Suspend & Resume

Pause workflows and continue them later. Perfect for human approvals, external events, or any async operation that takes time.

Quick Start

The simplest suspend & resume example:

import { createWorkflowChain } from "@voltagent/core";
import { z } from "zod";

const simpleApproval = createWorkflowChain({
  id: "simple-approval",
  name: "Simple Approval",
  input: z.object({ item: z.string() }),
  result: z.object({ approved: z.boolean() }),
}).andThen({
  id: "wait-for-approval",
  execute: async ({ data, suspend, resumeData }) => {
    // If we're resuming, return the decision
    if (resumeData) {
      return { approved: resumeData.approved };
    }

    // Otherwise, suspend and wait
    await suspend("Waiting for approval");
  },
});

// Run the workflow - it will suspend
const execution = await simpleApproval.run({ item: "New laptop" });
console.log(execution.status); // "suspended"

// Later, resume with a decision
const result = await execution.resume({ approved: true });
console.log(result.result); // { approved: true }

How It Works

When a workflow suspends:

Current state is saved
Workflow status becomes "suspended"
You get back an execution object with a resume() method
Later, call resume() with new data to continue

Using Schemas for Type Safety

Define what data you expect when resuming:

const approvalWorkflow = createWorkflowChain({
  id: "document-approval",
  name: "Document Approval",
  input: z.object({
    documentId: z.string(),
    authorId: z.string(),
  }),
  // Define what resume() accepts
  resumeSchema: z.object({
    approved: z.boolean(),
    reviewerId: z.string(),
    comments: z.string().optional(),
  }),
  result: z.object({
    status: z.enum(["approved", "rejected"]),
    reviewedBy: z.string(),
  }),
}).andThen({
  id: "review-document",
  execute: async ({ data, suspend, resumeData }) => {
    // resumeData is fully typed!
    if (resumeData) {
      return {
        status: resumeData.approved ? "approved" : "rejected",
        reviewedBy: resumeData.reviewerId,
      };
    }

    // Suspend for review
    await suspend("Document needs review");
  },
});

// TypeScript knows exactly what resume() expects
const result = await execution.resume({
  approved: true,
  reviewerId: "mgr-123",
  comments: "Looks good",
});

Step-Level Resume Schemas

Different steps can expect different resume data:

const multiStepApproval = createWorkflowChain({
  id: "multi-approval",
  input: z.object({ amount: z.number() }),
  // Default resume schema
  resumeSchema: z.object({ continue: z.boolean() }),
})
  .andThen({
    id: "manager-approval",
    // This step needs manager-specific data
    resumeSchema: z.object({
      approved: z.boolean(),
      managerId: z.string(),
    }),
    execute: async ({ data, suspend, resumeData }) => {
      if (resumeData) {
        return { ...data, managerApproved: resumeData.approved };
      }
      await suspend("Needs manager approval");
    },
  })
  .andThen({
    id: "finance-approval",
    // This step needs finance-specific data
    resumeSchema: z.object({
      approved: z.boolean(),
      financeId: z.string(),
      budgetCode: z.string(),
    }),
    execute: async ({ data, suspend, resumeData }) => {
      if (resumeData) {
        return {
          ...data,
          financeApproved: resumeData.approved,
          budgetCode: resumeData.budgetCode,
        };
      }
      if (data.amount > 1000) {
        await suspend("Needs finance approval");
      }
      return data;
    },
  });

Practical Example: User Verification

const userVerification = createWorkflowChain({
  id: "verify-user",
  input: z.object({
    userId: z.string(),
    email: z.string().email(),
  }),
  suspendSchema: z.object({
    verificationCode: z.string(),
    expiresAt: z.string(),
  }),
  resumeSchema: z.object({
    code: z.string(),
  }),
  result: z.object({
    verified: z.boolean(),
    verifiedAt: z.string().optional(),
  }),
})
  .andThen({
    id: "send-verification",
    execute: async ({ data, suspend }) => {
      const code = Math.random().toString(36).substring(2, 8);
      const expiresAt = new Date(Date.now() + 3600000).toISOString();

      // Send email (your implementation)
      await sendEmail(data.email, `Your code: ${code}`);

