feat: add reasoning model (#750)

Co-authored-by: Matt Apperson <me@mattapperson.com>

app/(chat)/page.tsx

@@ -1,7 +1,7 @@
 import { cookies } from 'next/headers';
 
 import { Chat } from '@/components/chat';
-import { DEFAULT_MODEL_NAME, models } from '@/lib/ai/models';
+import { DEFAULT_CHAT_MODEL } from '@/lib/ai/models';
 import { generateUUID } from '@/lib/utils';
 import { DataStreamHandler } from '@/components/data-stream-handler';
 
@@ -9,11 +9,23 @@ export default async function Page() {
   const id = generateUUID();
 
   const cookieStore = await cookies();
-  const modelIdFromCookie = cookieStore.get('model-id')?.value;
+  const modelIdFromCookie = cookieStore.get('chat-model');
 
-  const selectedModelId =
-    models.find((model) => model.id === modelIdFromCookie)?.id ||
-    DEFAULT_MODEL_NAME;
+  if (!modelIdFromCookie) {
+    return (
+      <>
+        <Chat
+          key={id}
+          id={id}
+          initialMessages={[]}
+          selectedChatModel={DEFAULT_CHAT_MODEL}
+          selectedVisibilityType="private"
+          isReadonly={false}
+        />
+        <DataStreamHandler id={id} />
+      </>
+    );
+  }
 
   return (
     <>
@@ -21,7 +33,7 @@ export default async function Page() {
         key={id}
         id={id}
         initialMessages={[]}
-        selectedModelId={selectedModelId}
+        selectedChatModel={modelIdFromCookie.value}
         selectedVisibilityType="private"
         isReadonly={false}
       />