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Run.stream()

The .stream() method allows you to monitor the execution of a workflow run, providing real-time updates on the status of steps.

Usage example​

const run = await workflow.createRunAsync();

const { stream } = await run.stream({
  inputData: {
    value: "initial data",
  },
});

Parameters​

inputData?:

z.infer<TInput>
Input data that matches the workflow's input schema

runtimeContext?:

RuntimeContext
Runtime context data to use during workflow execution

tracingContext?:

TracingContext
AI tracing context for creating child spans and adding metadata. Automatically injected when using Mastra's tracing system.

currentSpan?:

AISpan
Current AI span for creating child spans and adding metadata. Use this to create custom child spans or update span attributes during execution.

tracingOptions?:

TracingOptions
Options for AI tracing configuration.

metadata?:

Record<string, any>
Metadata to add to the root trace span. Useful for adding custom attributes like user IDs, session IDs, or feature flags.

Returns​

stream:

ReadableStream<StreamEvent>
A readable stream that emits workflow execution events in real-time

getWorkflowState:

() => Promise<WorkflowResult<TState, TOutput, TSteps>>
A function that returns a promise resolving to the final workflow result

traceId?:

string
The trace ID associated with this execution when AI tracing is enabled. Use this to correlate logs and debug execution flow.

Extended usage example​

const { getWorkflowState } = await run.stream({
  inputData: {
    value: "initial data",
  },
});

const result = await getWorkflowState();

Stream Events​

The stream emits various event types during workflow execution. Each event has a type field and a payload containing relevant data:

  • start: Workflow execution begins
  • step-start: A step begins execution
  • tool-call: A tool call is initiated
  • tool-call-streaming-start: Tool call streaming begins
  • tool-call-delta: Incremental tool output updates
  • step-result: A step completes with results
  • step-finish: A step finishes execution
  • finish: Workflow execution completes