workflowSnapshotToStream()

Converts a WorkflowState object (as returned by workflow.getWorkflowRunById()) into a ReadableStream of AI SDK UIMessage data parts. The stream contains the same WorkflowDataPart and WorkflowStepDataPart chunks that the live workflowRoute() produces.

Use this when you want to display a completed or suspended workflow run using the same UI components that render live workflow streams.

Usage example

Next.js App Router endpoint that replays a past workflow run as a stream:

app/api/workflow-replay/route.ts

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

export async function GET(req: Request) {
  const { searchParams } = new URL(req.url)
  const runId = searchParams.get('runId')!

  const workflowRun = await mastra.getWorkflow('myWorkflow').getWorkflowRunById(runId)

  if (!workflowRun) {
    return new Response('Not found', { status: 404 })
  }

  const stream = workflowSnapshotToStream(workflowRun)
  return createUIMessageStreamResponse({ stream })
}

Parameters

workflowRun:

WorkflowState

The workflow run state object, as returned by `getWorkflowRunById()` or the workflow runs API. Contains `runId`, `workflowName`, `status`, and `steps`.

Returns

ReadableStream — A stream of AI SDK UIMessage data parts containing:

• A start marker
• A WorkflowDataPart with the overall workflow status and all step summaries
• A WorkflowStepDataPart for each step with its full output
• A finish marker

Pass this stream to createUIMessageStreamResponse() or createUIMessageStream() from the AI SDK.

Related

• workflowRoute(): Stream live workflow runs
• handleWorkflowStream(): Framework-agnostic handler for live workflow streaming
• toAISdkStream(): Convert live Mastra streams to AI SDK format
• toAISdkMessages(): Convert stored agent messages to AI SDK format