) {
 			\status_header( 410 );
 			return ACTIVITYPUB_PLUGIN_DIR . 'templates/tombstone-json.php';
 		}
diff --git a/includes/class-http.php b/includes/class-http.php
index ba23e97fa..d4594c8ed 100644
--- a/includes/class-http.php
+++ b/includes/class-http.php
@@ -182,9 +182,9 @@ public static function get( $url, $cached = false ) {
 	 * @return bool True if the URL is a tombstone.
 	 */
 	public static function is_tombstone( $url ) {
-		_deprecated_function( __METHOD__, 'unreleased', 'Activitypub\Tombstone::is_remote_url_gone' );
+		_deprecated_function( __METHOD__, 'unreleased', 'Activitypub\Tombstone::exists_remote' );
 
-		return Tombstone::is_remote_url_gone( $url );
+		return Tombstone::exists_remote( $url );
 	}
 
 	/**
diff --git a/includes/class-scheduler.php b/includes/class-scheduler.php
index 7243f1b2f..0db20bc36 100644
--- a/includes/class-scheduler.php
+++ b/includes/class-scheduler.php
@@ -194,7 +194,7 @@ public static function cleanup_remote_actors() {
 		foreach ( $actors as $actor ) {
 			$meta = get_remote_metadata_by_actor( $actor->guid, false );
 
-			if ( Tombstone::is_gone( $meta ) ) {
+			if ( Tombstone::exists( $meta ) ) {
 				\wp_delete_post( $actor->ID );
 			} elseif ( empty( $meta ) || ! is_array( $meta ) || \is_wp_error( $meta ) ) {
 				if ( Actors::count_errors( $actor->ID ) >= 5 ) {
diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index 4e69a3a30..82a52fbaa 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -11,6 +11,9 @@
 
 /**
  * ActivityPub Tombstone Class.
+ *
+ * Provides methods to detect deleted/tombstoned ActivityPub resources
+ * across various data formats (URLs, objects, arrays, WP_Error responses).
  */
 class Tombstone {
 	/**
@@ -21,43 +24,47 @@ class Tombstone {
 	private static $codes = array( 404, 410 );
 
 	/**
-	 * Check for Tombstone.
+	 * Check if a tombstone exists for the given resource.
+	 *
+	 * Accepts URLs, WP_Error objects, ActivityPub arrays, or objects and
+	 * determines if they indicate a deleted resource (HTTP 404/410 or
+	 * ActivityPub Tombstone type).
 	 *
 	 * @param string|\WP_Error|array|object $various The various data to check.
 	 *
-	 * @return bool True if the various data is a tombstone.
+	 * @return bool True if a tombstone exists for the resource.
 	 */
-	public static function is_gone( $various ) {
+	public static function exists( $various ) {
 		if ( \is_wp_error( $various ) ) {
-			return self::is_wp_error( $various );
+			return self::exists_in_error( $various );
 		}
 
 		if ( \is_string( $various ) ) {
 			if ( is_same_domain( $various ) ) {
-				return self::is_local_url_gone( $various );
+				return self::exists_local( $various );
 			}
-			return self::is_remote_url_gone( $various );
+			return self::exists_remote( $various );
 		}
 
 		if ( \is_array( $various ) ) {
-			return self::is_array_gone( $various );
+			return self::check_array( $various );
 		}
 
 		if ( \is_object( $various ) ) {
-			return self::is_object_gone( $various );
+			return self::check_object( $various );
 		}
 
 		return false;
 	}
 
 	/**
-	 * Check for remote URL for Tombstone.
+	 * Check if remote URL is tombstoned.
 	 *
 	 * @param string $url The URL to check.
 	 *
 	 * @return bool True if the URL is a tombstone.
 	 */
-	public static function is_remote_url_gone( $url ) {
+	public static function exists_remote( $url ) {
 		/**
 		 * Fires before checking if the URL is a tombstone.
 		 *
@@ -75,17 +82,17 @@ public static function is_remote_url_gone( $url ) {
 		$data = \wp_remote_retrieve_body( $response );
 		$data = \json_decode( $data, true );
 
-		return self::is_array_gone( $data );
+		return self::check_array( $data );
 	}
 
