Rails Authorization Patterns: Pundit, CanCanCan, and Action Policy

A practical guide to Rails authorization covering three main approaches: Pundit, CanCanCan, and Action Policy. Explains when to use each library, the critical 'scope before find' pattern to prevent IDOR and cross-tenant data leaks, how to write tests that catch access-control bugs, and provides a pre-merge authorization checklist. Pundit is recommended as the default for serious Rails products due to its explicitness and testability.