OpenUI (thesysdev/openui)

OpenUI

https://github.com/thesysdev/openui
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OpenUI is a full-stack generative UI framework with a compact streaming-first language, React...

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# OpenUI — The Open Standard for Generative UI

OpenUI is a full-stack Generative UI framework consisting of a compact streaming-first language (OpenUI Lang), a React runtime with built-in component libraries, and ready-to-use chat interfaces. It enables AI models to generate structured, interactive UI components instead of plain text or JSON, achieving up to 67% fewer tokens than equivalent JSON-based approaches. The framework covers the entire pipeline: defining a component library with Zod schemas, generating a system prompt from that library, streaming OpenUI Lang output from an LLM, and progressively rendering parsed components in React as tokens arrive.

The SDK is organized into four packages: `@openuidev/react-lang` (core runtime — component definitions, parser, renderer, and prompt generation), `@openuidev/react-headless` (headless chat state, streaming adapters, and message format converters), `@openuidev/react-ui` (prebuilt chat layouts and two ready-to-use component libraries), and `@openuidev/cli` (CLI for scaffolding apps and generating system prompts). A fifth package, `@openuidev/lang-core`, provides a framework-agnostic `generatePrompt` function for server-side prompt construction without React dependencies.

---

## `@openuidev/cli` — Scaffold and generate

### `openui create` — scaffold a new Next.js chat app

Creates a Next.js app pre-configured with OpenUI Chat, auto-detects the package manager, installs dependencies, and optionally installs the OpenUI agent skill.

```bash
# Interactive — prompts for project name and agent skill
npx @openuidev/cli@latest create

# Non-interactive
npx @openuidev/cli@latest create --name my-app --no-skill

# With agent skill pre-installed for Claude Code / Cursor / Copilot
npx @openuidev/cli@latest create --name my-app --skill

# The generated app is immediately runnable
cd my-app
echo "OPENAI_API_KEY=sk-your-key-here" > .env
npm run dev   # http://localhost:3000
```

### `openui generate` — generate a system prompt or JSON schema from a library file

Bundles the entry file with esbuild, evaluates the exported `Library`, and writes the system prompt (or JSON schema) to stdout or a file. Auto-detects the library export and any `PromptOptions` export.

```bash
# Print system prompt to stdout
npx @openuidev/cli@latest generate ./src/library.ts

# Write system prompt to file (typical prebuild step)
npx @openuidev/cli@latest generate ./src/library.ts --out src/generated/system-prompt.txt

# Output JSON schema for use with generatePrompt() at runtime
npx @openuidev/cli@latest generate ./src/library.ts --json-schema --out generated/component-spec.json

# Explicit export names when auto-detection is ambiguous
npx @openuidev/cli@latest generate ./src/library.ts --export myLibrary --prompt-options myOptions
```

Add it as a prebuild step so the prompt stays in sync with the component library:

```json
{
  "scripts": {
    "generate:prompt": "openui generate src/library.ts --out src/generated/system-prompt.txt",
    "dev": "pnpm generate:prompt && next dev",
    "build": "pnpm generate:prompt && next build"
  }
}
```

---

## `@openuidev/react-lang` — Core runtime

### `defineComponent(config)` — register a UI component

Defines a single component with a name, Zod schema, natural-language description, and React renderer. Key order in the `z.object(...)` schema determines positional argument order in OpenUI Lang output. The returned `DefinedComponent` exposes a `.ref` for use in parent schemas.

```tsx
import { defineComponent, createLibrary } from "@openuidev/react-lang";
import { z } from "zod/v4";

// Leaf component
const StatCard = defineComponent({
  name: "StatCard",
  description: "Displays a metric label and its current value.",
  props: z.object({
    label: z.string(),
    value: z.string(),
    trend: z.enum(["up", "down", "neutral"]).optional(),
  }),
  component: ({ props }) => (
    <div className="stat-card">
      <span className="label">{props.label}</span>
      <span className="value">{props.value}</span>
    </div>
  ),
});

// Container that nests children via .ref
const Dashboard = defineComponent({
  name: "Dashboard",
  description: "Full-page dashboard container.",
  props: z.object({
    title: z.string(),
    cards: z.array(StatCard.ref),
  }),
  component: ({ props, renderNode }) => (
    <div>
      <h1>{props.title}</h1>
      <div className="grid">{renderNode(props.cards)}</div>
    </div>
  ),
});
```

