Generative blocks

Generative blocks are Arco's Tier 2 components — data-driven composites the AI assembles (stat cards, calendars, media grids, forms, etc.).

Today: OpenUI Lang

Chat and generated apps currently render through:

• @openuidev/lang-core — grammar and patch semantics
• @openuidev/react-lang — React renderer
• @openuidev/react-ui — component vocabulary

The agent emits Lang statements; AppSurface and AssistantBlock resolve them to React components with live tool binding.

Target: block registry

The planned defineBlock() contract replaces implicit type unions with one manifest per block:

defineBlock({
  type: "statCards",
  schema: z.object({ /* … */ }),
  description: "Grid of KPI stat cards…",
  adaptivity: {
    inputProfiles: ["pointer", "touch"],
    minWidth: 220,
    idealColumns: { compact: 1, medium: 2, expanded: 4 },
    onCompact: "stack",
  },
  examples: [ /* golden samples */ ],
  render: (props) => <StatCards {...props} />,
});

One definition drives:

Output	Purpose
Runtime validation	Reject or repair malformed AI output
JSON Schema	Constrained decoding
System prompt	Generated vocabulary — never hand-maintained
Docs / catalog	Examples from the same source
Render mapping	registry[type].render

Generation flow

1. Prompt — registry generates allowed vocabulary for the target surface.
2. Emit — agent streams Lang or returns block JSON.
3. Validate — Zod schemas check and repair output.
4. Render — each node resolves through the registry.
5. Persist — ephemeral blocks stay in chat; durable ones become apps via app_create.

Agent blocks in chat

Chat-specific blocks live in src/components/agent-blocks/. These are Tier 2 renderers optimized for the conversation thread — tool results, diffs, code previews, etc.

See block registry for the full contract spec.