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/auth.ts

@@ -0,0 +1,68 @@
+import { SignJWT, jwtVerify } from 'jose';
+import bcrypt from 'bcryptjs';
+import { cookies } from 'next/headers';
+
+const JWT_SECRET = new TextEncoder().encode(
+  process.env.JWT_SECRET ?? 'dev-secret-change-in-production-please'
+);
+const COOKIE_NAME = 'professor_auth';
+const COOKIE_MAX_AGE = 60 * 60 * 24 * 30; // 30 days
+
+export interface JWTPayload {
+  userId: string;
+  email: string;
+}
+
+// ─── Password helpers ────────────────────────────────────────────────────────
+
+export async function hashPassword(password: string): Promise<string> {
+  return bcrypt.hash(password, 12);
+}
+
+export async function verifyPassword(password: string, hash: string): Promise<boolean> {
+  return bcrypt.compare(password, hash);
+}
+
+// ─── JWT helpers ─────────────────────────────────────────────────────────────
+
+export async function signToken(payload: JWTPayload): Promise<string> {
+  return new SignJWT(payload as unknown as Record<string, unknown>)
+    .setProtectedHeader({ alg: 'HS256' })
+    .setIssuedAt()
+    .setExpirationTime('30d')
+    .sign(JWT_SECRET);
+}
+
+export async function verifyToken(token: string): Promise<JWTPayload | null> {
+  try {
+    const { payload } = await jwtVerify(token, JWT_SECRET);
+    return payload as unknown as JWTPayload;
+  } catch {
+    return null;
+  }
+}
+
+// ─── Cookie helpers ───────────────────────────────────────────────────────────
+
+export async function setAuthCookie(token: string): Promise<void> {
+  const cookieStore = await cookies();
+  cookieStore.set(COOKIE_NAME, token, {
+    httpOnly: true,
+    secure: process.env.NODE_ENV === 'production',
+    sameSite: 'lax',
+    maxAge: COOKIE_MAX_AGE,
+    path: '/',
+  });
+}
+
+export async function clearAuthCookie(): Promise<void> {
+  const cookieStore = await cookies();
+  cookieStore.delete(COOKIE_NAME);
+}
+
+export async function getAuthUser(): Promise<JWTPayload | null> {
+  const cookieStore = await cookies();
+  const token = cookieStore.get(COOKIE_NAME)?.value;
+  if (!token) return null;
+  return verifyToken(token);
+}

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);
+}

lib/pistonClient.ts

@@ -0,0 +1,57 @@
+import type { ExecutionResult } from '@/types';
+
+// Wandbox — free public code execution API, no auth required
+// https://github.com/melpon/wandbox
+const WANDBOX_API = 'https://wandbox.org/api/compile.json';
+const TIMEOUT_MS = 15_000;
+
+export async function executePython(code: string, stdin = ''): Promise<ExecutionResult> {
+  const controller = new AbortController();
+  const timer = setTimeout(() => controller.abort(), TIMEOUT_MS);
+
+  try {
+    const res = await fetch(WANDBOX_API, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      signal: controller.signal,
+      body: JSON.stringify({
+        compiler: 'cpython-3.12.7',
+        code,
+        stdin,
+      }),
+    });
+
+    if (!res.ok) {
+      throw new Error(`Execution service error: ${res.status}`);
+    }
+
+    const data = await res.json();
+    const exitCode = parseInt(data.status ?? '0', 10);
+
+    // Wandbox separates compiler errors from runtime errors
+    const stderr = [data.program_error, data.compiler_error]
+      .filter(Boolean)
+      .join('\n')
+      .trim();
+
+    return {
+      stdout: data.program_output ?? '',
+      stderr,
+      exitCode,
+      timedOut: !!data.signal,
+    };
+  } catch (err: unknown) {
+    if (err instanceof Error && err.name === 'AbortError') {
+      return { stdout: '', stderr: '', exitCode: -1, timedOut: true, error: 'Execution timed out after 15 seconds.' };
+    }
+    return {
+      stdout: '',
+      stderr: '',
+      exitCode: -1,
+      timedOut: false,
+      error: err instanceof Error ? err.message : 'Unknown execution error',
+    };
+  } finally {
+    clearTimeout(timer);
+  }
+}

