patched always true inside Signal

[ianmateusES]

Required

What is the issue?

How can we reproduce the issue?

Create a long-running workflow with a signal and start it. Then, make some changes to that signal and use patched to point to the new version.

What is the expected behavior?

Example

Additional context (optional—the more we know, the faster it goes)

Screenshots:
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Browser and version:
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Expected Behavior

Existing workflows are expected to use the previous signal flow, while new ones are redirected by patched. However, what happens is that they all end up going to the new flow, since patched always returns true.

Actual Behavior

How patched works inside the setHandler of a Signal. For every patchId set, wf.patched(patchId) returns true

Steps to Reproduce the Problem

• Workflow v1:

import { sleep, defineSignal, defineQuery, setHandler, log, patched } from '@temporalio/workflow';

export const updateMessage = defineSignal<[string]>('updateMessage');
export const query = defineQuery('query');

export async function longRunningWorkflow(): Promise<void> {
  let message = 'Initial message';

  setHandler(updateMessage, (newMessage: string) => {
    message = newMessage;
  });

  setHandler(query, () => message);

  await sleep(10 * 60 * 1000);
}

• Workflow v2:

import { sleep, defineSignal, defineQuery, setHandler, log, patched } from '@temporalio/workflow';

export const updateMessage = defineSignal<[string]>('updateMessage');
export const query = defineQuery('query');

export async function longRunningWorkflow(): Promise<void> {
  let message = 'Initial message';

  setHandler(updateMessage, (newMessage: string) => {
    if (patched('v2')) {
      log.info('Workflow was patched');
      message = newMessage + ' v2';
    } else {
      message = newMessage;
    }
  });

  setHandler(query, () => message);

  await sleep(10 * 60 * 1000);
}

Specifications

• Version: 1.8.0
• Platform: Docker v27.3.1