diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index e564c54a1e80..8aab0d4151d8 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -646,6 +646,7 @@ export namespace ProviderTransform {
     if (input.model.api.id.includes("gpt-5") && !input.model.api.id.includes("gpt-5-chat")) {
       if (!input.model.api.id.includes("gpt-5-pro")) {
         result["reasoningEffort"] = "medium"
+        result["reasoningSummary"] = "auto"
       }
 
       // Only set textVerbosity for non-chat gpt-5.x models