A Durable Coding Agent — with Modal and Restate

The blog post discusses the transformation of a coding agent from a local setup to a scalable, cloud-based system capable of handling millions of executions, using tools like Modal for sandbox environments and serverless compute, and Restate for managing durable execution and state management. The approach focuses on creating a resilient, fault-tolerant architecture that can withstand failures and interruptions, utilizing OpenAI's GPT-5 for the language model, and leveraging Restate's capabilities to manage workflows and ensure reliable execution. The coding agent operates by creating a TODO list from user goals, executing multi-step workflows, and adapting to new inputs, while Modal provides secure and scalable sandbox environments. Restate offers a robust framework for handling stateful functions, ensuring tasks can recover from interruptions and failures, and maintaining consistent interaction histories through virtual objects. The setup is demonstrated to handle infrastructure failures automatically and quickly scale out to meet demand, showcasing an efficient, serverless solution for deploying coding agents in the cloud.