diff --git a/.changeset/nervous-dolphins-allow.md b/.changeset/nervous-dolphins-allow.md
new file mode 100644
index 0000000000..c59dc94c06
--- /dev/null
+++ b/.changeset/nervous-dolphins-allow.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+chore: add warning for invalid render function of createRawSnippet
diff --git a/.changeset/pre.json b/.changeset/pre.json
index 675c79f28c..5826fb7f66 100644
--- a/.changeset/pre.json
+++ b/.changeset/pre.json
@@ -185,6 +185,7 @@
     "fluffy-dolls-share",
     "fluffy-humans-worry",
     "fluffy-ravens-juggle",
+    "forty-bikes-buy",
     "forty-comics-invent",
     "forty-dogs-divide",
     "forty-dolls-wave",
@@ -193,6 +194,7 @@
     "four-balloons-beam",
     "four-flies-hammer",
     "four-mice-hammer",
+    "four-papayas-turn",
     "four-pugs-listen",
     "fresh-beds-wash",
     "fresh-dots-destroy",
diff --git a/documentation/docs/02-template-syntax/01-component-fundamentals.md b/documentation/docs/02-template-syntax/01-component-fundamentals.md
index 5e4d78e59a..debe4828d2 100644
--- a/documentation/docs/02-template-syntax/01-component-fundamentals.md
+++ b/documentation/docs/02-template-syntax/01-component-fundamentals.md
@@ -72,13 +72,31 @@ If you're using TypeScript, you can declare the prop types:
 ```svelte
 <script lang="ts">
 	interface Props {
-		a: number;
-		b: boolean;
-		c: string;
+		required: string;
+		optional?: number;
 		[key: string]: unknown;
 	}
 
-	let { a, b, c, ...everythingElse }: Props = $props();
+	let { required, optional, ...everythingElse }: Props = $props();
+</script>
+```
+
+If you're using JavaScript, you can declare the prop types using JSDoc:
+
+```svelte
+<script>
+	/** @type {{ x: string }} */
+	let { x } = $props();
+
+	// or use @typedef if you want to document the properties:
+
+	/**
+	 * @typedef {Object} MyProps
+	 * @property {string} y Some documentation
+	 */
+
+	/** @type {MyProps} */
+	let { y } = $props();
 </script>
 ```
 
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 3c7523801d..b67d217c81 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,13 @@
 # svelte
 
+## 5.0.0-next.193
+
+### Patch Changes
+
+- fix: improve validation error that occurs when using `{@render ...}` to render default slotted content ([#12521](https://github.com/sveltejs/svelte/pull/12521))
+
+- fix: reset hydrate node after `hydrate(...)` ([#12512](https://github.com/sveltejs/svelte/pull/12512))
+
 ## 5.0.0-next.192
 
 ### Patch Changes
diff --git a/packages/svelte/messages/client-warnings/warnings.md b/packages/svelte/messages/client-warnings/warnings.md
index 9ffef25b01..7a5a495251 100644
--- a/packages/svelte/messages/client-warnings/warnings.md
+++ b/packages/svelte/messages/client-warnings/warnings.md
@@ -20,6 +20,10 @@
 
 > Hydration failed because the initial UI does not match what was rendered on the server. The error occurred near %location%
 
+## invalid_raw_snippet_render
+
+> The `render` function passed to `createRawSnippet` should return HTML for a single element
+
 ## lifecycle_double_unmount
 
 > Tried to unmount a component that was not mounted
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 6484b8cb58..5067c4ad51 100644
--- a/packages/svelte/package.json
+++ b/packages/svelte/package.json
@@ -2,7 +2,7 @@
   "name": "svelte",
   "description": "Cybernetically enhanced web apps",
   "license": "MIT",
-  "version": "5.0.0-next.192",
+  "version": "5.0.0-next.193",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
index 76329a09bb..79bc9889e1 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
@@ -2352,7 +2352,6 @@ export const template_visitors = {
 	EachBlock(node, context) {
 		const each_node_meta = node.metadata;
 		const collection = /** @type {Expression} */ (context.visit(node.expression));
-		let each_item_is_reactive = true;
 
 		if (!each_node_meta.is_controlled) {
 			context.state.template.push('<!>');
@@ -2362,36 +2361,29 @@ export const template_visitors = {
 			context.state.init.push(b.const(each_node_meta.array_name, b.thunk(collection)));
 		}
 
