oh my, searching actually works

public/class-partnerexpo-core-public.php

@@ -79,6 +79,28 @@ class Partnerexpo_Core_Public {
 			'pexpo_tags'	 => $params['tags'] ?? '',
 		];
 
+		if ( ! empty( $params['tags'] ) ) {
+			$tag_string = $params['tags'];
+			$operator   = 'IN';
+			$delimiter  = ',';
+
+			if ( strpos( $tag_string, '+' ) !== false ) {
+				$operator  = 'AND';
+				$delimiter = '+';
+			}
+
+			$tag_slugs = explode( $delimiter, $tag_string );
+
+			$args['tax_query'] = [
+				[
+					'taxonomy' => 'pexpo_tags',
+					'field'    => 'slug',
+					'terms'    => $tag_slugs,
+					'operator' => $operator,
+				],
+			];
+		}
+
 		switch ($params['sort'] ?? 'relevance') {
 			case 'date_asc':
 				$args['orderby'] = 'date';
@@ -97,12 +119,13 @@ class Partnerexpo_Core_Public {
 				$args['order']   = 'DESC';
 				break;
 			case 'relevance':
+				$args['orderby'] = 'relevance';
+				break;
 			default:
-				// Default WordPress search sorting
 				break;
 		}
 
-		$query = new WP_Query($args);
+		$query = new WP_Query_WithRelevance($args);
 
 		$posts = [];