dynamic import of genai in nest.js

apps/api/src/utils/genai.ts

@@ -1,21 +1,34 @@
 import { ConfigService } from '@nestjs/config';
 
-let genaiModule: typeof import('@google/genai') | null = null;
-
-async function loadGenAI() {
-  if (!genaiModule) {
-    genaiModule = await import('@google/genai');
-  }
-  return genaiModule;
+export interface GoogleAIInstance {
+  files: {
+    get(params: { name: string }): Promise<{ state: string; uri?: string; stateDescription?: string }>;
+    upload(params: { file: string; config: { mimeType: string } }): Promise<{ name: string; uri: string; mimeType: string }>;
+  };
+  models: {
+    generateContent(params: {
+      model: string;
+      contents: Array<{ role: string; parts: Array<{ text?: string; fileData?: { fileUri: string; mimeType: string } }> }>;
+      config?: { responseMimeType?: string };
+    }): Promise<{ text: string }>;
+  };
 }
 
-export async function createGoogleAI(configService: ConfigService) {
-  const { GoogleGenAI } = await loadGenAI();
+let cachedGoogleAI: GoogleAIInstance | null = null;
+let cachedApiKey: string | null = null;
+
+export async function createGoogleAI(configService: ConfigService): Promise<GoogleAIInstance> {
   const apiKey = configService.get<string>('GOOGLE_GENERATIVE_AI_API_KEY');
   if (!apiKey) {
     throw new Error('GOOGLE_GENERATIVE_AI_API_KEY is not configured');
   }
-  return new GoogleGenAI({ apiKey });
-}
 
-export type GoogleAIInstance = Awaited<ReturnType<typeof createGoogleAI>>;
+  if (cachedGoogleAI && cachedApiKey === apiKey) {
+    return cachedGoogleAI;
+  }
+
+  const mod = await (Function('return import("@google/genai")')() as Promise<{ GoogleGenAI: new (opts: { apiKey: string }) => GoogleAIInstance }>);
+  cachedGoogleAI = new mod.GoogleGenAI({ apiKey });
+  cachedApiKey = apiKey;
+  return cachedGoogleAI;
+}