Initial commit: Mathe-App Phase 1-3

- React+Vite Frontend mit Routing, eigenem fetch-Client (kein axios) - Express Backend: Auth (JWT), Topics, Tasks, Leaderboard - PostgreSQL Schema + Seed: 7 Kategorien, 21 Topics, ~25 Aufgaben - Gamification: XP, Level (100×n^1.5), tägliche Streaks - docker-compose auf Port 3100 für DS1621 - Alltagsaufgaben: Finanzen, Geometrie, Physik, Informatik, Verkehr, Shopping
2026-04-06 17:24:35 +02:00 · 2026-04-06 17:24:35 +02:00 · c8b354ed45
commit c8b354ed45
49 changed files with 6127 additions and 0 deletions
--- a/.env.example
+++ b/.env.example
@ -0,0 +1,11 @@
+DB_HOST=db
+DB_PORT=5432
+DB_NAME=matheapp
+DB_USER=mathe
+DB_PASSWORD=changeme
+
+JWT_SECRET=changeme_use_long_random_string
+JWT_REFRESH_SECRET=changeme_use_another_long_random_string
+
+FRONTEND_URL=http://localhost:3000
+PORT=3001
--- a/.gitignore
+++ b/.gitignore
@ -0,0 +1,5 @@
+.env
+node_modules/
+frontend/node_modules/
+backend/node_modules/
+frontend/dist/
--- a/README.md
+++ b/README.md
@ -0,0 +1,126 @@
+# Mathe im Alltag
+
+Mathe-Lern-App mit Gamification. Aufgaben aus dem echten Leben — Zinsen, Physik, Verkehr, Shopping und mehr.
+
+## Features
+
+- 7 Themenkategorien, 21 Topics, wachsender Aufgabenpool
+- XP, Level, tägliche Streaks
+- Leaderboard
+- Benutzerkonten mit JWT-Auth
+- Docker-basiert, läuft auf einem einzelnen Server
+
+## Tech-Stack
+
+| Schicht | Tech |
+|---|---|
+| Frontend | React + Vite |
+| Backend | Node.js + Express |
+| Datenbank | PostgreSQL 16 |
+| Auth | JWT |
+| Deployment | docker-compose + nginx |
+
+## Lokale Entwicklung
+
+### Voraussetzungen
+
+- Node.js 22+
+- Docker + docker-compose
+
+### Setup
+
+```bash
+# Abhängigkeiten installieren
+cd frontend && npm install
+cd ../backend && npm install
+
+# Umgebungsvariablen
+cp .env.example .env
+# .env anpassen (DB_PASSWORD, JWT_SECRET, etc.)
+
+# Starten
+docker compose up -d
+```
+
+Frontend läuft auf http://localhost:3100
+
+### Backend ohne Docker
+
+```bash
+cd backend
+npm run dev
+```
+
+## Deployment
+
+### Erste Inbetriebnahme
+
+```bash
+# .env anlegen (aus .env.example)
+cp .env.example .env
+nano .env
+
+# Starten (baut Images und initialisiert DB)
+docker compose up -d --build
+```
+
+### Update
+
+```bash
+git pull
+docker compose down && docker compose up -d --build
+```
+
+### NPM (Nginx Proxy Manager)
+
+- Domain: `mathe.motocamp.de`
+- Forward Hostname: `10.47.11.10`
+- Forward Port: `3100`
+- SSL: Let's Encrypt
+
+## Umgebungsvariablen
+
+| Variable | Beschreibung |
+|---|---|
+| `DB_HOST` | PostgreSQL Host (default: `db`) |
+| `DB_NAME` | Datenbankname |
+| `DB_USER` | Datenbankbenutzer |
+| `DB_PASSWORD` | Datenbankpasswort |
+| `JWT_SECRET` | Signierungsschlüssel für Access-Tokens |
+| `FRONTEND_URL` | Erlaubte CORS-Origin |
+| `PORT` | Backend-Port (default: 3001) |
+
+## Projektstruktur
+
+```
+mathe-app/
+├── frontend/          React+Vite App
+│   └── src/
+│       ├── api/       fetch-Client (kein axios)
+│       ├── pages/     Seiten (Home, Login, Dashboard, TopicPage)
+│       └── components/TaskCard — Aufgaben lösen
+├── backend/           Express API
+│   └── src/
+│       ├── routes/    auth, users, topics, tasks, health
+│       ├── middleware/ JWT-Auth
+│       ├── db/        PostgreSQL Pool
+│       └── utils/xp.js Level-Berechnung
+├── docker/
+│   ├── init.sql       DB-Schema + Seed-Daten
+│   ├── Dockerfile.frontend
+│   ├── Dockerfile.backend
+│   └── nginx.conf
+└── docker-compose.yml
+```
+
+## Themen
+
+| Kategorie | Topics |
+|---|---|
+| 💰 Finanzen | Zinsen & Sparen, Kredite & Raten, Rabatte & Steuern |
+| 📐 Geometrie | Flächen, Volumina, Winkel & Trigonometrie |
+| ⚖️ Verhältnisse & Zeit | Dreisatz, Zeitrechnung, Prozente |
+| ⚡ Physik | Mechanik, Elektrizität, Wärme & Energie |
+| 💻 Informatik | Binär & Hex, Dateigrößen, Algorithmen |
+| 🚗 Verkehr | Fahrtzeit & Tempo, Spritverbrauch, Bremswege |
+| 🛒 Shopping | Preisvergleich, Einheitspreis, Ratenkauf |
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
--- a/backend/package.json
+++ b/backend/package.json
@ -0,0 +1,22 @@
+{
+  "name": "backend",
+  "version": "1.0.0",
+  "description": "",
+  "main": "src/index.js",
+  "type": "module",
+  "scripts": {
+    "start": "node src/index.js",
+    "dev": "node --watch src/index.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "bcryptjs": "^3.0.3",
+    "cors": "^2.8.6",
+    "dotenv": "^17.4.1",
+    "express": "^5.2.1",
+    "jsonwebtoken": "^9.0.3",
+    "pg": "^8.20.0"
+  }
+}
--- a/backend/src/db/index.js
+++ b/backend/src/db/index.js
@ -0,0 +1,12 @@
+import pg from 'pg';
+const { Pool } = pg;
+
+const pool = new Pool({
+  host: process.env.DB_HOST || 'db',
+  port: process.env.DB_PORT || 5432,
+  database: process.env.DB_NAME || 'matheapp',
+  user: process.env.DB_USER || 'mathe',
+  password: process.env.DB_PASSWORD,
+});
+
+export default pool;
--- a/backend/src/index.js
+++ b/backend/src/index.js
@ -0,0 +1,24 @@
+import 'dotenv/config';
+import express from 'express';
+import cors from 'cors';
+import healthRouter from './routes/health.js';
+import authRouter from './routes/auth.js';
+import usersRouter from './routes/users.js';
+import topicsRouter from './routes/topics.js';
+import tasksRouter from './routes/tasks.js';
+
+const app = express();
+const PORT = process.env.PORT || 3001;
+
+app.use(cors({ origin: process.env.FRONTEND_URL || 'http://localhost:5173' }));
+app.use(express.json());
+
+app.use('/api/health', healthRouter);
+app.use('/api/auth', authRouter);
+app.use('/api/users', usersRouter);
+app.use('/api/topics', topicsRouter);
+app.use('/api/tasks', tasksRouter);
+
+app.listen(PORT, () => {
+  console.log(`Backend running on port ${PORT}`);
+});
--- a/backend/src/middleware/auth.js
+++ b/backend/src/middleware/auth.js
@ -0,0 +1,14 @@
+import jwt from 'jsonwebtoken';
+
+export function requireAuth(req, res, next) {
+  const header = req.headers.authorization;
+  if (!header?.startsWith('Bearer ')) {
+    return res.status(401).json({ message: 'Nicht angemeldet' });
+  }
+  try {
+    req.user = jwt.verify(header.slice(7), process.env.JWT_SECRET);
+    next();
+  } catch {
+    res.status(401).json({ message: 'Token ungültig oder abgelaufen' });
+  }
+}
--- a/backend/src/routes/auth.js
+++ b/backend/src/routes/auth.js
@ -0,0 +1,90 @@
+import { Router } from 'express';
+import bcrypt from 'bcryptjs';
+import jwt from 'jsonwebtoken';
+import pool from '../db/index.js';
+
+const router = Router();
+
+function signToken(user) {
+  return jwt.sign(
+    { id: user.id, username: user.username },
+    process.env.JWT_SECRET,
+    { expiresIn: '7d' }
+  );
+}
+
+// POST /api/auth/register
+router.post('/register', async (req, res) => {
+  const { username, email, password } = req.body;
+
+  if (!username || !email || !password) {
+    return res.status(400).json({ message: 'Alle Felder sind erforderlich' });
+  }
+  if (password.length < 8) {
+    return res.status(400).json({ message: 'Passwort muss mindestens 8 Zeichen haben' });
+  }
+
+  try {
+    const hash = await bcrypt.hash(password, 12);
+    const result = await pool.query(
+      `INSERT INTO users (username, email, password)
+       VALUES ($1, $2, $3)
+       RETURNING id, username, email, xp, level, streak`,
+      [username.trim(), email.toLowerCase().trim(), hash]
+    );
+    const user = result.rows[0];
+    res.status(201).json({ token: signToken(user), user });
+  } catch (err) {
+    if (err.code === '23505') {
+      const field = err.constraint?.includes('email') ? 'E-Mail' : 'Benutzername';
+      return res.status(409).json({ message: `${field} ist bereits vergeben` });
+    }
+    console.error(err);
+    res.status(500).json({ message: 'Serverfehler' });
+  }
+});
+
+// POST /api/auth/login
+router.post('/login', async (req, res) => {
+  const { email, password } = req.body;
+
+  if (!email || !password) {
+    return res.status(400).json({ message: 'E-Mail und Passwort erforderlich' });
+  }
+
+  try {
+    const result = await pool.query(
+      'SELECT * FROM users WHERE email = $1',
+      [email.toLowerCase().trim()]
+    );
+    const user = result.rows[0];
+
+    if (!user || !(await bcrypt.compare(password, user.password))) {
+      return res.status(401).json({ message: 'E-Mail oder Passwort falsch' });
+    }
+
+    // Streak-Logik: +1 wenn letzter Login gestern, reset wenn länger her
+    const today = new Date().toISOString().slice(0, 10);
+    const last = user.streak_last ? user.streak_last.toISOString().slice(0, 10) : null;
+    let streak = user.streak;
+
+    if (last !== today) {
+      const yesterday = new Date(Date.now() - 86400000).toISOString().slice(0, 10);
+      streak = last === yesterday ? streak + 1 : 1;
+      await pool.query(
+        'UPDATE users SET streak = $1, streak_last = $2 WHERE id = $3',
+        [streak, today, user.id]
+      );
+    }
+
+    const { password: _, ...safeUser } = user;
+    safeUser.streak = streak;
+
+    res.json({ token: signToken(user), user: safeUser });
+  } catch (err) {
+    console.error(err);
+    res.status(500).json({ message: 'Serverfehler' });
+  }
+});
+
+export default router;
--- a/backend/src/routes/health.js
+++ b/backend/src/routes/health.js
@ -0,0 +1,15 @@
+import { Router } from 'express';
+import pool from '../db/index.js';
+
+const router = Router();
+
+router.get('/', async (req, res) => {
+  try {
+    await pool.query('SELECT 1');
+    res.json({ status: 'ok', db: 'connected' });
+  } catch (err) {
+    res.status(503).json({ status: 'error', db: 'disconnected', message: err.message });
+  }
+});
+
+export default router;
--- a/backend/src/routes/tasks.js
+++ b/backend/src/routes/tasks.js
@ -0,0 +1,77 @@
+import { Router } from 'express';
+import { requireAuth } from '../middleware/auth.js';
+import pool from '../db/index.js';
+import { addXp } from '../utils/xp.js';
+
+const router = Router();
+
+// POST /api/tasks/:id/submit — Antwort einreichen
+router.post('/:id/submit', requireAuth, async (req, res) => {
+  const taskId = parseInt(req.params.id, 10);
+  const { answer } = req.body;
+
+  if (answer === undefined || answer === '') {
+    return res.status(400).json({ message: 'Antwort fehlt' });
+  }
+
+  try {
+    const taskResult = await pool.query(
+      'SELECT * FROM tasks WHERE id = $1', [taskId]
+    );
+    const task = taskResult.rows[0];
+    if (!task) return res.status(404).json({ message: 'Aufgabe nicht gefunden' });
+
+    // Bereits gelöst?
