tweak: add support for medium reasoning w/ gemini 3.1 (#14316)

packages/opencode/src/provider/transform.ts

@@ -599,8 +599,13 @@ export namespace ProviderTransform {
             },
           }
         }
+        let levels = ["low", "high"]
+        if (id.includes("3.1")) {
+          levels = ["low", "medium", "high"]
+        }
+
         return Object.fromEntries(
-          ["low", "high"].map((effort) => [
+          levels.map((effort) => [
             effort,
             {
               includeThoughts: true,