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useLiveQuery with localOnlyCollection does not show changes applied during component mount #439
Description
When inserting into a localOnlyCollection inside a useEffect, useLiveQuery does not return the expected data immediately. However, if the insert/delete calls are wrapped in a setTimeout, the query works as expected. This also applies to changes in useLayoutEffect and directly in the component body.
Stackblitz reproduction: https://stackblitz.com/edit/react-ts-bjof6j6d?file=App.tsx
Activity
samwillis commentedon Oct 4, 2025
Thanks for the report @doepnern, particularly the repo as thats super helpful.
I've been trying to reproduce it in an isolated test but can't, I think this is an issue that only manifests in a real browser with a "real" browser event loop - React in tests does behave slightly differently. Having said that I also tried to set up a playwright test for it and didn't get that working. I'm keen to get a unit test for this as we need to be sure any change we make isn't reverted in future.
KyleAMathews commentedon Sep 15, 2026
This is fixed by the shared-observer work in #1642. The exact local-only mount-window checks pass for
useEffect,useLayoutEffect, and guarded render-body insertion without a timeout. Real-browser timing was not rerun, and mutation during render remains an unsupported React side effect. Closing as completed; please reopen with a current browser reproduction if necessary.