Feature: Plugin Loader Coverage Boost
  Scenarios targeting uncovered lines in the PluginLoader class:
  - Lines 203-209: entry point load failure exception handler
  - validate_protocol: issubclass succeeds (class satisfies protocol structurally)
  - validate_protocol: issubclass raises TypeError with unverifiable protocol
  - validate_protocol: issubclass returns False (class missing required members)

  Background:
    Given the plugin loader module is imported

  # -----------------------------------------------------------------------
  # Entry-point discovery: failure path (lines 203-209)
  # -----------------------------------------------------------------------

  Scenario: Entry point that fails to load is skipped with a warning
    Given the entry points are mocked with one that raises on load
    When I call load_from_entry_points
    Then the plugin result should be an empty descriptor list
    And the failed entry point should have been logged as a warning

  # -----------------------------------------------------------------------
  # validate_protocol: issubclass succeeds for class satisfying protocol
  # -----------------------------------------------------------------------

  Scenario: validate_protocol returns True when class satisfies protocol via issubclass
    Given I have a class that requires constructor arguments
    And I have a runtime checkable protocol the class satisfies via issubclass
    When I call validate_protocol with the non-instantiable class and protocol
    Then validate_protocol should return True

  # -----------------------------------------------------------------------
  # validate_protocol: issubclass raises TypeError for unverifiable protocol
  # -----------------------------------------------------------------------

  Scenario: validate_protocol raises ProtocolMismatchError when issubclass raises TypeError
    Given I have a class that cannot be instantiated without arguments
    And I have a protocol-like object that causes issubclass to raise TypeError
    When I call validate_protocol expecting a mismatch error
    Then a plugin-loader ProtocolMismatchError should be raised

  # -----------------------------------------------------------------------
  # validate_protocol: issubclass returns False (class missing required members)
  # -----------------------------------------------------------------------

  Scenario: validate_protocol raises ProtocolMismatchError when issubclass returns False
    Given I have a class that cannot be instantiated without arguments
    And I have a runtime checkable protocol the class does not satisfy
    When I call validate_protocol expecting a mismatch error
    Then a plugin-loader ProtocolMismatchError should be raised