Initial commit — AI-powered coding tutor (Professor)

Next.js 16, React 19, Monaco editor, Anthropic SDK, multi-provider AI,
Wandbox Python execution, iframe HTML preview, SQLite auth + session persistence.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/api/session/route.ts

@@ -0,0 +1,62 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { db } from '@/db';
+import { savedSessions } from '@/db/schema';
+import { getAuthUser } from '@/lib/auth';
+import { eq } from 'drizzle-orm';
+
+export async function GET() {
+  const authUser = await getAuthUser();
+  if (!authUser) return NextResponse.json({ session: null }, { status: 401 });
+
+  const row = await db
+    .select()
+    .from(savedSessions)
+    .where(eq(savedSessions.userId, authUser.userId))
+    .get();
+
+  if (!row) return NextResponse.json({ session: null });
+
+  return NextResponse.json({
+    session: {
+      topicId: row.topicId,
+      task: row.taskJson ? JSON.parse(row.taskJson) : null,
+      code: row.code,
+      messages: row.messagesJson ? JSON.parse(row.messagesJson) : [],
+      executionResult: row.executionResultJson ? JSON.parse(row.executionResultJson) : null,
+    },
+  });
+}
+
+export async function PUT(req: NextRequest) {
+  const authUser = await getAuthUser();
+  if (!authUser) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+
+  const { topicId, task, code, messages, executionResult } = await req.json();
+
+  const existing = await db
+    .select()
+    .from(savedSessions)
+    .where(eq(savedSessions.userId, authUser.userId))
+    .get();
+
+  const data = {
+    userId: authUser.userId,
+    topicId: topicId ?? null,
+    taskJson: task ? JSON.stringify(task) : null,
+    code: code ?? null,
+    messagesJson: messages ? JSON.stringify(messages) : null,
+    executionResultJson: executionResult ? JSON.stringify(executionResult) : null,
+    updatedAt: new Date().toISOString(),
+  };
+
+  if (existing) {
+    await db
+      .update(savedSessions)
+      .set(data)
+      .where(eq(savedSessions.userId, authUser.userId));
+  } else {
+    await db.insert(savedSessions).values({ id: crypto.randomUUID(), ...data });
+  }
+
+  return NextResponse.json({ ok: true });
+}