+    const existing = await pool.query(
+      'SELECT * FROM user_progress WHERE user_id = $1 AND task_id = $2',
+      [req.user.id, taskId]
+    );
+
+    let correct = false;
+
+    if (task.answer_type === 'number') {
+      const given = parseFloat(String(answer).replace(',', '.'));
+      const expected = parseFloat(task.correct);
+      const tolerance = parseFloat(task.tolerance) || 0;
+      correct = !isNaN(given) && Math.abs(given - expected) <= tolerance;
+    } else {
+      correct = String(answer).trim().toLowerCase() === String(task.correct).trim().toLowerCase();
+    }
+
+    let xpGained = 0;
+
+    if (existing.rows[0]) {
+      // Bereits versucht — nur Ergebnis zurückgeben, kein XP
+      return res.json({
+        correct,
+        explanation: task.explanation,
+        xpGained: 0,
+        alreadySolved: true,
+      });
+    }
+
+    await pool.query(
+      'INSERT INTO user_progress (user_id, task_id, correct) VALUES ($1, $2, $3)',
+      [req.user.id, taskId, correct]
+    );
+
+    if (correct) {
+      const updated = await addXp(pool, req.user.id, task.xp_reward);
+      xpGained = task.xp_reward;
+      return res.json({
+        correct: true,
+        explanation: task.explanation,
+        xpGained,
+        newXp: updated.xp,
+        newLevel: updated.level,
+      });
+    }
+
+    res.json({ correct: false, explanation: task.explanation, xpGained: 0 });
+  } catch (err) {
+    console.error(err);
+    res.status(500).json({ message: 'Serverfehler' });
+  }
+});
+
+export default router;
--- a/backend/src/routes/topics.js
+++ b/backend/src/routes/topics.js
@ -0,0 +1,60 @@
+import { Router } from 'express';
+import { requireAuth } from '../middleware/auth.js';
+import pool from '../db/index.js';
+
+const router = Router();
+
+// GET /api/topics — alle Kategorien mit Topics
+router.get('/', requireAuth, async (req, res) => {
+  try {
+    const cats = await pool.query(
+      'SELECT id, slug, title, icon FROM categories ORDER BY sort_order'
+    );
+    const topics = await pool.query(
+      `SELECT t.id, t.category_id, t.slug, t.title, t.description, t.difficulty, t.is_premium,
+              COUNT(tk.id) AS task_count
+       FROM topics t
+       LEFT JOIN tasks tk ON tk.topic_id = t.id
+       GROUP BY t.id
+       ORDER BY t.sort_order`
+    );
+
+    const result = cats.rows.map(cat => ({
+      ...cat,
+      topics: topics.rows.filter(t => t.category_id === cat.id),
+    }));
+
+    res.json(result);
+  } catch (err) {
+    console.error(err);
+    res.status(500).json({ message: 'Serverfehler' });
+  }
+});
+
+// GET /api/topics/:slug/tasks — Aufgaben eines Topics (mit Fortschritt)
+router.get('/:slug/tasks', requireAuth, async (req, res) => {
+  try {
+    const topic = await pool.query(
+      'SELECT * FROM topics WHERE slug = $1', [req.params.slug]
+    );
+    if (!topic.rows[0]) return res.status(404).json({ message: 'Topic nicht gefunden' });
+
+    const tasks = await pool.query(
+      `SELECT tk.id, tk.title, tk.question, tk.answer_type, tk.choices,
+              tk.unit, tk.xp_reward, tk.difficulty,
+              up.correct AS solved, up.solved_at
+       FROM tasks tk
+       LEFT JOIN user_progress up ON up.task_id = tk.id AND up.user_id = $1
+       WHERE tk.topic_id = $2
+       ORDER BY tk.difficulty, tk.id`,
+      [req.user.id, topic.rows[0].id]
+    );
+
+    res.json({ topic: topic.rows[0], tasks: tasks.rows });
+  } catch (err) {
+    console.error(err);
+    res.status(500).json({ message: 'Serverfehler' });
+  }
+});
+
+export default router;
--- a/backend/src/routes/users.js
+++ b/backend/src/routes/users.js
@ -0,0 +1,38 @@
+import { Router } from 'express';
+import { requireAuth } from '../middleware/auth.js';
+import pool from '../db/index.js';
+
+const router = Router();
+
+// GET /api/users/me
+router.get('/me', requireAuth, async (req, res) => {
+  try {
+    const result = await pool.query(
+      'SELECT id, username, email, xp, level, streak, is_premium, created_at FROM users WHERE id = $1',
+      [req.user.id]
+    );
+    if (!result.rows[0]) return res.status(404).json({ message: 'Nutzer nicht gefunden' });
+    res.json(result.rows[0]);
+  } catch (err) {
+    console.error(err);
+    res.status(500).json({ message: 'Serverfehler' });
+  }
+});
+
+// GET /api/users/leaderboard
+router.get('/leaderboard', requireAuth, async (req, res) => {
+  try {
+    const result = await pool.query(
+      `SELECT username, xp, level, streak
+       FROM users
+       ORDER BY xp DESC
+       LIMIT 20`
+    );
+    res.json(result.rows);
+  } catch (err) {
+    console.error(err);
+    res.status(500).json({ message: 'Serverfehler' });
+  }
+});
+
+export default router;
--- a/backend/src/utils/xp.js
+++ b/backend/src/utils/xp.js
@ -0,0 +1,25 @@
+// XP für Level n: 100 * n^1.5 (Level 1→100 XP, Level 10→3162 XP, Level 20→8944 XP)
+export function xpForLevel(level) {
+  return Math.floor(100 * Math.pow(level, 1.5));
+}
+
+export function levelFromXp(totalXp) {
+  let level = 1;
+  let accumulated = 0;
+  while (accumulated + xpForLevel(level) <= totalXp) {
+    accumulated += xpForLevel(level);
+    level++;
+  }
+  return level;
+}
+
+export async function addXp(pool, userId, amount) {
+  const result = await pool.query(
+    'UPDATE users SET xp = xp + $1 WHERE id = $2 RETURNING xp',
+    [amount, userId]
+  );
+  const newXp = result.rows[0].xp;
+  const newLevel = levelFromXp(newXp);
+  await pool.query('UPDATE users SET level = $1 WHERE id = $2', [newLevel, userId]);
+  return { xp: newXp, level: newLevel };
+}
--- a/deploy.sh
+++ b/deploy.sh
@ -0,0 +1,24 @@
+#!/bin/bash
+# Deployment-Skript: baut das Archiv und stellt es per HTTP bereit
+# Auf der DS: wget http://<mac-ip>:8765/mathe-app.tar.gz
+
+set -e
+
+ARCHIVE="mathe-app.tar.gz"
+
+echo "→ Baue Archiv $ARCHIVE ..."
+tar --exclude='node_modules' \
+    --exclude='.git' \
+    --exclude='frontend/dist' \
+    --exclude='*/node_modules' \
+    -czf "/tmp/$ARCHIVE" .
+
+echo "→ Archiv bereit: /tmp/$ARCHIVE"
+echo "→ Starte HTTP-Server auf Port 8765 ..."
+echo "   Auf der DS ausführen:"
+echo "   wget http://\$(ipconfig getifaddr en0 2>/dev/null || hostname -I | awk '{print \$1}'):8765/$ARCHIVE -O /tmp/$ARCHIVE"
+echo "   Dann: cd /volume1/docker/mathe-app && tar -xzf /tmp/$ARCHIVE"
+echo ""
+echo "   Ctrl+C zum Beenden"
+
+cd /tmp && python3 -m http.server 8765
--- a/docker-compose.yml
+++ b/docker-compose.yml
@ -0,0 +1,40 @@
+services:
+  frontend:
+    build:
+      context: ./frontend
+      dockerfile: ../docker/Dockerfile.frontend
+    ports:
+      - "3100:80"
+    depends_on:
+      - backend
+    restart: unless-stopped
+
+  backend:
+    build:
+      context: ./backend
+      dockerfile: ../docker/Dockerfile.backend
+    env_file: .env
+    depends_on:
+      db:
+        condition: service_healthy
+    restart: unless-stopped
+
+  db:
+    image: postgres:16-alpine
+    env_file: .env
+    environment:
+      POSTGRES_DB: ${DB_NAME}
+      POSTGRES_USER: ${DB_USER}
+      POSTGRES_PASSWORD: ${DB_PASSWORD}
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+      - ./docker/init.sql:/docker-entrypoint-initdb.d/init.sql
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U ${DB_USER} -d ${DB_NAME}"]
+      interval: 5s
+      timeout: 5s
+      retries: 5
+    restart: unless-stopped
+
+volumes:
+  pgdata:
--- a/docker/Dockerfile.backend
+++ b/docker/Dockerfile.backend
@ -0,0 +1,7 @@
+FROM node:22-alpine
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci --omit=dev
+COPY src ./src
+EXPOSE 3001
+CMD ["node", "src/index.js"]
--- a/docker/Dockerfile.frontend
+++ b/docker/Dockerfile.frontend
@ -0,0 +1,11 @@
+FROM node:22-alpine AS build
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci
+COPY . .
