Can I use both Restate and Catalyst together in a hybrid architecture for durable execution?

Yes, you can combine them, but it adds complexity. Catalyst handles orchestrated workflows and AI-agent runners, while Restate can manage simpler journaled services that don't need workflow orchestration. They communicate via standard protocols (HTTP/gRPC). This hybrid approach works if you have existing Restate services and want to adopt Catalyst for new agentic workflows. However, you'll need to manage two runtimes and their operational tooling separately.