LongHorizonAgent is an AI agent architecture designed to work reliably across hundreds or thousands of steps without continuously growing its context. Instead of replaying the full conversation history, it maintains a small, structured working state containing what is true now, archives outdated or evicted information, and recalls it only when needed. The project demonstrates this approach through DesignDesk, an AI mechanical-engineering environment where natural-language design intent is converted into structured state, updated through engineering changes, and used to generate and validate real CAD geometry with build123d and OpenCascade. A Memory State Inspector makes state changes, archived facts, recalls, provenance, and context savings visible, while AWS Bedrock provides the main reasoning model, Nimble provides web tools, and Tinybird provides telemetry and analytics. The core idea is simple: History grows. State doesn’t have to.
