A standard for agent-ready design systems Text and diagrams CC BY 4.0
Colophon
Version 1.0 · September 2026
Free to use and cite

Everything here can be checked.

Correct by Design is a definition, six properties, a reference implementation and a protocol for testing systems against them. It is published as a resource, maintained by one person, and built on work that can be read rather than on opinion.

1
Scope

Not a certification. There is no badge.

Nothing here confers status on a design system, and nothing is withheld behind membership or a fee. There is no organisation, no committee and no vendor.

A score is a measurement with the working attached, so anyone can disagree with any part of it and check it themselves. Where something cannot be measured in a given repository it is recorded as not measured, with the reason, and that is never rendered as a failure.

2
Provenance

Three things, each of which can be read.

2.1
One production system.Nivoda, a global B2B marketplace running Material UI, counted before and after. 81 per-component override files, 723 inline style escapes, 32 hand-maintained token files, and the rebuild those numbers decided.Read the case →
2.2
A frozen protocol.The protocol behind the index was written and frozen in July 2026, before any run happened. Its git history is the record, and any change since is published as a deviation with its date and reason.
2.3
A reference implementation.A design system built to all six properties, and an application a coding agent built from it with no design direction. Both are in one public repository.The code →
3
Governance

Versioned, dated, and never changed silently.

The canonical text is version 1.0, September 2026. The definition and the six properties are versioned: a change to their wording carries a new version number and an entry in the changelog. Each property has a stable anchor so it can be cited on its own.

It is the discipline the protocol already has, applied to the prose.

The changelog →

4
Maintainer

Chris Learey.

One person, working alone. The standard came out of building the system in the Nivoda case, and the index exists so the claim is tested against systems built by other people.

5
Licence

Cite it, build to it, argue with it.

The definition, the six properties and the diagrams are published under CC BY 4.0. Use them with attribution.

How to cite
Learey, C. (2026). Correct by Design: six properties of a design system a coding agent can build with. Version 1.0. correctby.design/thesis.html

A system can be submitted to the index and scored by the same protocol. Public systems only.

6
Contact

Assessments, occasionally.

Assessments are run for organisations that want one against their own repository, with the evidence attached and the limits stated. Some systems come out of it needing a rebuild. Plenty do not.