Cross Device SSO

// Server-side Session Management for Cross-Device SSO
const sessions = {}; // { userId: [{ deviceId, sessionId, expiresAt }] }

// Login on Device A
app.post('/login', (req, res) => {
  const user = authenticate(req.body);
  const sessionId = generateSessionId();
  
  // Store session server-side, linked to user
  if (!sessions[user.id]) sessions[user.id] = [];
  sessions[user.id].push({
    deviceId: req.body.deviceId,
    sessionId,
    expiresAt: Date.now() + 3600000
  });
  
  res.cookie('sessionId', sessionId);
  res.json({ success: true });
});

// Check session on Device B
app.get('/check-session', (req, res) => {
  const userSessions = sessions[req.user.id] || [];
  const hasActiveSession = userSessions.some(s => s.expiresAt > Date.now());
  res.json({ loggedIn: hasActiveSession });
});