first implé

src/lib/gemini.ts

@@ -0,0 +1,56 @@
+import { GoogleGenAI } from '@google/genai';
+import { ChatMessage, PersonaMode } from '@/types/chat';
+import { SYSTEM_PROMPT, MODE_MODIFIERS } from './prompts';
+
+const apiKey = process.env.GEMINI_API_KEY;
+
+export function getGeminiClient() {
+  if (!apiKey) {
+    throw new Error('GEMINI_API_KEY is not defined in your environment variables.');
+  }
+  return new GoogleGenAI({ apiKey });
+}
+
+export async function streamSchopenhauerReply(
+  messages: ChatMessage[],
+  mode: PersonaMode
+) {
+  const ai = getGeminiClient();
+  const systemInstruction = `${SYSTEM_PROMPT}\n\n${MODE_MODIFIERS[mode]}`;
+
+  // Map our messages to Gemini API format.
+  // Gemini expects: { role: 'user' | 'model', parts: [{ text: string }] }
+  // We limit the history to the last 16 messages for performance.
+  const historyLimit = 16;
+  const recentMessages = messages.slice(-historyLimit);
+
+  const contents = recentMessages.map((msg) => ({
+    role: msg.role === 'assistant' ? 'model' : 'user',
+    parts: [{ text: msg.content }],
+  }));
+
+  const modelCandidates = [
+    process.env.GEMINI_MODEL || 'gemini-3.1-flash',
+    'gemini-2.5-flash',
+    'gemini-1.5-flash',
+  ];
+
+  let lastError: any = null;
+  for (const modelName of modelCandidates) {
+    try {
+      const responseStream = await ai.models.generateContentStream({
+        model: modelName,
+        contents,
+        config: {
+          systemInstruction,
+          temperature: 0.7,
+        },
+      });
+      return { responseStream, modelUsed: modelName };
+    } catch (err) {
+      console.warn(`Failed to start stream with model ${modelName}:`, err);
+      lastError = err;
+    }
+  }
+  throw lastError || new Error('All Gemini model candidates failed to initialize.');
+}