examples/showcases/open-mcp-client/README.md
Production go-live: docs/TRACKER.md · Stakeholder / product handoff (shipped scope, CopilotKit open questions): docs/HANDOFF.md
This monorepo demonstrates MCP Apps with CopilotKit: the MCP App builder web UI (apps/web) drives a Mastra agent (/api/mastra-agent) that can provision E2B sandboxes running the mcp-use-server template (apps/mcp-use-server). An optional local sample is the Three.js MCP example in apps/threejs-server (used for sidebar defaults when running everything locally).
https://github.com/user-attachments/assets/4bb35806-5e42-43c0-a8fe-01c0d1e5b8b3
OPENAI_API_KEY); optional OPENAI_MODEL for /api/mastra-agent (default gpt-5.2)Lockfile:
pnpm-lock.yamlis committed and should stay in version control so installs are reproducible (--frozen-lockfile). This repo’s.gitignoreonly excludespackage-lock.json,yarn.lock, andbun.lockb— not pnpm’s lockfile.
From the repository root (with-mcp-apps):
pnpm i
Copy-Item .env.example .env
# Edit .env: set OPENAI_API_KEY=sk-proj-... at minimum; add E2B_* for sandbox provisioning (see below)
pnpm dev
pnpm dev runs Turbo and starts workspace dev tasks (the Next.js app and other configured apps — see root package.json / turbo.json).
Run pieces individually
| Goal | Command |
|---|---|
| Web app only | pnpm --filter web dev (from repo root) or cd apps/web && pnpm dev |
| Three.js MCP sample (local sidebar default) | cd apps/threejs-server && pnpm dev |
mcp-use-server (local MCP, not the E2B image) | cd apps/mcp-use-server && pnpm dev |
Open the URL shown by Next (usually http://localhost:3000).
package.json)| Script | Description |
|---|---|
pnpm dev | Turbo: all packages’ dev scripts |
pnpm build | Turbo: all packages’ build (for web, runs prebuild first — see below) |
pnpm lint | Turbo lint |
pnpm clean / pnpm fresh | Remove installs / lockfile helpers (see script definitions) |
apps/web| Script | Description |
|---|---|
pnpm dev | Next.js dev (Turbopack) |
pnpm build | Runs prebuild → pack-download-kit (writes .download-kit/base.tar.gz for full app kit download), then next build |
pnpm pack-download-kit | Regenerate .download-kit/base.tar.gz without a full Next build |
pnpm start | Production Next server |
pnpm lint | ESLint |
pnpm run test:download-kit | Integration test: Next + E2B + POST /api/workspace/download (see apps/web/test/) |
pnpm run test:e2b-download | Smoke test: E2B tarball only |
pnpm run dev:mcp | Starts the Three.js sample MCP from apps/threejs-server (for local MCP alongside web) |
Manual scripts under apps/web/test/: run from apps/web as node test/<file>.mjs (paths and env documented in each file).
apps/mcp-use-server)The agent provisions sandboxes from an E2B template defined in template.ts. Rebuild the image when you change dependencies, tools, or widgets there.
| Script | When to use | Command (from repo root) |
|---|---|---|
Dev template (mcp-use-server-dev) | Day-to-day iteration | cd apps/mcp-use-server && npx tsx --env-file=../../.env build.dev.ts |
Prod template (mcp-use-server) | Stable snapshot for production | cd apps/mcp-use-server && npx tsx --env-file=../../.env build.prod.ts |
Requirements: E2B_API_KEY in .env (or environment). The CLI prints a BuildInfo object; set E2B_TEMPLATE to templateId from that output (and the same in your hosting dashboard). Template name (e.g. mcp-use-server-dev) is not the same as templateId.
The app title is MCP App builder (subtitle Powered by CopilotKit), logo apps/web/app/image.png, agent route /api/mastra-agent. Header CTAs use NEXT_PUBLIC_HEADER_* (and NEXT_PUBLIC_GITHUB_REPO_URL for the secondary link; code default points at this demo repo). Chat starters: NEXT_PUBLIC_CHAT_STARTER_PROMPTS (JSON) or three built-in bounded demos — tic tac toe, tip calculator, dice roller (docs/HANDOFF.md). Reference CopilotKit route: apps/web/app/api/copilotkit/route.ts.
Starter prompts use useCopilotChatSuggestions (ChatSuggestions.tsx) with v2 CopilotChat.
Post-provision test chips: frontend action show_mcp_test_prompts (McpTestPromptsAction.tsx) — JSON string of { label, message }[] for clickable chips (appendMessage).
Download: restart_server / sidebar download can return a full app kit (.tar.gz): E2B workspace merged into mcp-apps-starter/ when apps/web/.download-kit/base.tar.gz exists (created by pnpm build / prebuild in apps/web). Otherwise download is MCP-only. Details: docs/HANDOFF.md.
Debug agent traffic: set MASTRA_AGENT_DEBUG=1 in .env for verbose /api/mastra-agent logs (see .env.example).
Mastra can reuse the same messageId for tool-call parents and text events; CopilotKit then collides keys. mastra-agent/route.ts remaps ids when collisions are detected — see docs/HANDOFF.md / inline comments.
serverId); list is sent as x-mcp-servers. Built-in default: Excalidraw (https://mcp.excalidraw.com). Override via NEXT_PUBLIC_DEFAULT_MCP_SERVERS / DEFAULT_MCP_SERVERS.More: docs/DYNAMIC_MCP.md.
md+).| Variable | Description |
|---|---|
E2B_API_KEY | From e2b.dev/dashboard |
E2B_TEMPLATE | templateId from Template.build output after build.dev.ts / build.prod.ts |
E2B_REPO_URL | Used when E2B_TEMPLATE is empty — clones repo into sandbox (slower cold start). Default in code: mcp-use-server-template GitHub URL |
render.yaml.OPENAI_API_KEY; for sandboxes add E2B_API_KEY + E2B_TEMPLATE.NODE_VERSION, and HOSTNAME automatically.Render runs a long-lived Node.js process (not serverless), so there are no per-function timeout limits. See docs/DEPLOY-RENDER.md for full setup, env var tables, and troubleshooting.
Widget tools should include _meta["ui/previewData"] for offline sidebar preview (example: apps/mcp-use-server/tools/product-search.ts).
In this repo
docs/TRACKER.md — production go-live checklistdocs/HANDOFF.md — shipped scope, CopilotKit open questionsdocs/DEPLOY-RENDER.md — Render deployment guidedocs/DYNAMIC_MCP.md — dynamic MCP patternsdocs/PLAN.md / docs/E2B-IMPLEMENTATION.md — roadmap and E2B designUI entry: apps/web/app/page.tsx (theme, layout, CopilotKit wiring).
External
Issues and PRs welcome.
MIT — see LICENSE.