Chained optimistic store ignores a move back to the previous value after an action settles

[GabbeV]

Describe the bug

With createOptimisticStore(base) where base is a createStore, a second action can update moving while its optimistic position write is ignored. The first action has fully settled and the base store has confirmed its result before the second action starts. Reproduces on Solid 2.0.0-rc.9 and the 40c65cd preview.

Your Example Website or App

https://s.olid.uk/id/fgVOue6FQCG8bUXFA9Nj3A

Steps to Reproduce the Bug or Issue

1. Open the linked playground.
2. Click Run reproduction once.
3. Observe the values while the second move is pending. The first action is confirmed and settled before the second starts.

Expected behavior

Expected: base position 1, optimistic position 0, moving true.
Actual: base position 1, optimistic position 1, moving true. The optimistic setter ran, but only moving appears in the view.

Screenshots or Videos

No response

Platform

• OS: Linux
• Browser: Chromium (Playwright)
• Solid: 2.0.0-rc.9 in the playground; also reproduced with the 40c65cd preview in development and production builds

Additional context

The repro uses one object and no router, network, drag handling, keyed list, or CSS. A control that sources the optimistic store from a plain derived object instead of chaining createOptimisticStore(base) shows position 0 correctly.

[ryansolid]

Fixed by #3674 (merged to next as 658eecd); ships in the next RC.

Root cause: a chained optimistic store's nodes are links that serve the base's live value, and their _value is never updated when the base commits — so both places the engine consulted it went stale: optimisticWrite's no-op check dropped a write equal to the pre-action value (your report), and resolveOptimisticNodes' revert compare could leave a memo reader stuck when the confirmation landed while an override was active. The engine is now handed the base's live value at both consult moments; a confirmed guess settles with no reader re-run. Pinned for the write-back, re-add, pop, chained-over-chained, and mid-flight-confirmation shapes.

— Claude via Cursor