Can I send an abortSignal to a workflow?

can i send an abortSignal to a workflow?

Now I have a comprehensive understanding. Here's the answer:

No, you cannot send an AbortSignal to a workflow run itself — but there are other mechanisms for cancellation, and AbortSignal is supported in specific sub-contexts.

###Cancelling a Workflow Run

Workflows don't accept an AbortSignal when started. The start() function (packages/core/src/runtime/start.ts) only accepts these options:

export interface StartOptions {
  deploymentId?: string;
  world?: World;
  specVersion?: number;
}

Instead, cancellation is done after the fact via the event-sourced run_cancelled event. You have two ways to cancel a running workflow:

1. Programmatically using the Run object (packages/core/src/runtime/run.ts:69-73):

   const run = await start(myWorkflow, args);
   // later...
   await run.cancel();
   

2. Via the cancelRun function (packages/core/src/runtime/runs.ts:88):

   import { cancelRun } from '@workflow/core/runtime';
   await cancelRun(world, runId);
   

3. Via the CLI:

   npx workflow cancel <run_id>
   

This sets the run's status to 'cancelled' and throws a WorkflowRunCancelledError if you're awaiting the returnValue.

###Why No AbortSignal?

Workflows are durable and event-sourced — they survive across serverless invocations and can be suspended/resumed. A JavaScript AbortSignal is an in-process, in-memory construct that doesn't survive across those boundaries. The cancellation model is instead based on persisted events (run_cancelled), which fits the durable execution model.

###Where AbortSignal is Supported

• @workflow/ai Durable Agent (packages/ai/src/agent/durable-agent.ts:197): The durableAgent() function accepts an abortSignal option to cancel AI generation within a step. It also has an onAbort callback.

• @workflow/ai Chat Transport (packages/ai/src/workflow-chat-transport.ts:18): Accepts an abortSignal to cancel HTTP requests to the workflow backend.

• Client-side stream reading (e.g., packages/web/app/lib/client/workflow-streams.ts:20): You can pass a signal when fetching a workflow's output stream, but this only cancels the read — not the workflow itself.

###Summary