fix advanced settings issue (#3849)

Author: rbren

frontend/src/components/modals/settings/ModelSelector.tsx

@@ -48,7 +48,11 @@ export function ModelSelector({
 
   const handleChangeModel = (model: string) => {
     const separator = models[selectedProvider || ""]?.separator || "";
-    const fullModel = selectedProvider + separator + model;
+    let fullModel = selectedProvider + separator + model;
+    if (selectedProvider === "openai") {
+      // LiteLLM lists OpenAI models without the openai/ prefix
+      fullModel = model;
+    }
     setLitellmId(fullModel);
     onModelChange(fullModel);
     setSelectedModel(model);

frontend/src/services/settings.ts

@@ -11,7 +11,7 @@ export type Settings = {
 };
 
 export const DEFAULT_SETTINGS: Settings = {
-  LLM_MODEL: "openai/gpt-4o",
+  LLM_MODEL: "gpt-4o",
   LLM_BASE_URL: "",
   AGENT: "CodeActAgent",
   LANGUAGE: "en",