fix: write child posts to their canonical hierarchical path

inc/native/class-wp-markdown-native-query-executor.php

@@ -564,6 +564,11 @@ private function execute_query_plan( WP_Markdown_Native_Query_Plan $plan, bool $
 			? array()
 			: array_values( array_filter( $predicates, static fn( WP_Markdown_Native_Query_Predicate $predicate ): bool => $predicate !== $pushdown ) );
 		$provider_projection = $plan->counts_all() ? array() : array_merge( $projection, $scalar_columns );
+		// A residual predicate is matched here, after the provider read, so the
+		// provider has to return the columns it reads. A provider that resolves
+		// a column lazily returns it empty when it is absent from the
+		// projection, and the residual then matches against that empty value.
+		foreach ( $residual as $predicate ) { $provider_projection = array_merge( $provider_projection, $predicate->columns() ); }
 		foreach ( $scalar_predicates as $predicate ) { $provider_projection = array_merge( $provider_projection, $predicate->columns() ); }
 		if ( null !== $boolean_predicate ) { $provider_projection = array_merge( $provider_projection, $boolean_predicate->columns() ); }
 		foreach ( array_merge( $plan->subqueries(), $this->boolean_subqueries( $boolean_predicate ) ) as $subquery ) {

inc/native/class-wp-markdown-native-query-runtime.php

@@ -408,7 +408,14 @@ private static function shared_storage( string $content_root, bool $network_root
 		$key = ( $network_root ? 'network:' : 'site:' ) . rtrim( $content_root, '/\\' );
 		if ( ! isset( self::$storages[ $key ] ) ) {
 			// The network root owns sites/{blog_id}; it is not a post-type tree.
-			self::$storages[ $key ] = new WP_Markdown_Storage( $content_root, $network_root ? array( 'sites' ) : array() );
+			$storage = new WP_Markdown_Storage( $content_root, $network_root ? array( 'sites' ) : array() );
+			// A post with a parent belongs inside its parent's directory, and
+			// the writer walks the ancestor chain to find that directory. Without
+			// a resolver it cannot read an ancestor, so it writes the child flat
+			// at the post-type root while the row still records the parent. The
+			// path then disagrees with the hierarchy the row declares.
+			$storage->set_post_resolver( static fn( int $post_id ): ?object => $storage->read_post( $post_id ) );
+			self::$storages[ $key ] = $storage;
 		}
 		return self::$storages[ $key ];
 	}

tests/smoke-native-markdown-post-write.php

@@ -50,6 +50,31 @@
 $wp_id = (int) $wp_insert->wpdb_state()['insert_id'];
 $wp_read = $runtime->execute( new WP_Markdown_Query_Request( 'SELECT post_title, comment_count FROM wp_posts WHERE ID = ' . $wp_id, 'wp_' ) );
 
+// A child post belongs inside its parent's directory. The writer walks the
+// ancestor chain through the runtime's post resolver to find that directory,
+// so a runtime without one writes the child flat while the row still records
+// the parent, and the canonical path then disagrees with the hierarchy.
+$parent_insert = $runtime->execute(
+	new WP_Markdown_Query_Request(
+		"INSERT INTO wp_posts (post_author, post_date, post_date_gmt, post_content, post_title, post_excerpt, post_status, comment_status, ping_status, post_password, post_name, to_ping, pinged, post_modified, post_modified_gmt, post_content_filtered, post_parent, guid, menu_order, post_type, post_mime_type, comment_count) VALUES (1, '2026-08-27 12:00:00', '2026-08-27 12:00:00', 'Parent body', 'Parent', '', 'publish', 'open', 'open', '', 'parent-slug', '', '', '2026-08-27 12:00:00', '2026-08-27 12:00:00', '', 0, 'http://localhost/parent-slug/', 0, 'post', '', 0)",
+		'wp_'
+	)
+);
+$parent_id = (int) ( $parent_insert->wpdb_state()['insert_id'] ?? 0 );
+$child_insert = $runtime->execute(
+	new WP_Markdown_Query_Request(
+		"INSERT INTO wp_posts (post_author, post_date, post_date_gmt, post_content, post_title, post_excerpt, post_status, comment_status, ping_status, post_password, post_name, to_ping, pinged, post_modified, post_modified_gmt, post_content_filtered, post_parent, guid, menu_order, post_type, post_mime_type, comment_count) VALUES (1, '2026-08-27 12:00:00', '2026-08-27 12:00:00', 'Child body needle', 'Child', '', 'publish', 'open', 'open', '', 'child-slug', '', '', '2026-08-27 12:00:00', '2026-08-27 12:00:00', '', {$parent_id}, 'http://localhost/child-slug/', 0, 'post', '', 0)",
+		'wp_'
+	)
+);
+$child_id = (int) ( $child_insert->wpdb_state()['insert_id'] ?? 0 );
+$child_files = array_values( array_filter( $markdown_files( $content ), static fn( string $path ): bool => str_ends_with( $path, 'child-slug.md' ) ) );
+$child_nested = array() !== $child_files && str_ends_with( $child_files[0], '/post/parent-slug/child-slug.md' );
+// A body predicate is matched after the provider read, so a child whose file
+// the provider cannot resolve returns empty content and matches nothing.
+$child_body = $runtime->execute( new WP_Markdown_Query_Request( "SELECT ID FROM wp_posts WHERE post_content LIKE '%needle%'", 'wp_' ) );
+$child_body_ids = array_map( static fn( object $row ): int => (int) $row->ID, $child_body->wpdb_state()['last_result'] ?? array() );
+
 $checks = array(
 	'an INSERT assigns an identity and writes markdown' => 1 === $insert->return_value()
 		&& 1 === $insert->wpdb_state()['insert_id']
@@ -62,6 +87,8 @@
 	'a DELETE removes the canonical file' => 1 === $delete->return_value()
 		&& 0 === $after_delete->return_value()
 		&& array() === $files_after_delete,
+	'a child post is written inside its parent directory' => $parent_id > 0 && $child_id > 0 && $child_nested,
+	'a child post body is searchable at its canonical path' => in_array( $child_id, $child_body_ids, true ),
 	'a WordPress wp_insert_post row fills integer defaults' => 1 === $wp_insert->return_value()
 		&& $wp_id > 0
 		&& 'Native Save Probe' === ( $wp_read->wpdb_state()['last_result'][0]->post_title ?? null )
@@ -74,6 +101,8 @@
 	$failed = $failed || ! $passed;
 }
 
+array_map( 'unlink', glob( $content . '/post/parent-slug/*' ) ?: array() );
+@rmdir( $content . '/post/parent-slug' );
 array_map( 'unlink', glob( $content . '/post/*' ) ?: array() );
 @rmdir( $content . '/post' );
 @rmdir( $content );