### `createLibrary(input)` — assemble a component library

Accepts an array of defined components, optional component groups (for prompt organization), and a root component name. Returns a `Library` with `prompt()`, `toJSONSchema()`, and `toSpec()` methods.

```ts
import { createLibrary } from "@openuidev/react-lang";
import type { PromptOptions } from "@openuidev/react-lang";

export const library = createLibrary({
  root: "Dashboard",   // LLM always starts with: root = Dashboard(...)
  components: [StatCard, Dashboard],
  componentGroups: [
    {
      name: "Metrics",
      components: ["StatCard"],
      notes: [
        "- Always show a trend indicator when data is available.",
        "- Use 'large-heavy' text style for the value.",
      ],
    },
    {
      name: "Layout",
      components: ["Dashboard"],
    },
  ],
});

// Inline prompt generation (imports React — use generatePrompt for pure backends)
export const promptOptions: PromptOptions = {
  preamble: "You are a dashboard builder. Always output structured UI.",
  additionalRules: ["Prefer compact number formats (1.2k instead of 1200)."],
  examples: [
    `root = Dashboard("Revenue", [revenue, users])\nrevenue = StatCard("Revenue", "$12.4k", "up")\nusers = StatCard("Users", "1,200", "up")`,
  ],
  toolCalls: true,   // enables Query(), Mutation(), @Run
  bindings: true,    // enables $variables, @Set, @Reset
};

const systemPrompt = library.prompt(promptOptions);
```

### `<Renderer />` — parse and render OpenUI Lang streams

Parses OpenUI Lang text and renders nodes using the provided library. Re-parses incrementally as streaming chunks arrive; forward references resolve when their statements arrive.

```tsx
import { Renderer } from "@openuidev/react-lang";
import { library } from "@/lib/library";

function AssistantMessage({
  content,
  isStreaming,
}: {
  content: string | null;
  isStreaming: boolean;
}) {
  return (
    <Renderer
      response={content}
      library={library}
      isStreaming={isStreaming}
      // Wire tool calls to real functions or an MCP client
      toolProvider={{
        list_tickets: async (args) =>
          fetch("/api/tickets").then((r) => r.json()),
        create_ticket: async (args) =>
          fetch("/api/tickets", {
            method: "POST",
            body: JSON.stringify(args),
          }).then((r) => r.json()),
      }}
      // Receive interactive actions (form submits, button clicks)
      onAction={(event) => {
        if (event.type === "continue_conversation") {
          sendToChat(event.humanFriendlyMessage, event.formState);
        }
      }}
      // Structured errors suitable for LLM self-correction loops
      onError={(errors) => {
        if (!errors.length) return;
        const msg = errors
          .map(
            (e) =>
              `[${e.source}] ${e.statementId ? `"${e.statementId}": ` : ""}${e.message}${e.hint ? `\nHint: ${e.hint}` : ""}`,
          )
          .join("\n\n");
        sendToChat(`Fix these errors:\n\n${msg}`);
      }}
      // Persist and restore form state across messages
      initialState={savedFormState}
      onStateUpdate={(state) => saveFormState(state)}
    />
  );
}
```

### `generatePrompt` / `@openuidev/lang-core` — server-side prompt generation

Framework-agnostic prompt builder. Use this in Node/Edge/serverless routes that must not import React components.

```ts
import { generatePrompt } from "@openuidev/lang-core";
import componentSpec from "./generated/component-spec.json";  // from: openui generate --json-schema
import OpenAI from "openai";

const client = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });

const systemPrompt = generatePrompt({
  ...componentSpec,
  tools: [
    { name: "list_tickets", description: "Return open support tickets." },
    { name: "create_ticket", description: "Create a new ticket." },
  ],
  toolExamples: [
    `tickets = Query("list_tickets", {}, {rows: []})\nroot = Stack([tbl])\ntbl = Table([Col("Title", tickets.rows.title)])`,
  ],
  toolCalls: true,
  bindings: true,
  editMode: true,    // LLM patches only changed statements
  inlineMode: true,  // LLM can mix text + code in the same response
  preamble: "You are a helpful support dashboard assistant.",
  additionalRules: ['Use @Reset after form submit, not @Set($var, "")'],
});

export async function POST(req: Request) {
  const { messages } = await req.json();
  const completion = await client.chat.completions.create({
    model: "gpt-4o",
    stream: true,
    messages: [{ role: "system", content: systemPrompt }, ...messages],
  });
  return new Response(completion.toReadableStream(), {
    headers: { "Content-Type": "text/event-stream" },
  });
}
```

