Welcome back to the Harness Engineering series — a 10-part journey from raw language model to production-ready agentic system. Made by builders. For builders.
In Part 6, we closed on a limitation the previous four components can't solve on their own: the agent forgets.
Once a session ends — or the context window fills up mid-task — everything the agent learned, discovered, or decided vanishes. Next time the user comes back, the agent greets them like a stranger. Next time the token budget runs out, earlier turns get truncated away, and the agent's earlier reasoning is just gone.
That's the gap this article closes. The Memory Layer is how the harness gives the agent persistence — inside a task, and across sessions.
What's ahead:
