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>

lib/localSession.ts

@@ -0,0 +1,36 @@
+import type { Task, Message, ExecutionResult } from '@/types';
+
+const STORAGE_KEY = 'professor_session';
+
+export interface LocalSession {
+  topicId: string;
+  task: Task;
+  code: string;
+  messages: Message[];
+  executionResult: ExecutionResult | null;
+}
+
+export function saveLocalSession(session: LocalSession): void {
+  if (typeof window === 'undefined') return;
+  try {
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(session));
+  } catch {
+    // Ignore quota errors
+  }
+}
+
+export function loadLocalSession(): LocalSession | null {
+  if (typeof window === 'undefined') return null;
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (!raw) return null;
+    return JSON.parse(raw) as LocalSession;
+  } catch {
+    return null;
+  }
+}
+
+export function clearLocalSession(): void {
+  if (typeof window === 'undefined') return;
+  localStorage.removeItem(STORAGE_KEY);
+}