### Parser APIs — `createParser` and `createStreamingParser`

Low-level parsing utilities. Both accept a JSON schema from `library.toJSONSchema()`.

```ts
import { createParser, createStreamingParser } from "@openuidev/react-lang";

// One-shot parse
const parser = createParser(library.toJSONSchema());
const result = parser.parse(`
  root = Stack([header, card])
  header = CardHeader("Dashboard")
  card = StatCard("Revenue", "$12k")
`);
console.log(result.root);          // ElementNode tree
console.log(result.meta.errors);   // ValidationError[]
console.log(result.queryStatements); // Query() calls extracted from parse

// Streaming parse — push chunks as they arrive
const streamParser = createStreamingParser(library.toJSONSchema());
for await (const chunk of stream) {
  const partial = streamParser.push(chunk);
  renderPartialResult(partial);
}
const final = streamParser.getResult();
```

### Context hooks for component renderers

These hooks are available inside components defined with `defineComponent`. They must only be called within a component renderer function, not outside of it.

```tsx
import {
  useStateField,
  useTriggerAction,
  useIsStreaming,
  useRenderNode,
  useFormValidation,
} from "@openuidev/react-lang";

// Example: a custom Select component that binds to a $variable
const FilterSelect = defineComponent({
  name: "FilterSelect",
  description: "Dropdown bound to a reactive $variable.",
  props: z.object({
    name: z.string(),
    value: z.any().optional(),   // receives the $variable reference at runtime
    options: z.array(z.string()),
  }),
  component: ({ props }) => {
    // useStateField binds to $variable — changes propagate to all expressions referencing it
    const { value, setValue } = useStateField(props.name, props.value);
    const isStreaming = useIsStreaming();

    return (
      <select
        value={String(value ?? "")}
        onChange={(e) => setValue(e.target.value)}
        disabled={isStreaming}
      >
        {props.options.map((opt) => (
          <option key={opt} value={opt}>
            {opt}
          </option>
        ))}
      </select>
    );
  },
});
```

### `tagSchemaId` — name helper schemas in prompt output

Annotates a standalone Zod schema with a readable type name so the generated system prompt shows meaningful signatures instead of `any`.

```ts
import { defineComponent, tagSchemaId } from "@openuidev/react-lang";
import { z } from "zod/v4";

// Without tagSchemaId: action?: any
// With tagSchemaId:    action?: ActionExpression
const ActionExpression = z.any();
tagSchemaId(ActionExpression, "ActionExpression");

const Button = defineComponent({
  name: "Button",
  description: "Triggers an action on click.",
  props: z.object({
    label: z.string(),
    action: ActionExpression.optional(),
    variant: z.enum(["primary", "secondary", "danger"]).optional(),
  }),
  component: ({ props }) => <button>{props.label}</button>,
});
```

---

## `@openuidev/react-headless` — Chat state and streaming

### `ChatProvider` — root provider for headless chat

Wraps the component tree with shared chat state. Configure either `apiUrl` (simple) or `processMessage` (full control). Optionally configure thread history via `threadApiUrl` or custom thread functions.

```tsx
import {
  ChatProvider,
  openAIMessageFormat,
  openAIReadableStreamAdapter,
} from "@openuidev/react-headless";

export function App() {
  return (
    <ChatProvider
      // Full request control — auth headers, payload shaping, dynamic URLs
      processMessage={async ({ threadId, messages, abortController }) => {
        return fetch("/api/chat", {
          method: "POST",
          headers: {
            "Content-Type": "application/json",
            Authorization: `Bearer ${getToken()}`,
          },
          body: JSON.stringify({
            threadId,
            messages: openAIMessageFormat.toApi(messages),
          }),
          signal: abortController.signal,
        });
      }}
      threadApiUrl="/api/threads"
      streamProtocol={openAIReadableStreamAdapter()}
      messageFormat={openAIMessageFormat}
    >
      <MyChatUI />
    </ChatProvider>
  );
}
```