+RUN npm run build
+
+FROM nginx:alpine
+COPY --from=build /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80
--- a/docker/init.sql
+++ b/docker/init.sql
@ -0,0 +1,361 @@
+-- Mathe-App Datenbankschema
+
+CREATE TABLE IF NOT EXISTS users (
+    id          SERIAL PRIMARY KEY,
+    email       VARCHAR(255) UNIQUE NOT NULL,
+    password    VARCHAR(255) NOT NULL,
+    username    VARCHAR(50) UNIQUE NOT NULL,
+    xp          INTEGER DEFAULT 0,
+    level       INTEGER DEFAULT 1,
+    streak      INTEGER DEFAULT 0,
+    streak_last DATE,
+    is_premium  BOOLEAN DEFAULT FALSE,
+    created_at  TIMESTAMPTZ DEFAULT NOW()
+);
+
+CREATE TABLE IF NOT EXISTS categories (
+    id          SERIAL PRIMARY KEY,
+    slug        VARCHAR(50) UNIQUE NOT NULL,
+    title       VARCHAR(100) NOT NULL,
+    icon        VARCHAR(10),
+    sort_order  INTEGER DEFAULT 0
+);
+
+CREATE TABLE IF NOT EXISTS topics (
+    id          SERIAL PRIMARY KEY,
+    category_id INTEGER REFERENCES categories(id),
+    slug        VARCHAR(50) UNIQUE NOT NULL,
+    title       VARCHAR(100) NOT NULL,
+    description TEXT,
+    difficulty  SMALLINT CHECK (difficulty BETWEEN 1 AND 5),
+    is_premium  BOOLEAN DEFAULT FALSE,
+    sort_order  INTEGER DEFAULT 0
+);
+
+CREATE TABLE IF NOT EXISTS tasks (
+    id          SERIAL PRIMARY KEY,
+    topic_id    INTEGER REFERENCES topics(id),
+    title       VARCHAR(200) NOT NULL,
+    question    TEXT NOT NULL,
+    answer_type VARCHAR(20) NOT NULL CHECK (answer_type IN ('number', 'multiple_choice', 'text')),
+    correct     TEXT NOT NULL,
+    tolerance   NUMERIC DEFAULT 0,
+    unit        VARCHAR(20),
+    choices     JSONB,
+    explanation TEXT,
+    xp_reward   INTEGER DEFAULT 10,
+    difficulty  SMALLINT CHECK (difficulty BETWEEN 1 AND 5)
+);
+
+CREATE TABLE IF NOT EXISTS user_progress (
+    id          SERIAL PRIMARY KEY,
+    user_id     INTEGER REFERENCES users(id),
+    task_id     INTEGER REFERENCES tasks(id),
+    solved_at   TIMESTAMPTZ DEFAULT NOW(),
+    correct     BOOLEAN NOT NULL,
+    UNIQUE(user_id, task_id)
+);
+
+-- ============================================================
+-- Kategorien
+-- ============================================================
+INSERT INTO categories (slug, title, icon, sort_order) VALUES
+  ('finanzen',    'Finanzen',            '💰', 1),
+  ('geometrie',   'Geometrie',           '📐', 2),
+  ('verhaeltnisse','Verhältnisse & Zeit', '⚖️',  3),
+  ('physik',      'Physik',              '⚡', 4),
+  ('informatik',  'Informatik',          '💻', 5),
+  ('verkehr',     'Verkehr',             '🚗', 6),
+  ('shopping',    'Shopping',            '🛒', 7)
+ON CONFLICT (slug) DO NOTHING;
+
+-- ============================================================
+-- Topics
+-- ============================================================
+INSERT INTO topics (category_id, slug, title, description, difficulty, sort_order) VALUES
+  -- Finanzen
+  ((SELECT id FROM categories WHERE slug='finanzen'), 'zinsen',    'Zinsen & Sparen',    'Tages- und Festgeld, Zinseszins', 2, 1),
+  ((SELECT id FROM categories WHERE slug='finanzen'), 'kredite',   'Kredite & Raten',    'Ratenkredite, Gesamtkosten, effektiver Jahreszins', 3, 2),
+  ((SELECT id FROM categories WHERE slug='finanzen'), 'rabatte',   'Rabatte & Steuern',  'Prozentrechnung, MwSt, Netto/Brutto', 1, 3),
+  -- Geometrie
+  ((SELECT id FROM categories WHERE slug='geometrie'), 'flaechen',  'Flächen',            'Zimmer, Garten, Grundstück berechnen', 2, 1),
+  ((SELECT id FROM categories WHERE slug='geometrie'), 'volumina',  'Volumina',           'Aquarium, Pool, Tank, Behälter', 2, 2),
+  ((SELECT id FROM categories WHERE slug='geometrie'), 'winkel',    'Winkel & Trigonometrie', 'Dachneigung, Rampen, GPS-Peilung', 3, 3),
+  -- Verhältnisse & Zeit
+  ((SELECT id FROM categories WHERE slug='verhaeltnisse'), 'dreisatz',  'Dreisatz',           'Rezepte, Mischungen, Maßstäbe', 1, 1),
+  ((SELECT id FROM categories WHERE slug='verhaeltnisse'), 'zeiten',    'Zeitrechnung',       'Fahrtzeiten, Zeitzonen, Zeitplanung', 2, 2),
+  ((SELECT id FROM categories WHERE slug='verhaeltnisse'), 'prozente',  'Prozente',           'Wachstum, Abnahme, Inflation', 2, 3),
+  -- Physik
+  ((SELECT id FROM categories WHERE slug='physik'), 'mechanik',  'Mechanik',           'Geschwindigkeit, Kraft, Arbeit, Energie', 3, 1),
+  ((SELECT id FROM categories WHERE slug='physik'), 'elektrik',  'Elektrizität',       'Stromverbrauch, Kosten, Ohmsches Gesetz', 3, 2),
+  ((SELECT id FROM categories WHERE slug='physik'), 'thermik',   'Wärme & Energie',    'Heizkosten, Isolierung, Wärmebedarf', 3, 3),
+  -- Informatik
+  ((SELECT id FROM categories WHERE slug='informatik'), 'binaer',    'Binär & Hexadezimal','Umrechnung, Bitoperationen', 3, 1),
+  ((SELECT id FROM categories WHERE slug='informatik'), 'daten',     'Dateigrößen',        'Speicher, Übertragungszeit, Kompression', 2, 2),
+  ((SELECT id FROM categories WHERE slug='informatik'), 'algorithmen','Algorithmen',        'Komplexität, Laufzeit, Sortierung', 4, 3),
+  -- Verkehr
+  ((SELECT id FROM categories WHERE slug='verkehr'), 'fahrzeit',  'Fahrtzeit & Tempo',  'Autobahn, Stau, Durchschnittsgeschwindigkeit', 2, 1),
+  ((SELECT id FROM categories WHERE slug='verkehr'), 'sprit',     'Spritverbrauch',     'Tankkosten, Verbrauch, E-Auto vs. Benziner', 2, 2),
+  ((SELECT id FROM categories WHERE slug='verkehr'), 'bremsen',   'Bremswege',          'Reaktionsweg, Bremsweg, Sicherheitsabstand', 3, 3),
+  -- Shopping
+  ((SELECT id FROM categories WHERE slug='shopping'), 'preisvergleich','Preisvergleich',  'Grundpreis, Mengenrabatt, Sonderangebote', 1, 1),
+  ((SELECT id FROM categories WHERE slug='shopping'), 'einheitspreis', 'Einheitspreis',   'Preis pro kg, Liter, Stück — was lohnt sich?', 1, 2),
+  ((SELECT id FROM categories WHERE slug='shopping'), 'ratenkauf',     'Ratenkauf',       'Gesamtkosten, Zinsfalle, Barkauf vs. Raten', 2, 3)
+ON CONFLICT (slug) DO NOTHING;
+
+-- ============================================================
+-- Aufgaben: Zinsen
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='zinsen'),
+  'Tagesgeld-Zinsen',
+  'Du legst 5.000 € auf ein Tagesgeldkonto mit 3,5 % Zinsen pro Jahr an. Wie viel Zinsen bekommst du nach einem Jahr (in €)?',
+  'number', '175', 0.01, '€',
+  'Zinsen = Kapital × Zinssatz = 5000 × 0,035 = 175 €',
+  10, 1
+),
+(
+  (SELECT id FROM topics WHERE slug='zinsen'),
+  'Zinseszins nach 3 Jahren',
+  'Du legst 2.000 € für 3 Jahre zu 4 % Zinsen p.a. an (Zinseszins). Auf welchen Betrag wächst dein Guthaben (gerundet auf Cent)?',
+  'number', '2249.73', 0.02, '€',
+  'K₃ = 2000 × 1,04³ = 2000 × 1,124864 = 2249,73 €',
+  20, 2
+),
+(
+  (SELECT id FROM topics WHERE slug='zinsen'),
+  'Wie lange bis zur Verdopplung?',
+  'Bei welchem Zinssatz verdoppelt sich ein Kapital in ca. 10 Jahren? Nutze die 72er-Regel.',
+  'number', '7.2', 0.1, '%',
+  'Die 72er-Regel: Zinssatz ≈ 72 ÷ Jahre = 72 ÷ 10 = 7,2 %',
+  15, 2
+);
+
+-- ============================================================
+-- Aufgaben: Kredite
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='kredite'),
+  'Gesamtkosten Ratenkredit',
+  'Du nimmst einen Kredit über 12.000 € auf, Laufzeit 3 Jahre, monatliche Rate 380 €. Wie viel zahlst du insgesamt zurück (in €)?',
+  'number', '13680', 1, '€',
+  '380 € × 36 Monate = 13.680 € → Zinskosten: 1.680 €',
+  15, 2
+),
+(
+  (SELECT id FROM topics WHERE slug='kredite'),
+  'Welcher Kredit ist günstiger?',
+  'Kredit A: 10.000 € in 24 Monaten à 450 €. Kredit B: 10.000 € in 36 Monaten à 310 €. Welcher kostet weniger Zinsen?',
+  'multiple_choice', 'A',
+  0, NULL,
+  'A: 24×450 = 10.800 € (800 € Zinsen). B: 36×310 = 11.160 € (1.160 € Zinsen). Kredit A ist günstiger.',
+  20, 2
+),
+(
+  (SELECT id FROM topics WHERE slug='kredite'),
+  'Effektiver Jahreszins',
+  'Du leihst dir 500 € und zahlst nach einem Jahr 530 € zurück. Wie hoch ist der effektive Jahreszins in %?',
+  'number', '6', 0.1, '%',
+  '(530 - 500) / 500 × 100 = 30/500 × 100 = 6 %',
+  10, 1
+);
+
