Resonate Recursive Fan-Out Pattern (TypeScript)

Overview

The recursive fan-out pattern enables workflows to spawn multiple child workflows in parallel, either collecting their results or letting them execute independently. Resonate provides two primitives for this: ctx.detached() for fire-and-forget execution and ctx.beginRpc() for parallel execution with result gathering.

Core principle: Break complex work into parallel subtasks that recursively break down further, with automatic deduplication via promise IDs and transparent load balancing across workers.

Mental Model

Parent Workflow
      │
      ├─────────┬─────────┬─────────┐
      │         │         │         │
   Child 1   Child 2   Child 3   Child 4
      │         │         │
      ├──┬──┐   ├──┐      └──┬──┐
   G1 G2 G3  G4 G5        G6 G7