Mirror of https://github.com/modelcontextprotocol/ext-apps — Official repo for spec & SDK of MCP Apps protocol - standard for UIs embedded AI chatbots, served by MCP servers
- TypeScript 76.4%
- MDX 19.3%
- JavaScript 4.3%
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6bb63c3bae* feat: add transcript-server example with live speech transcription - New example: transcript-server with Web Speech API transcription - Start/stop recording with timer display - Live transcript with interim results - Send button to send transcript as ui/message to host - Copy button to copy full transcript - Sent messages marked with divider, greyed out - Experimental ui/update-model-context for live context updates - Transparent background, respects host theme - Enable microphone and clipboard in basic-host sandbox iframes - Add allow="microphone; clipboard-write" to both outer and inner iframes - Required for Web Speech API, audio capture, and clipboard access - Add alert popup in basic-host for ui/message from apps 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * style: format transcript-server files 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * test: add e2e test and golden for transcript-server 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * refactor: use @types/dom-speech-recognition instead of hand-rolled types Removes ~50 lines of manually defined Web Speech API types in favor of the community-maintained type package. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com> * fix: add newlines between transcript chunks when copying to clipboard * refactor: unify transcript formatting with timestamps - Add formatEntry() helper that includes [timestamp] prefix - Add formatEntries() helper that joins entries with newlines - Use same format for clipboard copy, send message, and model context - DRY up duplicate code in send button handler * fix: log model context update failures instead of silently swallowing * fix: log model context updates for debugging * refactor: pass permissions through loadSandboxProxy like csp - Add permissions parameter to loadSandboxProxy in implementation.ts - Build iframe allow attribute from permissions instead of hardcoding - Update sandbox.ts to not hardcode allow attribute (set via notification) - Add microphone + clipboardWrite permissions to transcript-server resource - Update README to reflect permission configuration via resource _meta.ui * fix(transcript-server): auto-expand instead of scroll - Remove min-height: 100vh and overflow-y: auto - Let content grow naturally with autoResize (default) - Remove unnecessary scrollTop calls * test: remove transcript timer mask (no longer dynamic) * refactor: pass permissions through loadSandboxProxy like csp * docs: document updateModelContext for transitional speech * test: update e2e screenshots * refactor: use app.updateModelContext() instead of raw request * package-lock.json * src/generated/schema.json * test: update e2e screenshots from CI --------- Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com> |
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@modelcontextprotocol/ext-apps
This repo contains the SDK and specification for MCP Apps Extension (SEP-1865).
MCP Apps are a proposed standard inspired by MCP-UI and OpenAI's Apps SDK to allow MCP Servers to display interactive UI elements in conversational MCP clients / chatbots.
How It Works
MCP Apps extend the Model Context Protocol to let servers deliver interactive UIs to MCP hosts. Here's how it works:
- Tool call — The LLM calls a tool on your server
- UI Resource — The tool's definition links to a predeclared
ui://resource containing its HTML interface - Host renders — The host fetches the resource and displays it in a sandboxed iframe
- Bidirectional communication — The host passes tool data to the UI via notifications, and the UI can call other tools through the host
This enables dashboards, forms, visualizations, and other rich experiences inside chat interfaces.
Overview
This SDK serves two audiences:
App Developers
Build interactive UIs that run inside MCP-enabled chat clients.
- SDK for Apps:
@modelcontextprotocol/ext-apps— API Docs - React hooks:
@modelcontextprotocol/ext-apps/react— API Docs
Host Developers
Embed and communicate with MCP Apps in your chat application.
- SDK for Hosts:
@modelcontextprotocol/ext-apps/app-bridge— API Docs
There's no supported host implementation in this repo (beyond the examples/basic-host example).
We have contributed a tentative implementation of hosting / iframing / sandboxing logic to the MCP-UI repository, and expect OSS clients may use it, while other clients might roll their own hosting logic.
Installation
npm install -S @modelcontextprotocol/ext-apps
Or edit your package.json manually:
{
"dependencies": {
"@modelcontextprotocol/ext-apps": "^0.0.1"
}
}
Examples
Start with these foundational examples to learn the SDK:
examples/basic-server-vanillajs— MCP server + MCP App using vanilla JSexamples/basic-server-react— MCP server + MCP App using Reactexamples/basic-server-vue— MCP server + MCP App using Vueexamples/basic-server-svelte— MCP server + MCP App using Svelteexamples/basic-server-preact— MCP server + MCP App using Preactexamples/basic-server-solid— MCP server + MCP App using Solidexamples/basic-host— MCP host application supporting MCP Apps
The examples/ directory contains additional demo apps showcasing real-world use cases.
To run all examples together:
npm install
npm start
Then open http://localhost:8080/.