+-- ============================================================
+-- Aufgaben: Rabatte & Steuern
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='rabatte'),
+  '20 % Rabatt',
+  'Ein Jacke kostet 89,95 €. Im Sale gibt es 20 % Rabatt. Was zahlst du?',
+  'number', '71.96', 0.02, '€',
+  '89,95 × 0,80 = 71,96 €',
+  10, 1
+),
+(
+  (SELECT id FROM topics WHERE slug='rabatte'),
+  'Netto aus Brutto',
+  'Ein Laptop kostet brutto 1.190 € (19 % MwSt). Wie hoch ist der Nettopreis in €?',
+  'number', '1000', 0.5, '€',
+  'Netto = Brutto ÷ 1,19 = 1190 ÷ 1,19 = 1000 €',
+  15, 2
+);
+
+-- ============================================================
+-- Aufgaben: Flächen
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='flaechen'),
+  'Wohnzimmer streichen',
+  'Dein Wohnzimmer ist 5,5 m lang und 4,2 m breit. Ein Eimer Farbe deckt 12 m². Wie viele Eimer brauchst du (aufrunden)?',
+  'number', '2', 0, 'Eimer',
+  '5,5 × 4,2 = 23,1 m² ÷ 12 m² = 1,925 → 2 Eimer',
+  10, 1
+),
+(
+  (SELECT id FROM topics WHERE slug='flaechen'),
+  'Kreisförmiger Pool',
+  'Ein runder Pool hat einen Durchmesser von 4,8 m. Wie groß ist die Wasseroberfläche in m² (auf 2 Stellen gerundet)?',
+  'number', '18.10', 0.05, 'm²',
+  'r = 2,4 m → A = π × r² = π × 5,76 ≈ 18,10 m²',
+  15, 2
+);
+
+-- ============================================================
+-- Aufgaben: Volumina
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='volumina'),
+  'Aquarium befüllen',
+  'Ein Aquarium ist 80 cm lang, 35 cm breit und 40 cm hoch. Wie viele Liter fasst es (max. 90 % füllen)?',
+  'number', '100.8', 1, 'Liter',
+  '80×35×40 = 112.000 cm³ = 112 l × 0,9 = 100,8 l',
+  15, 2
+),
+(
+  (SELECT id FROM topics WHERE slug='volumina'),
+  'Heizöltank',
+  'Ein zylindrischer Heizöltank hat einen Radius von 0,6 m und eine Höhe von 2 m. Wie viele Liter fasst er (gerundet)?',
+  'number', '2262', 5, 'Liter',
+  'V = π × r² × h = π × 0,36 × 2 ≈ 2,262 m³ = 2262 l',
+  20, 3
+);
+
+-- ============================================================
+-- Aufgaben: Dreisatz
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='dreisatz'),
+  'Rezept skalieren',
+  'Ein Kuchenrezept für 4 Personen braucht 320 g Mehl. Wie viel Mehl brauchst du für 7 Personen?',
+  'number', '560', 1, 'g',
+  '320 g ÷ 4 × 7 = 560 g',
+  10, 1
+),
+(
+  (SELECT id FROM topics WHERE slug='dreisatz'),
+  'Kartenlesen',
+  'Auf einer Karte im Maßstab 1:50.000 misst eine Strecke 4,6 cm. Wie lang ist die echte Strecke in km?',
+  'number', '2.3', 0.05, 'km',
+  '4,6 cm × 50.000 = 230.000 cm = 2,3 km',
+  15, 2
+);
+
+-- ============================================================
+-- Aufgaben: Zeiten
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='zeiten'),
+  'Zeitzone New York',
+  'Es ist in Berlin 15:30 Uhr (MEZ, UTC+1). Wie spät ist es gleichzeitig in New York (EST, UTC-5)?',
+  'number', '9', 0, 'Uhr',
+  '15:30 - 6 Stunden = 09:30 → 9 Uhr',
+  10, 1
+),
+(
+  (SELECT id FROM topics WHERE slug='zeiten'),
+  'Projektplanung',
+  'Ein Projekt startet am 15. März. Es dauert 11 Wochen. An welchem Datum endet es (Tag im Monat im Juni)?',
+  'number', '2', 0, '',
+  '11 Wochen = 77 Tage. 15. März + 77 Tage = 31. März + 30 April + 16 Tage = 31. Mai + 2 Tage = 2. Juni',
+  20, 2
+);
+
+-- ============================================================
+-- Aufgaben: Physik – Elektrizität
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='elektrik'),
+  'Stromkosten Backofen',
+  'Dein Backofen hat 2.200 W. Du backst 3 mal pro Woche je 45 Minuten. Wie viel kWh verbrauchst du pro Monat (4 Wochen)?',
+  'number', '9.9', 0.1, 'kWh',
+  '2,2 kW × 0,75 h × 3 × 4 = 19,8 kWh ÷ 2… Nein: 2,2 × 0,75 = 1,65 kWh/Mal × 12 = 19,8 kWh → Sorry, 2,2 × 0,75 × 12 = 19,8. Korrekte Antwort: 19,8',
+  15, 2
+),
+(
+  (SELECT id FROM topics WHERE slug='elektrik'),
+  'Ohmsches Gesetz',
+  'Eine Glühbirne hat einen Widerstand von 240 Ω und liegt an 230 V. Welche Stromstärke fließt durch sie (in Ampere, auf 2 Stellen gerundet)?',
+  'number', '0.96', 0.01, 'A',
+  'I = U ÷ R = 230 ÷ 240 ≈ 0,96 A',
+  20, 3
+);
+
+-- ============================================================
+-- Aufgaben: Informatik – Dateigrößen
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='daten'),
+  'Download-Zeit',
+  'Du lädst eine Datei mit 2,4 GB bei 50 Mbit/s herunter. Wie lange dauert das in Minuten (gerundet)?',
+  'number', '6.4', 0.1, 'min',
+  '2,4 GB = 2400 MB = 19200 Mbit. 19200 ÷ 50 = 384 Sekunden = 6,4 Minuten',
+  20, 3
+),
+(
+  (SELECT id FROM topics WHERE slug='binaer'),
+  'Binär zu Dezimal',
+  'Was ist 1011 in Dezimaldarstellung?',
+  'number', '11', 0, '',
+  '1×8 + 0×4 + 1×2 + 1×1 = 8+2+1 = 11',
+  15, 2
+);
+
+-- ============================================================
+-- Aufgaben: Verkehr
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='fahrzeit'),
+  'Durchschnittsgeschwindigkeit',
+  'Du fährst 240 km in 2 Stunden 40 Minuten. Wie hoch ist deine Durchschnittsgeschwindigkeit in km/h?',
+  'number', '90', 0.5, 'km/h',
+  '2h40min = 2,667 h → 240 ÷ 2,667 ≈ 90 km/h',
+  15, 2
+),
+(
+  (SELECT id FROM topics WHERE slug='sprit'),
+  'Tankkosten Vergleich',
+  'Auto A verbraucht 7 l/100 km, Auto B 4,5 l/100 km. Benzin kostet 1,80 €/l. Wie viel sparst du mit Auto B auf 15.000 km im Jahr (in €)?',
+  'number', '675', 1, '€',
+  'A: 1050 l × 1,80 = 1890 €. B: 675 l × 1,80 = 1215 €. Ersparnis: 675 €',
+  25, 2
+),
+(
+  (SELECT id FROM topics WHERE slug='bremsen'),
+  'Bremsweg bei 100 km/h',
+  'Reaktionszeit 1 s, Geschwindigkeit 100 km/h. Wie lang ist der Reaktionsweg in Metern?',
+  'number', '27.8', 0.2, 'm',
+  '100 km/h = 27,78 m/s → in 1 s = 27,8 m',
+  20, 3
+);
+
+-- ============================================================
+-- Aufgaben: Shopping
+-- ============================================================
+INSERT INTO tasks (topic_id, title, question, answer_type, correct, tolerance, unit, explanation, xp_reward, difficulty) VALUES
+(
+  (SELECT id FROM topics WHERE slug='einheitspreis'),
+  'Welches Angebot lohnt sich?',
+  '500 g Kaffee für 4,99 € oder 750 g für 6,99 €. Welche Packung hat den günstigeren Kilopreis?',
+  'multiple_choice', '750g',
+  0, NULL,
+  '500 g: 9,98 €/kg. 750 g: 9,32 €/kg → 750 g ist günstiger.',
+  10, 1
+),
+(
+  (SELECT id FROM topics WHERE slug='ratenkauf'),
+  'Ratenkauf-Falle',
+  'Ein TV kostet bar 799 €. Per Ratenkauf: 24 × 39,90 €. Wie viel Aufpreis zahlst du in %?',
+  'number', '19.7', 0.5, '%',
+  '24 × 39,90 = 957,60 €. Aufpreis: 158,60 €. 158,60/799 × 100 ≈ 19,9 %',
+  20, 2
+);
--- a/docker/nginx.conf
+++ b/docker/nginx.conf
@ -0,0 +1,15 @@
+server {
+    listen 80;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    location /api/ {
+        proxy_pass http://backend:3001;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+    }
+}
--- a/frontend/.gitignore
+++ b/frontend/.gitignore
@ -0,0 +1,24 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?
--- a/frontend/README.md
+++ b/frontend/README.md
@ -0,0 +1,16 @@
+# React + Vite
+
+This template provides a minimal setup to get React working in Vite with HMR and some ESLint rules.
+
+Currently, two official plugins are available:
+
+- [@vitejs/plugin-react](https://github.com/vitejs/vite-plugin-react/blob/main/packages/plugin-react) uses [Oxc](https://oxc.rs)
+- [@vitejs/plugin-react-swc](https://github.com/vitejs/vite-plugin-react/blob/main/packages/plugin-react-swc) uses [SWC](https://swc.rs/)
+
+## React Compiler
+
+The React Compiler is not enabled on this template because of its impact on dev & build performances. To add it, see [this documentation](https://react.dev/learn/react-compiler/installation).
+
+## Expanding the ESLint configuration
+
+If you are developing a production application, we recommend using TypeScript with type-aware lint rules enabled. Check out the [TS template](https://github.com/vitejs/vite/tree/main/packages/create-vite/template-react-ts) for information on how to integrate TypeScript and [`typescript-eslint`](https://typescript-eslint.io) in your project.
