A bulk invoice generation workflow with cancellation support built with Vercel Workflow DevKit. Spot wrong prices mid-batch? Cancel before more customers get billed incorrectly.

• Run management: Using start() to get a Run object with runId
• Run retrieval: Using getRun(runId) to access an existing run
• Cancellation: Using run.cancel() to stop a running workflow
• Status checking: Using run.status, run.startedAt, run.completedAt properties
• Progress streaming: Real-time progress updates via getWritable() and run.readable
• Graceful interruption: Sleep points where cancellation can occur cleanly

05-cancellable-export/
├── app/
│   ├── api/
│   │   ├── start/
│   │   │   └── route.ts      # POST - Start invoicing workflow
│   │   ├── status/
│   │   │   └── route.ts      # GET - Check workflow status
│   │   ├── cancel/
│   │   │   └── route.ts      # POST - Cancel running workflow
│   │   └── stream/
│   │       └── [runId]/
│   │           └── route.ts  # GET - Stream progress (SSE)
│   ├── globals.css
│   ├── layout.tsx
│   └── page.tsx
├── workflows/
│   └── report-generator.ts      # The report generation workflow
├── next.config.ts               # Uses withWorkflow() wrapper
├── package.json
├── tsconfig.json
├── .env.example
└── README.md

1. Install dependencies:

pnpm install

1. Run the development server:

pnpm dev

Start a new invoicing workflow.

Request Body:

{
  "accountId": "acct_1",
  "total": 50,
  "delay": "1s"
}

Response:

{
  "runId": "run_abc123",
  "accountId": "acct_1",
  "total": 50,
  "delay": "1s",
  "message": "Invoice workflow started"
}

Check the status of a workflow run.

Query Parameters:

• runId (required): The workflow run ID

Response:

{
  "runId": "run_abc123",
  "status": "running",
  "startedAt": "2024-01-15T10:30:00.000Z",
  "completedAt": null
}

Status Values:

• pending - Workflow is queued but not started
• running - Workflow is currently executing
• completed - Workflow finished successfully
• failed - Workflow encountered an error
• cancelled - Workflow was cancelled

Cancel a running workflow.

Request Body:

{
  "runId": "run_abc123"
}

Response:

{
  "runId": "run_abc123",
  "message": "Workflow cancelled successfully",
  "previousStatus": "running",
  "currentStatus": "cancelled"
}

Stream real-time progress updates via Server-Sent Events (SSE).

Response (SSE format):

data: {"type":"progress","current":1,"total":50,"accountId":"acct_1","invoiceId":"INV-acct_1-0001","message":"Generated invoice 1 of 50"}

data: {"type":"progress","current":2,"total":50,"accountId":"acct_1","invoiceId":"INV-acct_1-0002","message":"Generated invoice 2 of 50"}

data: {"type":"complete","current":50,"total":50,"accountId":"acct_1","message":"Invoice batch completed: 50 invoices generated"}

curl -X POST http://localhost:3000/api/start \
  -H "Content-Type: application/json" \
  -d '{"accountId": "acct_1", "total": 10, "delay": "500ms"}'

curl "http://localhost:3000/api/status?runId=YOUR_RUN_ID"

curl -X POST http://localhost:3000/api/cancel \
  -H "Content-Type: application/json" \
  -d '{"runId": "YOUR_RUN_ID"}'

curl -N "http://localhost:3000/api/stream/YOUR_RUN_ID"

Here's a typical workflow for testing cancellation:

# Terminal 1: Start invoicing with slow delay
RUN_ID=$(curl -s -X POST http://localhost:3000/api/start \
  -H "Content-Type: application/json" \
  -d '{"accountId": "acct_1", "total": 20, "delay": "2s"}' | jq -r '.runId')

echo "Started run: $RUN_ID"

# Terminal 2: Watch progress (in another terminal)
curl -N "http://localhost:3000/api/stream/$RUN_ID"

# Terminal 3: Cancel after a few seconds (in another terminal)
sleep 5
curl -X POST http://localhost:3000/api/cancel \
  -H "Content-Type: application/json" \
  -d "{\"runId\": \"$RUN_ID\"}"

# Verify cancelled status
curl "http://localhost:3000/api/status?runId=$RUN_ID"

• Cancellation is effective for pending or running workflows
• Already completed, failed, or cancelled workflows cannot be cancelled
• Cancellation occurs at sleep boundaries - the workflow will finish its current step before stopping
• Cancelled workflows have their status set to cancelled and completedAt timestamp is recorded

You're generating 1,000 invoices and realize the pricing table was wrong. Without cancellation, those invoices go out to customers with incorrect amounts. With run.cancel(), you stop the batch at the next sleep boundary — only the invoices already generated need correction, not all 1,000.