The agent-interop gem of Poetry, the AI-native frontend framework for Rails. Five surfaces: the boot-free poetry-agent MCP server (the component contract over Model Context Protocol, with runtime skill delivery); the WebMCP runtime that registers rendered components' declared tools with in-browser agents (document.modelContext) behind safe-by-default, opt-in registration, declarative forms, and an origin-trial middleware; the AG-UI relay, a Rails client of the Agent-User Interaction protocol that runs an agent and relays its events as Turbo Streams, with frontend tools and interrupts; the A2UI catalog projected from the component registry; and the A2UI renderer that folds the envelope into server-rendered surfaces with forms, checks, functions, and morphing updates.