svelte@5.55.9

sveltejs/sveltesvelte@5.55.9May 20, 2026by github-actions[bot]

AI Summary

Patch release addressing SSR hydration issues with `{#await}` blocks, deduplication logic, and false-positive invariant errors.

Key Highlights

Fix hydration of `{#await await ...}` expressions on the server
Deduplicate dependencies added outside the init/update cycle
Fix false-positive batch invariant error
Inline primitive constants in attribute values during SSR

Full Release Notes

### Patch Changes

-   fix: don't unset batch when calling `{#await ...}` promise ([#18243](https://github.com/sveltejs/svelte/pull/18243))

-   fix: promise-ify `{#await await ...}` expressions on the server and correctly hydrate them on the client ([#18243](https://github.com/sveltejs/svelte/pull/18243))

-   fix: deduplicate dependencies that are added outside the init/update cycle ([#18243](https://github.com/sveltejs/svelte/pull/18243))

-   fix: avoid false-positive batch invariant error ([#18246](https://github.com/sveltejs/svelte/pull/18246))

-   fix: inline primitive constants in attribute values during SSR ([#18232](https://github.com/sveltejs/svelte/pull/18232))