handleWorkflowStream()

Framework-agnostic handler for streaming workflow execution in AI SDK-compatible format. Use this function directly when you need to handle workflow streaming outside Hono or Mastra's own apiRoutes feature.

handleWorkflowStream() returns a ReadableStream that you can wrap with createUIMessageStreamResponse().

Use workflowRoute() if you want to create a workflow route inside a Mastra server.

Agent streaming in workflows

When a workflow step pipes an agent's stream to the workflow writer (e.g., await response.fullStream.pipeTo(writer)), the agent's text chunks and tool calls are forwarded to the UI stream in real time, even when the agent runs inside workflow steps.

See Workflow Streaming for more details.

Usage example

Next.js App Router example:

app/api/workflow/route.ts

import { handleWorkflowStream } from '@mastra/ai-sdk';
import { createUIMessageStreamResponse } from 'ai';
import { mastra } from '@/src/mastra';

export async function POST(req: Request) {
  const params = await req.json();
  const stream = await handleWorkflowStream({
    mastra,
    workflowId: 'weatherWorkflow',
    params,
  });
  return createUIMessageStreamResponse({ stream });
}

Parameters

mastra:

Mastra

The Mastra instance containing registered workflows.

workflowId:

string

The ID of the workflow to execute.

params:

WorkflowStreamHandlerParams

Parameters for the workflow stream.

params.runId?:

string

Optional run ID for the workflow execution.

params.resourceId?:

string

Optional resource ID for the workflow run.

params.inputData?:

Record<string, any>

Input data for starting a new workflow execution.

params.resumeData?:

Record<string, any>

Data for resuming a suspended workflow execution.

params.requestContext?:

RequestContext

Request context to pass to the workflow execution.

params.tracingOptions?:

TracingOptions

Options for tracing and observability.

params.step?:

string

Specific step to target in the workflow.

includeTextStreamParts?:

boolean

= true

Whether to include text stream parts in the output.