      // Suspend with the code for later verification
      await suspend("Waiting for verification", {
        verificationCode: code,
        expiresAt,
      });
    },
  })
  .andThen({
    id: "verify-code",
    execute: async ({ data, resumeData, suspendData }) => {
      // suspendData contains what was saved during suspend
      if (new Date(suspendData.expiresAt) < new Date()) {
        return { verified: false };
      }

      if (resumeData.code === suspendData.verificationCode) {
        return {
          verified: true,
          verifiedAt: new Date().toISOString(),
        };
      }

      return { verified: false };
    },
  });

// Usage
const execution = await userVerification.run({
  userId: "user-123",
  email: "[email protected]",
});

// Email sent, workflow suspended
console.log(execution.status); // "suspended"

// User enters code from email
const result = await execution.resume({ code: "abc123" });
console.log(result.result); // { verified: true, verifiedAt: "..." }

Resume From Specific Steps

Skip ahead or go back to any step when resuming:

const reviewWorkflow = createWorkflowChain({
  id: "multi-review",
  input: z.object({ docId: z.string() }),
})
  .andThen({
    id: "step-1-legal",
    resumeSchema: z.object({ approved: z.boolean() }),
    execute: async ({ data, suspend, resumeData }) => {
      if (resumeData) return { ...data, legal: resumeData.approved };
      await suspend("Legal review needed");
    },
  })
  .andThen({
    id: "step-2-finance",
    resumeSchema: z.object({ approved: z.boolean() }),
    execute: async ({ data, suspend, resumeData }) => {
      if (resumeData) return { ...data, finance: resumeData.approved };
      await suspend("Finance review needed");
    },
  })
  .andThen({
    id: "step-3-final",
    execute: async ({ data }) => {
      return { approved: data.legal && data.finance };
    },
  });

// Normal resume - continues from suspended step
const exec = await reviewWorkflow.run({ docId: "doc-123" });
await exec.resume({ approved: true }); // Resumes at step-1-legal

// Skip to different step
const exec2 = await reviewWorkflow.run({ docId: "doc-456" });
await exec2.resume(
  { approved: true },
  { stepId: "step-2-finance" } // Jump directly to finance review
);

Key Concepts

What Happens During Suspend?

Workflow pauses at current step
State is saved automatically
You get an execution object back
Call resume() when ready to continue

What Happens During Resume?

The suspended step runs again from the start
resumeData contains your new data
Workflow continues with next steps

Important Variables

data - The accumulated data from all previous steps
suspend - Function to pause the workflow
resumeData - Data provided when resuming (undefined on first run)
suspendData - Data that was saved during suspension

Common Patterns

Auto-Approve Pattern

.andThen({
  id: "approval",
  execute: async ({ data, suspend, resumeData }) => {
    if (resumeData) {
      return { approved: resumeData.approved };
    }

    // Auto-approve small amounts
    if (data.amount < 100) {
      return { approved: true };
    }

    // Otherwise suspend for manual approval
    await suspend("Manual approval required");
  }
})

Timeout Pattern

.andThen({
  id: "wait-for-payment",
  suspendSchema: z.object({
    orderId: z.string(),
    expiresAt: z.string()
  }),
  resumeSchema: z.object({
    paid: z.boolean()
  }),
  execute: async ({ data, suspend, resumeData, suspendData }) => {
    if (resumeData) {
      // Check if expired
      if (new Date() > new Date(suspendData.expiresAt)) {
        return { status: "expired" };
      }
      return { status: resumeData.paid ? "completed" : "cancelled" };
    }

    await suspend("Waiting for payment", {
      orderId: data.orderId,
      expiresAt: new Date(Date.now() + 3600000).toISOString() // 1 hour
    });
  }
})

Best Practices

1. Always Check resumeData First

execute: async ({ data, suspend, resumeData }) => {
  if (resumeData) {
    // Handle resume case
    return { ...data, approved: resumeData.approved };
  }

  // Normal execution
  await suspend("Needs approval");
};

2. Use Clear Schema Names

resumeSchema: z.object({
  approved: z.boolean(), // Not just "value"
  approvedBy: z.string(), // Not just "user"
  rejectionReason: z.string(), // Not just "reason"
});

3. Handle Timeouts

if (resumeData) {
  const expired = new Date() > new Date(suspendData.expiresAt);
  if (expired) {
    return { status: "timeout" };
  }
}

Quick Reference

Functions

suspend(reason?, data?) - Pause workflow
execution.resume(data?, options?) - Continue workflow

