Feature: Executor Constructor Argument Validation
  As a router developer
  I want Executor.__init__ to reject invalid argument types immediately
  So that misconfigurations fail fast with a clear error message

  # These scenarios exercise the argument-type validation guards in
  # Executor.__init__ (src/cleveractors/runtime.py:79-95).  Each guard
  # raises ConfigurationError when the argument is not a dict.

  Scenario: Executor rejects non-dict config_dict
    Given I construct an Executor with config_dict set to "not a dict"
    Then a ConfigurationError should be raised containing "config_dict must be a dict"

  Scenario: Executor rejects non-dict credentials
    Given I construct an Executor with credentials set to "not a dict"
    Then a ConfigurationError should be raised containing "credentials must be a dict"

  Scenario: Executor rejects non-dict limits
    Given I construct an Executor with limits set to "not a dict"
    Then a ConfigurationError should be raised containing "limits must be a dict"

  Scenario: Executor rejects non-dict pricing
    Given I construct an Executor with pricing set to "not a dict"
    Then a ConfigurationError should be raised containing "pricing must be a dict"