fix: handle deferred transitions aborted before initialization by svelte-triage-bot[bot] · Pull Request #18776 · sveltejs/svelte

svelte-triage-bot · 2026-09-04T12:44:37Z

Summary

make deferred transition facade methods safe before the inner animation initializes
report the transition's initial position from the facade until initialization
add a runtime regression test for an out-only crossfade branch restored in the same update

Fixes #18773

Tests and linting

pnpm test runtime-runes -t deferred-outro-restored
pnpm test runtime-runes
pnpm test
pnpm lint

Changeset

Added a patch changeset for svelte.

pkg-svelte-dev · 2026-09-04T12:44:40Z

Install the latest version of svelte from 2a96c9b:

pnpm add https://pkg.svelte.dev/svelte/c/2a96c9b5d5ee176c6aa35b7c26db97cb5e473851

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/svelte/pr/18776

Note

This PR is from a fork. A maintainer must approve approve each commit before it can be built and installed.

changeset-bot · 2026-09-04T12:44:48Z

🦋 Changeset detected

Latest commit: 2a96c9b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
svelte	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

dummdidumm · 2026-09-04T12:56:58Z

@svelte-triage-bot analyse your own agent run to see if there's anything we can do to make it faster (e.g. skills, additional instructions, pointers to where which code lives)

dummdidumm · 2026-09-04T16:03:09Z

@svelte-triage-bot analyse your own agent run to see if there's anything we can do to make it faster (e.g. skills, additional instructions, pointers to where which code lives)

gyzerok · 2026-09-25T04:07:53Z

@dummdidumm is this one good to be merged? seems like you were looking in it at some point, but then got distracted :)

…tored/_config.js

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## svelte@5.57.2 ### Patch Changes - fix: don't create async deriveds for a component destroyed while waiting for its top-level `await` ([#18931](#18931)) - fix: prevent untracked derived reads from retaining disconnected dependencies ([#18829](#18829)) - fix: error if `{:else}` is followed by another `{:else}` or `{:else if ...}` ([#18900](#18900)) - fix: avoid tracking SvelteURLSearchParams during URL updates ([#18791](#18791)) - fix: restore hydration state when custom element attribute updates throw ([#18467](#18467)) - fix: attach event handlers that are assigned after a top-level `await` in production ([#18933](#18933)) - fix: flush anything pending before invoking flushSync callback function ([#18878](#18878)) - fix: preserve location information for `await` wrappers ([#18859](#18859)) - fix: keep a reactive assignment with no dependencies when `migrate` cannot turn it into a declaration ([#18817](#18817)) - fix: don't hang `migrate` on a declaration that shares a line with its script tag ([#18816](#18816)) - fix: prevent duplicate subscriptions when reconnecting deriveds ([#18899](#18899)) - fix: recover when an unexpected node replaces a nested boundary comment during hydration ([#18925](#18925)) - fix: print `{#await}` blocks that only have a pending branch ([#18908](#18908)) - fix: don't warn about a redundant `link` role on `<area>` elements without an `href` ([#18872](#18872)) - fix: don't throw `state_unsafe_mutation` when the focused element is removed while `bind:activeElement` is used ([#18921](#18921)) - fix: don't overwrite an unchanged spread `value`, preserving incomplete number input ([#18864](#18864)) - fix: read batch-local array on each-block commit ([#18879](#18879)) - fix: error at compile time when a declaration in a snippet redeclares one of its parameters ([#18842](#18842)) - fix: error when using `let:` directives on a component with a `children` snippet ([#18873](#18873)) - fix: ignore stale boundary reset callbacks ([#18886](#18886)) - fix: handle deferred transitions aborted before initialization ([#18776](#18776)) - fix: prevent hydration mismatch recovery from being intercepted by error boundaries ([#18841](#18841)) - fix: preserve dynamic element connections during hydration ([#18855](#18855)) Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

