Event Types

Every event is one JSON object per line in the NDJSON stream. Each event has a type field, an optional data payload, and a streamIndex number.

Event structure

type EveStreamEvent = {
  type: string
  data?: Record<string, unknown>
  streamIndex: number
}

Session lifecycle events

session.started

A new session was created.

{ "type": "session.started", "data": {}, "streamIndex": 0 }

session.waiting

The session is idle and ready for the next user turn. This unlocks the composer in useEveAgent.

{ "type": "session.waiting", "streamIndex": 15 }

session.failed

A terminal error occurred. The session cannot be resumed.

{
  "type": "session.failed",
  "data": {
    "sessionId": "ses_abc123",
    "error": "Admission failed: Flue server unreachable"
  },
  "streamIndex": 16
}

Agent turn events

agent.start

An agent turn has begun.

{ "type": "agent.start", "streamIndex": 0 }

agent.content.delta

A fragment of streaming text from the agent.

{
  "type": "agent.content.delta",
  "data": { "text": "Hello" },
  "streamIndex": 1
}

Multiple content.delta events form the full text response.

message.appended

A complete message state update. Contains the full message with all accumulated content.

{
  "type": "message.appended",
  "data": {
    "id": "msg_abc123",
    "role": "assistant",
    "content": "Hello! How can I help?",
    "toolCalls": []
  },
  "streamIndex": 4
}

agent.tool_call

The agent invoked a tool.

{
  "type": "agent.tool_call",
  "data": {
    "toolCallId": "call_xyz",
    "tool": {
      "name": "connection__github_search",
      "description": "Search GitHub repositories",
      "parameters": { "type": "object", "properties": { "query": { "type": "string" } } }
    },
    "args": { "query": "flue-eve" }
  },
  "streamIndex": 5
}

agent.tool_result

A tool call completed.

{
  "type": "agent.tool_result",
  "data": {
    "toolCallId": "call_xyz",
    "tool": { "name": "connection__github_search" },
    "result": {
      "repositories": [
        { "name": "flue-eve", "stars": 42 }
      ]
    },
    "isError": false
  },
  "streamIndex": 7
}

When isError is true, result contains error details.

agent.complete

The agent turn finished successfully.

{ "type": "agent.complete", "streamIndex": 10 }

result.completed

A structured result when outputSchema was provided in the request.

{
  "type": "result.completed",
  "data": {
    "result": {
      "answer": "The capital of France is Paris",
      "confidence": 0.99
    }
  },
  "streamIndex": 11
}

HITL (Human-in-the-loop) events

input.requested

The agent is paused and waiting for user input.

{
  "type": "input.requested",
  "data": {
    "type": "approval",
    "prompt": "Should I proceed with deleting this resource?",
    "options": ["Approve", "Reject"]
  },
  "streamIndex": 6
}

The client sends inputResponses in the next POST /session/:id to resume.

input.resolved

The HITL input was received and the agent is resuming.

{ "type": "input.resolved", "streamIndex": 7 }

Authorization events (OAuth)

authorization.required

A connection needs OAuth authorization.

{
  "type": "authorization.required",
  "data": {
    "connection": "github",
    "authUrl": "https://github.com/login/oauth/authorize?client_id=..."
  },
  "streamIndex": 3
}

authorization.granted

OAuth authorization was completed.

{
  "type": "authorization.granted",
  "data": { "connection": "github" },
  "streamIndex": 5
}

Message event shapes

message.appended

{
  "type": "message.appended",
  "data": {
    "id": "msg_abc",
    "role": "assistant" | "user",
    "content": "Full message text",
    "toolCalls": [
      {
        "id": "tc_1",
        "toolCallId": "call_xyz",
        "toolName": "connection__github_search",
        "args": { "query": "..." },
        "result": { "repositories": [...] },
        "isError": false,
        "status": "complete"
      }
    ]
  },
  "streamIndex": 8
}

message.completed

{
  "type": "message.completed",
  "data": {
    "id": "msg_abc",
    "role": "assistant",
    "content": "Full message text"
  },
  "streamIndex": 12
}

Stream constants

Constant	Value	Description
`STREAM_FORMAT`	`"ndjson"`	Stream format identifier
`STREAM_VERSION`	`16`	Eve stream protocol version
`STREAM_CONTENT_TYPE`	`"application/x-ndjson; charset=utf-8"`	HTTP content type

See eve-to-flue mapping for how Flue internal events map to these Eve event types.