Data fetching is a perfect fit for state machines: idle → loading → success / error, with retry, refresh, and cancellation as transitions.

• States: idle → loading → success / error / empty

• Guard: canRefresh, canRetry

• Context for response data and error info

• Cancellation via abort signal

• Data Fetching → Forms — Form submissions as async flows

• Data Fetching → Navigation — Route-based data loading

• Tooling: Testing — Testing async machines

• Case Study: Document Editor — Real-world async flow

• Add retry with exponential backoff machine

• Add caching machine

• Add polling machine