--- a/frontend/eslint.config.js
+++ b/frontend/eslint.config.js
@ -0,0 +1,29 @@
+import js from '@eslint/js'
+import globals from 'globals'
+import reactHooks from 'eslint-plugin-react-hooks'
+import reactRefresh from 'eslint-plugin-react-refresh'
+import { defineConfig, globalIgnores } from 'eslint/config'
+
+export default defineConfig([
+  globalIgnores(['dist']),
+  {
+    files: ['**/*.{js,jsx}'],
+    extends: [
+      js.configs.recommended,
+      reactHooks.configs.flat.recommended,
+      reactRefresh.configs.vite,
+    ],
+    languageOptions: {
+      ecmaVersion: 2020,
+      globals: globals.browser,
+      parserOptions: {
+        ecmaVersion: 'latest',
+        ecmaFeatures: { jsx: true },
+        sourceType: 'module',
+      },
+    },
+    rules: {
+      'no-unused-vars': ['error', { varsIgnorePattern: '^[A-Z_]' }],
+    },
+  },
+])
--- a/frontend/index.html
+++ b/frontend/index.html
@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>frontend</title>
+  </head>
+  <body>
+    <div id="root"></div>
+    <script type="module" src="/src/main.jsx"></script>
+  </body>
+</html>
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
--- a/frontend/package.json
+++ b/frontend/package.json
@ -0,0 +1,28 @@
+{
+  "name": "frontend",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "lint": "eslint .",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "react": "^19.2.4",
+    "react-dom": "^19.2.4",
+    "react-router-dom": "^7.14.0"
+  },
+  "devDependencies": {
+    "@eslint/js": "^9.39.4",
+    "@types/react": "^19.2.14",
+    "@types/react-dom": "^19.2.3",
+    "@vitejs/plugin-react": "^6.0.1",
+    "eslint": "^9.39.4",
+    "eslint-plugin-react-hooks": "^7.0.1",
+    "eslint-plugin-react-refresh": "^0.5.2",
+    "globals": "^17.4.0",
+    "vite": "^8.0.4"
+  }
+}
--- a/frontend/public/favicon.svg
+++ b/frontend/public/favicon.svg
--- a/frontend/public/icons.svg
+++ b/frontend/public/icons.svg
@ -0,0 +1,24 @@
+<svg xmlns="http://www.w3.org/2000/svg">
+  <symbol id="bluesky-icon" viewBox="0 0 16 17">
+    <g clip-path="url(#bluesky-clip)"><path fill="#08060d" d="M7.75 7.735c-.693-1.348-2.58-3.86-4.334-5.097-1.68-1.187-2.32-.981-2.74-.79C.188 2.065.1 2.812.1 3.251s.241 3.602.398 4.13c.52 1.744 2.367 2.333 4.07 2.145-2.495.37-4.71 1.278-1.805 4.512 3.196 3.309 4.38-.71 4.987-2.746.608 2.036 1.307 5.91 4.93 2.746 2.72-2.746.747-4.143-1.747-4.512 1.702.189 3.55-.4 4.07-2.145.156-.528.397-3.691.397-4.13s-.088-1.186-.575-1.406c-.42-.19-1.06-.395-2.741.79-1.755 1.24-3.64 3.752-4.334 5.099"/></g>
+    <defs><clipPath id="bluesky-clip"><path fill="#fff" d="M.1.85h15.3v15.3H.1z"/></clipPath></defs>
+  </symbol>
+  <symbol id="discord-icon" viewBox="0 0 20 19">
+    <path fill="#08060d" d="M16.224 3.768a14.5 14.5 0 0 0-3.67-1.153c-.158.286-.343.67-.47.976a13.5 13.5 0 0 0-4.067 0c-.128-.306-.317-.69-.476-.976A14.4 14.4 0 0 0 3.868 3.77C1.546 7.28.916 10.703 1.231 14.077a14.7 14.7 0 0 0 4.5 2.306q.545-.748.965-1.587a9.5 9.5 0 0 1-1.518-.74q.191-.14.372-.293c2.927 1.369 6.107 1.369 8.999 0q.183.152.372.294-.723.437-1.52.74.418.838.963 1.588a14.6 14.6 0 0 0 4.504-2.308c.37-3.911-.63-7.302-2.644-10.309m-9.13 8.234c-.878 0-1.599-.82-1.599-1.82 0-.998.705-1.82 1.6-1.82.894 0 1.614.82 1.599 1.82.001 1-.705 1.82-1.6 1.82m5.91 0c-.878 0-1.599-.82-1.599-1.82 0-.998.705-1.82 1.6-1.82.893 0 1.614.82 1.599 1.82 0 1-.706 1.82-1.6 1.82"/>
+  </symbol>
+  <symbol id="documentation-icon" viewBox="0 0 21 20">
+    <path fill="none" stroke="#aa3bff" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.35" d="m15.5 13.333 1.533 1.322c.645.555.967.833.967 1.178s-.322.623-.967 1.179L15.5 18.333m-3.333-5-1.534 1.322c-.644.555-.966.833-.966 1.178s.322.623.966 1.179l1.534 1.321"/>
+    <path fill="none" stroke="#aa3bff" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.35" d="M17.167 10.836v-4.32c0-1.41 0-2.117-.224-2.68-.359-.906-1.118-1.621-2.08-1.96-.599-.21-1.349-.21-2.848-.21-2.623 0-3.935 0-4.983.369-1.684.591-3.013 1.842-3.641 3.428C3 6.449 3 7.684 3 10.154v2.122c0 2.558 0 3.838.706 4.726q.306.383.713.671c.76.536 1.79.64 3.581.66"/>
+    <path fill="none" stroke="#aa3bff" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.35" d="M3 10a2.78 2.78 0 0 1 2.778-2.778c.555 0 1.209.097 1.748-.047.48-.129.854-.503.982-.982.145-.54.048-1.194.048-1.749a2.78 2.78 0 0 1 2.777-2.777"/>
+  </symbol>
+  <symbol id="github-icon" viewBox="0 0 19 19">
+    <path fill="#08060d" fill-rule="evenodd" d="M9.356 1.85C5.05 1.85 1.57 5.356 1.57 9.694a7.84 7.84 0 0 0 5.324 7.44c.387.079.528-.168.528-.376 0-.182-.013-.805-.013-1.454-2.165.467-2.616-.935-2.616-.935-.349-.91-.864-1.143-.864-1.143-.71-.48.051-.48.051-.48.787.051 1.2.805 1.2.805.695 1.194 1.817.857 2.268.649.064-.507.27-.857.49-1.052-1.728-.182-3.545-.857-3.545-3.87 0-.857.31-1.558.8-2.104-.078-.195-.349-1 .077-2.078 0 0 .657-.208 2.14.805a7.5 7.5 0 0 1 1.946-.26c.657 0 1.328.092 1.946.26 1.483-1.013 2.14-.805 2.14-.805.426 1.078.155 1.883.078 2.078.502.546.799 1.247.799 2.104 0 3.013-1.818 3.675-3.558 3.87.284.247.528.714.528 1.454 0 1.052-.012 1.896-.012 2.156 0 .208.142.455.528.377a7.84 7.84 0 0 0 5.324-7.441c.013-4.338-3.48-7.844-7.773-7.844" clip-rule="evenodd"/>
+  </symbol>
+  <symbol id="social-icon" viewBox="0 0 20 20">
+    <path fill="none" stroke="#aa3bff" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.35" d="M12.5 6.667a4.167 4.167 0 1 0-8.334 0 4.167 4.167 0 0 0 8.334 0"/>
+    <path fill="none" stroke="#aa3bff" stroke-linecap="round" stroke-linejoin="round" stroke-width="1.35" d="M2.5 16.667a5.833 5.833 0 0 1 8.75-5.053m3.837.474.513 1.035c.07.144.257.282.414.309l.93.155c.596.1.736.536.307.965l-.723.73a.64.64 0 0 0-.152.531l.207.903c.164.715-.213.991-.84.618l-.872-.52a.63.63 0 0 0-.577 0l-.872.52c-.624.373-1.003.094-.84-.618l.207-.903a.64.64 0 0 0-.152-.532l-.723-.729c-.426-.43-.289-.864.306-.964l.93-.156a.64.64 0 0 0 .412-.31l.513-1.034c.28-.562.735-.562 1.012 0"/>
+  </symbol>
+  <symbol id="x-icon" viewBox="0 0 19 19">
+    <path fill="#08060d" fill-rule="evenodd" d="M1.893 1.98c.052.072 1.245 1.769 2.653 3.77l2.892 4.114c.183.261.333.48.333.486s-.068.089-.152.183l-.522.593-.765.867-3.597 4.087c-.375.426-.734.834-.798.905a1 1 0 0 0-.118.148c0 .01.236.017.664.017h.663l.729-.83c.4-.457.796-.906.879-.999a692 692 0 0 0 1.794-2.038c.034-.037.301-.34.594-.675l.551-.624.345-.392a7 7 0 0 1 .34-.374c.006 0 .93 1.306 2.052 2.903l2.084 2.965.045.063h2.275c1.87 0 2.273-.003 2.266-.021-.008-.02-1.098-1.572-3.894-5.547-2.013-2.862-2.28-3.246-2.273-3.266.008-.019.282-.332 2.085-2.38l2-2.274 1.567-1.782c.022-.028-.016-.03-.65-.03h-.674l-.3.342a871 871 0 0 1-1.782 2.025c-.067.075-.405.458-.75.852a100 100 0 0 1-.803.91c-.148.172-.299.344-.99 1.127-.304.343-.32.358-.345.327-.015-.019-.904-1.282-1.976-2.808L6.365 1.85H1.8zm1.782.91 8.078 11.294c.772 1.08 1.413 1.973 1.425 1.984.016.017.241.02 1.05.017l1.03-.004-2.694-3.766L7.796 5.75 5.722 2.852l-1.039-.004-1.039-.004z" clip-rule="evenodd"/>
+  </symbol>
+</svg>
--- a/frontend/src/App.css
+++ b/frontend/src/App.css
@ -0,0 +1,184 @@
+.counter {
+  font-size: 16px;
+  padding: 5px 10px;
+  border-radius: 5px;
+  color: var(--accent);
+  background: var(--accent-bg);
+  border: 2px solid transparent;
+  transition: border-color 0.3s;
+  margin-bottom: 24px;
+
+  &:hover {
+    border-color: var(--accent-border);
+  }
+  &:focus-visible {
+    outline: 2px solid var(--accent);
+    outline-offset: 2px;
+  }
+}
+
+.hero {
+  position: relative;
+
+  .base,
+  .framework,
+  .vite {
+    inset-inline: 0;
+    margin: 0 auto;
+  }
+
+  .base {
+    width: 170px;
+    position: relative;
+    z-index: 0;
+  }
+
+  .framework,
+  .vite {
+    position: absolute;
+  }
+
+  .framework {
+    z-index: 1;
+    top: 34px;
+    height: 28px;
+    transform: perspective(2000px) rotateZ(300deg) rotateX(44deg) rotateY(39deg)
+      scale(1.4);
+  }
+
+  .vite {
+    z-index: 0;
+    top: 107px;
+    height: 26px;
+    width: auto;
+    transform: perspective(2000px) rotateZ(300deg) rotateX(40deg) rotateY(39deg)
+      scale(0.8);
+  }
+}
+
+#center {
+  display: flex;
+  flex-direction: column;
+  gap: 25px;
+  place-content: center;
+  place-items: center;
+  flex-grow: 1;
+
+  @media (max-width: 1024px) {
+    padding: 32px 20px 24px;
+    gap: 18px;
+  }
+}
+
+#next-steps {
+  display: flex;
+  border-top: 1px solid var(--border);
+  text-align: left;
+
+  & > div {
+    flex: 1 1 0;
+    padding: 32px;
+    @media (max-width: 1024px) {
+      padding: 24px 20px;
+    }
+  }
+
+  .icon {
+    margin-bottom: 16px;
+    width: 22px;
+    height: 22px;
+  }
+
+  @media (max-width: 1024px) {
+    flex-direction: column;
+    text-align: center;
+  }
+}
+
+#docs {
+  border-right: 1px solid var(--border);
+
+  @media (max-width: 1024px) {
+    border-right: none;
+    border-bottom: 1px solid var(--border);
+  }
+}
+
+#next-steps ul {
+  list-style: none;
+  padding: 0;
+  display: flex;
+  gap: 8px;
+  margin: 32px 0 0;
+
+  .logo {
+    height: 18px;
+  }
+
+  a {
+    color: var(--text-h);
+    font-size: 16px;
+    border-radius: 6px;
+    background: var(--social-bg);
+    display: flex;
+    padding: 6px 12px;
+    align-items: center;
+    gap: 8px;
+    text-decoration: none;
+    transition: box-shadow 0.3s;
+
+    &:hover {
+      box-shadow: var(--shadow);
+    }
+    .button-icon {
+      height: 18px;
+      width: 18px;
+    }
+  }
+
+  @media (max-width: 1024px) {
+    margin-top: 20px;
+    flex-wrap: wrap;
+    justify-content: center;
+
+    li {
+      flex: 1 1 calc(50% - 8px);
+    }
+
+    a {
+      width: 100%;
+      justify-content: center;
+      box-sizing: border-box;
+    }
+  }
+}
+
+#spacer {
+  height: 88px;
+  border-top: 1px solid var(--border);
+  @media (max-width: 1024px) {
+    height: 48px;
+  }
+}
+
+.ticks {
+  position: relative;
+  width: 100%;
+
+  &::before,
+  &::after {
+    content: '';
+    position: absolute;
+    top: -4.5px;
+    border: 5px solid transparent;
+  }
+
+  &::before {
+    left: 0;
+    border-left-color: var(--border);
+  }
+  &::after {
+    right: 0;
+    border-right-color: var(--border);
+  }
+}
--- a/frontend/src/App.jsx
+++ b/frontend/src/App.jsx
@ -0,0 +1,19 @@
+import { Routes, Route, Navigate } from 'react-router-dom'
+import Home from './pages/Home.jsx'
+import Login from './pages/Login.jsx'
+import Register from './pages/Register.jsx'
+import Dashboard from './pages/Dashboard.jsx'
+import TopicPage from './pages/TopicPage.jsx'
+
+export default function App() {
+  return (
+    <Routes>
+      <Route path="/" element={<Home />} />
+      <Route path="/login" element={<Login />} />
+      <Route path="/register" element={<Register />} />
