fix: keep deriveds reactive after their original parent effect was destroyed#17171
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…stroyed Use case: Remote queries that are created on one screen, then are used again on another screen. Original parent effect is destroyed in that case but derived should still be reactive. It wasn't prior to this fix because inside `get` the `destroyed` variable would be true and so deps would not properly be recorded. Fixes sveltejs/kit#14814
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Rich-Harris
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Nov 17, 2025
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) Per #17862 (comment), this freezes the value of a derived if it was created inside a parent effect that is now destroyed. This prevents the sort of bug where a derived reads `foo.bar` even though `foo` is now `undefined`. If the derived is dirty, a warning will be printed. This PR also gets rid of some weirdness around `derived.parent` — it can only ever be an `Effect | null`, and there's no need for `get_derived_parent_effect`. Blocked on sveltejs/kit#15533 and a follow-up that switches remote functions to use `$effect.root` (since this effectively undoes #17171), hence draft. ### Before submitting the PR, please make sure you do the following - [x] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs - [x] Prefix your PR title with `feat:`, `fix:`, `chore:`, or `docs:`. - [x] This message body should clearly illustrate what problems it solves. - [x] Ideally, include a test that fails without this PR but passes with it. - [x] If this PR changes code within `packages/svelte/src`, add a changeset (`npx changeset`). ### Tests and linting - [x] Run the tests with `pnpm test` and lint the project with `pnpm lint` --------- Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com> Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
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Use case: Remote queries that are created on one screen, then are used again on another screen. Original parent effect is destroyed in that case but derived should still be reactive. It wasn't prior to this fix because inside
getthedestroyedvariable would be true and so deps would not properly be recorded.Fixes sveltejs/kit#14814
Fixes #17082
Before submitting the PR, please make sure you do the following
feat:,fix:,chore:, ordocs:.packages/svelte/src, add a changeset (npx changeset).Tests and linting
pnpm testand lint the project withpnpm lint