### `useThread()` — active conversation state and actions

Provides messages, send/cancel actions, and message mutation helpers. Use selectors to avoid unnecessary re-renders.

```tsx
import { useThread } from "@openuidev/react-headless";

function Composer() {
  const { processMessage, cancelMessage, isRunning } = useThread();
  const [input, setInput] = useState("");

  return (
    <form
      onSubmit={(e) => {
        e.preventDefault();
        if (!input.trim() || isRunning) return;
        processMessage({ role: "user", content: input });
        setInput("");
      }}
    >
      <input value={input} onChange={(e) => setInput(e.target.value)} />
      {isRunning ? (
        <button type="button" onClick={cancelMessage}>Stop</button>
      ) : (
        <button type="submit">Send</button>
      )}
    </form>
  );
}

// Selector form — re-renders only when messages change
const messages = useThread((state) => state.messages);
```

### `useThreadList()` — thread sidebar state

Manages thread loading, pagination, selection, creation, and deletion.

```tsx
import { useThreadList } from "@openuidev/react-headless";

function ThreadSidebar() {
  const {
    threads,
    selectedThreadId,
    hasMoreThreads,
    isLoadingThreads,
    loadMoreThreads,
    switchToNewThread,
    selectThread,
    deleteThread,
    updateThread,
  } = useThreadList();

  return (
    <aside>
      <button onClick={switchToNewThread}>New chat</button>
      {isLoadingThreads && <p>Loading...</p>}
      {threads.map((thread) => (
        <div key={thread.id}>
          <button
            onClick={() => selectThread(thread.id)}
            aria-pressed={thread.id === selectedThreadId}
          >
            {thread.title}
          </button>
          <button onClick={() => deleteThread(thread.id)}>✕</button>
        </div>
      ))}
      {hasMoreThreads && (
        <button onClick={() => loadMoreThreads()} disabled={isLoadingThreads}>
          Load more
        </button>
      )}
    </aside>
  );
}
```

### Stream protocol adapters

Select the adapter that matches what your backend actually emits. Mix and match with message format converters independently.

```tsx
import {
  openAIAdapter,
  openAIReadableStreamAdapter,
  openAIResponsesAdapter,
  agUIAdapter,
  openAIMessageFormat,
  openAIConversationMessageFormat,
} from "@openuidev/react-headless";
import { FullScreen } from "@openuidev/react-ui";

// OpenAI SDK response.toReadableStream() (most common)
<FullScreen
  apiUrl="/api/chat"
  streamProtocol={openAIReadableStreamAdapter()}
  messageFormat={openAIMessageFormat}
  agentName="Assistant"
/>

// Raw Chat Completions SSE (direct forwarding of data: chunks)
<FullScreen
  apiUrl="/api/chat"
  streamProtocol={openAIAdapter()}
  messageFormat={openAIMessageFormat}
  agentName="Assistant"
/>

// OpenAI Responses API
<FullScreen
  apiUrl="/api/chat"
  streamProtocol={openAIResponsesAdapter()}
  messageFormat={openAIConversationMessageFormat}
  agentName="Assistant"
/>

// AG-UI protocol (no adapter or converter needed — it's the default)
<FullScreen apiUrl="/api/chat" agentName="Assistant" />
```

### Artifact hooks — `useArtifact` and `useActiveArtifact`

Headless hooks for managing artifact panel state in custom layouts.

```tsx
import { useArtifact, useActiveArtifact } from "@openuidev/react-headless";
import { useId } from "react";

// Inside a defineComponent renderer — bind to a specific artifact
function MyArtifactPreview({ props }: { props: { code: string; title: string } }) {
  const artifactId = useId();
  const { isActive, open, close } = useArtifact(artifactId);

  return (
    <>
      <button onClick={open} className={isActive ? "active" : ""}>
        {isActive ? "Viewing" : "Open"} {props.title}
      </button>
      {/* ArtifactPanel portals to ArtifactPortalTarget in the layout */}
    </>
  );
}

// In a layout component — know when any artifact is open
function Layout({ children }: { children: React.ReactNode }) {
  const { isArtifactActive, closeArtifact } = useActiveArtifact();

  return (
    <div className={`layout ${isArtifactActive ? "panel-open" : ""}`}>
      <main className="flex-1">{children}</main>
      {isArtifactActive && <button onClick={closeArtifact}>Close panel</button>}
    </div>
  );
}
```

