Announcing Worker Versioning Public Preview: Pin Workflows to a single code version

Introduces Worker Versioning, a feature allowing Workflows to be pinned to a single code version (Pinned Workflows) or automatically upgrade (Auto-upgrade Workflows). This is enabled by a built-in task router that substitutes for traditional load balancers and first-class support for rainbow deployments. A Temporal Worker Controller for Kubernetes is also provided as a drop-in solution. The post details three deployment strategies: rolling, blue-green, and rainbow, highlighting the benefits of rainbow deploys for long-running, multi-process Workflows. It also outlines the design philosophy (ease of adoption, reliability, deployment safety, flexibility) and project status (public preview) with a roadmap towards General Availability (GA) in Q4 2025.