Function condition

Pauses the workflow until a signal with the given signalId is received. The workflow suspends durably — it survives process restarts and will resume exactly once when the matching signal() call delivers data.

condition is the receive side of the signal coordination pair. The send side is signal(), which can be called from another workflow, a hook function, or externally via Durable.Client.workflow.signal().

On replay, condition returns the previously stored signal payload immediately (no actual suspension occurs).

Examples

import { Durable } from '@hotmeshio/hotmesh';

// Human-in-the-loop approval pattern
export async function approvalWorkflow(orderId: string): Promise<boolean> {
  const { submitForReview } = Durable.workflow.proxyActivities<typeof activities>();

  await submitForReview(orderId);

  // Pause indefinitely until a human approves or rejects
  const decision = await Durable.workflow.condition<{ approved: boolean }>('approval');

  return decision.approved;
}

// Later, from outside the workflow (e.g., an API handler):
await client.workflow.signal('approval', { approved: true });
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// Fan-in: wait for multiple signals in parallel
export async function gatherWorkflow(): Promise<[string, number]> {
  const [name, score] = await Promise.all([
    Durable.workflow.condition<string>('name-signal'),
    Durable.workflow.condition<number>('score-signal'),
  ]);
  return [name, score];
}
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// Paired with hook: spawn work and wait for the result
export async function orchestrator(input: string): Promise<string> {
  const signalId = `result-${Durable.workflow.random()}`;

  // Spawn a hook that will signal back when done
  await Durable.workflow.hook({
    taskQueue: 'processors',
    workflowName: 'processItem',
    args: [input, signalId],
  });

  // Wait for the hook to signal completion
  return await Durable.workflow.condition<string>(signalId);
}
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