Key Parameters

data - Accumulated data from all steps
resumeData - Data provided when resuming
suspendData - Data saved during suspension

Resume Options

// Resume from suspended step
await execution.resume({ approved: true });

// Resume from specific step
await execution.resume({ approved: true }, { stepId: "step-2" });

External Suspension

You can also pause workflows from outside using createSuspendController:

import { createWorkflowChain, createSuspendController } from "@voltagent/core";
import { z } from "zod";

const workflow = createWorkflowChain({
  id: "long-process",
  name: "Long Process",
  input: z.object({ items: z.number() }),
  result: z.object({ processed: z.number() }),
}).andThen({
  id: "process-items",
  execute: async ({ data }) => {
    // Simulate long processing
    for (let i = 0; i < data.items; i++) {
      await new Promise((resolve) => setTimeout(resolve, 1000));
      console.log(`Processed ${i + 1}/${data.items}`);
    }
    return { processed: data.items };
  },
});

// Create controller to control the workflow externally
const controller = createSuspendController();

// Run workflow with the controller
const execution = await workflow.run({ items: 10 }, { suspendController: controller });

// Pause from outside (e.g., when user clicks pause button)
setTimeout(() => {
  controller.suspend("User clicked pause");
}, 3000);

// Check the result
if (execution.status === "suspended") {
  console.log("Paused:", execution.suspension?.reason);
  // Resume later
  const result = await execution.resume();
}

UI Integration Example

class WorkflowManager {
  private controller = createSuspendController();

  async start(workflow: any, input: any) {
    return workflow.run(input, {
      suspendController: this.controller,
    });
  }

  pause(reason?: string) {
    this.controller.suspend(reason || "User paused");
  }

  isPaused() {
    return this.controller.isSuspended();
  }
}

// In your UI
const manager = new WorkflowManager();
const execution = await manager.start(myWorkflow, input);

// Pause button handler
onPauseClick(() => {
  manager.pause("User clicked pause button");
});

REST API Usage

You can also control workflow suspension and resumption through the REST API. This is useful for web applications, mobile apps, or any external system that needs to manage workflows.

Suspend a Running Workflow

Endpoint: POST /workflows/{id}/executions/{executionId}/suspend

Suspend a running workflow execution from outside the workflow.

Request:

{
  "reason": "User clicked pause button" // Optional
}

Response:

{
  "success": true,
  "data": {
    "executionId": "exec_1234567890_abc123",
    "status": "suspended",
    "suspension": {
      "suspendedAt": "2024-01-15T10:30:45.123Z",
      "reason": "User clicked pause button"
    }
  }
}

cURL Example:

curl -X POST http://localhost:3141/workflows/order-approval/executions/exec_1234567890_abc123/suspend \
     -H "Content-Type: application/json" \
     -d '{"reason": "Manager is on vacation"}'

JavaScript Example:

async function suspendWorkflow(workflowId, executionId, reason) {
  const response = await fetch(
    `http://localhost:3141/workflows/${workflowId}/executions/${executionId}/suspend`,
    {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ reason }),
    }
  );

  const result = await response.json();
  if (result.success) {
    console.log("Workflow suspended:", result.data);
  }
}

// Usage
await suspendWorkflow(
  "order-approval",
  "exec_1234567890_abc123",
  "Waiting for payment confirmation"
);

Resume a Suspended Workflow

Endpoint: POST /workflows/{id}/executions/{executionId}/resume

Resume a suspended workflow with optional data and step selection.

Request:

{
  "resumeData": {
    "approved": true,
    "approvedBy": "[email protected]"
  },
  "options": {
    "stepId": "step-2" // Optional: resume from specific step
  }
}

Response:

{
  "success": true,
  "data": {
    "executionId": "exec_1234567890_abc123",
    "startAt": "2024-01-15T10:00:00.000Z",
    "endAt": "2024-01-15T10:31:15.456Z",
    "status": "completed",
    "result": {
      "approved": true,
      "processedBy": "[email protected]"
    }
  }
}

cURL Example:

curl -X POST http://localhost:3141/workflows/order-approval/executions/exec_1234567890_abc123/resume \
     -H "Content-Type: application/json" \
     -d '{
       "resumeData": {
         "approved": true,
         "managerId": "mgr-789",
         "comments": "Approved for urgent delivery"
       }
     }'

