Add generative UI shell for interactive React components

[RhysSullivan]

Summary

Adds a generative UI shell that enables the Executor MCP server to render interactive React components generated by LLMs. The shell runs in an iframe via MCP Apps, receives JSX code, compiles and evaluates it in a sandboxed context, and provides access to tools and data-fetching hooks.

Key Changes

Shell Runtime

• Compiles JSX with Sucrase and evaluates in a scoped context with React, hooks, shadcn/ui components, Recharts, and Lucide icons
• Direct typeof checks for App/Component/Main — no fragile regex export detection
• Listens to both ontoolinput (fires on page reload) and ontoolresult for rendering
• Non-JSX results render as a formatted JSON data view
• Configurable maxHeight (default 800px) via const config = { maxHeight: N }
• Error boundary with surfaced error messages instead of silent failures

Tools Proxy

• tRPC-style recursive proxy: tools.github.issues.create() maps to execute-action call
• Unwraps kernel result envelope { status, result, logs } to return raw data
• run() escape hatch for multi-step tool composition

Server

• execute tool registered with _meta.ui for MCP Apps — JSX detected via isReactCode heuristic (capitalized tags, className=, onClick={, fragments)
• execute-action auto-approves elicitations — UI-initiated actions do not pause for approval since user already consented
• Capability-based execute-action visibility

Styling and Theming

• @tailwindcss/browser runtime bundled inline — any Tailwind class works at runtime
• Fixed @source path for shadcn component scanning
• Removed height 100% constraint so auto-resize reports real content height
• Dark mode via prefers-color-scheme + host theme context

Tool Description

• Generative UI section documents available components, hooks, dark mode theming, and config options
• Instructs models to use dark variants or theme variables for dark mode compatibility

Test Plan

• JSX code renders interactive React components in ChatGPT and Claude
• Non-JSX code executes normally and returns JSON
• useQuery fetches data via tools proxy (verified with Vercel domains API)
• UI-initiated mutations auto-approve (verified with domain auto-renew toggle)
• Page reload restores previously rendered UIs via ontoolinput
• Dark/light theme applies correctly
• Iframe auto-resizes with configurable maxHeight

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commit: 7ccfc42

[RhysSullivan]

@claude you can keep yourself as a coauthor on this PR because you did a good job but i better not see that shit again

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Status	Name	Latest Commit	Updated (UTC)
✅ Deployment successful! View logs	executor-cloud	7ccfc42	May 20 2026, 07:32 AM