Starstruk Logo MarkStarstruk

svelte@5.49.0

sveltejs/sveltesvelte@5.49.0Jan 29, 2026by github-actions[bot]

AI Summary

This minor release introduces a new customization option for custom elements and numerous stability fixes for effects, reactivity, and transitions.

Key Highlights

  • Allowed passing `ShadowRootInit` object to custom element `shadow` option.
  • Reset effects inside skipped branches to prevent stale state issues.
  • Improved handling of `createContext` to throw errors on the server when unset.
  • Fixed introstart/outrostart events to respect delay specifications.

New Features

  • Allow passing `ShadowRootInit` object to custom element `shadow` option

Full Release Notes

### Minor Changes

-   feat: allow passing `ShadowRootInit` object to custom element `shadow` option ([#17088](https://github.com/sveltejs/svelte/pull/17088))

### Patch Changes

-   fix: throw for unset `createContext` get on the server ([#17580](https://github.com/sveltejs/svelte/pull/17580))

-   fix: reset effects inside skipped branches ([#17581](https://github.com/sveltejs/svelte/pull/17581))

-   fix: preserve old dependencies when updating reaction inside fork ([#17579](https://github.com/sveltejs/svelte/pull/17579))

-   fix: more conservative assignment_value_stale warnings ([#17574](https://github.com/sveltejs/svelte/pull/17574))

-   fix: disregard `popover` elements when determining whether an element has content ([#17367](https://github.com/sveltejs/svelte/pull/17367))

-   fix: fire introstart/outrostart events after delay, if specified ([#17567](https://github.com/sveltejs/svelte/pull/17567))

-   fix: increment signal versions when discarding forks ([#17577](https://github.com/sveltejs/svelte/pull/17577))