@tdd_issue @tdd_issue_10861
Feature: TDD Bug #10861 - agents actor run returns nothing for built-in LLM actors

  Bug #10861 reports that running agents actor run with a built-in LLM actor
  returns nothing instead of a response from the LLM.

  Root cause: built-in actors have a config_blob with provider and model
  fields but no type field. When serialised to YAML and fed to
  ReactiveConfigParser, the parser produces an empty ReactiveConfig with no
  agents and no routes, causing run_single_shot() to return empty string.

  Fix: resolve_config_files now synthesises a minimal v3 type: llm YAML
  when the actor has no yaml_text and the config_blob has provider and model
  but no type field.

  Scenario: resolve_config_files synthesises v3 llm YAML for built-in actor
    Given a built-in actor with provider and model but no type field for tdd-10861
    When resolve_config_files is called with the built-in actor name for tdd-10861
    Then the resulting YAML file contains type llm for tdd-10861
    And the resulting YAML file contains the provider and model for tdd-10861

  Scenario: synthesised YAML is parseable by ReactiveConfigParser for tdd-10861
    Given a built-in actor with provider and model but no type field for tdd-10861
    When resolve_config_files is called with the built-in actor name for tdd-10861
    Then the resulting YAML file is parseable as a v3 llm actor config for tdd-10861

  Scenario: actor with existing yaml_text is not affected by the fix for tdd-10861
    Given an actor with existing yaml_text for tdd-10861
    When resolve_config_files is called with the actor name for tdd-10861
    Then the original yaml_text is used without modification for tdd-10861