RFC: Agent-Composed UI via A2UI Protocol#25
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Proposes adopting Google's A2UI protocol as the rendering contract between capsules, the agent, and frontends. The agent owns the full layout composition with no predefined zones or hardcoded regions. The TUI is a dumb renderer. Key decisions: - A2UI adopted as-is, no custom extensions - Bus-based component discovery (same pattern as tools) - Agent composes the entire component tree - Natural language layout customization - Frontend-agnostic (CLI/web/Discord all render same descriptions) Tracks astrid#629.
joshuajbouw
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Topics carry no version — A2UI messages self-describe via the version field in every payload. Decouples IPC routing from spec evolution.
The LLM calls tools (compose_ui, delete_surface). A UI capsule bridges tool calls to A2UI IPC messages. IPC topics are internal plumbing between capsules and frontends, not the LLM's interface. Adds layers section, tool definitions, and updates composition flow.
Major revision: - Agent observes existing IPC traffic directly, no ui_describe needed - Capsules don't change — their existing events ARE the data sources - Agent publishes to a2ui.* as a bus participant, not through tools - Default layout on boot without LLM (static, cached on subsequent boots) - Multi-principal surfaces — each agent gets its own A2UI scope - Removed tool definitions, component discovery protocol, capsule changes
Components bind to IPC events via {topic, path} references. The runtime
subscribes to referenced topics and routes payload values to bound components
automatically. The agent describes structure + bindings, the runtime handles
plumbing. No agent involvement in routine data updates.
Traced through actual IpcPayload types and wire format:
- Custom payloads: field path is /payload/data/<field>
- Typed payloads (AgentResponse etc): path is /payload/<field>
Added end-to-end flow examples:
- Model name update: registry event → binding extraction → component render
- Layout change: user request → LLM → new structure+bindings → render
Binding syntax: {topic, path} where path is a JSON Pointer into the
full IPC message as it arrives on the wire.
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Summary
Proposes adopting Google's A2UI protocol as the rendering contract between capsules, the agent, and frontends. The agent owns the full layout composition — no predefined zones, slots, or hardcoded regions. The TUI is a dumb renderer that draws whatever component tree the agent describes.
Key decisions
ui.v1.request.describe, same pattern as tool discovery viatool.v1.request.describe. No manifest extensions.Tracking