Agent Changelog#

This file helps coding agents understand project evolution, key decisions,
and deprecated patterns. Updated: 2026-02-05

Current State Summary#

mcp-app-studio is an MCP-first SDK and CLI for building interactive apps that run in any MCP Apps host (including ChatGPT). The SDK uses the standard ui/* bridge everywhere, and can optionally layer ChatGPT-only extensions from window.openai (widget state, file APIs, host modals, etc.) when available. Current version: 0.6.0.

Stale Information Detected#

Timeline#

2026-02-05 — MCP-first + ChatGPT Extensions (window.openai)#

What changed: Major shift to match OpenAI’s “MCP Apps in ChatGPT” guidance:

• Removed the ChatGPT “platform” implementation (src/platforms/chatgpt/*) and the mcp-app-studio/chatgpt export.
• Platform is now "mcp" | "unknown"; detectPlatform() no longer returns "chatgpt".
• UniversalProvider always uses the MCP Apps bridge and optionally layers ChatGPT-only extensions via withChatGPTExtensions() when window.openai exists.
• Added a connect timeout guard in the MCP bridge to avoid hanging forever outside a host.

Why: ChatGPT is an MCP Apps host; window.openai is an optional extensions layer (not a separate platform/protocol). Aligning to this makes the SDK “MCP-first” and portable across hosts.

Agent impact:

• If you were importing mcp-app-studio/chatgpt, switch to the universal SDK (mcp-app-studio) and use hasChatGPTExtensions() / useFeature() for extension-only features.
• If you were checking platform === "chatgpt", switch to hasChatGPTExtensions() or useFeature("widgetState").

Deprecated: None.

2026-01-27 — Package Renamed to mcp-app-studio#

What changed: Package renamed from chatgpt-app-studio to mcp-app-studio. All internal references, docs, and CLI commands updated.

Why: The package now supports both ChatGPT and MCP platforms equally. The new name better reflects its dual-platform scope.

Agent impact:

• CLI command is now npx mcp-app-studio (not npx chatgpt-app-studio)
• Import paths: import { ... } from "mcp-app-studio"
• Template repo is mcp-app-studio-starter

Deprecated:

• chatgpt-app-studio package name — use mcp-app-studio
• Any references to the old CLI command

2026-01-27 — Universal SDK Architecture Added#

What changed: Major refactor adding a platform-agnostic abstraction layer with automatic runtime detection.

Why: Enable single codebase to run on both ChatGPT and MCP platforms without conditional code.

Agent impact:

• Use UniversalProvider (recommended)
• Use useFeature() hook to check capability availability at runtime
• Bridge pattern: HostBridge interface with MCP bridge + optional ChatGPT extensions

Key files:

• src/core/ — Types, bridge interface, capabilities
• src/universal/ — Platform detection, provider, hooks
• src/platforms/mcp/ — MCP implementation

2026-01 — Template Externalized to GitHub#

What changed: Templates moved from bundled files to external GitHub repository (mcp-app-studio-starter).

Why: Smaller package size, templates can be updated independently of SDK releases.

Agent impact:

• CLI downloads templates from https://github.com/assistant-ui/mcp-app-studio-starter
• Template changes don't require SDK version bumps
• Network access required during scaffolding

2026-01-08 — Initial Package Creation (as chatgpt-app-studio)#

What changed: Package created with CLI scaffolding tool and local development workbench for ChatGPT Apps.

Why: Streamline ChatGPT App development with unified tooling.

Agent impact: Historical context only — package has evolved significantly since.

Deprecated Patterns#

Trajectory#

The package is evolving toward a fully platform-agnostic SDK. Recent work has focused on:

1. MCP-first behavior across hosts (including ChatGPT)
2. Keeping window.openai as optional extensions with clear boundaries
3. Improved error handling when rendered outside a host

Future development will likely continue refining MCP bridge compatibility and selectively wrapping additional window.openai extensions when it benefits developers without harming portability.