svelte@5.57.0

### Minor Changes

-   feat: export `RenderOutput`, `SyncRenderOutput`, `Csp` and `Sha256Source` from `svelte/server` ([#18648](https://github.com/sveltejs/svelte/pull/18648))

-   feat: add `has` function to `createContext` ([#18472](https://github.com/sveltejs/svelte/pull/18472))

-   feat: support `defaultValue` on `<select>` ([#18591](https://github.com/sveltejs/svelte/pull/18591))

-   feat: add getOrInsert/getOrInsertComputed to SvelteMap ([#18728](https://github.com/sveltejs/svelte/pull/18728))

### Patch Changes

-   fix: block template store subscriptions on the promise that assigns the store ([#18582](https://github.com/sveltejs/svelte/pull/18582))

-   fix: route $derived teardown errors through invoke_error_boundary ([#18486](https://github.com/sveltejs/svelte/pull/18486))

-   fix: track SvelteDate snapshots in reactions ([#18700](https://github.com/sveltejs/svelte/pull/18700))

-   fix: remove `<svelte:head>` anchors on unmount ([#18697](https://github.com/sveltejs/svelte/pull/18697))

-   fix: warn on undeclared shorthand event handlers on `<svelte:window>`, `<svelte:document>` and `<svelte:body>` ([#18480](https://github.com/sveltejs/svelte/pull/18480))

-   perf: reuse the cached value in the `<option>`/`<select>` value guard ([#18713](https://github.com/sveltejs/svelte/pull/18713))

-   fix: prevent malformed AST output for `<select>` with static `value` attribute ([#18449](https://github.com/sveltejs/svelte/pull/18449))

-   fix: apply ownership mutation ignores to binding assignments ([#18718](https://github.com/sveltejs/svelte/pull/18718))

-   fix: prevent onoutroend from firing twice when compilerOptions.hmr is true ([#18655](https://github.com/sveltejs/svelte/pull/18655))

-   fix: preserve whitespace after inline elements when printing ([#18685](https://github.com/sveltejs/svelte/pull/18685))

-   perf: fold SSR block-open markers into the branch's first push ([#18712](https://github.com/sveltejs/svelte/pull/18712))

-   fix: run `onDestroy` callbacks when a server render throws ([#18585](https://github.com/sveltejs/svelte/pull/18585))

-   fix: report `derived_invalid_export` for `export let x = $derived(...)` in runes mode ([#18692](https://github.com/sveltejs/svelte/pull/18692))

-   fix: never apply class hash to elements inside `<svelte:head>` ([#18160](https://github.com/sveltejs/svelte/pull/18160))

-   fix: keep `defaultChecked` on hydrated radio inputs with spread attributes ([#18701](https://github.com/sveltejs/svelte/pull/18701))

-   fix: accept `onfocusin`/`onfocusout` in `a11y_mouse_events_have_key_events` ([#18689](https://github.com/sveltejs/svelte/pull/18689))

-   perf: O(n²)→O(n) Map lookups for legacy `$:` reactive statement ordering ([#18602](https://github.com/sveltejs/svelte/pull/18602))

-   fix: distinct memoizer on style/class directives ([#18466](https://github.com/sveltejs/svelte/pull/18466))

-   fix: measure nested transitions before applying their starting styles ([#18647](https://github.com/sveltejs/svelte/pull/18647))

-   fix: don't turn component instances stored in `$state` into state proxies ([#18646](https://github.com/sveltejs/svelte/pull/18646))

-   perf: emit `$.only_child` for elements with a single child ([#18717](https://github.com/sveltejs/svelte/pull/18717))

-   fix: omit `bind:focused` from SSR output (it has no HTML attribute) ([#18724](https://github.com/sveltejs/svelte/pull/18724))

-   fix: more robust rendering of Svelte custom element slots ([#18710](https://github.com/sveltejs/svelte/pull/18710))

-   perf: optimize simple object destructuring in `@const` tags ([#18390](https://github.com/sveltejs/svelte/pull/18390))

-   fix: properly apply static textarea value attribute during CSR ([#18727](https://github.com/sveltejs/svelte/pull/18727))

-   fix: end a restored reaction context at the end of its synchronous segment ([#18694](https://github.com/sveltejs/svelte/pull/18694))

-   fix: keep the dependencies of a reaction that throws, so deriveds it read are neither leaked nor stuck in their error ([#18703](https://github.com/sveltejs/svelte/pull/18703))

-   fix: don't resurrect outroing elements when an ancestor block is paused and resumed ([#18431](https://github.com/sveltejs/svelte/pull/18431))

-   perf: use `$.comment()` for single-comment templates ([#18714](https://github.com/sveltejs/svelte/pull/18714))

-   chore: move `@types/trusted-types` to devDependencies ([#18730](https://github.com/sveltejs/svelte/pull/18730))

-   perf: store setters cache as `Set` instead of `Array` ([#18251](https://github.com/sveltejs/svelte/pull/18251))

-   fix: transform derived assignments and select function bindings correctly during server-side rendering ([#18669](https://github.com/sveltejs/svelte/pull/18669))

-   fix: keep boolean attributes with an empty string value when rendering attribute objects on the server ([#18721](https://github.com/sveltejs/svelte/pull/18721))

-   fix: sync `SvelteURL` port signal when the protocol setter clears the port ([#18705](https://github.com/sveltejs/svelte/pull/18705))

-   fix: block declaration tags and `{@const}` on async values read inside closures ([#18533](https://github.com/sveltejs/svelte/pull/18533))

-   fix: avoid css tree-shaking for exported Snippet ([#18540](https://github.com/sveltejs/svelte/pull/18540))

-   perf: treat `<img loading>` as a static element again ([#18711](https://github.com/sveltejs/svelte/pull/18711))

-   fix: prevent `selectedcontent` mutation from changing the selected option ([#18495](https://github.com/sveltejs/svelte/pull/18495))

-   fix: avoid `NaN` keyframe values in `slide` transition for elements without a layout box ([#18430](https://github.com/sveltejs/svelte/pull/18430))

-   fix: preserve line feed character references in attribute values ([#18691](https://github.com/sveltejs/svelte/pull/18691))

-   fix: decode uppercase-`X` hex numeric character references (`&#X...;`) ([#18708](https://github.com/sveltejs/svelte/pull/18708))

-   chore: clarify when `$effect.pre` runs relative to DOM updates ([#18534](https://github.com/sveltejs/svelte/pull/18534))

-   fix: scope SSR boundary failed snippets to their boundary ([#18593](https://github.com/sveltejs/svelte/pull/18593))