Worked on enhancing retry tracking and job introspection for concurrent RPC execution in the google/langfun repository. Refactored the retry logic by introducing a RetryEntry structure and integrating retry statistics with LMSamplingUsage, enabling more granular cost and performance analysis. Extended the Job-based APIs so that concurrent_execute and concurrent_map now return Job objects, improving observability and debugging capabilities. Instrumentation was added to quantify the time impact of retried RPC calls, supporting better developer productivity and reliability. The work was implemented in Python, leveraging asynchronous programming, concurrency, and robust error handling, with a focus on maintainability and improved API ergonomics.