XState v5 introduces a simplified API, better TypeScript support, the actor model, and new actor types like fromPromise and fromTransition.

• Simplified createMachine API

• New fromPromise, fromCallback, fromObservable actors

• Built-in actor model with spawn and input

• Improved type inference

• Removed deprecated assign, send, sendParent in favor of new patterns

• Learn Fundamentals

• Testing — Testing v5 machines

• Stately — Visual editor

• DevTools — Debugging

• Add migration guide from v4 to v5

• Add comparison of old vs new APIs

• Add recipe book for common v5 patterns