Harness templates are, in the proposal made in Harness engineering for coding agent users, a bundle of Guides and sensors that “leash a coding agent to the structure, conventions and tech stack of a topology”. The article starts from the observation that most enterprises have a few common service topologies — business services exposing data via APIs, event processing services, data dashboards — covering most of what they need, and that mature engineering organisations often already codify these in service templates. It suggests these might evolve into harness templates, and that teams may start picking tech stacks and structures partly according to which harnesses are already available for them.
Usage
The article supports the idea with Ashby’s Law of Requisite Variety, which it summarises as saying that a regulator must have at least as much variety as the system it governs and can only regulate what it has a model of. An LLM-based coding agent can produce almost anything; committing to a topology narrows that space, making a comprehensive harness more achievable — “a variety-reduction move”.
When It Applies
This is a speculative proposal, framed as something that “might” happen, not a reported practice. It assumes an organisation already has a small set of recurring topologies. The author expects harness templates to face the same problems as service templates — instantiated copies falling out of sync with upstream improvements, and versioning and contribution difficulties — possibly worse, since non-deterministic guides and sensors are harder to test.