Handling Partial Authentication Flows

In this lesson, you will learn how to design multi-step onboarding flows that maintain user state without granting full account access until identity requirements are satisfied.

The Challenge of Partial Auth

Often, an application requires a user to pass through multiple stages—such as email verification, phone number confirmation, and profile completion—before they are considered fully authenticated. If you force a user to complete every step in one session, you increase abandonment rates. Instead, we use "Partial Authentication" to gate specific resources while keeping the user’s session alive in an "incomplete" state.

Implementation Strategy

The core idea is to attach a status or scope to the user's session token that reflects their progress. You can use a temporary session object or a JWT with a specific claim that limits what the user can do.

For example, consider a user who has verified their email but hasn't set up 2FA:

// Middleware to check for partial completion
function requireProfileSetup(req, res, next) {
  if (req.user.status === 'PARTIAL_ONBOARDING') {
    return res.status(403).json({ 
      message: 'Please complete your profile setup',
      nextStep: '/onboarding/step-2' 
    });
  }
  next();
}

// In your route handler
app.post('/api/user/update-profile', authenticateSession, requireProfileSetup, (req, res) => {
  // Logic to process profile data
});

Why This Matters

By implementing these flows, you prevent users from accessing sensitive "full-member" endpoints until they reach the final stage of your onboarding. This is also a security best practice: it limits the damage a compromised account can do if it is still in the middle of identity verification.

When designing these flows, ensure your backend keeps track of the "onboarding state" in your database. Every time the user interacts with your API, the session middleware should verify that the user has completed the necessary steps for the requested resource. This keeps the user engaged without sacrificing the security integrity of your platform.

Key Takeaway: Partial authentication uses granular session statuses to manage multi-step onboarding, ensuring users only access authorized resources based on their current progress in the identity verification lifecycle.