Harness: Agent-First Engineering Scaffolding The harness is the scaffolding that makes coding agents effective in a repository. It encodes the knowledge, boundaries, and rules that an agent needs to reason about the full business domain directly from the repo itself. The philosophy: agents execute, humans steer . The engineer's job is not to write code but to design environments, specify intent, and build feedback loops. The harness is what makes this possible. Why It Matters From the agent's point of view, anything it can't access in-context while running effectively doesn't exist. Slack dis…