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Run.resumeStreamVNext() (Experimental)

Experimental

This feature is experimental and the API may change in future releases.

The .resumeStreamVNext() method resumes a suspended workflow run with new data, allowing you to continue execution from a specific step and to observe the stream of events.

Usage example​

const run = await workflow.createRunAsync();

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

const result = await stream.result;

if (result!.status === "suspended") {
  const resumedStream = await run.resumeStreamVNext({
    resumeData: {
      value: "resume data",
    },
  });
}

Parameters​

resumeData?:

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

runtimeContext?:

RuntimeContext
Runtime context data to use during workflow execution

step?:

Step<string, any, any, any, any, TEngineType>
The step to resume execution from

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:

MastraWorkflowStream<ChunkType>
A custom stream that extends ReadableStream<ChunkType> with additional workflow-specific properties

stream.status:

Promise<RunStatus>
A promise that resolves to the current workflow run status

stream.result:

Promise<WorkflowResult<TState, TOutput, TSteps>>
A promise that resolves to the final workflow result

stream.usage:

Promise<{ inputTokens: number; outputTokens: number; totalTokens: number, reasoningTokens?: number, cacheInputTokens?: number }>
A promise that resolves to token usage statistics

Stream Events​

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

  • workflow-start: Workflow execution begins
  • workflow-step-start: A step begins execution
  • workflow-step-output: Custom output from a step
  • workflow-step-result: A step completes with results
  • workflow-finish: Workflow execution completes with usage statistics