Agent Runtime and AG-UI reference

July 12, 2026 · View on GitHub

This reference is for Web, TUI, and other client developers. After reading it, you can construct agent run requests, understand run_config, consume AG-UI events, and handle cancel, errors, and restore.

Runtime entry

POST /api/copilotkit

This endpoint starts one agent run and returns an AG-UI event stream. Resource management, file upload, artifact download, and similar actions use /api/v1/* REST APIs.

Request context

Common fields:

Field	Description
`threadId`	Session ID. The backend uses it for history, session restore, and artifact archival.
`runId`	Single-run ID. Clients use it to cancel, trace, and replay.
`messages`	User input for this turn. Do not include credentials.
`forwardedProps.run_config`	Resource selection for this run; takes priority over state.
`state.run_config`	Run configuration in client state.

Example:

{
  "threadId": "session-001",
  "runId": "run-001",
  "messages": [
    {
      "role": "user",
      "content": "Compute GMV by channel from the orders table."
    }
  ],
  "forwardedProps": {
    "run_config": {
      "activeDatasourceId": "dtc-growth-demo",
      "enabledDatasourceIds": ["dtc-growth-demo"],
      "activeLlmProfileId": "server-default"
    }
  }
}

`run_config` fields

Field	Purpose
`enabledDatasourceIds`	Data sources available for this run.
`activeDatasourceId`	Default data source.
`enabledKnowledgeIds`	Knowledge bases available for this run.
`enabledMcpServerIds`	MCP servers available for this run.
`enabledSkillIds`	Skills available for this run.
`activeSkillId`	User-specified Skill.
`activeLlmProfileId`	Model profile for this run.
`skill_mode`	Skill selection mode, e.g. `auto`.
`fileIds`	Workspace file IDs.
`pinnedPaths`	File or artifact paths pinned in this session.
`mentioned`	Resources mentioned via `@`.

Clients send resource IDs, selections, and references only. The backend validates permissions, state, and capability switches.

Configuration merge

workspace defaults
  + per-run overrides
  + server policy
  = effective run config

workspace defaults come from workspace configuration.
per-run overrides come from input box selection, session resource toggles, and @ mentions.
server policy is enforced by the backend; clients cannot bypass it.

Event consumption

Clients render using AG-UI event semantics—no custom SSE/chat protocol required.

Category	Purpose
Run state	Run started, completed, canceled, or failed.
Text messages	Agent replies.
Reasoning / thought	Public reasoning summaries or step descriptions.
Tool calls	Schema inspection, SQL queries, file reads, and similar tool invocations.
Custom events	Structured data such as artifacts, SQL audit, token usage, workspace metadata.

Clients should retain runId, threadId, tool call IDs, and artifact IDs for details, cancel, and restore.

Cancel, errors, and restore

Scenario	Client action
User cancel	Call `POST /api/v1/runs/:runId/cancel`; stop button enters canceling state.
Run failure	Show backend error; keep received events and outputs.
Network drop	Read session history with `threadId`, then restore UI state.
Page refresh	Call session and artifact APIs to rebuild conversation, trace, and outputs.

The backend persists run events; clients do not need to resend full history on the next request.

Security boundaries

Do not put database passwords, model API keys, or MCP tokens in messages, context, or forwardedProps.
Data source access goes through Data Gateway.
Files, knowledge bases, Skills, and MCP tools are filtered by backend policy.
Event streams are for display and replay; they do not carry sensitive plaintext.