Exo is an agent harness providing tools, messaging adapters, computer use, and state management that enables recursive self-improvement across prompts, memory, tooling, and harness code.

Its architecture splits a trusted substrate holding the append-only event log, secrets, and sandboxes from a swappable executor layer, so the agent can rewrite its own code while retaining the ability to rewind or fork any change. The public API is marked as unstable.