llm: add service.ModelName
diff --git a/llm/ant/ant.go b/llm/ant/ant.go
index d1c366a..efebf26 100644
--- a/llm/ant/ant.go
+++ b/llm/ant/ant.go
@@ -41,6 +41,10 @@
 	MaxTokens int          // defaults to DefaultMaxTokens if zero
 }
 
+func (s *Service) ModelName() string {
+	return cmp.Or(s.Model, DefaultModel)
+}
+
 var _ llm.Service = (*Service)(nil)
 
 type content struct {