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>

db/index.ts

@@ -0,0 +1,18 @@
+import Database from 'better-sqlite3';
+import { drizzle } from 'drizzle-orm/better-sqlite3';
+import * as schema from './schema';
+
+type DrizzleDb = ReturnType<typeof drizzle<typeof schema>>;
+const globalForDb = globalThis as unknown as { _professorDb?: DrizzleDb };
+
+function createDb(): DrizzleDb {
+  const sqlite = new Database('professor.db');
+  sqlite.pragma('journal_mode = WAL');
+  return drizzle(sqlite, { schema });
+}
+
+export const db: DrizzleDb = globalForDb._professorDb ?? createDb();
+
+if (process.env.NODE_ENV !== 'production') {
+  globalForDb._professorDb = db;
+}

db/schema.ts

@@ -0,0 +1,21 @@
+import { text, sqliteTable } from 'drizzle-orm/sqlite-core';
+
+export const users = sqliteTable('users', {
+  id: text('id').primaryKey(),
+  email: text('email').notNull().unique(),
+  passwordHash: text('password_hash').notNull(),
+  createdAt: text('created_at').notNull(),
+});
+
+export const savedSessions = sqliteTable('saved_sessions', {
+  id: text('id').primaryKey(),
+  userId: text('user_id')
+    .notNull()
+    .references(() => users.id),
+  topicId: text('topic_id'),
+  taskJson: text('task_json'),
+  code: text('code'),
+  messagesJson: text('messages_json'),
+  executionResultJson: text('execution_result_json'),
+  updatedAt: text('updated_at').notNull(),
+});