14.1 The new chain

FulfilOrderInput
   ├── box:     ChooseBoxJunction        → Box
   └── courier: GetCourierRatesJunction  → CourierRates
BuyLabelJunction                         → ShippingLabel
Checkpoint<ShippingLabel>
PackOrderJunction                        → FulfilOrderOutput

The two branches run at once. BuyLabelJunction runs when both have finished, with what each returned. The checkpoint stores the label. PackOrderJunction packs the order with the label on it.

SDK Reference

Parallel | Checkpoint | Checkpoints and branches | resumeExecution | runGraph

Next: 14.2 The courier and the warehouse