What Is ARIA, and How Did We Build It?

This post details the evolution of the ARIA agent, moving beyond a simple chat interface to a durable research process. Key technical contributions include: the concept of a persistent 'Turn' to store agent work and history, enabling investigations to survive browser sessions and recover from failures; a deliberate architectural separation of concerns (ARIA service, agent, environment, sandbox, driver) to improve failure analysis and modularity; and the use of Weave for end-to-end observability and offline evaluation of agent behavior against production-like conditions, using durable Turns as the basis for reproducible testing.