XState 6.0.0-alpha.50

Patch Changes

• 7f9fc4f: Invalid external events are now rejected at the delivery boundary instead of erroring the actor or throwing. This covers events whose payload fails a declared runtime validator schema and internal event types (internalEvents) sent from outside their owning actor. A rejected event is never delivered: the actor does not transition, does not error, and no API throws.

  Rejections are reported through:

  • a new onRejectedEvent dead-letter hook on createActor(...) options, which receives an EventRejection describing the event, target, source, origin, reason and validation issues;
  • the @xstate.deadletter inspection event, which now also carries the validation issues and underlying error for boundary rejections;
  • a development-mode console warning.

  const actor = createActor(machine, {
    onRejectedEvent: (rejection) => {
      console.log(rejection.event, rejection.reason, rejection.issues);
    }
  });
  

  Pure transition(...) calls no longer throw for invalid external events: the snapshot is returned unchanged with a @xstate.deadLetter effect carrying the rejection, so durable hosts can journal rejections and replay stays total even with poisoned queued events. The effect executes through the deadLetter runtime operation, so createDurable(...) adapters journal rejections by implementing deadLetter like any other runtime operation.

  Internal faults are unchanged: values the machine produces itself (input, context, output, emitted events and delayed raised events) that fail their schema still error the actor, and pure transitions still throw for them.