pomerium/chatgpt-app-typescript-template

Implements MCP Apps with dual-layer UI capability negotiation—servers advertise interactive React widgets via `text/html;profile=mcp-app` MIME type while gracefully degrading to text-only output for non-UI hosts. Architecture uses HTTPStreamable transport for bidirectional communication, with widgets receiving runtime context (theme, display modes, safe areas, container dimensions) and exposing server tools through the App API (`callServerTool`, `updateModelContext`, `sendMessage`). Includes production-ready tooling: Zod-validated tools, Storybook component development, Vitest with a11y checks, Pino structured logging, and multi-stage Docker builds—plus a `createMockApp()` helper for testing widgets without a live MCP connection.