# XState 6.0.0-alpha.37

- Product: XState (https://whatsnew.fyi/product/xstate)
- Vendor: Stately
- Date: 2026-08-15
- Version: 6.0.0-alpha.37
- Original notes: https://github.com/statelyai/xstate/releases/tag/xstate%406.0.0-alpha.37
- Permalink: https://whatsnew.fyi/product/xstate/releases/6.0.0-alpha.37
- Labels: Pre-release

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

---

- **added** — Add an experimental, host-neutral durable execution helper at `xstate/durable` that assigns stable IDs to effects and event waits from pure transitions while leaving durable execution, timers, messaging and child actors to the host
- **added** — Add experimental durable execution adapters for Inngest and Rivet workflows
- **changed** — Host runtime mappings now receive the complete built-in effect, allowing them to map timers, sends and child actors without coupling XState to either host
- **fixed** — Fix `invoke.onDone` transition argument inference when actor logic is passed directly as `src` in a machine with two or more differently-typed registered actors so that `event.output` is properly inferred from the invoked actor's output type

###### Minor Changes

- 86f7303: Add an experimental, host-neutral durable execution helper at `xstate/durable`.
  It assigns stable IDs to effects and event waits from pure transitions while
  leaving durable execution, timers, messaging and child actors to the host.
  Hosts can read `nextTransitionIndex` after every transition for checkpointing.
  
  ```ts
  const durable = createDurable(machine, adapter);
  const output = await durable.run(input);
  ```

###### Patch Changes

- 86f7303: Add experimental durable execution adapters for Inngest and Rivet workflows.
  Host runtime mappings now receive the complete built-in effect, allowing them
  to map timers, sends and child actors without coupling XState to either host.
  
  ```ts
  import { createDurable } from '@xstate/inngest';
  
  const output = await createDurable(machine, options).run(input);
  ```
- 6df07b8: Fixed `invoke.onDone` transition argument inference when actor logic is passed directly as `src` in a machine with two or more differently-typed registered actors. Previously, the transition function's arguments collapsed to `any` (`event.output` was unusable without annotations); now `event.output` is inferred from the invoked actor's output type.
  
  ```ts
  const fetchUser = createAsyncLogic({ run: async () => ({ name: 'David' }) });
  const fetchCount = createAsyncLogic({ run: async () => 42 });
  
  setup({
    actors: { fetchUser, fetchCount }
  }).createMachine({
    initial: 'loading',
    states: {
      loading: {
        invoke: {
          src: fetchUser,
          onDone: ({ event }) => {
            event.output.name; // string
            return { target: 'done' };
          }
        }
      },
      done: {}
    }
  });
  ```
  
  Note: when actors are registered, invoking *unregistered* inline logic now only supports the object/target forms of `onDone` (not the transition function form). Register the actor to get fully-typed function-form transitions.