This PR contains the following updates: | Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) | |---|---|---|---| | [svelte](https://svelte.dev) ([source](https://github.com/sveltejs/svelte/tree/HEAD/packages/svelte)) | [`5.57.1` → `5.57.2`](https://renovatebot.com/diffs/npm/svelte/5.57.1/5.57.2) | ![age](https://developer.mend.io/api/mc/badges/age/npm/svelte/5.57.2?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/svelte/5.57.1/5.57.2?slim=true) | --- ### Release Notes <details> <summary>sveltejs/svelte (svelte)</summary> ### [`v5.57.2`](https://github.com/sveltejs/svelte/blob/HEAD/packages/svelte/CHANGELOG.md#5572) [Compare Source](https://github.com/sveltejs/svelte/compare/svelte@5.57.1...svelte@5.57.2) ##### Patch Changes - fix: don't create async deriveds for a component destroyed while waiting for its top-level `await` ([#18931](sveltejs/svelte#18931)) - fix: prevent untracked derived reads from retaining disconnected dependencies ([#18829](sveltejs/svelte#18829)) - fix: error if `{:else}` is followed by another `{:else}` or `{:else if ...}` ([#18900](sveltejs/svelte#18900)) - fix: avoid tracking SvelteURLSearchParams during URL updates ([#18791](sveltejs/svelte#18791)) - fix: restore hydration state when custom element attribute updates throw ([#18467](sveltejs/svelte#18467)) - fix: attach event handlers that are assigned after a top-level `await` in production ([#18933](sveltejs/svelte#18933)) - fix: flush anything pending before invoking flushSync callback function ([#18878](sveltejs/svelte#18878)) - fix: preserve location information for `await` wrappers ([#18859](sveltejs/svelte#18859)) - fix: keep a reactive assignment with no dependencies when `migrate` cannot turn it into a declaration ([#18817](sveltejs/svelte#18817)) - fix: don't hang `migrate` on a declaration that shares a line with its script tag ([#18816](sveltejs/svelte#18816)) - fix: prevent duplicate subscriptions when reconnecting deriveds ([#18899](sveltejs/svelte#18899)) - fix: recover when an unexpected node replaces a nested boundary comment during hydration ([#18925](sveltejs/svelte#18925)) - fix: print `{#await}` blocks that only have a pending branch ([#18908](sveltejs/svelte#18908)) - fix: don't warn about a redundant `link` role on `<area>` elements without an `href` ([#18872](sveltejs/svelte#18872)) - fix: don't throw `state_unsafe_mutation` when the focused element is removed while `bind:activeElement` is used ([#18921](sveltejs/svelte#18921)) - fix: don't overwrite an unchanged spread `value`, preserving incomplete number input ([#18864](sveltejs/svelte#18864)) - fix: read batch-local array on each-block commit ([#18879](sveltejs/svelte#18879)) - fix: error at compile time when a declaration in a snippet redeclares one of its parameters ([#18842](sveltejs/svelte#18842)) - fix: error when using `let:` directives on a component with a `children` snippet ([#18873](sveltejs/svelte#18873)) - fix: ignore stale boundary reset callbacks ([#18886](sveltejs/svelte#18886)) - fix: handle deferred transitions aborted before initialization ([#18776](sveltejs/svelte#18776)) - fix: prevent hydration mismatch recovery from being intercepted by error boundaries ([#18841](sveltejs/svelte#18841)) - fix: preserve dynamic element connections during hydration ([#18855](sveltejs/svelte#18855)) </details> --- ### Configuration 📅 **Schedule**: (UTC) - Branch creation - At any time (no schedule defined) - Automerge - At any time (no schedule defined) 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Mend Renovate CLI](https://github.com/renovatebot/renovate).

fix: handle aborted deferred transitions

964e086

dummdidumm mentioned this pull request Sep 25, 2026

fix: tolerate abort/reset of deferred transitions before initialization #18875

Closed

dummdidumm approved these changes Sep 25, 2026

View reviewed changes

Comment thread packages/svelte/tests/runtime-runes/samples/deferred-outro-restored/_config.js Outdated

Update packages/svelte/tests/runtime-runes/samples/deferred-outro-res…

2a96c9b

…tored/_config.js

dummdidumm marked this pull request as ready for review September 25, 2026 22:11

dummdidumm merged commit 7fb397e into sveltejs:main Sep 28, 2026
12 of 13 checks passed

github-actions Bot mentioned this pull request Sep 28, 2026

Version Packages #18858

Merged

github-actions Bot mentioned this pull request Oct 7, 2026

chore: upgrade Svelte submodule to 5.57.2 baseballyama/rsvelte#4766

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fix: handle deferred transitions aborted before initialization - #18776

fix: handle deferred transitions aborted before initialization#18776
dummdidumm merged 2 commits into
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triage/svelte-18775-deferred-crossfade-reset

svelte-triage-bot Bot commented Sep 4, 2026 •

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Tests and linting

Changeset

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svelte-triage-bot Bot commented Sep 4, 2026 •

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