Harness engineering — Anand Ranjan

A bug ticket is a story. A harness is a machine.

Harness engineering is the practice of turning a production failure into an artifact the rest of the team — and any coding agent — can run. It is adjacent to testing, but the origin is different: you start from a real failure, not from a specification.

Properties

Deterministic inside a declared boundary.
Cheap in CI.
Free of production secrets.
Paired with notes about what was ruled out.

Failure mode to watch

Agents will green the harness by weakening it. The harness is not the product. Production behavior is. Keep a human in the loop for the first encoding of a nasty bug.

See also: the reproducible debugging notes and the harness case study.