diff --git a/providers/openai/responses_options.go b/providers/openai/responses_options.go
index f38b0bebe43bbd86b3f0b309eee6f2c361e0dc18..6dce9aaca95aec540ea4796d33adc18d7cbafaa0 100644
--- a/providers/openai/responses_options.go
+++ b/providers/openai/responses_options.go
@@ -155,6 +155,7 @@ var responsesReasoningModelIDs = []string{
 	"gpt-5-pro",
 	"gpt-5.1",
 	"gpt-5.1-codex",
+	"gpt-5.1-codex-max",
 	"gpt-5.1-codex-mini",
 	"gpt-5.1-chat",
 	"gpt-oss-120b",