{
 "acronym": "AG-UI",
 "adoption": {
  "by": null,
  "level": "observed",
  "probe_run": null
 },
 "aliases": [
  "AG-UI Protocol"
 ],
 "analog": "A server-sent-events/WebSocket API contract between a web frontend and its backend",
 "collisions": [
  "A2UI"
 ],
 "discovery": {
  "mechanism": "No fixed well-known path; a client is coded against a known agent backend endpoint that emits an AG-UI-compatible event stream over an agreed transport (SSE, WebSockets, webhooks)",
  "path": null
 },
 "dispute": null,
 "evidence": [
  {
   "claim": "CopilotKit's own announcement post, dated May 12, 2025, introduces AG-UI as 'an open, lightweight protocol that streams a single sequence of JSON events over standard HTTP or an optional binary channel.'",
   "date": "2025-05-12",
   "label": "VERIFIED",
   "url": "https://webflow.copilotkit.ai/blog/introducing-ag-ui-the-protocol-where-agents-meet-users"
  },
  {
   "claim": "docs.ag-ui.com/introduction (fetched 2026-09-05) describes AG-UI as an open, lightweight, event-based protocol, positions it as the 'Agent ↔ User Interaction' layer alongside MCP (Agent ↔ Tools & Data, from Anthropic) and A2A (Agent ↔ Agent, from Google), and lists 1st-party integrations from Microsoft Agent Framework, Google ADK, AWS Strands/Bedrock AgentCore, plus SDKs in Kotlin, Go, Dart, Java, Rust, Ruby, C++, .NET.",
   "date": "2026-09-05",
   "label": "VERIFIED",
   "url": "https://docs.ag-ui.com/introduction"
  },
  {
   "claim": "GitHub repo github.com/ag-ui-protocol/ag-ui carries an MIT license, 15.7k stars, 3,840+ commits, and daily commit activity as of Sep 4-5, 2026, indicating an actively maintained, multi-contributor project rather than a dormant announcement.",
   "date": "2026-09-05",
   "label": "VERIFIED",
   "url": "https://github.com/ag-ui-protocol/ag-ui"
  }
 ],
 "form": "endpoint",
 "governance": "AG-UI open-source project (github.com/ag-ui-protocol), originated and still primarily stewarded by CopilotKit; biweekly public working group",
 "group": null,
 "history": [
  {
   "date": "2026-09-05",
   "note": "seeded from Exa Agent research run"
  },
  {
   "date": "2026-09-06",
   "note": "verified against docs.ag-ui.com/introduction, github.com/ag-ui-protocol/ag-ui, and CopilotKit's original announcement"
  }
 ],
 "id": "ag-ui",
 "implementation": "multi-implementation",
 "last_verified": "2026-09-06",
 "name": "Agent-User Interaction Protocol",
 "native_status": "Open, lightweight, event-based protocol; described by its maintainers as the general-purpose, bi-directional connection between a user-facing application and any agentic backend",
 "origin": {
  "date": "2025-05-12",
  "org": "CopilotKit"
 },
 "part_of": null,
 "parties": [
  "agent-human"
 ],
 "phase": "living",
 "probe": {
  "method": "POST",
  "on_absent": "No AG-UI-shaped event stream; the backend is not exposing an AG-UI-compatible interface",
  "parse": "Response is an event stream using AG-UI's ~16 standard event types (e.g. TEXT_MESSAGE_START/CONTENT/END, RUN_ERROR, STATE_SNAPSHOT); presence of these event names confirms AG-UI compliance",
  "path": "{endpoint} — the application-defined AG-UI run endpoint (no fixed path; confirmed per-integration, e.g. via a framework's AG-UI adapter)"
 },
 "question": "How does an agent stream state, generative UI, messages, and tool activity into a user-facing application in real time?",
 "scope": "general",
 "spec_url": "https://docs.ag-ui.com/introduction",
 "step": "present",
 "summary_md": "AG-UI (Agent-User Interaction Protocol) is an open, lightweight, event-based protocol that standardizes how an AI agent backend streams state, messages, generative-UI updates, and tool activity into a user-facing frontend application, and how the frontend sends interactions and tool results back. CopilotKit announced it on May 12, 2025 as 'an open, lightweight protocol that streams a single sequence of JSON events over standard HTTP or an optional binary channel' [1]. Its own docs position it as one of three complementary 'agentic protocols': MCP handles Agent↔Tools/Data, A2A handles Agent↔Agent, and AG-UI handles Agent↔User Interaction — it is explicitly not a competitor to either [2].\n\nMechanically, an agent backend emits roughly sixteen standard event types (e.g. streaming text message chunks, tool-call events, state snapshots and diffs, run lifecycle/error events) over whatever transport the integration chooses — SSE, WebSockets, or webhooks are all named as compatible — and a middleware layer normalizes 'loose event format matching' so different backend frameworks and different frontend clients can interoperate without agreeing on a single wire transport [2]. AG-UI itself does not define a fixed origin path or well-known discovery file; a given application wires its own agent endpoint and a client library (or hand-rolled parser) that speaks the event vocabulary. AG-UI does not solve tool invocation (that is MCP's job) or agent-to-agent delegation (A2A's job), and it does not define authentication, payment, or content-permission mechanics.\n\nCurrent state (as of 2026-09-05): the protocol is actively developed under github.com/ag-ui-protocol/ag-ui (MIT license), which shows 15.7k stars, 170 branches, and near-daily commits including a merge less than a day before this check. It is described in its own docs as supported 'first-party' by Microsoft Agent Framework, Google ADK, AWS Strands Agents, Mastra, Pydantic AI, Agno, LlamaIndex, AG2, and AWS Bedrock AgentCore, with community-maintained SDKs in Kotlin, Go, Dart, Java, Rust, Ruby, C++, and .NET, and CopilotKit itself as the reference first-party client [2][3]. AG-UI also documents relationships with two adjacent generative-UI specs — A2UI (which it calls its own declarative generative-UI companion, with AG-UI as A2UI's 'standard transport binding') and MCP Apps — treating both as things it can carry rather than as competitors.\n\nWhat is disputed or unknown: there is no independent, documented count of production deployments; the evidence here is repository activity and named partner integrations, which is 'observed,' not a measured census. The relationship between AG-UI, originated and still steered largely by CopilotKit, and 'community' governance is informal — there is a public Discord and a biweekly working group, but no independent foundation. It is unclear how much of the 1st-party partner list reflects deployed production traffic versus documented compatibility.",
 "track": "community",
 "version": {
  "date": null,
  "label": "protocol stable, packages versioned independently (e.g. @ag-ui/core on npm)"
 }
}