i2y

Build desktop, web, or terminal UIs with Castella. Create widgets, components, layouts, manage reactive state, handle events, and use the theme system.

Package Castella applications for distribution using ux, PyInstaller, or Nuitka. Create executables, macOS app bundles, and cross-compile for other platforms.

Connect to A2A protocol agents from Castella. Communicate with agents, display agent cards, send messages, handle responses, and stream results.

Render A2UI JSON as native Castella widgets. Parse A2UI messages, handle actions, progressive rendering, data binding, and connect to A2UI-enabled agents.

Build chat interfaces and agent management UIs with Castella. Create chat components, display tool calls, manage multiple agents, and build agent hubs.

Enable AI agents to introspect and control Castella UIs via MCP. Create MCP servers, expose UI resources, handle MCP tools, and use semantic IDs.

Use Ramune — a JS/TS runtime with soundness-gated AOT native compilation (via `ramune compile --hybrid`), powered by JavaScriptCore, QuickJS-NG-on-wazero, or goja (no Cgo). Use this skill when the user wants to run JS/TS code, compile TS to a standalone binary, auto-extract typed functions into native Go with --hybrid, embed a JS engine in Go, transpile TypeScript to Go, create native extension modules, self-host Cloudflare Workers-style handlers with `ramune serve`, or use the Ramune CLI. Triggers on "ramune", "run javascript", "run typescript", "JS runtime", "embed JS in Go", "JavaScriptCore", "transpile typescript to go", "native module", "--hybrid", "soundness-gated", "AOT native compilation", "self-host workers".