lib/prompts.ts

@@ -0,0 +1,138 @@
+import type { Topic, ExecutionResult, ResponseMode } from '@/types';
+
+function buildContext(topic: Topic, code: string, result?: ExecutionResult): string {
+  const execSection = result
+    ? `\nEXECUTION OUTPUT:\nstdout: ${result.stdout || '(empty)'}\nstderr: ${result.stderr || '(empty)'}\nexit code: ${result.exitCode}`
+    : '';
+
+  return `CURRENT TOPIC: ${topic.label} (${topic.language})
+CURRENT CODE:
+\`\`\`${topic.language}
+${code}
+\`\`\`${execSection}`;
+}
+
+// ─── Task Generation ────────────────────────────────────────────────────────
+
+export function buildTaskGenerationPrompt(topic: Topic): string {
+  return `You are Professor, an expert and encouraging coding tutor. Generate a hands-on coding task for a student learning "${topic.label}" in ${topic.language}.
+
+Respond in EXACTLY this format — no preamble, no extra text:
+
+TITLE: <short task title>
+
+DESCRIPTION:
+<2-4 sentence description of what the student should build or accomplish. Be specific and concrete.>
+
+HINTS:
+- <hint 1>
+- <hint 2>
+- <hint 3>
+
+STARTER_CODE:
+\`\`\`${topic.language}
+<starter code with comments guiding the student. Leave key parts blank for them to fill in.>
+\`\`\`
+
+Rules:
+- The task should be completable in 10-15 minutes
+- Keep it focused on the topic, not broader concepts
+- The starter code should be runnable but incomplete — scaffold the structure, leave the logic for the student
+- For Python tasks, use print() to show output so the student can verify their work
+- For HTML tasks, include visible elements so the student can see results immediately`;
+}
+
+// ─── Code Review ────────────────────────────────────────────────────────────
+
+export function buildCodeReviewPrompt(topic: Topic, code: string, result?: ExecutionResult, responseMode?: ResponseMode): string {
+  const context = buildContext(topic, code, result);
+
+  const hintInstruction = responseMode && !responseMode.hintMode
+    ? '3. Do NOT proactively suggest hints or next steps — only confirm correctness or point out specific errors. The student must ask explicitly to receive hints.'
+    : '3. Give hints to fix issues rather than directly writing the correct code';
+
+  const strictInstruction = responseMode?.strict
+    ? `\n9. STRICT MODE: Only accept code that uses the exact approach and techniques the task requires. If the student\'s solution works but uses a different method (e.g. a built-in instead of a manual implementation, or a different algorithm), explicitly flag it as not meeting the task requirements and explain what approach is expected.`
+    : '';
+
+  return `You are Professor, a patient and encouraging coding tutor. Review the student's code for the topic "${topic.label}".
+
+${context}
+
+Guidelines for your review:
+1. Start by acknowledging what the student got right — be specific
+2. Point out any issues clearly but kindly — explain WHY it's a problem, not just what
+${hintInstruction}
+4. If the code is correct, praise it and challenge them to extend it
+5. Reference the execution output if provided — point out what the output reveals about correctness
+6. Keep your response concise and actionable — avoid walls of text
+7. Use markdown with code blocks where helpful${strictInstruction}`;
+}
+
+// ─── Classroom Lesson ───────────────────────────────────────────────────────
+
+export function buildLessonPrompt(topic: Topic): string {
+  return `You are Professor, an expert coding tutor. Write a comprehensive lesson on "${topic.label}" in ${topic.language}.
+
+Structure the lesson as a well-organised markdown document with these sections:
+
+## Introduction
+What this concept is and why it matters (2–3 sentences).
+
+## Key Concepts
+The core ideas, clearly explained with simple language.
+
+## Syntax & Usage
+Concrete ${topic.language} examples with labelled code blocks.
+
+## Common Patterns
+2–3 real-world usage patterns the student will encounter.
+
+## Common Mistakes
+Frequent pitfalls beginners make and how to avoid them.
+
+## Quick Reference
+A concise bullet-list summary of the most important points.
+
+Rules:
+- Use ${topic.language} fenced code blocks for all examples
+- Keep explanations beginner-friendly and concise
+- Include practical, runnable examples throughout
+- Do NOT include exercises or tasks — those belong in Homework mode`;
+}
+
+// ─── Classroom Q&A Chat ─────────────────────────────────────────────────────
+
+export function buildClassroomChatPrompt(topic: Topic): string {
+  return `You are Professor, a knowledgeable and patient coding tutor. You are in a Classroom session helping a student learn "${topic.label}" in ${topic.language}.
+
+The student has just read a lesson on this topic and may ask conceptual questions, request clarification, or ask for more examples.
+
+Guidelines:
+- Answer questions clearly and concisely
+- Use ${topic.language} code examples where helpful, with fenced code blocks
+- Focus on explanation and understanding — this is not a code review
+- If the student asks for an exercise or task, suggest they switch to Homework mode
+- Keep responses conversational and reasonably short`;
+}
+
+// ─── Free Chat ──────────────────────────────────────────────────────────────
+
+export function buildChatPrompt(topic: Topic, code: string, responseMode?: ResponseMode): string {
+  const context = buildContext(topic, code);
+
+  const hintInstruction = responseMode && !responseMode.hintMode
+    ? '- Do NOT proactively suggest hints or next steps. Answer only what is explicitly asked — no unsolicited guidance.'
+    : '- Never just give them the answer to their task — guide with hints and explanations';
+
+  return `You are Professor, a friendly and knowledgeable coding tutor. You are currently helping a student with the topic "${topic.label}".
+
+${context}
+
+Guidelines:
+- Answer the student's questions clearly and concisely
+- Stay focused on the current topic and their code, but help with related questions too
+${hintInstruction}
+- Use markdown with code blocks for code examples
+- Keep responses reasonably short — this is a conversation, not a lecture`;
+}

