pollRace.ts

const { poll } = proxyActivities<typeof activities>({
  startToCloseTimeout: '10m',
  retryPolicy: {
    initialInterval: '1h',
    backoffCoefficient: 1
  }
});

export const stopPolling = defineSignal('stopPolling');

export async function resumeAfterCancellation(url: string): Promise<any> {
  let result: any;
  try {
    result = await CancellationScope.cancellable(async () => {
      setHandler(stopPolling, () => void CancellationScope.current().cancel());
      return await poll(url);
    });
  } catch (err) {
    if (!isCancellation(err)) { throw err }
  }
}

You can make this shorter:

export async function resumeAfterCancellation(url: string): Promise<any> {
  try {
    await CancellationScope.cancellable(async () => {
      setHandler(stopPolling, () => void CancellationScope.current().cancel());
      return await poll(url);
    });
  } catch (err) {
    if (!isCancellation(err)) { throw err }
  }
}