Jonas Templestein

An Event-Sourced Agent Harness Separates State Replay From Side Effects

Jonas Templestein of Iterate argues that an agent harness can be reduced to an append-only event stream plus processors: synchronous reducers to derive state, and post-append hooks to perform side effects. His design puts model chunks, tool calls, errors, schedules, subscriptions and even processor deployment into the log, so a restarted agent can replay state without replaying old LLM calls. The larger claim is that agents and third-party services can compose by reading and appending to the same durable stream, with bounded waits and circuit breakers replacing tighter, blocking plugin interfaces.