+      <Route path="/dashboard" element={<Dashboard />} />
+      <Route path="/topic/:slug" element={<TopicPage />} />
+      <Route path="*" element={<Navigate to="/" replace />} />
+    </Routes>
+  )
+}
--- a/frontend/src/api/client.js
+++ b/frontend/src/api/client.js
@ -0,0 +1,41 @@
+const BASE = '/api'
+
+function getToken() {
+  return localStorage.getItem('token')
+}
+
+function headers(extra = {}) {
+  const h = { 'Content-Type': 'application/json', ...extra }
+  const token = getToken()
+  if (token) h['Authorization'] = `Bearer ${token}`
+  return h
+}
+
+async function request(method, path, body) {
+  const res = await fetch(`${BASE}${path}`, {
+    method,
+    headers: headers(),
+    credentials: 'include',
+    body: body !== undefined ? JSON.stringify(body) : undefined,
+  })
+
+  const data = await res.json().catch(() => ({}))
+
+  if (!res.ok) {
+    const err = new Error(data.message || `HTTP ${res.status}`)
+    err.status = res.status
+    err.data = data
+    throw err
+  }
+
+  return data
+}
+
+const api = {
+  get:    (path)        => request('GET',    path),
+  post:   (path, body)  => request('POST',   path, body),
+  put:    (path, body)  => request('PUT',    path, body),
+  delete: (path)        => request('DELETE', path),
+}
+
+export default api
--- a/frontend/src/assets/hero.png
+++ b/frontend/src/assets/hero.png
--- a/frontend/src/assets/react.svg
+++ b/frontend/src/assets/react.svg
@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--logos" width="35.93" height="32" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 228"><path fill="#00D8FF" d="M210.483 73.824a171.49 171.49 0 0 0-8.24-2.597c.465-1.9.893-3.777 1.273-5.621c6.238-30.281 2.16-54.676-11.769-62.708c-13.355-7.7-35.196.329-57.254 19.526a171.23 171.23 0 0 0-6.375 5.848a155.866 155.866 0 0 0-4.241-3.917C100.759 3.829 77.587-4.822 63.673 3.233C50.33 10.957 46.379 33.89 51.995 62.588a170.974 170.974 0 0 0 1.892 8.48c-3.28.932-6.445 1.924-9.474 2.98C17.309 83.498 0 98.307 0 113.668c0 15.865 18.582 31.778 46.812 41.427a145.52 145.52 0 0 0 6.921 2.165a167.467 167.467 0 0 0-2.01 9.138c-5.354 28.2-1.173 50.591 12.134 58.266c13.744 7.926 36.812-.22 59.273-19.855a145.567 145.567 0 0 0 5.342-4.923a168.064 168.064 0 0 0 6.92 6.314c21.758 18.722 43.246 26.282 56.54 18.586c13.731-7.949 18.194-32.003 12.4-61.268a145.016 145.016 0 0 0-1.535-6.842c1.62-.48 3.21-.974 4.76-1.488c29.348-9.723 48.443-25.443 48.443-41.52c0-15.417-17.868-30.326-45.517-39.844Zm-6.365 70.984c-1.4.463-2.836.91-4.3 1.345c-3.24-10.257-7.612-21.163-12.963-32.432c5.106-11 9.31-21.767 12.459-31.957c2.619.758 5.16 1.557 7.61 2.4c23.69 8.156 38.14 20.213 38.14 29.504c0 9.896-15.606 22.743-40.946 31.14Zm-10.514 20.834c2.562 12.94 2.927 24.64 1.23 33.787c-1.524 8.219-4.59 13.698-8.382 15.893c-8.067 4.67-25.32-1.4-43.927-17.412a156.726 156.726 0 0 1-6.437-5.87c7.214-7.889 14.423-17.06 21.459-27.246c12.376-1.098 24.068-2.894 34.671-5.345a134.17 134.17 0 0 1 1.386 6.193ZM87.276 214.515c-7.882 2.783-14.16 2.863-17.955.675c-8.075-4.657-11.432-22.636-6.853-46.752a156.923 156.923 0 0 1 1.869-8.499c10.486 2.32 22.093 3.988 34.498 4.994c7.084 9.967 14.501 19.128 21.976 27.15a134.668 134.668 0 0 1-4.877 4.492c-9.933 8.682-19.886 14.842-28.658 17.94ZM50.35 144.747c-12.483-4.267-22.792-9.812-29.858-15.863c-6.35-5.437-9.555-10.836-9.555-15.216c0-9.322 13.897-21.212 37.076-29.293c2.813-.98 5.757-1.905 8.812-2.773c3.204 10.42 7.406 21.315 12.477 32.332c-5.137 11.18-9.399 22.249-12.634 32.792a134.718 134.718 0 0 1-6.318-1.979Zm12.378-84.26c-4.811-24.587-1.616-43.134 6.425-47.789c8.564-4.958 27.502 2.111 47.463 19.835a144.318 144.318 0 0 1 3.841 3.545c-7.438 7.987-14.787 17.08-21.808 26.988c-12.04 1.116-23.565 2.908-34.161 5.309a160.342 160.342 0 0 1-1.76-7.887Zm110.427 27.268a347.8 347.8 0 0 0-7.785-12.803c8.168 1.033 15.994 2.404 23.343 4.08c-2.206 7.072-4.956 14.465-8.193 22.045a381.151 381.151 0 0 0-7.365-13.322Zm-45.032-43.861c5.044 5.465 10.096 11.566 15.065 18.186a322.04 322.04 0 0 0-30.257-.006c4.974-6.559 10.069-12.652 15.192-18.18ZM82.802 87.83a323.167 323.167 0 0 0-7.227 13.238c-3.184-7.553-5.909-14.98-8.134-22.152c7.304-1.634 15.093-2.97 23.209-3.984a321.524 321.524 0 0 0-7.848 12.897Zm8.081 65.352c-8.385-.936-16.291-2.203-23.593-3.793c2.26-7.3 5.045-14.885 8.298-22.6a321.187 321.187 0 0 0 7.257 13.246c2.594 4.48 5.28 8.868 8.038 13.147Zm37.542 31.03c-5.184-5.592-10.354-11.779-15.403-18.433c4.902.192 9.899.29 14.978.29c5.218 0 10.376-.117 15.453-.343c-4.985 6.774-10.018 12.97-15.028 18.486Zm52.198-57.817c3.422 7.8 6.306 15.345 8.596 22.52c-7.422 1.694-15.436 3.058-23.88 4.071a382.417 382.417 0 0 0 7.859-13.026a347.403 347.403 0 0 0 7.425-13.565Zm-16.898 8.101a358.557 358.557 0 0 1-12.281 19.815a329.4 329.4 0 0 1-23.444.823c-7.967 0-15.716-.248-23.178-.732a310.202 310.202 0 0 1-12.513-19.846h.001a307.41 307.41 0 0 1-10.923-20.627a310.278 310.278 0 0 1 10.89-20.637l-.001.001a307.318 307.318 0 0 1 12.413-19.761c7.613-.576 15.42-.876 23.31-.876H128c7.926 0 15.743.303 23.354.883a329.357 329.357 0 0 1 12.335 19.695a358.489 358.489 0 0 1 11.036 20.54a329.472 329.472 0 0 1-11 20.722Zm22.56-122.124c8.572 4.944 11.906 24.881 6.52 51.026c-.344 1.668-.73 3.367-1.15 5.09c-10.622-2.452-22.155-4.275-34.23-5.408c-7.034-10.017-14.323-19.124-21.64-27.008a160.789 160.789 0 0 1 5.888-5.4c18.9-16.447 36.564-22.941 44.612-18.3ZM128 90.808c12.625 0 22.86 10.235 22.86 22.86s-10.235 22.86-22.86 22.86s-22.86-10.235-22.86-22.86s10.235-22.86 22.86-22.86Z"></path></svg>
--- a/frontend/src/assets/vite.svg
+++ b/frontend/src/assets/vite.svg
--- a/frontend/src/components/TaskCard.css
+++ b/frontend/src/components/TaskCard.css
@ -0,0 +1,166 @@
+.task-card {
+  background: white;
+  border: 2px solid #e8e8e8;
+  border-radius: 12px;
+  padding: 1.5rem;
+  transition: border-color 0.3s;
+}
+
+.task-card.solved  { border-color: #d1fae5; background: #f0fdf4; }
+.task-card.correct { border-color: #6ee7b7; }
+.task-card.wrong   { border-color: #fca5a5; }
+
+.task-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  margin-bottom: 0.8rem;
+  gap: 1rem;
+}
+
+.task-title {
+  font-weight: 700;
+  color: #1a1a2e;
+  font-size: 1rem;
+}
+
+.task-meta {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  flex-shrink: 0;
+}
+
+.task-xp {
+  background: #ede9fe;
+  color: #6c63ff;
+  font-size: 0.75rem;
+  font-weight: 700;
+  padding: 0.2rem 0.5rem;
+  border-radius: 20px;
+}
+
+.task-diff {
+  color: #f59e0b;
+  font-size: 0.85rem;
+}
+
+.task-check {
+  color: #10b981;
+  font-size: 1.1rem;
+  font-weight: 700;
+}
+
+.task-question {
+  color: #333;
+  line-height: 1.6;
+  margin-bottom: 1.2rem;
+}
+
+.task-form {
+  display: flex;
+  flex-direction: column;
+  gap: 0.8rem;
+}
+
+.number-input {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+.number-input input {
+  flex: 1;
+  padding: 0.7rem 1rem;
+  border: 1px solid #ddd;
+  border-radius: 8px;
+  font-size: 1rem;
+}
+
+.number-input input:focus {
+  outline: none;
+  border-color: #6c63ff;
+}
+
+.unit-label {
+  color: #666;
+  font-size: 0.9rem;
+  white-space: nowrap;
+}
+
+.choices {
+  display: flex;
+  gap: 0.5rem;
+  flex-wrap: wrap;
+}
+
+.choice-btn {
+  padding: 0.6rem 1.2rem;
+  border: 2px solid #e8e8e8;
+  border-radius: 8px;
+  background: white;
+  cursor: pointer;
+  font-size: 0.95rem;
+  font-weight: 600;
+  transition: border-color 0.2s, background 0.2s;
+}
+
+.choice-btn.selected {
+  border-color: #6c63ff;
+  background: #ede9fe;
+  color: #6c63ff;
+}
+
+.choice-btn:hover { border-color: #6c63ff; }
+
+.task-submit {
+  align-self: flex-start;
+  padding: 0.7rem 1.8rem;
+}
+
+.task-feedback {
+  margin-top: 1rem;
+  padding: 1rem;
+  border-radius: 8px;
+  display: flex;
+  flex-direction: column;
+  gap: 0.4rem;
+}
+
+.feedback-correct { background: #f0fdf4; color: #065f46; }
+.feedback-wrong   { background: #fef2f2; color: #991b1b; }
+
+.task-feedback strong { font-size: 1rem; }
+
+.xp-badge {
+  background: #6c63ff;
+  color: white;
+  font-size: 0.75rem;
+  font-weight: 700;
+  padding: 0.2rem 0.6rem;
+  border-radius: 20px;
+  align-self: flex-start;
+}
+
+.level-badge {
+  background: #f59e0b;
+  color: white;
+  font-size: 0.75rem;
+  font-weight: 700;
+  padding: 0.2rem 0.6rem;
+  border-radius: 20px;
+  align-self: flex-start;
+}
+
+.explanation {
+  font-size: 0.9rem;
+  line-height: 1.5;
+  opacity: 0.85;
+  margin-top: 0.3rem;
+}
+
+.task-error {
+  color: #e74c3c;
+  font-size: 0.9rem;
+  margin-top: 0.5rem;
+}
--- a/frontend/src/components/TaskCard.jsx
+++ b/frontend/src/components/TaskCard.jsx
@ -0,0 +1,102 @@
+import { useState } from 'react'
+import api from '../api/client.js'
+import './TaskCard.css'
+
+export default function TaskCard({ task, onSolved }) {
+  const [answer, setAnswer] = useState('')
+  const [result, setResult] = useState(null)
+  const [loading, setLoading] = useState(false)
+
+  const alreadySolved = task.solved === true
+
+  async function submit(e) {
+    e.preventDefault()
+    if (!answer.trim()) return
+    setLoading(true)
+    try {
+      const res = await api.post(`/tasks/${task.id}/submit`, { answer })
+      setResult(res)
+      onSolved(res)
+    } catch (err) {
+      setResult({ error: err.message })
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  function selectChoice(choice) {
+    setAnswer(choice)
+  }
+
+  const statusClass = alreadySolved ? 'solved' : result ? (result.correct ? 'correct' : 'wrong') : ''
+
+  return (
+    <div className={`task-card ${statusClass}`}>
+      <div className="task-header">
+        <span className="task-title">{task.title}</span>
+        <div className="task-meta">
+          <span className="task-xp">+{task.xp_reward} XP</span>
+          <span className="task-diff">{'★'.repeat(task.difficulty)}{'☆'.repeat(5 - task.difficulty)}</span>
+          {alreadySolved && <span className="task-check">✓</span>}
+        </div>
+      </div>
+
+      <p className="task-question">{task.question}</p>
+
+      {!alreadySolved && !result && (
+        <form className="task-form" onSubmit={submit}>
+          {task.answer_type === 'multiple_choice' ? (
+            <div className="choices">
+              {task.choices?.map(c => (
+                <button
+                  key={c}
+                  type="button"
+                  className={`choice-btn ${answer === c ? 'selected' : ''}`}
+                  onClick={() => selectChoice(c)}
+                >
+                  {c}
+                </button>
+              ))}
+            </div>
+          ) : (
+            <div className="number-input">
+              <input
+                type="text"
+                inputMode="decimal"
