Complete developer tutorial: Building AI agent UIs with A2UI protocol

A comprehensive developer tutorial covering A2UI – a declarative protocol for AI agents to generate native UIs via JSON messages.

Technical highlights: - Adjacency list model (flat component list with ID refs) instead of nested trees – designed for LLM streaming and incremental generation - Data binding via JSON Pointer paths (RFC 6901) for reactive updates without component regeneration - Three-layer architecture: UI structure (surfaceUpdate), application state (dataModelUpdate), client rendering - Transport-agnostic: works with A2A Protocol, SSE, WebSockets, or AG UI

The tutorial includes: - Step-by-step agent setup with Python ADK (code examples included) - Client implementation guides for Lit, Angular, and Flutter renderers - Message processing & state management implementation checklist - Custom component catalog creation - Error handling and validation patterns

Production use: Google's Opal, Gemini Enterprise, Flutter GenUI SDK. React renderer coming Q1 2026. Full spec and samples on GitHub.

GitHub: https://github.com/google/a2ui