What is Agent UI?

Agent UI defines how structured agent work becomes visible and controllable in an AI client. It interoperates with runtimes, model streams, tools, workflows, context stores, permission systems, artifact services, evidence stores, sessions, and the host product interface.

Use Agent UI when an agent product needs stable UI semantics for:

• chat and final answers
• streaming status and tool progress
• queued, steered, or background tasks
• human approval, structured input, and interruption
• generated artifacts and editable canvases
• citations, evidence, review, and replay
• handoff between agents, users, sessions, and clients

Do not use it to store model prompts, tool protocols, business facts, executable workflows, artifact contents, evidence records, or permission policy. Those belong to adjacent runtime, workflow, context, artifact, evidence, or policy systems.

Surface layers

Layer	User question	Common surfaces	Runtime source
conversation	What did I ask and what was the final answer?	Messages, composer, final response, branch controls.	User input and assistant text parts.
process	What is the agent doing now?	Status strip, thinking summary, tool step, timeline.	Runtime status, reasoning, tool events, errors.
task	What work is running, queued, blocked, or awaiting me?	Task capsule, queue panel, approval card, subagent strip.	Queue, turn, task, and action-required records.
artifact	Where is the deliverable and how can I keep working on it?	Artifact Workspace, preview, editor/canvas, diff, version rail, export.	Artifact service, file store, generated object metadata.
evidence	Can I trust, replay, or audit the result?	Sources, evidence pack, verification, review decision.	Trace, source map, validation, replay, audit records.

The layers can be rendered in one page or across multiple panes. The contract is separation of responsibility, not a mandated layout.

Projection model

runtime facts + task facts + artifact facts + evidence facts
  -> UI projection model
  -> surfaces and controlled user actions

A UI projection may cache titles, labels, collapsed summaries, scroll windows, open panels, and local drafts. It must not become the owner of runtime identity, tool result, artifact contents, evidence verdict, or permission grant.

Why a standard?

Agent products repeatedly solve the same UI problems: streams arrive before final answers, tools produce large outputs, users need to approve actions, generated files need editing, and audits need evidence. Without shared terms, clients blend all of this into one message column.

Agent UI gives product teams and client implementors a small vocabulary for those decisions so products can interoperate without copying a visual skin or inventing a parallel runtime.