@nano-ui-kit/a2ui-validator

A2UI validation — three orthogonal layers that you compose based on how much assurance you want.

| Layer | What it checks | Cost | Determinism | |---|---|---|---| | Structural (./structural) | Shape, tag registration, required fields per NanoUI A2UI schema | µs | ✅ fully deterministic | | Catalog (./catalog) | Full prop types, enum values, slot names, validation rules from per-component a2ui.json schemas | ms | ✅ fully deterministic | | Semantic (./semantic) | Intent alignment via LLM judge (dominant pattern, required capabilities, forbidden noise) | seconds, API cost | ✱ cached per rubric+input |

Install

npm install @nano-ui-kit/a2ui-validator @nano-ui-kit/a2ui-utils

Structural validation

import { validateSchema } from '@nano-ui-kit/a2ui-validator';

const messages = [
  { type: 'updateComponents', surfaceId: 'default', components: [
    { id: 'root', component: 'Card', children: ['sec'] },
    { id: 'sec',  component: 'Section', children: ['btn'] },
    { id: 'btn',  component: 'Button', text: 'Hello' },
  ]},
];

const { valid, errors } = validateSchema(messages);

Catalog-aware validation

Needs the catalog shipped in @nano-ui-kit/a2ui-corpus:

import { validateMessages } from '@nano-ui-kit/a2ui-validator/catalog';
import catalog from '@nano-ui-kit/a2ui-corpus/catalog';

const { valid, errors } = validateMessages(messages, catalog);

Catches variant="fictional" on a component whose yaml only declares [default, info, success, warning, danger], wrong slot names, missing required props — the things structural validation is too coarse to see.

Semantic validation (optional)

import { validateSemantics } from '@nano-ui-kit/a2ui-validator/semantic';

const result = await validateSemantics({
  intent: 'password reset form',
  messages,
  rubric: {
    dominantPattern: 'forms/password-reset',
    requiredCapabilities: ['email input', 'submit button'],
    forbiddenNoise: ['login flow', 'signup'],
  },
});
// → { verdict: 'aligned' | 'partial' | 'misaligned' | 'off-topic', score, rationale }

Needs ANTHROPIC_API_KEY in the environment. Judgments are cached at <cwd>/.a2ui-semantic-cache/ keyed by sha256(rubricVersion + intent + messages) — the default Haiku-4.5 rubric is ~108k tokens per 100-intent run.

Development / design notes

• Layer 1 and 2 are framework-agnostic — they validate any A2UI message set against any component registry.
• Layer 3 is opinionated: specific rubric, specific model. If you want a different model, provide a custom judge function to validateSemantics.
• This package is Node-only today (fs-backed semantic cache). Browser builds of the structural/catalog layers work via standard ESM import.

License

MIT © Kim Granlund