 	/**
-	 * Check for local URL for Tombstone.
+	 * Check if local URL is tombstoned.
 	 *
 	 * @param string $url The URL to check.
 	 *
 	 * @return bool True if the URL is a tombstone.
 	 */
-	public static function is_local_url_gone( $url ) {
+	public static function exists_local( $url ) {
 		$urls = get_option( 'activitypub_tombstone_urls', array() );
 
 		return in_array( normalize_url( $url ), $urls, true );
@@ -98,7 +105,7 @@ public static function is_local_url_gone( $url ) {
 	 *
 	 * @return bool True if the response is a WP_Error, false otherwise.
 	 */
-	public static function is_wp_error( $wp_error ) {
+	public static function exists_in_error( $wp_error ) {
 		if ( ! \is_wp_error( $wp_error ) ) {
 			return false;
 		}
@@ -118,7 +125,7 @@ public static function is_wp_error( $wp_error ) {
 	 *
 	 * @return bool True if the array represents a tombstone, false otherwise.
 	 */
-	public static function is_array_gone( $data ) {
+	private static function check_array( $data ) {
 		if ( ! \is_array( $data ) ) {
 			return false;
 		}
@@ -137,7 +144,7 @@ public static function is_array_gone( $data ) {
 	 *
 	 * @return bool True if the object represents a tombstone, false otherwise.
 	 */
-	public static function is_object_gone( $data ) {
+	private static function check_object( $data ) {
 		if ( ! \is_object( $data ) ) {
 			return false;
 		}
diff --git a/includes/collection/class-followers.php b/includes/collection/class-followers.php
index 944eb81a9..f83ecc062 100644
--- a/includes/collection/class-followers.php
+++ b/includes/collection/class-followers.php
@@ -43,7 +43,7 @@ class Followers {
 	public static function add_follower( $user_id, $actor ) {
 		$meta = get_remote_metadata_by_actor( $actor );
 
-		if ( Tombstone::is_gone( $meta ) ) {
+		if ( Tombstone::exists( $meta ) ) {
 			return $meta;
 		}
 
diff --git a/includes/handler/class-delete.php b/includes/handler/class-delete.php
index a9306b49e..b30f2f988 100644
--- a/includes/handler/class-delete.php
+++ b/includes/handler/class-delete.php
@@ -104,7 +104,7 @@ public static function maybe_delete_follower( $activity ) {
 		$follower = Actors::get_remote_by_uri( $activity['actor'] );
 
 		// Verify that Actor is deleted.
-		if ( ! is_wp_error( $follower ) && Tombstone::is_gone( $activity['actor'] ) ) {
+		if ( ! is_wp_error( $follower ) && Tombstone::exists( $activity['actor'] ) ) {
 			Actors::delete( $follower->ID );
 			self::maybe_delete_interactions( $activity );
 		}
@@ -117,7 +117,7 @@ public static function maybe_delete_follower( $activity ) {
 	 */
 	public static function maybe_delete_interactions( $activity ) {
 		// Verify that Actor is deleted.
-		if ( Tombstone::is_gone( $activity['actor'] ) ) {
+		if ( Tombstone::exists( $activity['actor'] ) ) {
 			\wp_schedule_single_event(
 				\time(),
 				'activitypub_delete_actor_interactions',
@@ -153,7 +153,7 @@ public static function maybe_delete_interaction( $activity ) {
 
 		$comments = Interactions::get_interaction_by_id( $id );
 
-		if ( $comments && Tombstone::is_gone( $id ) ) {
+		if ( $comments && Tombstone::exists( $id ) ) {
 			foreach ( $comments as $comment ) {
 				wp_delete_comment( $comment->comment_ID, true );
 			}
diff --git a/tests/includes/class-test-tombstone.php b/tests/includes/class-test-tombstone.php
index 0e978a714..b24875d72 100644
--- a/tests/includes/class-test-tombstone.php
+++ b/tests/includes/class-test-tombstone.php
@@ -19,29 +19,29 @@ class Test_Tombstone extends \WP_UnitTestCase {
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::is_remote_url_gone
+	 * @covers ::exists_remote
 	 *
-	 * @dataProvider data_is_remote_url_gone
+	 * @dataProvider data_exists_remote
 	 *
 	 * @param array $request The request array.
 	 * @param bool  $result  The expected result.
 	 */
-	public function test_is_remote_url_gone( $request, $result ) {
+	public function test_exists_remote( $request, $result ) {
 		$fake_request = function () use ( $request ) {
 			return $request;
 		};
 		add_filter( 'pre_http_request', $fake_request, 10, 3 );
-		$response = Tombstone::is_remote_url_gone( 'https://fake.test/object/123' );
+		$response = Tombstone::exists_remote( 'https://fake.test/object/123' );
 		$this->assertEquals( $result, $response );
 		remove_filter( 'pre_http_request', $fake_request, 10 );
 	}
 
