Function execHook

Combines hook() + waitFor() into a single call: spawns a hook function on a target workflow and suspends the current workflow until the hook signals completion. This is the recommended pattern for request/response communication between workflow threads.

Signal Injection

A signalId is automatically generated (or use the one you provide) and injected as the last argument to the hooked function as { signal: string, $durable: true }. The hook function must call Durable.workflow.signal(signalInfo.signal, result) to deliver its response back to the waiting workflow.

Difference from execChild

• execChild spawns a new workflow job with its own lifecycle.
• execHook runs within an existing workflow's job, in an isolated dimensional thread. This is lighter-weight and shares the parent job's data namespace.

Examples

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

// Orchestrator: spawn a hook and await its result
export async function reviewWorkflow(docId: string): Promise<string> {
  const verdict = await Durable.workflow.execHook<{ approved: boolean }>({
    taskQueue: 'reviewers',
    workflowName: 'reviewDocument',
    args: [docId],
  });

  return verdict.approved ? 'accepted' : 'rejected';
}
Copy

// The hooked function (runs on the 'reviewers' worker)
export async function reviewDocument(
  docId: string,
  signalInfo?: { signal: string; $durable: boolean },
): Promise<{ approved: boolean }> {
  const { analyzeDocument } = Durable.workflow.proxyActivities<typeof activities>();
  const score = await analyzeDocument(docId);
  const result = { approved: score > 0.8 };

  // Signal the waiting workflow with the result
  if (signalInfo?.signal) {
    await Durable.workflow.signal(signalInfo.signal, result);
  }
  return result;
}
Copy

// With explicit signalId for traceability
const result = await Durable.workflow.execHook<AnalysisResult>({
  taskQueue: 'analyzers',
  workflowName: 'runAnalysis',
  args: [datasetId],
  signalId: `analysis-${datasetId}`,
});
Copy