fix: svelte 5 mount/hydrate api change. (#10224)

.changeset/smart-jobs-care.md

@@ -0,0 +1,5 @@
+---
+"@astrojs/svelte": minor
+---
+
+Bumps Svelte 5 peer dependency to `^5.0.0-next.56` and support its latest breaking changes

packages/integrations/svelte/client-v5.js

@@ -1,11 +1,11 @@
-import { mount } from 'svelte';
+import { hydrate, mount, unmount } from 'svelte';
 import { add_snippet_symbol } from 'svelte/internal';
 
 // Allow a slot to be rendered as a snippet (dev validation only)
 const tagSlotAsSnippet = import.meta.env.DEV ? add_snippet_symbol : (s) => s;
 
 export default (element) => {
-	return async (Component, props, slotted) => {
+	return async (Component, props, slotted, { client }) => {
 		if (!element.hasAttribute('ssr')) return;
 
 		let children = undefined;
@@ -19,7 +19,9 @@ export default (element) => {
 			}
 		}
 
-		const [, destroy] = mount(Component, {
+		const bootstrap = client !== 'only' ? hydrate : mount;
+
+		const component = bootstrap(Component, {
 			target: element,
 			props: {
 				...props,
@@ -28,7 +30,7 @@ export default (element) => {
 			},
 		});
 
-		element.addEventListener('astro:unmount', () => destroy(), { once: true });
+		element.addEventListener('astro:unmount', () => unmount(component), { once: true });
 	};
 };
 

packages/integrations/svelte/package.json

@@ -53,7 +53,7 @@
   },
   "peerDependencies": {
     "astro": "^4.0.0",
-    "svelte": "^4.0.0 || ^5.0.0-next.1"
+    "svelte": "^4.0.0 || ^5.0.0-next.56"
   },
   "engines": {
     "node": ">=18.14.1"