AG-UI 1.0 landed as a stable specification (CopilotKit blog 2026-09-30): clear rules for every event, backed by a JSON Schema, with TypeScript, Python, and .NET SDKs generated from that schema—standardizing the bidirectional event stream between agent backends and user-facing apps (blog, spec).
The lead is the Agent–User Interaction protocol. MCP (tools) and A2A (agent↔agent) are complementary layers, not this story’s focus.
What shipped
| Piece | As stated |
|---|---|
| Spec | Behavioural prose for order, run start/end, errors + JSON Schema for event fields (https://ag-ui.com/spec/1.0/schema.json); schema wins on field structure |
| SDKs | First-party TypeScript / Python / .NET generated from the schema |
| Wire | Shared bi-directional event stream: agent endpoint streams AG-UI events; client SDK validates and hands them to the UI |
Lifecycle examples on the blog include RUN_STARTED, tool calls, STATE_DELTA, TEXT_MESSAGE_CONTENT, RUN_FINISHED. Supporting 1.0 features as CopilotKit states: subagent events, metadata, multimodal tool results, human-in-the-loop interrupts, token usage on run finish (blog, schema).
Backwards compatible with 0.x per blog; “the 1.0 spec won’t change” is a vendor stability claim, not a legal freeze.
Layer contrast
Per AG-UI docs: AG-UI = Agent ↔ User Interaction; MCP = Agent ↔ Tools & Data; A2A = Agent ↔ Agent—complementary layers (docs).
Cloud adoption
Blog: “adopted by Google, Microsoft, Amazon and Oracle” and supported by frameworks including LangChain, Mastra, and Anthropic’s Claude Managed Agents—as CopilotKit states. This post is not claiming GA on every cloud (blog).
Who should care
Teams wiring agent backends to frontends who want a versioned event contract should start at the AG-UI 1.0 post and spec.
The Campfire
No commentsNobody has pulled up a log by this one yet. Be the first to say what you make of it.
Held for the desk. It appears after a look.