Downcity

From Agent Harness to product delivery—a shared runtime foundation for multiple agent products.

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Build worlds where agents live, work, and collaborate.

Downcity is a set of open-source kits for running agents and shipping agent products. Agent Harness provides a reliable execution environment; City, Federation, SDKs, and UI kits add product boundaries, shared services, and user interfaces. Together, they turn an agent capability inside a conversation into a product that can keep working and delivering.

Why Downcity

The first AI product is often quick to build. The second and third expose the repeated infrastructure work: model routing, user identity, service integration, usage metering, payment, and deployment.

Downcity brings these shared capabilities into one reusable runtime and backend. Multiple AI products can use the same foundation while retaining their own agents, workflows, and interfaces.

One runtime, many products.

Product Model

Downcity treats an agent product as a City:

• an Agent is an active participant that keeps working;
• its workspace, files, models, tools, skills, memory, and tasks form the working environment;
• agents with different roles can collaborate inside one City;
• multiple Cities access shared models, identity, data, and services through a Federation.

A City can become an independent product organized around a specific field of work, such as software creation, research and knowledge, team operations, or personal work.

Within the Genesis Cosmos framework, Downcity is an implementation of the Product System: it gives created structures a way to be built, run, shipped, and connected.