Feature: User preferences (theme)
  As a signed-in user
  I want to choose a light, dark, or system theme
  So that the app matches how I like to read it

  Scenario: A visitor without a session cannot read preferences
    When I send a GET request to "/preferences"
    Then the response status should be 401
    And the response error code should be "NOT_AUTHENTICATED"

  Scenario: A signed-in user with no preferences yet defaults to SYSTEM
    Given a profile already exists with email "alice@example.com" and password "correct-horse-battery-staple"
    And I log in with email "alice@example.com" and password "correct-horse-battery-staple"
    When I request my preferences
    Then the response status should be 200
    And my theme preference should be "SYSTEM"

  Scenario: A signed-in user sets their theme preference
    Given a profile already exists with email "alice@example.com" and password "correct-horse-battery-staple"
    And I log in with email "alice@example.com" and password "correct-horse-battery-staple"
    When I set my theme preference to "DARK"
    Then the response status should be 200
    And my theme preference should be "DARK"