Feature: TDD: ProviderType.GEMINI missing from ProviderRegistry.FALLBACK_ORDER
  As a user who configures only GEMINI_API_KEY
  I want get_default_provider_type() to return ProviderType.GEMINI via the fallback chain
  So that Gemini-only users can use auto-discovery without setting GOOGLE_API_KEY

  @tdd_issue @tdd_issue_4750 @tdd_expected_fail
  Scenario: Gemini-only user gets GEMINI as default provider via fallback order
    Given a ProviderRegistry configured with only gemini_api_key set
    And CLEVERAGENTS_DEFAULT_PROVIDER is not set for tdd test
    When I call get_default_provider_type on the tdd registry
    Then the tdd result should be ProviderType.GEMINI
