# XState 6.0.0-alpha.39

- Product: XState (https://whatsnew.fyi/product/xstate)
- Vendor: Stately
- Date: 2026-08-17
- Version: 6.0.0-alpha.39
- Original notes: https://github.com/statelyai/xstate/releases/tag/xstate%406.0.0-alpha.39
- Permalink: https://whatsnew.fyi/product/xstate/releases/6.0.0-alpha.39
- 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'.

---

- **fixed** — Fixed a bug where `enq.subscribeTo(…)` and `enq.listen(…)` silently did nothing when called inside a transition function, they now work the same as in `entry` actions
- **fixed** — Named imports from the root `xstate` entry such as actor logic creators and `SpecialTargets` now work in all environments, including tools that load the package as CommonJS
- **changed** — Optional event payload fields declared with `types()` are now preserved instead of being made required
- **changed** — `snapshot.value` is now structurally typed from the machine config instead of the generic `StateValue` type
- **fixed** — Fixed `createSystem(...).setup(...)` to preserve runtime validator types alongside typed actor registries

###### Patch Changes

- 7a7e564: Fixed a bug where `enq.subscribeTo(…)` and `enq.listen(…)` silently did nothing when called inside a transition function. They now work the same as in `entry` actions:
  
  ```ts
  const machine = createMachine({
    on: {
      start: (_, enq) => {
        const child = enq.spawn(childLogic);
        enq.subscribeTo(child, {
          done: (output) => ({ type: 'childDone', output })
        });
      },
      childDone: ({ event }) => {
        // event.output is the child's output
      }
    }
  });
  ```
- 4e6dbfd: Named imports from the root `xstate` entry (such as the actor logic creators and `SpecialTargets`) now work in all environments, including tools that load the package as CommonJS.
  
  ```ts
  import { createAsyncLogic } from 'xstate'; // now works everywhere
  ```
- 20a52b9: Optional event payload fields declared with `types()` are now preserved instead of being made required:
  
  ```ts
  const machine = setup({
    schemas: {
      events: {
        submit: types<{ email: string; referrer?: string }>()
      }
    }
  }).createMachine({
    // ...
  });
  
  // referrer can now be omitted
  actor.send({ type: 'submit', email: 'a@b.co' });
  ```
  
  Payloads inferred from validator libraries (e.g. Zod) are still wrapped in `Required<>`.
- 20a52b9: `snapshot.value` is now structurally typed from the machine config instead of the generic `StateValue` type. Flat machines get a union of state keys, and parallel machines get an object type with a key per region:
  
  ```ts
  const machine = createMachine({
    type: 'parallel',
    states: {
      bold: { initial: 'off', states: { off: {}, on: {} } },
      italic: { initial: 'off', states: { off: {}, on: {} } }
    }
  });
  
  const value = createActor(machine).getSnapshot().value;
  // { bold: 'off' | 'on'; italic: 'off' | 'on' }
  ```
- 90a173a: Fixed `createSystem(...).setup(...)` to preserve runtime validator types alongside typed actor registries. Validated setups now reject unsupported transforming schemas and carry validation into derived setups.
  
  Runtime validation can now also be installed on a derived setup when its inherited schemas are compatible:
  
  ```ts
  import { setup } from 'xstate';
  import { standardSchemaValidator } from 'xstate/validation';
  import { z } from 'zod';
  
  const validated = setup({
    schemas: { input: z.object({ id: z.string() }) }
  }).extend({ validator: standardSchemaValidator() });
  ```