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Optimistic writes disappear on rows retained from a derived store's draft #3859
Description
Describe the bug
A writable derived store retains a local row across a source refresh:
const [local, setLocal] = createStore<Row[]>(
draft => [...source(), ...draft.filter(row => row.id === "local")],
[],
);
const [view, setView] = createOptimisticStore(local);After the refresh, an action optimistically sets the retained row's value to 1 and waits two seconds. The optimistic view keeps showing 0 throughout the action.
There are no concurrent actions or pending source updates; the setup updates finish before the action starts.
Your Example Website or App
Steps to Reproduce the Bug or Issue
- Open the playground.
- Click Run once. The button creates a local row, refreshes the source, then starts the optimistic action, with 100 ms delays between setup updates.
- Observe that Local value stays at
0during the two-second action.
Expected behavior
The optimistic view should show Local value: 1 while the action is pending, then revert to 0 when the action finishes without persisting the change.
Screenshots or Videos
No response
Platform
- OS: Linux
- Browser: Chromium 153.0.8010.12
- Solid: published preview
mizulu/solid2@5c2174c
Additional context
Returning a copy of the retained row (draft.filter(...).map(row => ({ ...row }))) makes the optimistic update appear and revert as expected. Both variants were tested in the browser.
The retained-draft-row pattern is already covered for ordinary writes by the regression tests for #3767. This report concerns optimistic writes over that store.
The playground has Tailwind disabled.
Activity
ryansolid commentedon Oct 7, 2026
fix(signals): resolve a retained derived-store draft row under an opt…
ryansolid commentedon Oct 7, 2026