Add canvas interface (#461)

ai/index.ts

@@ -1,13 +1,11 @@
 import { openai } from '@ai-sdk/openai';
 import { experimental_wrapLanguageModel as wrapLanguageModel } from 'ai';
 
-import { type Model } from '@/lib/model';
-
 import { customMiddleware } from './custom-middleware';
 
-export const customModel = (modelName: Model['name']) => {
+export const customModel = (apiIdentifier: string) => {
   return wrapLanguageModel({
-    model: openai(modelName),
+    model: openai(apiIdentifier),
     middleware: customMiddleware,
   });
 };