use Guardian authorization classes

Always implement authorization checks using Guardian classes rather than ad-hoc permission logic. Guardian classes provide a centralized, consistent approach to authorization that helps prevent security vulnerabilities from inconsistent or missing permission checks.

The main Guardian class is defined in lib/guardian.rb, with additional Guardian classes available in the lib/guardian/ directory. These classes encapsulate authorization logic and should be used for all permission-related decisions in the application.

Example usage:

# In a controller
def show
  guardian.ensure_can_see!(@topic)
  # ... rest of action
end

# In a service or model
if guardian.can_edit_post?(@post)
  # ... perform edit operation
end

This pattern ensures that authorization logic is:

• Centralized and maintainable
• Consistently applied across the application
• Easier to audit for security vulnerabilities
• Following established architectural patterns

Avoid implementing custom authorization logic directly in controllers or services, as this can lead to inconsistent security enforcement and potential authorization bypass vulnerabilities.