Worked on the google/adk-python repository to implement a configurable user simulator for the generate_responses function, enabling callers to customize the LLM-backed user simulator through an optional user_simulator_config parameter. The approach preserved backward compatibility by defaulting to a base configuration when none was provided, ensuring existing workflows remained unaffected. Leveraged Python for back end development and async programming, and incorporated comprehensive unit testing to validate the new feature, with over 5,700 tests passing. The work included updating the EvaluationGenerator to forward configuration parameters, enhancing flexibility for multi-turn conversation simulations while maintaining robust test coverage and clear documentation.