lib/providers.ts

@@ -0,0 +1,95 @@
+import type { ProviderId, ProviderConfig } from '@/types';
+
+export interface ProviderDefinition {
+  id: ProviderId;
+  label: string;
+  requiresApiKey: boolean;
+  hasCustomBaseUrl: boolean;
+  defaultBaseUrl: string;
+  defaultModel: string;
+  modelSuggestions: string[];
+}
+
+export const PROVIDERS: ProviderDefinition[] = [
+  {
+    id: 'anthropic',
+    label: 'Anthropic (Claude)',
+    requiresApiKey: true,
+    hasCustomBaseUrl: false,
+    defaultBaseUrl: 'https://api.anthropic.com',
+    defaultModel: 'claude-sonnet-4-6',
+    modelSuggestions: [
+      'claude-sonnet-4-6',
+      'claude-haiku-4-5-20251001',
+      'claude-opus-4-6',
+    ],
+  },
+  {
+    id: 'openrouter',
+    label: 'OpenRouter',
+    requiresApiKey: true,
+    hasCustomBaseUrl: false,
+    defaultBaseUrl: 'https://openrouter.ai/api/v1',
+    defaultModel: 'meta-llama/llama-3.1-8b-instruct:free',
+    modelSuggestions: [
+      'meta-llama/llama-3.1-8b-instruct:free',
+      'google/gemma-3-27b-it:free',
+      'mistralai/mistral-7b-instruct:free',
+      'deepseek/deepseek-chat-v3-0324:free',
+      'qwen/qwen3-8b:free',
+    ],
+  },
+  {
+    id: 'lmstudio',
+    label: 'LM Studio',
+    requiresApiKey: false,
+    hasCustomBaseUrl: true,
+    defaultBaseUrl: 'http://localhost:1234/v1',
+    defaultModel: 'local-model',
+    modelSuggestions: [],
+  },
+  {
+    id: 'ollama',
+    label: 'Ollama',
+    requiresApiKey: false,
+    hasCustomBaseUrl: true,
+    defaultBaseUrl: 'http://localhost:11434/v1',
+    defaultModel: 'llama3.2',
+    modelSuggestions: [
+      'llama3.2',
+      'llama3.1',
+      'mistral',
+      'qwen2.5-coder',
+      'deepseek-coder-v2',
+      'phi4',
+    ],
+  },
+];
+
+export const PROVIDER_MAP = Object.fromEntries(PROVIDERS.map((p) => [p.id, p])) as Record<
+  ProviderId,
+  ProviderDefinition
+>;
+
+export const DEFAULT_PROVIDER_CONFIG: ProviderConfig = {
+  provider: 'anthropic',
+  model: 'claude-sonnet-4-6',
+};
+
+const STORAGE_KEY = 'professor_provider_config';
+
+export function loadProviderConfig(): ProviderConfig {
+  if (typeof window === 'undefined') return DEFAULT_PROVIDER_CONFIG;
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (!raw) return DEFAULT_PROVIDER_CONFIG;
+    return JSON.parse(raw) as ProviderConfig;
+  } catch {
+    return DEFAULT_PROVIDER_CONFIG;
+  }
+}
+
+export function saveProviderConfig(config: ProviderConfig): void {
+  if (typeof window === 'undefined') return;
+  localStorage.setItem(STORAGE_KEY, JSON.stringify(config));
+}

