#Build and deploy

modern build uses the MCP Apps plugin and server compiler to emit the root definition as dist/mcp_apps.js, preserving relative paths for imported handlers. .mts and .cts definitions emit .mjs and .cjs respectively. UI HTML is in dist/mcp-apps/ui/. modern serve uses those artifacts. modern deploy produces a relocatable .output/ that runs with node .output/index.js, without source code.

In MF mode, UI publishes ordinary MF artifacts independently. Remote URLs can use runtime environment variables; the local handler module set must stay unchanged since compilation. Files read at runtime, native addons and other application assets still require application-specific deployment handling.

Without app-tools, pass a loaded definition to createMcpHandler(definition). Use your application compiler for the definition and handlers; the core no longer provides a separate compiler.

Persistent sessions, resumable SSE and cross-request cancellation are not provided yet. Standard MF is verified; target product hosts require their own compatibility checks.

#Standalone Hono deployment

Deploy the compiled definition, its imported handlers, dist/mcp-apps/ resources and application static assets with an independent Hono app:

import path from 'node:path';
import { Hono } from 'hono';
import { mcpApps } from '@modern-js/mcp-apps/hono';
import { loadMcpAppsConfig, bindUiResources } from '@modern-js/mcp-apps/server';

const root = path.resolve('application');
const definition = await loadMcpAppsConfig(path.join(root, 'mcp_apps.js'));
const app = new Hono();
app.all(
  '/mcp',
  mcpApps({
    definition: bindUiResources(definition, {
      directory: path.join(root, 'mcp-apps/ui'),
      assetBase: 'request',
    }),
  }),
);

The adapter does not start a listener; add authentication middleware in the app. Modern.js automatically mounts the MCP endpoint through BFF. An optional local view.html HTTPS URL lets the server read independently hosted HTML; use view.csp for its network permissions. Configure dev.assetPrefix for public development assets and output.assetPrefix for production assets. Configure remotes[].baseUrl separately with the manifest URL. MF resolves its assets using the manifest.

Include ts-node (^10.9.2) in devDependencies for BFF TypeScript loading and API module hot reload on Node 20+. For ESM projects, use "type": "module" and TypeScript module: "esnext", moduleResolution: "bundler" together.

MF manifests and chunks are served by the application static server or a CDN. The MF scaffold includes server/modern.server.ts to configure CORS and OPTIONS for public /static/* assets in both development and production. It does not change /mcp. Configure CORS separately when publishing these assets to a CDN. The MCP plugin itself does not register MF asset routes or add CORS headers.

For standalone local views, copy the complete dist/ to application/, preserving package name, version, module type, and relative imported module paths. Serve /static/* separately or publish assets to the configured CDN. The adapter serves MCP requests, not static assets.

All MF views require an explicit complete remotes[].baseUrl and CSP configuration. The address is passed unchanged to the MF runtime for loading. The tools-only template uses manual BFF compilation under dist/api/.

For UI-only builds with an existing MCP Server, see Use a user-managed MCP Server.