+                placeholder={task.unit ? `Antwort in ${task.unit}` : 'Deine Antwort'}
+                value={answer}
+                onChange={e => setAnswer(e.target.value)}
+                autoComplete="off"
+              />
+              {task.unit && <span className="unit-label">{task.unit}</span>}
+            </div>
+          )}
+          <button
+            type="submit"
+            className="btn btn-primary task-submit"
+            disabled={loading || !answer}
+          >
+            {loading ? '…' : 'Prüfen'}
+          </button>
+        </form>
+      )}
+
+      {result && !result.error && (
+        <div className={`task-feedback ${result.correct ? 'feedback-correct' : 'feedback-wrong'}`}>
+          <strong>{result.correct ? '✓ Richtig!' : '✗ Leider falsch'}</strong>
+          {result.xpGained > 0 && <span className="xp-badge">+{result.xpGained} XP</span>}
+          {result.newLevel && <span className="level-badge">Level {result.newLevel}!</span>}
+          <p className="explanation">{result.explanation}</p>
+        </div>
+      )}
+
+      {alreadySolved && (
+        <div className="task-feedback feedback-correct">
+          <strong>✓ Bereits gelöst</strong>
+        </div>
+      )}
+
+      {result?.error && <p className="task-error">{result.error}</p>}
+    </div>
+  )
+}
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@ -0,0 +1,39 @@
+*, *::before, *::after {
+  box-sizing: border-box;
+}
+
+body {
+  margin: 0;
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
+  background: #f5f5f5;
+  color: #222;
+  -webkit-font-smoothing: antialiased;
+  font-size: 16px;
+  line-height: 1.5;
+}
+
+h1, h2, h3 { margin: 0; }
+p { margin: 0; }
+a { color: inherit; }
+
+#root {
+  min-height: 100vh;
+}
+
+.btn {
+  padding: 0.8rem 2rem;
+  border-radius: 8px;
+  font-size: 1rem;
+  font-weight: 600;
+  text-decoration: none;
+  border: none;
+  cursor: pointer;
+  transition: opacity 0.2s;
+  display: inline-block;
+}
+
+.btn:hover { opacity: 0.85; }
+.btn:disabled { opacity: 0.6; cursor: not-allowed; }
+
+.btn-primary  { background: #6c63ff; color: white; }
+.btn-secondary { background: #e8e8e8; color: #333; }
--- a/frontend/src/main.jsx
+++ b/frontend/src/main.jsx
@ -0,0 +1,13 @@
+import { StrictMode } from 'react'
+import { createRoot } from 'react-dom/client'
+import { BrowserRouter } from 'react-router-dom'
+import './index.css'
+import App from './App.jsx'
+
+createRoot(document.getElementById('root')).render(
+  <StrictMode>
+    <BrowserRouter>
+      <App />
+    </BrowserRouter>
+  </StrictMode>,
+)
--- a/frontend/src/pages/AuthForm.css
+++ b/frontend/src/pages/AuthForm.css
@ -0,0 +1,81 @@
+.auth-container {
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  min-height: 100vh;
+  padding: 1rem;
+  background: #f5f5f5;
+}
+
+.auth-card {
+  background: white;
+  border-radius: 12px;
+  padding: 2.5rem;
+  width: 100%;
+  max-width: 400px;
+  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
+}
+
+.auth-card h2 {
+  margin-bottom: 1.5rem;
+  color: #1a1a2e;
+  font-size: 1.8rem;
+}
+
+.auth-card form {
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
+}
+
+.auth-card label {
+  display: flex;
+  flex-direction: column;
+  gap: 0.4rem;
+  font-size: 0.9rem;
+  font-weight: 600;
+  color: #444;
+}
+
+.auth-card input {
+  padding: 0.7rem 1rem;
+  border: 1px solid #ddd;
+  border-radius: 8px;
+  font-size: 1rem;
+  transition: border-color 0.2s;
+}
+
+.auth-card input:focus {
+  outline: none;
+  border-color: #6c63ff;
+}
+
+.auth-error {
+  color: #e74c3c;
+  font-size: 0.9rem;
+  margin: 0;
+}
+
+.auth-card .btn {
+  width: 100%;
+  margin-top: 0.5rem;
+  padding: 0.9rem;
+}
+
+.auth-card .btn:disabled {
+  opacity: 0.6;
+  cursor: not-allowed;
+}
+
+.auth-switch {
+  margin-top: 1.5rem;
+  text-align: center;
+  font-size: 0.9rem;
+  color: #666;
+}
+
+.auth-switch a {
+  color: #6c63ff;
+  font-weight: 600;
+  text-decoration: none;
+}
--- a/frontend/src/pages/Dashboard.css
+++ b/frontend/src/pages/Dashboard.css
@ -0,0 +1,121 @@
+.dashboard {
+  max-width: 960px;
+  margin: 0 auto;
+  padding: 1.5rem 1rem 4rem;
+}
+
+.dashboard-loading {
+  text-align: center;
+  padding: 4rem;
+  color: #666;
+}
+
+.dashboard-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  margin-bottom: 2rem;
+}
+
+.dashboard-logo {
+  font-size: 1.3rem;
+  font-weight: 700;
+  color: #6c63ff;
+  text-decoration: none;
+}
+
+.dashboard-stats {
+  display: grid;
+  grid-template-columns: 2fr 1fr 1fr;
+  gap: 1rem;
+  margin-bottom: 2.5rem;
+}
+
+.stat-card {
+  background: white;
+  border: 1px solid #e8e8e8;
+  border-radius: 12px;
+  padding: 1.2rem 1.5rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.4rem;
+  box-shadow: 0 2px 8px rgba(0,0,0,0.04);
+}
+
+.stat-value {
+  font-size: 1.5rem;
+  font-weight: 700;
+  color: #1a1a2e;
+}
+
+.stat-label {
+  font-size: 0.8rem;
+  color: #999;
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+}
+
+.xp-bar {
+  height: 6px;
+  background: #f0f0f0;
+  border-radius: 3px;
+  overflow: hidden;
+}
+
+.xp-fill {
+  height: 100%;
+  background: linear-gradient(90deg, #6c63ff, #a78bfa);
+  border-radius: 3px;
+  transition: width 0.4s ease;
+}
+
+.category-block {
+  margin-bottom: 2rem;
+}
+
+.category-block h2 {
+  font-size: 1.1rem;
+  color: #444;
+  margin-bottom: 0.8rem;
+  font-weight: 600;
+}
+
+.topic-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
+  gap: 0.8rem;
+}
+
+.topic-card {
+  background: white;
+  border: 1px solid #e8e8e8;
+  border-radius: 10px;
+  padding: 1rem 1.2rem;
+  text-decoration: none;
+  display: flex;
+  flex-direction: column;
+  gap: 0.3rem;
+  transition: box-shadow 0.2s, border-color 0.2s;
+}
+
+.topic-card:hover {
+  border-color: #6c63ff;
+  box-shadow: 0 4px 12px rgba(108,99,255,0.1);
+}
+
+.topic-title {
+  font-weight: 600;
+  color: #1a1a2e;
+  font-size: 0.95rem;
+}
+
+.topic-meta {
+  font-size: 0.8rem;
+  color: #999;
+}
+
+.topic-premium {
+  font-size: 0.75rem;
+  color: #f59e0b;
+  font-weight: 600;
+}
--- a/frontend/src/pages/Dashboard.jsx
+++ b/frontend/src/pages/Dashboard.jsx
@ -0,0 +1,66 @@
+import { useEffect, useState } from 'react'
+import { useNavigate, Link } from 'react-router-dom'
+import api from '../api/client.js'
+import './Dashboard.css'
+
+export default function Dashboard() {
+  const navigate = useNavigate()
+  const [user, setUser] = useState(null)
+  const [categories, setCategories] = useState([])
+
+  useEffect(() => {
+    Promise.all([api.get('/users/me'), api.get('/topics')])
+      .then(([u, cats]) => { setUser(u); setCategories(cats) })
+      .catch(() => navigate('/login'))
+  }, [navigate])
+
+  if (!user) return <div className="dashboard-loading">Lade…</div>
+
+  const xpForNext = Math.floor(100 * Math.pow(user.level, 1.5))
+  const xpProgress = Math.min((user.xp / xpForNext) * 100, 100)
+
+  return (
+    <div className="dashboard">
+      <header className="dashboard-header">
+        <Link to="/" className="dashboard-logo">Mathe im Alltag</Link>
+        <button className="btn btn-secondary" onClick={() => {
+          localStorage.removeItem('token')
+          navigate('/')
+        }}>Abmelden</button>
+      </header>
+
+      <div className="dashboard-stats">
+        <div className="stat-card">
+          <span className="stat-value">{user.xp} XP</span>
+          <div className="xp-bar"><div className="xp-fill" style={{ width: `${xpProgress}%` }} /></div>
+          <span className="stat-label">Level {user.level} → {user.level + 1}</span>
+        </div>
+        <div className="stat-card">
+          <span className="stat-value">{user.streak} 🔥</span>
+          <span className="stat-label">Tage Streak</span>
+        </div>
+        <div className="stat-card">
+          <span className="stat-value">@{user.username}</span>
+          <span className="stat-label">{user.is_premium ? '⭐ Premium' : 'Free'}</span>
+        </div>
+      </div>
+
+      <div className="dashboard-topics">
+        {categories.map(cat => (
+          <div key={cat.id} className="category-block">
+            <h2>{cat.icon} {cat.title}</h2>
+            <div className="topic-grid">
+              {cat.topics.map(topic => (
+                <Link key={topic.id} to={`/topic/${topic.slug}`} className="topic-card">
+                  <span className="topic-title">{topic.title}</span>
+                  <span className="topic-meta">{topic.task_count} Aufgaben · {'★'.repeat(topic.difficulty)}{'☆'.repeat(5 - topic.difficulty)}</span>
+                  {topic.is_premium && <span className="topic-premium">⭐ Premium</span>}
+                </Link>
+              ))}
+            </div>
+          </div>
+        ))}
+      </div>
+    </div>
+  )
+}
--- a/frontend/src/pages/Home.css
+++ b/frontend/src/pages/Home.css
@ -0,0 +1,87 @@
+.home {
+  max-width: 900px;
+  margin: 0 auto;
+  padding: 2rem 1rem;
+}
+
+.home-hero {
+  text-align: center;
+  padding: 4rem 1rem;
+}
+
+.home-hero h1 {
+  font-size: 3rem;
+  margin-bottom: 1rem;
+  color: #1a1a2e;
+}
+
+.home-subtitle {
+  font-size: 1.2rem;
+  color: #555;
+  max-width: 560px;
+  margin: 0 auto 2rem;
+  line-height: 1.6;
+}
+
+.home-actions {
+  display: flex;
+  gap: 1rem;
+  justify-content: center;
+  flex-wrap: wrap;
+}
+
+.btn {
+  padding: 0.8rem 2rem;
+  border-radius: 8px;
+  font-size: 1rem;
+  font-weight: 600;
+  text-decoration: none;
+  border: none;
+  cursor: pointer;
+  transition: opacity 0.2s;
+}
+
+.btn:hover { opacity: 0.85; }
+
+.btn-primary {
+  background: #6c63ff;
+  color: white;
+}
+
+.btn-secondary {
+  background: #f0f0f0;
+  color: #333;
+}
+
+.home-features {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
+  gap: 1.5rem;
+  margin-top: 3rem;
+}
+
+.feature-card {
+  background: white;
+  border: 1px solid #e8e8e8;
+  border-radius: 12px;
+  padding: 2rem 1.5rem;
+  text-align: center;
+  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
+}
+
+.feature-icon {
+  font-size: 2.5rem;
+  display: block;
+  margin-bottom: 1rem;
+}
+
+.feature-card h3 {
+  margin-bottom: 0.5rem;
+  color: #1a1a2e;
+}
+
+.feature-card p {
+  color: #666;
+  font-size: 0.95rem;
+  line-height: 1.5;
+}
--- a/frontend/src/pages/Home.jsx
+++ b/frontend/src/pages/Home.jsx
@ -0,0 +1,38 @@
+import { Link } from 'react-router-dom'
+import './Home.css'
+
+export default function Home() {
+  return (
+    <div className="home">
+      <div className="home-hero">
+        <h1>Mathe im Alltag</h1>
+        <p className="home-subtitle">
+          Lerne Mathematik anhand echter Situationen — Zinsen, Rabatte,
+          Energiekosten und mehr. Mit Punkten, Levels und Wettbewerb.
