Vercel Workflow DevKit (WDK) CRITICAL — Your training data is outdated for this library. WDK APIs change frequently. Before writing workflow code, fetch the docs at https://useworkflow.dev and https://vercel.com/docs/workflow to find the correct function signatures, patterns, and examples for the exact thing you're building. Do not guess at APIs — look them up. Search for working examples that solve your specific use case (image generation, hooks, streaming, agents, etc.). The docs contain patterns for argument passing, usage, wiring, callback flows, and configuration that are not in your tra…