fix: persist user authentication using SQLite database

database.js

@@ -14,6 +14,13 @@ function initDb() {
       created_at DATETIME DEFAULT CURRENT_TIMESTAMP
     )`);
 
+    // Users Table
+    db.run(`CREATE TABLE IF NOT EXISTS users (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      email TEXT UNIQUE NOT NULL,
+      password TEXT NOT NULL,
+      created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+    )`);
     // Tasks Table
     db.run(`CREATE TABLE IF NOT EXISTS tasks (
       id TEXT PRIMARY KEY,

server.js

@@ -509,30 +509,32 @@ Text: "${text}"
   return res.json(tasks);
 });
 // ================= AUTH =================
-const users = {}; // Simple in-memory user store
-
+// Users stored in SQLite database (persistent)
 app.post('/api/auth/signup', (req, res) => {
   const { email, password } = req.body;
   if (!email || !password) {
     return res.status(400).json({ error: 'Email and password required' });
   }
-  if (users[email]) {
-    return res.status(400).json({ error: 'User already exists' });
-  }
-  users[email] = { email, password };
-  res.json({ success: true, message: 'Account created successfully' });
+  db.get('SELECT * FROM users WHERE email = ?', [email], (err, row) => {
+    if (err) return res.status(500).json({ error: err.message });
+    if (row) return res.status(400).json({ error: 'User already exists' });
+    db.run('INSERT INTO users (email, password) VALUES (?, ?)', [email, password], function(err) {
+      if (err) return res.status(500).json({ error: err.message });
+      res.json({ success: true, message: 'Account created successfully' });
+    });
+  });
 });
 
 app.post('/api/auth/login', (req, res) => {
   const { email, password } = req.body;
   if (!email || !password) {
     return res.status(400).json({ error: 'Email and password required' });
   }
-  const user = users[email];
-  if (!user || user.password !== password) {
-    return res.status(401).json({ error: 'Invalid email or password' });
-  }
-  res.json({ success: true, email: user.email });
+  db.get('SELECT * FROM users WHERE email = ? AND password = ?', [email, password], (err, row) => {
+    if (err) return res.status(500).json({ error: err.message });
+    if (!row) return res.status(401).json({ error: 'Invalid email or password' });
+    res.json({ success: true, email: row.email });
+  });
 });
 
 // Intentional test route for verifying server error page behavior.
@@ -572,4 +574,4 @@ app.use((err, req, res, next) => {
 const PORT = process.env.PORT || 3000;
 app.listen(PORT, () => {
   console.log('Server running on port ' + PORT);
-});
+});