---

## `@openuidev/react-ui` — Prebuilt layouts and component libraries

### `FullScreen` — full-page chat layout

Full-page chat with a thread sidebar. All three layouts share `ChatLayoutProps` and wrap `ChatProvider` internally.

```tsx
import { openAIMessageFormat, openAIReadableStreamAdapter } from "@openuidev/react-headless";
import { FullScreen, createTheme } from "@openuidev/react-ui";
import { openuiLibrary } from "@openuidev/react-ui/genui-lib";

export default function Page() {
  return (
    <div className="h-screen">
      <FullScreen
        processMessage={async ({ messages, abortController }) => {
          return fetch("/api/chat", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({
              messages: openAIMessageFormat.toApi(messages),
            }),
            signal: abortController.signal,
          });
        }}
        streamProtocol={openAIReadableStreamAdapter()}
        componentLibrary={openuiLibrary}
        agentName="Assistant"
        threadApiUrl="/api/threads"
        messageFormat={openAIMessageFormat}
        welcomeMessage={{
          title: "Hello!",
          description: "How can I help you today?",
        }}
        conversationStarters={{
          variant: "short",
          options: [
            { label: "Show sales dashboard" },
            { label: "Create a support ticket" },
          ],
        }}
        theme={{
          mode: "dark",
          darkTheme: createTheme({
            interactiveAccentDefault: "oklch(0.72 0.18 260)",
          }),
        }}
      />
    </div>
  );
}
```

### `Copilot` — sidebar overlay layout

```tsx
import { Copilot } from "@openuidev/react-ui";
import { openuiChatLibrary } from "@openuidev/react-ui/genui-lib";

<Copilot
  apiUrl="/api/chat"
  componentLibrary={openuiChatLibrary}
  agentName="Copilot"
  theme={{ mode: "light" }}
/>
```

### `BottomTray` — floating collapsible chat widget

```tsx
import { useState } from "react";
import { BottomTray } from "@openuidev/react-ui";

function App() {
  const [isOpen, setIsOpen] = useState(false);

  return (
    <>
      <button onClick={() => setIsOpen(true)}>Open Chat</button>
      <BottomTray
        apiUrl="/api/chat"
        agentName="Support"
        isOpen={isOpen}
        onOpenChange={setIsOpen}
      />
    </>
  );
}
```

### Built-in component libraries (`genui-lib`)

Two ready-to-use libraries ship with `@openuidev/react-ui`, selectable from the `genui-lib` subpath.

```tsx
import {
  // Chat-optimized: root=Card, includes FollowUpBlock, ListBlock, SectionBlock
  openuiChatLibrary,
  openuiChatPromptOptions,

  // General-purpose: root=Stack, full layout/chart/form suite
  openuiLibrary,
  openuiPromptOptions,
} from "@openuidev/react-ui/genui-lib";

// Chat interface (card-based responses, follow-ups, sections)
<FullScreen componentLibrary={openuiChatLibrary} ... />

// Standalone renderer or dashboards (Stack root, Tabs, Accordion, Charts, etc.)
<Renderer response={message} library={openuiLibrary} />
```

### `Artifact()` — inline preview + side panel factory

Wraps a component with a preview/panel split. The preview renders inline in the chat message; clicking it activates the full-size panel.

```tsx
import { defineComponent } from "@openuidev/react-lang";
import { Artifact, ArtifactPortalTarget } from "@openuidev/react-ui";
import { z } from "zod";
import { Prism as SyntaxHighlighter } from "react-syntax-highlighter";

const CodeArtifact = defineComponent({
  name: "CodeArtifact",
  description: "Code block that expands into a full artifact panel.",
  props: z.object({
    language: z.string(),
    title: z.string(),
    code: z.string(),
  }),
  component: Artifact({
    title: (props) => props.title,
    preview: (props, { open, isActive }) => (
      <button
        onClick={open}
        className={`code-chip ${isActive ? "active" : ""}`}
      >
        📄 {props.title} ({props.language})
      </button>
    ),
    panel: (props, { close }) => (
      <div>
        <button onClick={close}>✕</button>
        <SyntaxHighlighter language={props.language}>{props.code}</SyntaxHighlighter>
      </div>
    ),
  }),
});

// For custom layouts, mount one ArtifactPortalTarget where panels should appear
function CustomLayout() {
  return (
    <div className="flex h-screen">
      <main className="flex-1">{/* chat area */}</main>
      <ArtifactPortalTarget className="w-[480px] border-l" />
    </div>
  );
}
```

