Fix Pixelfed interactions (Likes)

.github/changelog/2448-from-description

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Fixed compatibility with Pixelfed and similar platforms by treating activities without recipients as public, ensuring boosts and reposts work correctly.

includes/functions.php

@@ -588,6 +588,12 @@ function get_activity_visibility( $activity ) {
 		return ACTIVITYPUB_CONTENT_VISIBILITY_QUIET_PUBLIC;
 	}
 
+	// Activities with no recipients are treated as public.
+	$recipients = extract_recipients_from_activity( $activity );
+	if ( empty( $recipients ) ) {
+		return ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC;
+	}
+
 	return ACTIVITYPUB_CONTENT_VISIBILITY_PRIVATE;
 }
 
@@ -607,6 +613,10 @@ function is_activity_public( $data ) {
 
 	$recipients = extract_recipients_from_activity( $data );
 
+	if ( empty( $recipients ) ) {
+		return true;
+	}
+
 	return ! empty( array_intersect( $recipients, ACTIVITYPUB_PUBLIC_AUDIENCE_IDENTIFIERS ) );
 }
 

tests/phpunit/tests/includes/class-test-functions.php

@@ -1003,7 +1003,7 @@ public function public_activity_provider() {
 						'monkey' => 'https://www.w3.org/ns/activitystreams#Public',
 					),
 				),
-				false,
+				true,
 			),
 			array(
 				array(
@@ -1334,13 +1334,13 @@ public function visibility_data_provider() {
 				'expected'    => ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC,
 				'description' => 'Public visibility via as:Public identifier',
 			),
-			// Empty activity.
+			// Empty activity - no recipients means public.
 			array(
 				'activity'    => array(
 					'type' => 'Create',
 				),
-				'expected'    => ACTIVITYPUB_CONTENT_VISIBILITY_PRIVATE,
-				'description' => 'Empty activity defaults to private',
+				'expected'    => ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC,
+				'description' => 'Empty activity (no recipients) is treated as public',
 			),
 		);
 	}

tests/phpunit/tests/includes/collection/class-test-inbox.php

@@ -75,9 +75,9 @@ public function test_add_activity_with_post_meta() {
 		$remote_actor_meta = \get_post_meta( $inbox_id, '_activitypub_activity_remote_actor', true );
 		$this->assertEquals( 'https://remote.example.com/users/testuser', $remote_actor_meta );
 
-		// Test activitypub_content_visibility meta.
+		// Activities with no recipients are treated as public.
 		$visibility_meta = \get_post_meta( $inbox_id, 'activitypub_content_visibility', true );
-		$this->assertEquals( ACTIVITYPUB_CONTENT_VISIBILITY_PRIVATE, $visibility_meta );
+		$this->assertEquals( ACTIVITYPUB_CONTENT_VISIBILITY_PUBLIC, $visibility_meta );
 	}
 
