This is the official Temporal Ruby SDK (temporalio gem) for building durable workflow and activity applications on the Temporal platform. It provides a full client and worker implementation, allowing Ruby applications to start, signal, query, update, and cancel workflows, as well as define and execute activities. The SDK uses a Rust native extension (bridge) to interface with the Temporal Core SDK for performance-critical operations like polling and metric buffering, and relies on generated protobuf definitions for all API types. Architecture is library-based: users define workflow and activity classes using declarative DSL annotations, and the SDK handles lifecycle, determinism enforcement, replay, and interceptor chains for extensibility. The codebase demonstrates high craftsmanship with clean abstractions for cancellation tokens, future combinators, fiber-based deterministic scheduling, illegal call detection via TracePoint, and pluggable payload converters and codecs. It includes comprehensive test suites covering workflows, activities, versioning, OpenTelemetry tracing, and cloud integration. The SDK is actively maintained with frequent releases, CI/CD pipelines, and type signature coverage enforcement via both RBI and RBS files. While the generated protobuf code is voluminous and requires regeneration on API updates, the core Ruby code is well-structured and modular, making this a strong example of a production-grade SDK for distributed orchestration.