### Thread history — `threadApiUrl` contract

Pass `threadApiUrl` to enable saved thread loading. OpenUI appends its own segments to the base URL.

```tsx
// Minimal setup — implements the default URL contract
<FullScreen
  apiUrl="/api/chat"
  threadApiUrl="/api/threads"
  messageFormat={openAIMessageFormat}
  agentName="Assistant"
/>

// Custom thread functions — for non-standard APIs (GraphQL, auth headers, etc.)
<FullScreen
  apiUrl="/api/chat"
  fetchThreadList={async (cursor) => {
    const res = await fetch(`/api/conversations?cursor=${cursor ?? ""}`);
    return res.json();  // { threads: Thread[], nextCursor?: any }
  }}
  createThread={async (firstMessage) => {
    const res = await fetch("/api/conversations", {
      method: "POST",
      headers: { "Content-Type": "application/json", Authorization: `Bearer ${getToken()}` },
      body: JSON.stringify({ firstMessage }),
    });
    return res.json();  // Thread
  }}
  updateThread={async (thread) => {
    const res = await fetch(`/api/conversations/${thread.id}`, {
      method: "PUT",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(thread),
    });
    return res.json();
  }}
  deleteThread={async (id) => {
    await fetch(`/api/conversations/${id}`, { method: "DELETE" });
  }}
  loadThread={async (threadId) => {
    const res = await fetch(`/api/conversations/${threadId}/messages`);
    return res.json();
  }}
  agentName="Assistant"
/>
```

---

## OpenUI Lang — Language Reference

### Syntax overview

OpenUI Lang is a line-oriented assignment language: one statement per line. The LLM generates it; the runtime executes it.

```text
# Component statement
identifier = ComponentName(positionalArg1, positionalArg2)

# Reactive state declaration
$variableName = defaultValue

# Data statement (read)
data = Query("tool_name", {arg: $variable}, {defaultValue}, refreshIntervalSeconds?)

# Data statement (write — only runs when triggered by @Run)
result = Mutation("tool_name", {arg: $variable})

# Root entry point — always required
root = Stack([header, content])
```

### Reactive state with `$variables`

```text
# Declare variables with defaults
$days = "7"
$search = ""
$showModal = false

# Two-way binding to input components
filter = Select("days", $days, [SelectItem("7", "7 days"), SelectItem("30", "30 days")])

# Variables in expressions — auto-re-evaluates when $days changes
title = TextContent("Last " + $days + " days")
data = Query("analytics", {days: $days}, {rows: []})

# Conditional rendering
$showModal ? Modal("Edit", $showModal, [editForm]) : null

# Change state from buttons
showBtn = Button("Edit", Action([@Set($showModal, true)]))
resetBtn = Button("Clear", Action([@Reset($search, $days)]))
```

### Query and Mutation — data fetching

```text
# Query: executes on load, re-fetches when $variables in args change
tickets = Query("list_tickets", {}, {rows: []})
filtered = Query("get_tickets", {status: $status, days: $days}, {rows: []}, 30)

# Access results with dot notation and array pluck
tbl = Table([
  Col("Title",  tickets.rows.title),
  Col("Status", tickets.rows.status),
  Col("Count",  "" + @Count(@Filter(tickets.rows, "status", "==", "open")))
])

# Mutation: only runs when triggered by @Run
createResult = Mutation("create_ticket", {title: $title, priority: $priority})
submitBtn = Button("Create", Action([
  @Run(createResult),
  @Run(tickets),
  @Reset($title, $priority)
]))

# Mutation error/success feedback
createResult.status == "error"   ? Callout("error",   "Failed",  createResult.error)  : null
createResult.status == "success" ? Callout("success", "Created", "Ticket added.")      : null
```

