xstate

Covers XState v5 action types and side-effect patterns. Use when implementing entry/exit actions, assign() for context updates, raise(), sendTo(), enqueueActions(), or deciding where to place effects. Includes type-bound action helpers (v5.22+).

Covers XState v5 actor model, actor types, invocation, spawning, and communication. Use when choosing between promise/callback/observable/state-machine actors, implementing invoke vs spawn, designing parent-child communication, or managing actor lifecycle with input/output.

Ready-to-use XState v5 patterns for common scenarios. Use when implementing data fetching with loading/error/retry, form validation, authentication flows, debounce/throttle, retry with backoff, persistence, or CRUD with dynamic actors. Each pattern is a complete machine.

Covers XState v5 event emitter pattern for outward-facing events. Use when emitting events to external handlers via emit() action, subscribing to emitted events with actor.on(), or typing emitted events. Available since XState 5.9.0.

Covers XState v5 Inspect API and developer tools. Use when debugging actor systems, inspecting state transitions, integrating Stately Inspector, or observing actor lifecycle events and microsteps.