lib/topics.ts

@@ -0,0 +1,79 @@
+import type { Topic } from '@/types';
+
+export const TOPICS: Topic[] = [
+  // ─── Python ──────────────────────────────────────────────────────────────
+  {
+    id: 'python-variables',
+    label: 'Python Variables',
+    language: 'python',
+    description: 'Learn how to store and work with different types of data',
+    starterCode: '# Your code here\n',
+  },
+  {
+    id: 'python-lists',
+    label: 'Python Lists',
+    language: 'python',
+    description: 'Create, modify, and iterate over collections of items',
+    starterCode: '# Your code here\n',
+  },
+  {
+    id: 'python-loops',
+    label: 'Python Loops',
+    language: 'python',
+    description: 'Repeat actions with for and while loops',
+    starterCode: '# Your code here\n',
+  },
+  {
+    id: 'python-functions',
+    label: 'Python Functions',
+    language: 'python',
+    description: 'Define reusable blocks of code that accept inputs and return outputs',
+    starterCode: '# Your code here\n',
+  },
+  {
+    id: 'python-dicts',
+    label: 'Python Dictionaries',
+    language: 'python',
+    description: 'Store and retrieve data using key-value pairs',
+    starterCode: '# Your code here\n',
+  },
+  {
+    id: 'python-strings',
+    label: 'Python Strings',
+    language: 'python',
+    description: 'Manipulate text with string methods and formatting',
+    starterCode: '# Your code here\n',
+  },
+
+  // ─── HTML / CSS ───────────────────────────────────────────────────────────
+  {
+    id: 'html-structure',
+    label: 'HTML Structure',
+    language: 'html',
+    description: 'Build the skeleton of a webpage with semantic HTML elements',
+    starterCode: '<!DOCTYPE html>\n<html lang="en">\n<head>\n  <meta charset="UTF-8">\n  <title>My Page</title>\n</head>\n<body>\n  <!-- Your code here -->\n</body>\n</html>\n',
+  },
+  {
+    id: 'css-box-model',
+    label: 'CSS Box Model',
+    language: 'html',
+    description: 'Understand margin, border, padding, and content sizing',
+    starterCode: '<!DOCTYPE html>\n<html lang="en">\n<head>\n  <meta charset="UTF-8">\n  <title>Box Model</title>\n  <style>\n    /* Your styles here */\n  </style>\n</head>\n<body>\n  <!-- Your code here -->\n</body>\n</html>\n',
+  },
+  {
+    id: 'css-flexbox',
+    label: 'CSS Flexbox',
+    language: 'html',
+    description: 'Arrange elements in rows and columns with flexbox layout',
+    starterCode: '<!DOCTYPE html>\n<html lang="en">\n<head>\n  <meta charset="UTF-8">\n  <title>Flexbox</title>\n  <style>\n    /* Your styles here */\n  </style>\n</head>\n<body>\n  <!-- Your code here -->\n</body>\n</html>\n',
+  },
+  {
+    id: 'html-forms',
+    label: 'HTML Forms',
+    language: 'html',
+    description: 'Collect user input with form elements and validation attributes',
+    starterCode: '<!DOCTYPE html>\n<html lang="en">\n<head>\n  <meta charset="UTF-8">\n  <title>Forms</title>\n</head>\n<body>\n  <!-- Your form here -->\n</body>\n</html>\n',
+  },
+];
+
+export const TOPIC_BY_ID = Object.fromEntries(TOPICS.map((t) => [t.id, t]));