diff --git a/frontend/src/components/workspace/input-box.tsx b/frontend/src/components/workspace/input-box.tsx
index 158f61a..0c28673 100644
--- a/frontend/src/components/workspace/input-box.tsx
+++ b/frontend/src/components/workspace/input-box.tsx
@@ -72,10 +72,18 @@ export function InputBox({
   const { t } = useI18n();
   const [modelDialogOpen, setModelDialogOpen] = useState(false);
   const { models } = useModels();
-  const selectedModel = useMemo(
-    () => models.find((m) => m.name === context.model_name),
-    [context.model_name, models],
-  );
+  const selectedModel = useMemo(() => {
+    if (!context.model_name && models.length > 0) {
+      setTimeout(() => {
+        onContextChange?.({
+          ...context,
+          model_name: models[0]!.name,
+        });
+      }, 0);
+      return models[0]!;
+    }
+    return models.find((m) => m.name === context.model_name);
+  }, [context, models, onContextChange]);
   const supportThinking = useMemo(
     () => selectedModel?.supports_thinking ?? false,
     [selectedModel],
diff --git a/frontend/src/core/models/hooks.ts b/frontend/src/core/models/hooks.ts
index 4c96946..0627593 100644
--- a/frontend/src/core/models/hooks.ts
+++ b/frontend/src/core/models/hooks.ts
@@ -2,10 +2,11 @@ import { useQuery } from "@tanstack/react-query";
 
 import { loadModels } from "./api";
 
-export function useModels() {
+export function useModels({ enabled = true }: { enabled?: boolean } = {}) {
   const { data, isLoading, error } = useQuery({
     queryKey: ["models"],
     queryFn: () => loadModels(),
+    enabled,
   });
   return { models: data ?? [], isLoading, error };
 }
diff --git a/frontend/src/core/settings/local.ts b/frontend/src/core/settings/local.ts
index 34ed995..7f8af3d 100644
--- a/frontend/src/core/settings/local.ts
+++ b/frontend/src/core/settings/local.ts
@@ -2,9 +2,9 @@ import type { AgentThreadContext } from "../threads";
 
 export const DEFAULT_LOCAL_SETTINGS: LocalSettings = {
   context: {
-    model_name: "deepseek-v3.2",
+    model_name: undefined,
     thinking_enabled: true,
-    is_plan_mode: false,
+    is_plan_mode: true,
   },
   layout: {
     sidebar_collapsed: false,
diff --git a/frontend/src/core/threads/types.ts b/frontend/src/core/threads/types.ts
index 5d4bc43..90232ba 100644
--- a/frontend/src/core/threads/types.ts
+++ b/frontend/src/core/threads/types.ts
@@ -14,7 +14,7 @@ export interface AgentThread extends Thread<AgentThreadState> {}
 
 export interface AgentThreadContext extends Record<string, unknown> {
   thread_id: string;
-  model_name: string;
+  model_name: string | undefined;
   thinking_enabled: boolean;
   is_plan_mode: boolean;
 }