Method●Since v1.4

streamEvents

Executes the agent with the v3 streaming interface, returning an AgentRunStream that provides ergonomic, typed projections for messages, tool calls, and middleware events — without requiring knowledge of Pregel channels, stream modes, or namespace routing.

Pass version: "v3" to opt into this projection-oriented stream. Omitting version preserves the legacy internal LangGraph event-stream behavior for compatibility with LangGraph Platform integrations.

This v3 stream is experimental and its API may change in future releases. It will become the default in a future major release.

streamEvents(
  state: InvokeStateParameter<Types>,
  config: InvokeConfiguration<InferContextInput<Types["Context"] extends InteropZodObject | AnyAnnotationRoot  any[any] : AnyAnnotationRoot>  InferMiddlewareContextInputs<Types["Middleware"]>>  __type
): Promise<AgentRunStream<MergedAgentState<Types>, Types["Tools"], InferStreamExtensions<Types["StreamTransformers"]>>>

Parameters

Name	Type	Description
`state`*	`InvokeStateParameter<Types>`	The initial state for the agent execution. Can be: An object containing `messages` array and any middleware-specific state properties A Command object for more advanced control flow
`config`*	`InvokeConfiguration<InferContextInput<Types["Context"] extends InteropZodObject \| AnyAnnotationRoot ? any[any] : AnyAnnotationRoot> & InferMiddlewareContextInputs<Types["Middleware"]>> & __type`	Runtime configuration including:

Example

const run = await agent.streamEvents(
  {
    messages: [{ role: "user", content: "What's the weather in Paris?" }],
  },
  { version: "v3" }
);

// Stream all messages
for await (const msg of run.messages) {
  for await (const token of msg.text) {
    process.stdout.write(token);
  }
}

// Observe tool calls
for await (const call of run.toolCalls) {
  console.log(`Tool: ${call.name}`, call.input);
  console.log(`Result:`, await call.output);
}

// Get final state
const state = await run.output;

View source on GitHub

streamEvents

This v3 stream is experimental and its API may change in future releases. It will become the default in a future major release.

streamEvents( state: InvokeStateParameter<Types>, config: InvokeConfiguration<InferContextInput<Types["Context"] extends InteropZodObject | AnyAnnotationRoot any[any] : AnyAnnotationRoot> InferMiddlewareContextInputs<Types["Middleware"]>> __type ): Promise<AgentRunStream<MergedAgentState<Types>, Types["Tools"], InferStreamExtensions<Types["StreamTransformers"]>>>

Parameters

Name	Type	Description
`state`*	`InvokeStateParameter<Types>`	The initial state for the agent execution. Can be: An object containing `messages` array and any middleware-specific state properties A Command object for more advanced control flow
`config`*	`InvokeConfiguration<InferContextInput<Types["Context"] extends InteropZodObject \| AnyAnnotationRoot ? any[any] : AnyAnnotationRoot> & InferMiddlewareContextInputs<Types["Middleware"]>> & __type`	Runtime configuration including:

Example

const run = await agent.streamEvents(
  {
    messages: [{ role: "user", content: "What's the weather in Paris?" }],
  },
  { version: "v3" }
);

// Stream all messages
for await (const msg of run.messages) {
  for await (const token of msg.text) {
    process.stdout.write(token);
  }
}

// Observe tool calls
for await (const call of run.toolCalls) {
  console.log(`Tool: ${call.name}`, call.input);
  console.log(`Result:`, await call.output);
}

// Get final state
const state = await run.output;

streamEvents

Parameters

Example

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streamEvents

Parameters

Example