# API-Layer Delivery Precedes Interface Delivery in Layered Systems ## Claim In a layered system the underlying API ships a capability before any interface exposes it, because the API is what everything else composes on while an interface must first resolve how to explain the capability to people who do not know it exists. <!-- atomicity: 1 idea ✓ --> ## Evidence **Source**: *Gutenberg Changelog #134* ([listen](https://www.youtube.com/watch?v=Shd2fE9S-s4)) — Birgit Pauli-Haack and Jessica Lyschik — Birgit Pauli-Haack and Jessica Lyschik > [!quote] > that's pretty much the cadence of any of the styling things. that they are first coming into theme JSON for theme builders because that's the basis of it. That's kind of the API. The reason the interface lags is not resourcing. It is that an interface has to serve both a theme developer and someone who has never heard of a pseudo-state, which the hosts name directly as a language problem before it is a design problem. The cost lands on practitioners, and Lyschik states it from the agency side: the editor is where everyone looks first, and the answer to clients is that they have to code. The workaround also has teeth — `theme.json` is only editable in a theme you control, because another author's update overwrites your changes. ## Scope & conditions - Holds where the API is a public contract other layers depend on, and where interface design genuinely must serve multiple skill levels. - Produces a real two-tier experience: capable users get the feature, everyone else is told "not yet." That has to be managed through documentation and expectation-setting, not denied. - **Fails as an excuse** where the interface work is simply never scheduled. The cadence justifies a lag, not an indefinite one. - The practical rule for anyone supporting the platform: before concluding a feature is missing, check the configuration layer. ## Links - [[Open Source Governance MOC]] — the theme.json-first cadence, and the two-tier experience it hands to non-developers - [[3. Resources/Permanent Notes/Declarative Configuration Lets a Platform Absorb Its Ecosystem's Migration Cost]] — the payoff on the far side: a stable declarative layer lets the platform change the renderer for everyone - [[3. Resources/Permanent Notes/Caller Distance Determines the Right WordPress Interface]] — applies-in: choosing which layer to build against in the first place - [[3. Resources/Permanent Notes/Adoption Gaps in Standards Are Usually Documentation Gaps]] — the mitigation this cadence requires - [[3. Resources/Permanent Notes/Interface Surface Area Costs Selection Accuracy Not Just Tokens]] — contrasts on who gets access first and why - [[WordPress Platform Design MOC]] — the theme.json-first cadence and the two-tier experience it creates