Sync svelte docs (#1633)

sync svelte docs

Co-authored-by: svelte-docs-bot[bot] <196124396+svelte-docs-bot[bot]@users.noreply.github.com>

Author: github-actions[bot]

apps/svelte.dev/content/docs/svelte/03-template-syntax/19-await-expressions.md

@@ -136,6 +136,54 @@ If a `<svelte:boundary>` with a `pending` snippet is encountered during SSR, tha
 
 > [!NOTE] In the future, we plan to add a streaming implementation that renders the content in the background.
 
+## Forking
+
+The [`fork(...)`](svelte#fork) API, added in 5.42, makes it possible to run `await` expressions that you _expect_ to happen in the near future. This is mainly intended for frameworks like SvelteKit to implement preloading when (for example) users signal an intent to navigate.
+
+```svelte
+<script>
+	import { fork } from 'svelte';
+	import Menu from './Menu.svelte';
+
+	let open = $state(false);
+
+	/** @type {import('svelte').Fork | null} */
+	let pending = null;
+
+	function preload() {
+		pending ??= fork(() => {
+			open = true;
+		});
+	}
+
+	function discard() {
+		pending?.discard();
+		pending = null;
+	}
+</script>
+
+<button
+	onfocusin={preload}
+	onfocusout={discard}
+	onpointerenter={preload}
+	onpointerleave={discard}
+	onclick={() => {
+		pending?.commit();
+		pending = null;
+
+		// in case `pending` didn't exist
+		// (if it did, this is a no-op)
+		open = true;
+	}}
+>open menu</button>
+
+{#if open}
+	<!-- any async work inside this component will start
+	     as soon as the fork is created -->
+	<Menu onclose={() => open = false} />
+{/if}
+```
+
 ## Caveats
 
 As an experimental feature, the details of how `await` is handled (and related APIs like `$effect.pending()`) are subject to breaking changes outside of a semver major release, though we intend to keep such changes to a bare minimum.

apps/svelte.dev/content/docs/svelte/98-reference/.generated/client-errors.md

@@ -130,6 +130,12 @@ $effect(() => {
 
 Often when encountering this issue, the value in question shouldn't be state (for example, if you are pushing to a `logs` array in an effect, make `logs` a normal array rather than `$state([])`). In the rare cases where you really _do_ need to write to state in an effect — [which you should avoid]($effect#When-not-to-use-$effect) — you can read the state with [untrack](svelte#untrack) to avoid adding it as a dependency.
 
+### experimental_async_fork
+
+```
+Cannot use `fork(...)` unless the `experimental.async` compiler option is `true`
+```
+
 ### flush_sync_in_effect
 
 ```
@@ -140,6 +146,18 @@ The `flushSync()` function can be used to flush any pending effects synchronousl
 
 This restriction only applies when using the `experimental.async` option, which will be active by default in Svelte 6.
 
+### fork_discarded
+
+```
+Cannot commit a fork that was already committed or discarded
+```
+
+### fork_timing
+
+```
+Cannot create a fork inside an effect or when state changes are pending
+```
+
 ### get_abort_signal_outside_reaction
 
 ```

apps/svelte.dev/content/docs/svelte/98-reference/20-svelte.md

@@ -16,6 +16,7 @@ import {
 	createEventDispatcher,
 	createRawSnippet,
 	flushSync,
+	fork,
 	getAbortSignal,
 	getAllContexts,
 	getContext,
@@ -316,6 +317,38 @@ function flushSync<T = void>(fn?: (() => T) | undefined): T;
 
 
 
+## fork
+
+<blockquote class="since note">
+
+Available since 5.42
+
+</blockquote>
+
+Creates a 'fork', in which state changes are evaluated but not applied to the DOM.
+This is useful for speculatively loading data (for example) when you suspect that
+the user is about to take some action.
+
+Frameworks like SvelteKit can use this to preload data when the user touches or
+hovers over a link, making any subsequent navigation feel instantaneous.
+
+The `fn` parameter is a synchronous function that modifies some state. The
+state changes will be reverted after the fork is initialised, then reapplied
+if and when the fork is eventually committed.
+
+When it becomes clear that a fork will _not_ be committed (e.g. because the
+user navigated elsewhere), it must be discarded to avoid leaking memory.
+
+<div class="ts-block">
+
+```dts
+function fork(fn: () => void): Fork;
+```
+
+</div>
+
+
+
 ## getAbortSignal
 
 Returns an [`AbortSignal`](https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal) that aborts when the current [derived](/docs/svelte/$derived) or [effect](/docs/svelte/$effect) re-runs or is destroyed.
@@ -938,6 +971,49 @@ interface EventDispatcher<
 <div class="ts-block-property-details"></div>
 </div></div>
 
+## Fork
+
+<blockquote class="since note">
+
+Available since 5.42
+
+</blockquote>
+
+Represents work that is happening off-screen, such as data being preloaded
+in anticipation of the user navigating
+
+<div class="ts-block">
+
+```dts
+interface Fork {/*…*/}
+```
+
+<div class="ts-block-property">
+
+```dts
+commit(): Promise<void>;
+```
+
+<div class="ts-block-property-details">
+
+Commit the fork. The promise will resolve once the state change has been applied
+
+</div>
+</div>
+
+<div class="ts-block-property">
+
+```dts
+discard(): void;
+```
+
+<div class="ts-block-property-details">
+
+Discard the fork
+
+</div>
+</div></div>
+
 ## MountOptions
 
 Defines the options accepted by the `mount()` function.

apps/svelte.dev/content/docs/svelte/98-reference/30-runtime-errors.md

@@ -137,6 +137,12 @@ $effect(() => {
 
 Often when encountering this issue, the value in question shouldn't be state (for example, if you are pushing to a `logs` array in an effect, make `logs` a normal array rather than `$state([])`). In the rare cases where you really _do_ need to write to state in an effect — [which you should avoid]($effect#When-not-to-use-$effect) — you can read the state with [untrack](svelte#untrack) to avoid adding it as a dependency.
 
+### experimental_async_fork
+
+```
+Cannot use `fork(...)` unless the `experimental.async` compiler option is `true`
+```
+
 ### flush_sync_in_effect
 
 ```
@@ -147,6 +153,18 @@ The `flushSync()` function can be used to flush any pending effects synchronousl
 
 This restriction only applies when using the `experimental.async` option, which will be active by default in Svelte 6.
 
+### fork_discarded
+
+```
+Cannot commit a fork that was already committed or discarded
+```
+
+### fork_timing
+
+```
+Cannot create a fork inside an effect or when state changes are pending
+```
+
 ### get_abort_signal_outside_reaction
 
 ```