 	/**
@@ -723,4 +723,60 @@ public function test_deduplicate_non_existent() {
 		$result = Inbox::deduplicate( 'https://remote.example.com/activities/non-existent' );
 		$this->assertFalse( $result );
 	}
+
+	/**
+	 * Test adding Like activity with trailing slash in object URL.
+	 *
+	 * This test verifies that Like activities from Pixelfed and other platforms
+	 * that include trailing slashes in object URLs are stored correctly in the inbox.
+	 *
+	 * @covers ::add
+	 */
+	public function test_add_like_activity_with_trailing_slash() {
+		// Create a post to be liked.
+		$post_id        = self::factory()->post->create(
+			array(
+				'post_title'   => 'Test Post for Like',
+				'post_content' => 'Test content',
+				'post_status'  => 'publish',
+			)
+		);
+		$post_permalink = \get_permalink( $post_id );
+
+		// Create a Like activity with trailing slash in object URL (as Pixelfed sends).
+		$activity = new Activity();
+		$activity->set_id( 'https://pixelfed.social/users/pfefferle#likes/30434186' );
+		$activity->set_type( 'Like' );
+		$activity->set_actor( 'https://pixelfed.social/users/pfefferle' );
+		$activity->set_object( $post_permalink . '/' ); // Add trailing slash.
+
+		$user_id = 1;
+
+		// Add activity to inbox.
+		$inbox_id = Inbox::add( $activity, $user_id );
+
+		$this->assertIsInt( $inbox_id );
+		$this->assertGreaterThan( 0, $inbox_id );
+
+		// Verify the post was created.
+		$post = \get_post( $inbox_id );
+		$this->assertInstanceOf( 'WP_Post', $post );
+		$this->assertEquals( Inbox::POST_TYPE, $post->post_type );
+
+		// Test _activitypub_object_id meta - should preserve the trailing slash as-is.
+		$object_id_meta = \get_post_meta( $inbox_id, '_activitypub_object_id', true );
+		$this->assertEquals( $post_permalink . '/', $object_id_meta );
+
+		// Test _activitypub_activity_type meta.
+		$activity_type_meta = \get_post_meta( $inbox_id, '_activitypub_activity_type', true );
+		$this->assertEquals( 'Like', $activity_type_meta );
+
+		// Test _activitypub_user_id meta.
+		$user_id_meta = \get_post_meta( $inbox_id, '_activitypub_user_id', true );
+		$this->assertEquals( $user_id, $user_id_meta );
+
+		// Test _activitypub_activity_remote_actor meta.
+		$remote_actor_meta = \get_post_meta( $inbox_id, '_activitypub_activity_remote_actor', true );
+		$this->assertEquals( 'https://pixelfed.social/users/pfefferle', $remote_actor_meta );
+	}
 }

tests/phpunit/tests/includes/handler/class-test-like.php

@@ -185,6 +185,50 @@ public function handle_like_provider() {
 		);
 	}
 
+	/**
+	 * Test Like activity with trailing slash in object URL.
+	 *
+	 * This test verifies that Like activities from Pixelfed and other platforms
+	 * that include trailing slashes in object URLs are processed correctly.
+	 *
+	 * @covers ::handle_like
+	 * @covers \Activitypub\Collection\Interactions::add_reaction
+	 */
+	public function test_handle_like_with_trailing_slash() {
+		// Create activity with trailing slash in object URL (as Pixelfed sends).
+		$activity = array(
+			'@context' => 'https://www.w3.org/ns/activitystreams',
+			'id'       => 'https://pixelfed.social/users/pfefferle#likes/30434186',
+			'type'     => 'Like',
+			'actor'    => $this->user_url,
+			'object'   => $this->post_permalink . '/', // Add trailing slash.
+		);
+
+		// Get comment count before.
+		$comments_before = \get_comments(
+			array(
+				'type'    => 'like',
+				'post_id' => $this->post_id,
+			)
+		);
+		$count_before    = count( $comments_before );
+
+		// Process the like.
+		Like::handle_like( $activity, $this->user_id );
+
+		// Check that comment was created despite trailing slash.
+		$comments_after = \get_comments(
+			array(
+				'type'    => 'like',
+				'post_id' => $this->post_id,
+			)
+		);
+		$count_after    = count( $comments_after );
+
+		$this->assertEquals( $count_before + 1, $count_after, 'Like with trailing slash should create comment' );
+		$this->assertInstanceOf( 'WP_Comment', $comments_after[0], 'Should create WP_Comment object' );
+	}
+
 	/**
 	 * Test duplicate like handling.
 	 *

tests/phpunit/tests/includes/rest/class-test-inbox-controller.php

@@ -475,7 +475,9 @@ public function test_get_local_recipients_no_recipients() {
 		$method->setAccessible( true );
 
 		$result = $method->invoke( $this->inbox_controller, $activity );
-		$this->assertEmpty( $result, 'Should return empty array when no recipients' );
+		// Activities with no recipients are treated as public and delivered to all local actors.
+		$this->assertNotEmpty( $result, 'Should return all local actors when no recipients (treated as public)' );
+		$this->assertEquals( Actors::get_all_ids(), $result, 'Should match all local actor IDs' );
 	}
 
 	/**