Feature: Application Container coverage boost for _build_checkpoint_service, _build_trace_service, and _build_session_factory
  As a developer
  I want to exercise the _build_checkpoint_service, _build_trace_service, and _build_session_factory helper functions
  So that the corresponding builder functions in container.py are covered by tests

  Background:
    Given a clean container state for coverage boost tests

  # -----------------------------------------------------------------
  # _build_checkpoint_service  (lines 187-195)
  # -----------------------------------------------------------------

  @coverage
  Scenario: Build checkpoint service with in-memory database and no lifecycle service
    When I build a checkpoint service with an in-memory database URL
    Then acbs the result should be a CheckpointService instance
    And the checkpoint service should have a repository
    And the checkpoint service should have no plan lifecycle service

  @coverage
  Scenario: Build checkpoint service with an explicit plan lifecycle service
    Given a mock plan lifecycle service
    When I build a checkpoint service with the mock plan lifecycle service
    Then acbs the result should be a CheckpointService instance
    And the checkpoint service should reference the mock plan lifecycle service

  # -----------------------------------------------------------------
  # _build_trace_service  (lines 204-211)
  # -----------------------------------------------------------------

  @coverage
  Scenario: Build trace service with in-memory database using default settings
    When I build a trace service with an in-memory database URL and no explicit settings
    Then acbs the result should be a TraceService instance
    And the trace service should have a repository
    And the trace service should have resolved settings from defaults

  @coverage
  Scenario: Build trace service with explicit settings
    Given explicit application settings for trace service
    When I build a trace service with the explicit settings
    Then acbs the result should be a TraceService instance
    And the trace service should use the explicitly provided settings

  # -----------------------------------------------------------------
  # _build_session_factory
  # -----------------------------------------------------------------

  Scenario: Build session factory with in-memory database returns callable sessionmaker
    When I build a session factory with an in-memory database URL
    Then the result should be a callable sessionmaker
    And calling the session factory should produce a Session

  Scenario: Build session factory with invalid URL raises an error
    When I build a session factory with an invalid database URL
    Then a database error should be raised when the factory is called

  Scenario: Container.session_factory resolves a usable session factory
    When I resolve session_factory from the container with an in-memory database URL
    Then the resolved session factory should be callable
    And calling the resolved session factory should produce a Session

  # -----------------------------------------------------------------
  # _build_skill_service  (happy path + fallback)
  # -----------------------------------------------------------------

  @coverage
  Scenario: Build skill service with in-memory database succeeds
    When I build a skill service with an in-memory database URL
    Then the result should be a SkillService instance
    And the skill service should have a repository

  @coverage
  Scenario: Build skill service falls back to in-memory on DB error
    When I build a skill service with an invalid database URL
    Then the result should be a SkillService instance
    And the skill service should have no repository