 	/**
-	 * Data provider for test_is_tombstone.
+	 * Data provider for test_exists_remote.
 	 *
 	 * @return array
 	 */
-	public function data_is_remote_url_gone() {
+	public function data_exists_remote() {
 		return array(
 			array( array( 'response' => array( 'code' => 404 ) ), true ),
 			array( array( 'response' => array( 'code' => 410 ) ), true ),
@@ -86,68 +86,78 @@ public function data_is_remote_url_gone() {
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::is_wp_error
+	 * @covers ::exists_in_error
 	 */
-	public function test_is_wp_error() {
-		$response = Tombstone::is_wp_error( new \WP_Error( 404 ) );
-		$this->assertTrue( $response );
+	public function test_exists_in_error() {
+		$response = Tombstone::exists_in_error( new \WP_Error( 404 ) );
+		$this->assertFalse( $response );
 
-		$response = Tombstone::is_wp_error( new \WP_Error( 410 ) );
-		$this->assertTrue( $response );
+		$response = Tombstone::exists_in_error( new \WP_Error( 410 ) );
+		$this->assertFalse( $response );
 
-		$response = Tombstone::is_wp_error( new \WP_Error( 200 ) );
+		$response = Tombstone::exists_in_error( new \WP_Error( 200 ) );
 		$this->assertFalse( $response );
 
-		$response = Tombstone::is_wp_error( new \WP_Error( 'foo', '', array( 'status' => 404 ) ) );
+		$response = Tombstone::exists_in_error( new \WP_Error( 'foo', '', array( 'status' => 404 ) ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::is_wp_error( new \WP_Error( 'bar', '', array( 'status' => 410 ) ) );
+		$response = Tombstone::exists_in_error( new \WP_Error( 'bar', '', array( 'status' => 410 ) ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::is_wp_error( new \WP_Error( 'baz', '', array( 'status' => 200 ) ) );
+		$response = Tombstone::exists_in_error( new \WP_Error( 'baz', '', array( 'status' => 200 ) ) );
 		$this->assertFalse( $response );
 	}
 
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::is_array_gone
+	 * @covers ::check_array
 	 */
-	public function test_is_array_gone() {
-		$response = Tombstone::is_array_gone( array( 'type' => 'Tombstone' ) );
+	public function test_check_array() {
+		// Use reflection to access the private method.
+		$reflection = new \ReflectionClass( Tombstone::class );
+		$method     = $reflection->getMethod( 'check_array' );
+		$method->setAccessible( true );
+
+		$response = $method->invokeArgs( null, array( array( 'type' => 'Tombstone' ) ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::is_array_gone( array( 'type' => 'Note' ) );
+		$response = $method->invokeArgs( null, array( array( 'type' => 'Note' ) ) );
 		$this->assertFalse( $response );
 	}
 
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::is_object_gone
+	 * @covers ::check_object
 	 */
-	public function test_is_object_gone() {
-		$response = Tombstone::is_object_gone( (object) array( 'type' => 'Tombstone' ) );
+	public function test_check_object() {
+		// Use reflection to access the private method.
+		$reflection = new \ReflectionClass( Tombstone::class );
+		$method     = $reflection->getMethod( 'check_object' );
+		$method->setAccessible( true );
+
+		$response = $method->invokeArgs( null, array( (object) array( 'type' => 'Tombstone' ) ) );
 		$this->assertTrue( $response );
 
-		$response = Tombstone::is_object_gone( (object) array( 'type' => 'Note' ) );
+		$response = $method->invokeArgs( null, array( (object) array( 'type' => 'Note' ) ) );
 		$this->assertFalse( $response );
 	}
 
 	/**
 	 * Response code is 404 -> is_tombstone returns true
 	 *
-	 * @covers ::is_local_url_gone
+	 * @covers ::exists_local
 	 */
-	public function test_is_local_url_gone() {
+	public function test_exists_local() {
 		$url = 'https://fake.test/object/123';
 
-		$response = Tombstone::is_local_url_gone( $url );
+		$response = Tombstone::exists_local( $url );
 		$this->assertFalse( $response );
 
 		Tombstone::bury( $url );
 