JavaScript Example:

async function resumeWorkflow(workflowId, executionId, resumeData, stepId) {
  const response = await fetch(
    `http://localhost:3141/workflows/${workflowId}/executions/${executionId}/resume`,
    {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({
        resumeData,
        ...(stepId && { options: { stepId } }),
      }),
    }
  );

  const result = await response.json();
  if (result.success) {
    console.log("Workflow resumed:", result.data);
    return result.data;
  }
}

// Resume with approval data
const result = await resumeWorkflow("order-approval", "exec_1234567890_abc123", {
  approved: true,
  approvedBy: "[email protected]",
});

// Resume from specific step
const result2 = await resumeWorkflow(
  "multi-step-workflow",
  "exec_9876543210_xyz789",
  { retryData: true },
  "step-3" // Jump to step-3
);

Complete Workflow Example with REST API

Here's a full example showing how to execute, suspend, and resume a workflow via REST API:

// 1. Execute workflow
async function executeWorkflow(workflowId, input) {
  const response = await fetch(`http://localhost:3141/workflows/${workflowId}/execute`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ input }),
  });

  const result = await response.json();
  return result.data;
}

// 2. Monitor workflow and suspend if needed
async function monitorAndSuspend(workflowId, executionId) {
  // In a real app, you might poll the status or use webhooks
  setTimeout(async () => {
    // User clicked pause
    await fetch(`http://localhost:3141/workflows/${workflowId}/executions/${executionId}/suspend`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ reason: "User requested pause" }),
    });
    console.log("Workflow suspended");
  }, 2000);
}

// 3. Resume after user input
async function handleUserApproval(workflowId, executionId, approved) {
  const response = await fetch(
    `http://localhost:3141/workflows/${workflowId}/executions/${executionId}/resume`,
    {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({
        resumeData: {
          approved,
          timestamp: new Date().toISOString(),
          userId: "current-user-id",
        },
      }),
    }
  );

  const result = await response.json();
  return result.data;
}

// Usage flow
async function processOrder() {
  // Start workflow
  const execution = await executeWorkflow("order-approval", {
    orderId: "order-123",
    amount: 5000,
    items: ["laptop", "mouse"],
  });

  console.log("Workflow started:", execution.executionId);

  // Monitor and possibly suspend
  await monitorAndSuspend("order-approval", execution.executionId);

  // Later, after user makes decision
  const finalResult = await handleUserApproval(
    "order-approval",
    execution.executionId,
    true // approved
  );

  console.log("Order processed:", finalResult);
}

Error Handling

Both endpoints return appropriate HTTP status codes:

Suspend Errors:

404: Workflow execution not found
400: Cannot suspend workflow in current state (e.g., already completed)
500: Server error

Resume Errors:

404: Workflow execution not found or not suspended
400: Invalid resume data (schema validation failed)
500: Server error

Error Response Format:

{
  "success": false,
  "error": "Cannot suspend workflow in completed state"
}

Example Error Handling:

try {
  const response = await fetch(
    `http://localhost:3141/workflows/${workflowId}/executions/${executionId}/resume`,
    {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ resumeData }),
    }
  );

  const result = await response.json();

  if (!result.success) {
    console.error("Resume failed:", result.error);
    // Handle specific error cases
    if (response.status === 404) {
      alert("Workflow not found or not suspended");
    } else if (response.status === 400) {
      alert("Invalid resume data provided");
    }
  }
} catch (error) {
  console.error("Network error:", error);
}

Next Steps

Learn about Workflow Schemas for type safety
Explore Step Types that support suspension
Try the VoltOps Console to manage suspended workflows
See REST API Documentation for complete API reference

Suspend & Resume

Quick Start​

How It Works​

Using Schemas for Type Safety​

Step-Level Resume Schemas​

Practical Example: User Verification​

Resume From Specific Steps​

Key Concepts​

What Happens During Suspend?​

What Happens During Resume?​

Important Variables​

Common Patterns​

Auto-Approve Pattern​

Timeout Pattern​

Best Practices​

1. Always Check resumeData First​

2. Use Clear Schema Names​

3. Handle Timeouts​

Quick Reference​

Functions​

Key Parameters​

Resume Options​

External Suspension​

UI Integration Example​

REST API Usage​

Suspend a Running Workflow​

Resume a Suspended Workflow​

Complete Workflow Example with REST API​

Error Handling​

Next Steps​

Table of Contents