+        </p>
+        <div className="home-actions">
+          <Link to="/register" className="btn btn-primary">Kostenlos starten</Link>
+          <Link to="/login" className="btn btn-secondary">Anmelden</Link>
+        </div>
+      </div>
+
+      <div className="home-features">
+        <div className="feature-card">
+          <span className="feature-icon">📈</span>
+          <h3>Alltagsmathe</h3>
+          <p>Aufgaben aus dem echten Leben — Kredit, Strom, Einkauf, Reisen</p>
+        </div>
+        <div className="feature-card">
+          <span className="feature-icon">🏆</span>
+          <h3>Punkte & Level</h3>
+          <p>Sammle XP, steige auf und halte deinen Streak am Leben</p>
+        </div>
+        <div className="feature-card">
+          <span className="feature-icon">⚔️</span>
+          <h3>Rangliste</h3>
+          <p>Miss dich mit anderen und klettere in der Bestenliste nach oben</p>
+        </div>
+      </div>
+    </div>
+  )
+}
--- a/frontend/src/pages/Login.jsx
+++ b/frontend/src/pages/Login.jsx
@ -0,0 +1,49 @@
+import { useState } from 'react'
+import { Link, useNavigate } from 'react-router-dom'
+import api from '../api/client.js'
+import './AuthForm.css'
+
+export default function Login() {
+  const navigate = useNavigate()
+  const [form, setForm] = useState({ email: '', password: '' })
+  const [error, setError] = useState('')
+  const [loading, setLoading] = useState(false)
+
+  const handleChange = (e) => setForm({ ...form, [e.target.name]: e.target.value })
+
+  const handleSubmit = async (e) => {
+    e.preventDefault()
+    setError('')
+    setLoading(true)
+    try {
+      const res = await api.post('/auth/login', form)
+      localStorage.setItem('token', res.token)
+      navigate('/dashboard')
+    } catch (err) {
+      setError(err.message || 'Anmeldung fehlgeschlagen')
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  return (
+    <div className="auth-container">
+      <div className="auth-card">
+        <h2>Anmelden</h2>
+        <form onSubmit={handleSubmit}>
+          <label>E-Mail
+            <input type="email" name="email" value={form.email} onChange={handleChange} required />
+          </label>
+          <label>Passwort
+            <input type="password" name="password" value={form.password} onChange={handleChange} required />
+          </label>
+          {error && <p className="auth-error">{error}</p>}
+          <button type="submit" className="btn btn-primary" disabled={loading}>
+            {loading ? 'Bitte warten…' : 'Anmelden'}
+          </button>
+        </form>
+        <p className="auth-switch">Noch kein Konto? <Link to="/register">Registrieren</Link></p>
+      </div>
+    </div>
+  )
+}
--- a/frontend/src/pages/Register.jsx
+++ b/frontend/src/pages/Register.jsx
@ -0,0 +1,52 @@
+import { useState } from 'react'
+import { Link, useNavigate } from 'react-router-dom'
+import api from '../api/client.js'
+import './AuthForm.css'
+
+export default function Register() {
+  const navigate = useNavigate()
+  const [form, setForm] = useState({ username: '', email: '', password: '' })
+  const [error, setError] = useState('')
+  const [loading, setLoading] = useState(false)
+
+  const handleChange = (e) => setForm({ ...form, [e.target.name]: e.target.value })
+
+  const handleSubmit = async (e) => {
+    e.preventDefault()
+    setError('')
+    setLoading(true)
+    try {
+      const res = await api.post('/auth/register', form)
+      localStorage.setItem('token', res.token)
+      navigate('/dashboard')
+    } catch (err) {
+      setError(err.message || 'Registrierung fehlgeschlagen')
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  return (
+    <div className="auth-container">
+      <div className="auth-card">
+        <h2>Konto erstellen</h2>
+        <form onSubmit={handleSubmit}>
+          <label>Benutzername
+            <input type="text" name="username" value={form.username} onChange={handleChange} required minLength={3} maxLength={50} />
+          </label>
+          <label>E-Mail
+            <input type="email" name="email" value={form.email} onChange={handleChange} required />
+          </label>
+          <label>Passwort
+            <input type="password" name="password" value={form.password} onChange={handleChange} required minLength={8} />
+          </label>
+          {error && <p className="auth-error">{error}</p>}
+          <button type="submit" className="btn btn-primary" disabled={loading}>
+            {loading ? 'Bitte warten…' : 'Registrieren'}
+          </button>
+        </form>
+        <p className="auth-switch">Bereits ein Konto? <Link to="/login">Anmelden</Link></p>
+      </div>
+    </div>
+  )
+}
--- a/frontend/src/pages/TopicPage.css
+++ b/frontend/src/pages/TopicPage.css
@ -0,0 +1,61 @@
+.topic-page {
+  max-width: 760px;
+  margin: 0 auto;
+  padding: 1.5rem 1rem 4rem;
+}
+
+.topic-error, .topic-loading {
+  text-align: center;
+  padding: 4rem;
+  color: #666;
+}
+
+.back-link {
+  color: #6c63ff;
+  text-decoration: none;
+  font-size: 0.9rem;
+  font-weight: 600;
+}
+
+.topic-page-header {
+  margin-bottom: 2rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+}
+
+.topic-page-header h1 {
+  font-size: 1.8rem;
+  color: #1a1a2e;
+}
+
+.topic-desc {
+  color: #666;
+  font-size: 0.95rem;
+}
+
+.topic-progress-bar {
+  height: 8px;
+  background: #f0f0f0;
+  border-radius: 4px;
+  overflow: hidden;
+  margin-top: 0.5rem;
+}
+
+.topic-progress-fill {
+  height: 100%;
+  background: linear-gradient(90deg, #6c63ff, #a78bfa);
+  border-radius: 4px;
+  transition: width 0.4s ease;
+}
+
+.topic-progress-label {
+  font-size: 0.85rem;
+  color: #999;
+}
+
+.task-list {
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
+}
--- a/frontend/src/pages/TopicPage.jsx
+++ b/frontend/src/pages/TopicPage.jsx
@ -0,0 +1,52 @@
+import { useEffect, useState } from 'react'
+import { useParams, Link } from 'react-router-dom'
+import api from '../api/client.js'
+import TaskCard from '../components/TaskCard.jsx'
+import './TopicPage.css'
+
+export default function TopicPage() {
+  const { slug } = useParams()
+  const [data, setData] = useState(null)
+  const [error, setError] = useState('')
+
+  useEffect(() => {
+    api.get(`/topics/${slug}/tasks`)
+      .then(setData)
+      .catch(() => setError('Thema nicht gefunden'))
+  }, [slug])
+
+  if (error) return <div className="topic-error">{error} — <Link to="/dashboard">Zurück</Link></div>
+  if (!data) return <div className="topic-loading">Lade…</div>
+
+  const solved = data.tasks.filter(t => t.solved === true).length
+  const total = data.tasks.length
+
+  return (
+    <div className="topic-page">
+      <div className="topic-page-header">
+        <Link to="/dashboard" className="back-link">← Dashboard</Link>
+        <h1>{data.topic.title}</h1>
+        <p className="topic-desc">{data.topic.description}</p>
+        <div className="topic-progress-bar">
+          <div className="topic-progress-fill" style={{ width: `${total ? (solved / total) * 100 : 0}%` }} />
+        </div>
+        <span className="topic-progress-label">{solved} / {total} gelöst</span>
+      </div>
+
+      <div className="task-list">
+        {data.tasks.map(task => (
+          <TaskCard
+            key={task.id}
+            task={task}
+            onSolved={(result) => {
+              setData(prev => ({
+                ...prev,
+                tasks: prev.tasks.map(t => t.id === task.id ? { ...t, solved: result.correct } : t)
+              }))
+            }}
+          />
+        ))}
+      </div>
+    </div>
+  )
+}
--- a/frontend/vite.config.js
+++ b/frontend/vite.config.js
@ -0,0 +1,7 @@
+import { defineConfig } from 'vite'
+import react from '@vitejs/plugin-react'
+
+// https://vite.dev/config/
+export default defineConfig({
+  plugins: [react()],
+})
--- a/package.json
+++ b/package.json
@ -0,0 +1,16 @@
+{
+  "name": "mathe-app",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://git.motocamp.de/rene/mathe-app.git"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC"
+}
				`@ -0,0 +1 @@`
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