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run.watch()

The .watch() function subscribes to state changes on a mastra run, allowing you to monitor execution progress and react to state updates.

Usage Example​

import { LegacyWorkflow } from "@mastra/core/workflows/legacy";

const workflow = new LegacyWorkflow({
  name: "document-processor",
});

const run = workflow.createRun();

// Subscribe to state changes
const unsubscribe = run.watch(({ results, activePaths }) => {
  console.log("Results:", results);
  console.log("Active paths:", activePaths);
});

// Run the workflow
await run.start({
  input: { text: "Process this document" },
});

// Stop watching
unsubscribe();

Parameters​

callback:

(state: LegacyWorkflowState) => void
Function called whenever the workflow state changes

LegacyWorkflowState Properties​

results:

Record<string, any>
Outputs from completed workflow steps

activePaths:

Map<string, { status: string; suspendPayload?: any; stepPath: string[] }>
Current status of each step

runId:

string
ID of the workflow run

timestamp:

number
Timestamp of the workflow run

Returns​

unsubscribe:

() => void
Function to stop watching workflow state changes

Additional Examples​

Monitor specific step completion:

run.watch(({ results, activePaths }) => {
  if (activePaths.get("processDocument")?.status === "completed") {
    console.log(
      "Document processing output:",
      results["processDocument"].output,
    );
  }
});

Error handling:

run.watch(({ results, activePaths }) => {
  if (activePaths.get("processDocument")?.status === "failed") {
    console.error(
      "Document processing failed:",
      results["processDocument"].error,
    );
    // Implement error recovery logic
  }
});