public static function ajax_term_search() {
        if (!current_user_can('edit_products')) wp_send_json([]);
        check_ajax_referer('pmg_fitment_search');

        $q = isset($_GET['q']) ? sanitize_text_field(wp_unslash($_GET['q'])) : '';
        if ($q === '') wp_send_json([]);

        // Normalize query spacing
        $q_norm = trim(preg_replace('/\s+/', ' ', $q));
        $tokens = preg_split('/\s+/', $q_norm);
        $out    = [];

        // Helper to normalize strings for matching (lowercase, remove spaces and non-alnum)
        $normalize = function($s){ return strtolower(preg_replace('/[^a-z0-9]+/i', '', $s)); };

        if (count($tokens) >= 2) {
            $make_token   = array_shift($tokens);                    // first token = Make
            $model_tokens = $tokens;                                 // rest = Model tokens
            $make_need    = $normalize($make_token);

            // Use the last model token to narrow DB search, then filter in PHP for all tokens
            $model_hint   = end($model_tokens);
            reset($model_tokens);

            $model_terms = get_terms([
                'taxonomy'   => self::TAX,
                'hide_empty' => false,
                'name__like' => $model_hint,   // narrow; we will filter more precisely below
                'number'     => 200,
                'orderby'    => 'name',
                'order'      => 'ASC',
            ]);

            if (!is_wp_error($model_terms) && $model_terms) {
                // Build a normalized needle for the full model tokens (e.g., "cr500" or "cr500r")
                $model_needles = array_map($normalize, $model_tokens);

                foreach ($model_terms as $model_term) {
                    $model_name_norm = $normalize($model_term->name);
                    // Ensure all model needles are present in the term name
                    $all_present = true;
                    foreach ($model_needles as $needle) {
                        if ($needle === '') continue;
                        if (strpos($model_name_norm, $needle) === false) { $all_present = false; break; }
                    }
                    if (!$all_present) continue;

                    // Confirm the Make exists somewhere in the ancestor chain (space-insensitive)
                    $anc_ids = get_ancestors($model_term->term_id, self::TAX, 'taxonomy');
                    if (empty($anc_ids)) continue;
                    $has_make = false;
                    foreach ($anc_ids as $aid) {
                        $p = get_term($aid, self::TAX);
                        if ($p && !is_wp_error($p)) {
                            if (strpos($normalize($p->name), $make_need) !== false) { $has_make = true; break; }
                        }
                    }
                    if (!$has_make) continue;

                    // Pull ALL descendants under the model and filter to 4-digit year names
                    $desc = get_terms([
                        'taxonomy'   => self::TAX,
                        'hide_empty' => false,
                        'child_of'   => $model_term->term_id,
                        'number'     => 0,   // get all in subtree (guard allows child_of)
                    ]);

                    if (!is_wp_error($desc) && $desc) {
                        foreach ($desc as $term) {
                            if (preg_match('/^\d{4}$/', $term->name)) {
                                $label = self::breadcrumb_label($term); // e.g. "1998 — CR500 → Honda"
                                $out[] = ['id' => (int)$term->term_id, 'text' => esc_html($label)];
                            }
                        }
                    }

                    // If we found any years for this model, that's enough for this result set
                    if (!empty($out)) break;
                }
            }

            if (!empty($out)) {
                // Sort years ascending by numeric value, then unique
                usort($out, function($a, $b){ return intval($a['text']) <=> intval($b['text']); });
                $seen = [];
                $out  = array_values(array_filter($out, function($row) use (&$seen){
                    $key = $row['id']; if (isset($seen[$key])) return false; $seen[$key]=1; return true; }));
                wp_send_json($out);
            }
        }

        // Fallback: generic name search with breadcrumb labels
        $terms = get_terms([
            'taxonomy'   => self::TAX,
            'hide_empty' => false,
            'name__like' => $q_norm,
            'number'     => 20,
            'orderby'    => 'name',
            'order'      => 'ASC',
        ]);
        if (is_wp_error($terms) || empty($terms)) wp_send_json([]);

        foreach ($terms as $t) {
            $label = self::breadcrumb_label($t);
            $out[] = ['id' => (int)$t->term_id, 'text' => esc_html($label) ];
        }
        wp_send_json($out);
    }