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import type {
  McpUiHostContext,
  McpUiHostCapabilities,
  McpUiAppCapabilities,
  McpUiClientCapabilities,
  McpUiTheme,
  McpUiDisplayMode,
  McpUiStyles,
  McpUiStyleVariableKey,
  McpUiHostStyles,
  McpUiHostCss,
  McpUiToolMeta,
  McpUiToolVisibility,
  McpUiResourceMeta,
  McpUiResourceCsp,
  McpUiResourcePermissions,
  McpUiSupportedContentBlockModalities,
} from "sunpeak";

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McpUiHostContext

Rich context about the host environment, provided during initialization and updated via onhostcontextchanged. 
interface McpUiHostContext {
  toolInfo?: {
    id?: RequestId;
    tool: Tool;
  };
  theme?: McpUiTheme;
  styles?: McpUiHostStyles;
  displayMode?: McpUiDisplayMode;
  availableDisplayModes?: McpUiDisplayMode[];
  containerDimensions?: {
    width?: number;
    maxWidth?: number;
    height?: number;
    maxHeight?: number;
  };
  locale?: string;           // BCP 47 format (e.g., "en-US")
  timeZone?: string;         // IANA format (e.g., "America/New_York")
  userAgent?: string;        // Host application identifier
  platform?: "web" | "desktop" | "mobile";
  deviceCapabilities?: {
    touch?: boolean;
    hover?: boolean;
  };
  safeAreaInsets?: {
    top: number;
    right: number;
    bottom: number;
    left: number;
  };
}

​
McpUiHostCapabilities

Capabilities supported by the host, received during initialization. 
interface McpUiHostCapabilities {
  experimental?: {};
  openLinks?: {};
  downloadFile?: {};
  serverTools?: { listChanged?: boolean };
  serverResources?: { listChanged?: boolean };
  logging?: {};
  sandbox?: {
    permissions?: McpUiResourcePermissions;
    csp?: McpUiResourceCsp;
  };
  updateModelContext?: McpUiSupportedContentBlockModalities;
  message?: McpUiSupportedContentBlockModalities;
}
FieldDescription
openLinksHost supports openLink()
downloadFileHost supports downloadFile()
serverToolsHost can proxy callServerTool() to the MCP server
serverResourcesHost can proxy resources/read to the MCP server
loggingHost accepts sendLog() messages
sandboxPermissions and CSP applied by the host
updateModelContextHost accepts updateModelContext()
messageHost accepts sendMessage()

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McpUiAppCapabilities

Capabilities provided by the View, sent during initialization. 
interface McpUiAppCapabilities {
  experimental?: {};
  tools?: { listChanged?: boolean };
  availableDisplayModes?: McpUiDisplayMode[];
}
FieldDescription
toolsApp exposes tools that the host can call via oncalltool
availableDisplayModesDisplay modes the app supports

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McpUiClientCapabilities

Advertised by hosts to servers via the MCP extensions field. Used with getUiCapability(). 
interface McpUiClientCapabilities {
  mimeTypes?: string[];  // Must include "text/html;profile=mcp-app"
}

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McpUiTheme

type McpUiTheme = "light" | "dark";

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McpUiDisplayMode

type McpUiDisplayMode = "inline" | "fullscreen" | "pip";

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McpUiHostStyles

interface McpUiHostStyles {
  variables?: McpUiStyles;
  css?: McpUiHostCss;
}

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McpUiHostCss

interface McpUiHostCss {
  fonts?: string;  // @font-face rules or @import statements
}

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McpUiStyles

A record mapping CSS variable names to string values. All keys are optional. 
type McpUiStyles = Record<McpUiStyleVariableKey, string | undefined>;
See CSS Variables for the full list of variable keys.

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McpUiToolMeta

UI metadata for tools, set in _meta.ui of tool configuration. 
interface McpUiToolMeta {
  resourceUri?: string;
  visibility?: McpUiToolVisibility[];  // Default: ["model", "app"]
}

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McpUiToolVisibility

type McpUiToolVisibility = "model" | "app";

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McpUiResourceMeta

UI metadata for resources, set in _meta.ui of resource content items. 
interface McpUiResourceMeta {
  csp?: McpUiResourceCsp;
  permissions?: McpUiResourcePermissions;
  domain?: string;
  prefersBorder?: boolean;
}

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McpUiResourceCsp

Content Security Policy configuration. 
interface McpUiResourceCsp {
  connectDomains?: string[];     // fetch/XHR/WebSocket origins
  resourceDomains?: string[];    // img/script/style/font/media origins
  frameDomains?: string[];       // Nested iframe origins
  baseUriDomains?: string[];     // Allowed base URIs
}

​
McpUiResourcePermissions

Browser capabilities requested by the resource. 
interface McpUiResourcePermissions {
  camera?: {};
  microphone?: {};
  geolocation?: {};
  clipboardWrite?: {};
}

​
McpUiSupportedContentBlockModalities

Content block types supported by the host for sendMessage and updateModelContext. 
interface McpUiSupportedContentBlockModalities {
  text?: {};
  image?: {};
  audio?: {};
  resource?: {};
  resourceLink?: {};
  structuredContent?: {};
}