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Building a Login Feature

Let's compare approaches.

Vibecoding​

Prompt:

Create a login page.

Result:

LoginPage.tsx

Maybe 300 lines.

Contains:

  • Form
  • Validation
  • State
  • API calls
  • Error handling

All in one file.

Works.

Until requirements grow.

Predictive Development​

Requirement:

Create authentication.

Analysis:

Domain:
Identity

Subdomain:
Authentication

Architecture:

LoginModel
AuthService
AuthState
AuthApi

UI:

Input
Label
Button
LoginForm
LoginPage

Implementation follows architecture.

The result scales much more effectively.

Mini Exercise​

Compare the Vibecoding and Predictive Development versions of this login feature and list the biggest structural difference.

Example​

The Vibecoding version puts everything in one page, while the predictive version separates model, service, state, API, and UI responsibilities.