Optional JSON replay example for a synchronous draft actor

[PerchAnton]

I built an external adapter and replay example for small, shareable regression traces. Three scenarios exercise a small synchronous edit/save/cancel machine on XState 5.33.3: cancellation, validation guards and persisted-snapshot restore. All 18 steps pass.

This shares fixed example traces; it does not replace model-based testing, graph traversal or v6 durable execution. Timers and async actors are outside its scope.

I maintain the experimental interaction-check runner. The example uses pinned stable packages, stays outside the project and adds no runtime dependency. Feedback on whether this helps share small reproducers is welcome.

[beenish-majeed]

Thanks for sharing this. Keeping the adapter external and dependency-free is a sensible approach.

I see value in small, shareable JSON traces that reproduce a specific sequence of events and verify the resulting snapshots, particularly for regression reports that are difficult to reproduce from prose alone.

This complements rather than replaces XState’s existing [actor testing and model-based testing tools](https://stately.ai/docs/testing). The synchronous scope and explicit limitations are also good choices.

One useful next step would be to document the trace format and expected state after each step, making examples easy to review and reuse in regression tests. If a recurring need emerges, that could help establish whether a shared trace format belongs in XState itself.

[PerchAnton]

Thanks for reviewing it. Here is the concrete format used by the cancel trace: a JSON object with schema: 1, name, and ordered steps. Each step contains an event and the state fields to check in expect. Only the event is sent to the adapter; expectations stay in the runner. The adapter returns value, context, status and can_save from the real actor snapshot.

For that example, the states after each step are:

Event	value	saved	draft	can_save
new	idle	original	original	false
EDIT	editing	original	original	true
CHANGE("preview")	editing	original	preview	true
CANCEL	idle	original	preview	false
EDIT	editing	original	original	true

CANCEL leaves the saved value unchanged; the next EDIT resets the draft from it. The validation trace separately checks that a blank draft cannot SAVE.

The current files assert selected fields, not every field in this table. This explanation fills in the example here; the README still needs the same format/state walkthrough. It remains an external example for a synchronous machine, with no timer/async coverage and no replacement for XState's own testing tools.