AgentChatEvent

Type

Covers every event in the message stream as one union discriminated on `type`.

Every event sendMessage streams, as one union discriminated on type, delivered raw to onEvent. The named callbacks cover the common members (text, thinking, tool_call_start, tool_call_result, client_tool_call, error); reach for the union to handle the lower-level ones like tool_use and tool_input_delta. Every member also carries a ts timestamp.

AgentChatEvent.ts

type AgentChatEvent =
  | { type: 'text'; text: string; ts: number }
  | { type: 'thinking'; text: string; ts: number }
  | { type: 'thinking_complete'; thinking: string; signature: string; ts: number }
  | { type: 'tool_use'; id: string; name: string; input: object; ts: number }
  | { type: 'tool_input_delta'; id: string; name: string; delta: string; ts: number }
  | { type: 'tool_call_start'; id: string; name: string; ts: number }
  | { type: 'tool_call_result'; id: string; output: unknown; ts: number }
  | { type: 'client_tool_call'; id: string; name: string; input: unknown; ts: number }
  | { type: 'done'; stopReason: string; usage: { inputTokens: number; outputTokens: number }; ts: number }
  | { type: 'error'; error: string; ts: number }

Fields

'text'

{ text }

An assistant text delta; append it. Covered by onText.

'thinking'

{ text }

An extended-thinking delta. Covered by onThinking.

'thinking_complete'

{ thinking, signature }

Thinking finished, with its full text and signature.

'tool_use'

{ id, name, input }

The model requested a tool call, with parsed input.

'tool_input_delta'

{ id, name, delta }

A streaming fragment of a tool call's input JSON.

'tool_call_start'

{ id, name }

A tool call began executing. Covered by onToolCallStart.

'tool_call_result'

{ id, output }

A tool call returned its result. Covered by onToolCallResult.

'client_tool_call'

{ id, name, input }

The agent invoked a browser-side client tool. Covered by onClientToolCall.

'done'

{ stopReason, usage }

The stream is complete; the promise resolves with this.

'error'

{ error }

A stream-level error. Covered by onError.

Handle the raw stream

chat.sendMessage(threadId, text, {
  onEvent: (e: AgentChatEvent) => {
    if (e.type === 'tool_input_delta') appendToolInput(e.id, e.delta);
  },
});