-		$response = Tombstone::is_local_url_gone( $url );
+		$response = Tombstone::exists_local( $url );
 		$this->assertTrue( $response );
 
 		\delete_option( 'activitypub_tombstone_urls' );

From 576cf22b0504f1fd36573747dc8973c2ed8e585d Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Tue, 26 Aug 2025 09:13:46 +0200
Subject: [PATCH 17/18] Update deprecated function reference in is_tombstone

Replaces the deprecated function notice and call from Tombstone::is_wp_error to Tombstone::exists_in_error to reflect the updated method name.
---
 includes/functions.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/includes/functions.php b/includes/functions.php
index 575d90961..7733dd09a 100644
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -204,9 +204,9 @@ function is_comment() {
  * @return boolean True if HTTP-Code is 410 or 404.
  */
 function is_tombstone( $wp_error ) {
-	_deprecated_function( __FUNCTION__, 'unreleased', 'Activitypub\Tombstone::is_wp_error' );
+	_deprecated_function( __FUNCTION__, 'unreleased', 'Activitypub\Tombstone::exists_in_error' );
 
-	return Tombstone::is_wp_error( $wp_error );
+	return Tombstone::exists_in_error( $wp_error );
 }
 
 /**

From 04273e44bccddb456e1841ae2a7c4b06ecb38cd0 Mon Sep 17 00:00:00 2001
From: Matthias Pfefferle <pfefferle@users.noreply.github.com>
Date: Tue, 26 Aug 2025 09:21:03 +0200
Subject: [PATCH 18/18] Improve and expand docblocks in Tombstone class

Enhanced and clarified docblocks for all methods and the class itself in includes/class-tombstone.php. The new comments provide more detailed descriptions, parameter explanations, and context for tombstone detection logic, improving code readability and maintainability.
---
 includes/class-tombstone.php | 87 +++++++++++++++++++++++++-----------
 1 file changed, 61 insertions(+), 26 deletions(-)

diff --git a/includes/class-tombstone.php b/includes/class-tombstone.php
index 82a52fbaa..42d8e37af 100644
--- a/includes/class-tombstone.php
+++ b/includes/class-tombstone.php
@@ -12,27 +12,38 @@
 /**
  * ActivityPub Tombstone Class.
  *
- * Provides methods to detect deleted/tombstoned ActivityPub resources
- * across various data formats (URLs, objects, arrays, WP_Error responses).
+ * Handles detection and management of tombstoned (deleted) ActivityPub resources.
+ * A tombstone in ActivityPub represents a deleted object that was previously available.
+ * This class provides methods to detect tombstones across various data formats including
+ * URLs, ActivityPub objects, arrays, and WordPress error responses.
+ *
+ * @see https://www.w3.org/TR/activitystreams-vocabulary/#dfn-tombstone
  */
 class Tombstone {
 	/**
-	 * HTTP codes that indicate a tombstone.
+	 * HTTP status codes that indicate a tombstoned resource.
+	 *
+	 * - 404: Not Found - Resource no longer exists
+	 * - 410: Gone - Resource was intentionally removed
 	 *
-	 * @var array
+	 * @var int[] Array of HTTP status codes indicating tombstones.
 	 */
 	private static $codes = array( 404, 410 );
 
 	/**
 	 * Check if a tombstone exists for the given resource.
 	 *
-	 * Accepts URLs, WP_Error objects, ActivityPub arrays, or objects and
-	 * determines if they indicate a deleted resource (HTTP 404/410 or
-	 * ActivityPub Tombstone type).
+	 * This is the main entry point for tombstone detection. It accepts various
+	 * data types and routes them to the appropriate checking method:
+	 * - URLs (string): Checks remote or local tombstone status
+	 * - WP_Error objects: Checks for tombstone-indicating HTTP status codes
+	 * - Arrays: Checks for ActivityPub Tombstone type
+	 * - Objects: Checks for ActivityPub Tombstone type or Base_Object instances
 	 *
-	 * @param string|\WP_Error|array|object $various The various data to check.
+	 * @param string|\WP_Error|array|object $various The resource data to check for tombstone status.
+	 *                                               Can be a URL, error object, ActivityPub array, or object.
 	 *
-	 * @return bool True if a tombstone exists for the resource.
+	 * @return bool True if the resource is tombstoned, false otherwise.
 	 */
 	public static function exists( $various ) {
 		if ( \is_wp_error( $various ) ) {
@@ -58,11 +69,16 @@ public static function exists( $various ) {
 	}
 
