Resource Server API

startResourceServer(options)

Creates and starts the Resource Server.

import { startResourceServer } from "@casys/mcp-bridge";

// Synchronous — do NOT use await
const server = startResourceServer({
  assetDirectories: { "my-app": "./ui-dist" },
  platform: "telegram",
  telegramBotToken: Deno.env.get("TELEGRAM_BOT_TOKEN"),
  onMessage: async (session, message) => {
    // Forward tool calls to your MCP server and return the response
    return null;
  },
  options: { resourceServerPort: 4000, debug: true },
  csp: {},
});

console.log(`Listening at ${server.baseUrl}`);

Options (ResourceServerConfig)

Parameter	Type	Required	Description
assetDirectories	Record<string, string>	Yes	Directory containing UI assets, keyed by server name (from ui:// URI)
platform	"telegram" | "line"	Yes	Platform name for bridge.js configuration
telegramBotToken	string	Yes (telegram)	Telegram bot token for HMAC-SHA256 initData validation. Required when platform is "telegram" (fail-fast if omitted)
onMessage	(session, message) => Promise<McpAppsMessage | null>	No	Handler called when a JSON-RPC message is received from a webview
options	BridgeOptions	No	Bridge options: resourceServerPort, allowedOrigins, debug
csp	CspOptions	No	Custom CSP options applied to served HTML pages

Return Value

interface ResourceServer {
  readonly baseUrl: string;        // Base URL at which the server is listening
  readonly sessions: SessionStore; // Session store (for inspection/testing)
  stop(): Promise<void>;           // Stop the server and release resources
}

PlatformAdapter Interface

Implement this interface to add support for new platforms. This is the high-level platform SDK abstraction used by the BridgeClient client-side.

interface PlatformAdapter {
  readonly name: string;
  initialize(): Promise<HostContext>;
  getTheme(): "light" | "dark";
  getContainerDimensions(): ContainerDimensions;
  onLifecycleEvent(handler: LifecycleEventHandler): void;
  openLink(url: string): Promise<void>;
  sendMessage?(text: string): Promise<void>;
  getAuthData?(): Record<string, unknown>;
}