Add LLM tutor API endpoints

src/app/api/v1/llm/chat/route.ts

@@ -0,0 +1,78 @@
+import { NextRequest, NextResponse } from "next/server";
+import { getGenAIModel } from "@/lib/gemini";
+import { PERSONALITIES } from "@/lib/personalities";
+import { SupportedLanguage } from "@/lib/i18n/translations";
+import {
+  buildTutorPrompt,
+  buildTutorSystemHistory,
+  normalizeHistory,
+  TutorContext,
+  TutorPlayerColor,
+} from "@/lib/server/tutorPrompt";
+
+export const runtime = "nodejs";
+
+type ChatHistory = { role: "user" | "model"; text: string }[];
+
+type ChatBody = {
+  apiKey: string;
+  personalityId: string;
+  language: SupportedLanguage;
+  playerColor: TutorPlayerColor;
+  message: string;
+  context?: TutorContext;
+  history?: ChatHistory;
+  modelName?: string;
+};
+
+export async function POST(request: NextRequest) {
+  try {
+    const body = (await request.json()) as Partial<ChatBody> | null;
+    const {
+      apiKey,
+      personalityId,
+      language,
+      playerColor,
+      message,
+      context,
+      history = [],
+      modelName,
+    } = body ?? {};
+
+    if (!apiKey || typeof apiKey !== "string") {
+      return NextResponse.json({ error: "Missing apiKey" }, { status: 400 });
+    }
+    if (!personalityId || typeof personalityId !== "string") {
+      return NextResponse.json({ error: "Missing personalityId" }, { status: 400 });
+    }
+    if (!language || typeof language !== "string") {
+      return NextResponse.json({ error: "Missing language" }, { status: 400 });
+    }
+    if (playerColor !== "white" && playerColor !== "black") {
+      return NextResponse.json({ error: "playerColor must be 'white' or 'black'" }, { status: 400 });
+    }
+    if (!message || typeof message !== "string") {
+      return NextResponse.json({ error: "Missing message" }, { status: 400 });
+    }
+
+    const personality = PERSONALITIES.find((p) => p.id === personalityId);
+    if (!personality) {
+      return NextResponse.json({ error: "Unknown personality" }, { status: 400 });
+    }
+
+    const model = getGenAIModel(apiKey, modelName ?? "gemini-2.5-flash");
+    const systemHistory = buildTutorSystemHistory(personality, language, playerColor);
+    const chat = model.startChat({
+      history: [...systemHistory, ...normalizeHistory(history)],
+    });
+
+    const prompt = buildTutorPrompt(message, context, language);
+    const response = await chat.sendMessage(prompt);
+    const text = response.response.text();
+
+    return NextResponse.json({ reply: text });
+  } catch (error) {
+    console.error("LLM chat error", error);
+    return NextResponse.json({ error: "Failed to generate tutor response" }, { status: 500 });
+  }
+}

src/app/api/v1/personalities/route.ts

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+import { NextResponse } from "next/server";
+import { PERSONALITIES } from "@/lib/personalities";
+
+export const runtime = "nodejs";
+
+export async function GET() {
+  const safePersonalities = PERSONALITIES.map(({ id, name, description, image }) => ({
+    id,
+    name,
+    description,
+    image,
+  }));
+
+  return NextResponse.json({ personalities: safePersonalities });
+}