@czap/genui

Host-owned generated UI: validate the structured UI trees a model proposes against a catalog you control, then render trusted components only — never model HTML.

You usually don't install this directly — it's host-wired through @czap/astro, @czap/web, and @czap/mcp-server, which own the catalog and interaction authority for you. Install one of those unless you need the validator standalone.

Install

pnpm add @czap/genui

30 seconds

import {
  DEMO_COMPONENT_CATALOG,
  tryParseGeneratedUIChunk,
  validateGeneratedUITree,
  renderHash,
} from '@czap/genui';

// A model emits one structured chunk: { "_genui": true, "name": ..., "props": ... }
const node = tryParseGeneratedUIChunk(
  '{"_genui":true,"name":"Card","props":{"title":"Hello"},"children":[{"name":"Text","props":{"text":"From the model"}}]}',
);

if (node) {
  const result = validateGeneratedUITree(node, DEMO_COMPONENT_CATALOG);
  if (result.ok) {
    console.log(renderHash(node, DEMO_COMPONENT_CATALOG)); // stable content address
  } else {
    console.error(result.error.code, result.error.path); // e.g. 'genui/unknown-component'
  }
}

tryParseGeneratedUIChunk returns null for ordinary token/text/HTML output, so this is safe to run over every streamed chunk. validateGeneratedUITree rejects unknown component names, bad props, and malformed children/slots before anything reaches the DOM. In the browser, renderFromCatalog(node, { catalog, target }) validates then builds elements from your trusted catalog, wiring interaction props to genui:interaction CustomEvents the host interprets — model strings are opaque action ids, never markup.

Where it sits

Define a catalog with defineComponentCatalog — the only components that can ever render. Its only @czap dependencies are @czap/_spine (the shared genui type vocabulary), @czap/canonical (catalog/render bytes), and @czap/error. The model proposes a tree; this package validates it against the catalog and renders allowlisted attributes only. catalogHash and renderHash mint stable content addresses for cache, replay, and tests. What to generate is decided elsewhere — @czap/mcp-server projects the catalog to a model, hosts own admission and interaction authority.

Trust boundary

This package never renders model HTML and never trusts model-controlled keys — component and prop names are looked up as own-properties only, so constructor/__proto__-style names are unknown components, full stop. A tree that fails validation is not rendered. The catalog, and what each interaction does, are always the host's.

Docs

• Getting started
• Generated UI catalog (ADR-0014) — the trust model above
• Glossary — the vocabulary used above
• API reference — generated from source

Part of LiteShip — powered by the CZAP engine (Content-Zoned Adaptive Projection), distributed as @czap/* packages.