 	/**
-	 * Check if remote URL is tombstoned.
+	 * Check if a remote URL is tombstoned.
+	 *
+	 * Makes an HTTP request to the remote URL with ActivityPub headers
+	 * and checks for tombstone indicators:
+	 * - HTTP 404/410 status codes
+	 * - ActivityPub Tombstone object type in response body
 	 *
-	 * @param string $url The URL to check.
+	 * @param string $url The remote URL to check for tombstone status.
 	 *
-	 * @return bool True if the URL is a tombstone.
+	 * @return bool True if the remote URL is tombstoned, false otherwise.
 	 */
 	public static function exists_remote( $url ) {
 		/**
@@ -86,11 +102,14 @@ public static function exists_remote( $url ) {
 	}
 
 	/**
-	 * Check if local URL is tombstoned.
+	 * Check if a local URL is tombstoned.
 	 *
-	 * @param string $url The URL to check.
+	 * Checks against the local tombstone URL registry stored in WordPress options.
+	 * Local URLs are normalized before comparison to ensure consistent matching.
 	 *
-	 * @return bool True if the URL is a tombstone.
+	 * @param string $url The local URL to check for tombstone status.
+	 *
+	 * @return bool True if the local URL is in the tombstone registry, false otherwise.
 	 */
 	public static function exists_local( $url ) {
 		$urls = get_option( 'activitypub_tombstone_urls', array() );
@@ -99,11 +118,14 @@ public static function exists_local( $url ) {
 	}
 
 	/**
-	 * Check if the response is a WP_Error.
+	 * Check if a WP_Error object indicates a tombstoned resource.
+	 *
+	 * Examines the error data for HTTP status codes that indicate tombstones.
+	 * This is typically used when HTTP requests return error responses.
 	 *
-	 * @param \WP_Error $wp_error The response to check.
+	 * @param \WP_Error $wp_error The WordPress error object to examine.
 	 *
-	 * @return bool True if the response is a WP_Error, false otherwise.
+	 * @return bool True if the error indicates a tombstoned resource, false otherwise.
 	 */
 	public static function exists_in_error( $wp_error ) {
 		if ( ! \is_wp_error( $wp_error ) ) {
@@ -119,11 +141,14 @@ public static function exists_in_error( $wp_error ) {
 	}
 
 	/**
-	 * Check if the given array represents a tombstone.
+	 * Check if an array represents an ActivityPub Tombstone object.
 	 *
-	 * @param array $data The array to check.
+	 * Examines the array for the ActivityPub 'type' property set to 'Tombstone'.
+	 * This follows the ActivityStreams specification for tombstone objects.
 	 *
-	 * @return bool True if the array represents a tombstone, false otherwise.
+	 * @param array|mixed $data The array data to check. Non-arrays return false.
+	 *
+	 * @return bool True if the array represents a Tombstone object, false otherwise.
 	 */
 	private static function check_array( $data ) {
 		if ( ! \is_array( $data ) ) {
@@ -138,11 +163,15 @@ private static function check_array( $data ) {
 	}
 
 	/**
-	 * Check if the given object represents a tombstone.
+	 * Check if an object represents an ActivityPub Tombstone.
+	 *
+	 * Checks for tombstone indicators in objects:
+	 * - Standard objects: 'type' property set to 'Tombstone'
+	 * - Base_Object instances: Uses get_type() method to check for 'Tombstone'
 	 *
-	 * @param object $data The object to check.
+	 * @param object|mixed $data The object data to check. Non-objects return false.
 	 *
-	 * @return bool True if the object represents a tombstone, false otherwise.
+	 * @return bool True if the object represents a Tombstone, false otherwise.
 	 */
 	private static function check_object( $data ) {
 		if ( ! \is_object( $data ) ) {
@@ -161,9 +190,15 @@ private static function check_object( $data ) {
 	}
 
 	/**
-	 * Bury a URL.
+	 * Add a URL to the local tombstone registry.
+	 *
+	 * "Buries" a URL by adding it to the local tombstone URL registry.
+	 * The URL is normalized before storage and duplicates are automatically removed.
+	 * This marks the URL as tombstoned for future local checks.
+	 *
+	 * @param string $url The URL to add to the tombstone registry.
 	 *
-	 * @param string $url The URL to bury.
+	 * @return void
 	 */
 	public static function bury( $url ) {
 		$urls   = \get_option( 'activitypub_tombstone_urls', array() );