feat: add reasoning model (#750)

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

app/(chat)/actions.ts

@@ -1,19 +1,19 @@
 'use server';
 
-import { type CoreUserMessage, generateText, Message } from 'ai';
+import { generateText, Message } from 'ai';
 import { cookies } from 'next/headers';
 
-import { customModel } from '@/lib/ai';
 import {
   deleteMessagesByChatIdAfterTimestamp,
   getMessageById,
   updateChatVisiblityById,
 } from '@/lib/db/queries';
 import { VisibilityType } from '@/components/visibility-selector';
+import { myProvider } from '@/lib/ai/models';
 
-export async function saveModelId(model: string) {
+export async function saveChatModelAsCookie(model: string) {
   const cookieStore = await cookies();
-  cookieStore.set('model-id', model);
+  cookieStore.set('chat-model', model);
 }
 
 export async function generateTitleFromUserMessage({
@@ -22,7 +22,7 @@ export async function generateTitleFromUserMessage({
   message: Message;
 }) {
   const { text: title } = await generateText({
-    model: customModel('gpt-4o-mini'),
+    model: myProvider.languageModel('title-model'),
     system: `\n
     - you will generate a short title based on the first message a user begins a conversation with
     - ensure it is not more than 80 characters long