sunpeak is all-in on MCP Apps

Source: Dev.to

Overview

MCP Apps now run in ChatGPT, Claude, Goose, and VS Code. Claude announced MCP App support on January 26, and ChatGPT followed on February 4. As of February 2026 the major hosts have implemented the open standard.

Sunpeak’s APIs are built around the MCP App standard. ChatGPT‑ and Claude‑specific features are layered on top as optional imports, allowing you to write an app once and run it everywhere—including on localhost.

Core APIs

Sunpeak’s core APIs target the MCP App interface, not any single host. They are imported from the top‑level sunpeak package and work across all supported platforms.

import {
  useToolData,
  useHostContext,
  useDisplayMode,
  AppProvider,
} from 'sunpeak';
import type { ResourceConfig } from 'sunpeak';

export const resource: ResourceConfig = {
  name: 'dashboard',
  description: 'Show analytics dashboard',
};

export function DashboardResource() {
  const { output } = useToolData();
  const context = useHostContext();
  const displayMode = useDisplayMode();

  return {/* Your UI — runs in ChatGPT, Claude, Goose, VS Code */};
}

Host‑Specific APIs

Host‑specific functionality is provided via sub‑path imports, keeping the core code portable.

ChatGPT

import {
  ChatGPTSimulator,
  buildDevSimulations,
} from 'sunpeak/chatgpt';

The simulator, development‑simulation builder, and any ChatGPT‑only runtime features live in this namespace. They are first‑class components that do not pollute the portable resource code.

Additional host‑specific sub‑paths will be added as other platforms expose unique extensions.

Migration to v0.13

Version 0.13 refactors many APIs to align with MCP App abstractions and nomenclature. See the release notes for detailed migration instructions and the Sunpeak documentation for a complete overview of Sunpeak and MCP Apps.

Supported Hosts

The MCP App specification is now under the Linux Foundation and is actively developed at modelcontextprotocol/ext-apps.

Extensibility

MCP‑App‑first does not imply a lowest‑common‑denominator approach. Platform‑specific features are treated as first‑class extensions:

• ChatGPT – full access to OpenAI’s apps-sdk-ui component library, the ChatGPT simulator, and runtime APIs.
• Claude and other hosts – will receive their own sub‑path imports as platform‑specific features mature.

This pattern ensures the core remains portable while extensions stay organized.

Getting Started

pnpm add -g sunpeak && sunpeak new

Your app will run across ChatGPT, Claude, Goose, VS Code, and any future MCP App host from the first line of code.

Resources

• Documentation – guides, API reference, and tutorials
• GitHub – source code and issue tracker
• MCP App Framework – overview of Sunpeak’s capabilities