### Built-in functions

```text
# Aggregation
@Count(array)              → number
@Sum(array)                → number
@Avg(array)                → number
@Min(array) / @Max(array)  → value

# Filtering and sorting
openItems = @Filter(tickets.rows, "status", "==", "open")
sorted    = @Sort(tickets.rows, "created", "desc")

# Composition (KPI card pattern)
kpi = Card([
  TextContent("Open Tickets", "small"),
  TextContent("" + @Count(@Filter(data.rows, "status", "==", "open")), "large-heavy")
])

# Iteration — render a template for each array element
tags = @Each(tickets.rows, "t", Tag(t.priority, null, "sm"))

# Math
@Round(@Avg(data.rows.score), 1)   → 4.2
@Abs(-42)                          → 42
@Floor(3.9)                        → 3
@Ceil(3.1)                         → 4

# Action steps inside Action([...])
Button("Submit", Action([
  @Run(mutation),       # execute mutation or re-fetch query
  @Set($var, "value"),  # change a $variable
  @Reset($a, $b),       # restore $variables to defaults
  @ToAssistant("msg"),  # send message to LLM
  @OpenUrl("url"),      # open URL in new tab
]))
```

### Complete dashboard pattern

```text
$days = "7"
$search = ""
data      = Query("get_usage_metrics", {days: $days}, {totalEvents: 0, data: []})
endpoints = Query("get_top_endpoints", {days: $days}, {endpoints: []})

filter = FormControl("Date Range", Select("days", [
  SelectItem("7", "7 days"),
  SelectItem("30", "30 days")
], null, null, $days))

kpiRow = Stack([
  Card([TextContent("Events",  "small"), TextContent("" + data.totalEvents,                       "large-heavy")]),
  Card([TextContent("Avg/Day", "small"), TextContent("" + @Round(@Avg(data.data.events), 0),      "large-heavy")])
], "row", "m", "stretch", "start", true)

overviewTab  = TabItem("overview",  "Overview",  [LineChart(data.data.day, [Series("Events", data.data.events)])])
endpointsTab = TabItem("endpoints", "Endpoints", [
  Table([
    Col("Path",     endpoints.endpoints.path),
    Col("Requests", endpoints.endpoints.requests, "number"),
    Col("Latency",  endpoints.endpoints.avgLatency, "number")
  ])
])

root = Stack([CardHeader("Analytics Dashboard"), filter, kpiRow, Tabs([overviewTab, endpointsTab])])
```

### Incremental editing (`editMode`)

When `editMode: true` is set in the prompt config, the LLM emits only changed or new statements. The parser merges by statement name: same name replaces, new name is added, missing names are kept from the previous state.

```text
# Initial LLM output (full generation)
root = Stack([header, tbl])
header = CardHeader("Tickets")
tickets = Query("list_tickets", {}, {rows: []})
tbl = Table([Col("Title", tickets.rows.title)])

# User says: "add a pie chart of ticket status"
# LLM patch (only 2 lines — ~85% fewer tokens):
root = Stack([header, chart, tbl])
chart = PieChart(
  ["Open", "Closed"],
  [@Count(@Filter(tickets.rows, "status", "==", "open")),
   @Count(@Filter(tickets.rows, "status", "==", "closed"))],
  "donut"
)
# header, tickets, tbl — kept from original unchanged
```

---

## Summary

OpenUI is designed for two primary integration patterns: **chat interfaces** with rich generative UI responses, and **standalone interactive dashboards** rendered entirely from LLM-generated OpenUI Lang. For chat interfaces, the typical stack is `FullScreen`/`Copilot`/`BottomTray` from `@openuidev/react-ui` backed by `openAIReadableStreamAdapter()` and `openAIMessageFormat` from `@openuidev/react-headless`, with `openuiChatLibrary` for card-based chat responses or a custom `createLibrary()` definition for domain-specific components. For dashboards and embedded widgets, the `<Renderer />` component from `@openuidev/react-lang` is used directly, with a `toolProvider` map or MCP client supplying live data through `Query()` and `Mutation()` statements in the generated OpenUI Lang.

Across both patterns, the workflow is: define components with `defineComponent` + Zod schemas, assemble a `createLibrary()` result, run `openui generate` at build time to produce a system prompt (or use `generatePrompt` from `@openuidev/lang-core` for dynamic runtime prompts), include that prompt in every LLM request, and pass `componentLibrary` (or `library`) to the rendering layer. The headless layer (`@openuidev/react-headless`) is independent of the rendering layer and can be used alone to build fully custom chat UIs with `ChatProvider`, `useThread()`, and `useThreadList()` while still benefiting from built-in stream adapters, message format converters, and thread history persistence.