-		// The runtime needs to know what kind of each block this is in order to optimize for the
-		// key === item (we avoid extra allocations). In that case, the item doesn't need to be reactive.
-		// We can guarantee this by knowing that in order for the item of the each block to change, they
-		// would need to mutate the key/item directly in the array. Given that in runes mode we use ===
-		// equality, we can apply a fast-path (as long as the index isn't reactive).
-		let each_type = 0;
+		let flags = 0;
 
 		if (
 			node.key &&
 			(node.key.type !== 'Identifier' || !node.index || node.key.name !== node.index)
 		) {
-			each_type |= EACH_KEYED;
-			// If there's a destructuring, then we likely need the generated $$index
-			if (node.index || node.context.type !== 'Identifier') {
-				each_type |= EACH_INDEX_REACTIVE;
+			flags |= EACH_KEYED;
+
+			if (node.index) {
+				flags |= EACH_INDEX_REACTIVE;
 			}
-			if (
-				context.state.analysis.runes &&
+
+			// In runes mode, if key === item, we don't need to wrap the item in a source
+			const key_is_item =
 				node.key.type === 'Identifier' &&
 				node.context.type === 'Identifier' &&
-				node.context.name === node.key.name &&
-				(each_type & EACH_INDEX_REACTIVE) === 0
-			) {
-				// Fast-path for when the key === item
-				each_item_is_reactive = false;
-			} else {
-				each_type |= EACH_ITEM_REACTIVE;
+				node.context.name === node.key.name;
+
+			if (!context.state.analysis.runes || !key_is_item) {
+				flags |= EACH_ITEM_REACTIVE;
 			}
 		} else {
-			each_type |= EACH_ITEM_REACTIVE;
+			flags |= EACH_ITEM_REACTIVE;
 		}
 
 		// Since `animate:` can only appear on elements that are the sole child of a keyed each block,
@@ -2404,15 +2396,15 @@ export const template_visitors = {
 				return child.attributes.some((attr) => attr.type === 'AnimateDirective');
 			})
 		) {
-			each_type |= EACH_IS_ANIMATED;
+			flags |= EACH_IS_ANIMATED;
 		}
 
 		if (each_node_meta.is_controlled) {
-			each_type |= EACH_IS_CONTROLLED;
+			flags |= EACH_IS_CONTROLLED;
 		}
 
 		if (context.state.analysis.runes) {
-			each_type |= EACH_IS_STRICT_EQUALS;
+			flags |= EACH_IS_STRICT_EQUALS;
 		}
 
 		// If the array is a store expression, we need to invalidate it when the array is changed.
@@ -2437,10 +2429,12 @@ export const template_visitors = {
 			);
 			return [array, ...transitive_dependencies];
 		});
+
 		if (each_node_meta.array_name) {
 			indirect_dependencies.push(b.call(each_node_meta.array_name));
 		} else {
 			indirect_dependencies.push(collection);
+
 			const transitive_dependencies = serialize_transitive_dependencies(
 				each_node_meta.references,
 				context
@@ -2459,6 +2453,7 @@ export const template_visitors = {
 					// into separate expressions, at which point this is called again with an identifier or member expression
 					return serialize_set_binding(assignment, context, () => assignment);
 				}
+
 				const left = object(assignment.left);
 				const value = get_assignment_value(assignment, context);
 				const invalidate = b.call(
@@ -2499,10 +2494,12 @@ export const template_visitors = {
 			const item_with_loc = with_loc(item, id);
 			return b.call('$.unwrap', item_with_loc);
 		};
+
 		if (node.index) {
 			const index_binding = /** @type {import('#compiler').Binding} */ (
 				context.state.scope.get(node.index)
 			);
+
 			index_binding.expression = (id) => {
 				const index_with_loc = with_loc(index, id);
 				return b.call('$.unwrap', index_with_loc);
@@ -2565,7 +2562,7 @@ export const template_visitors = {
 			declarations.push(b.let(node.index, index));
 		}
 
-		if (context.state.options.dev && (each_type & EACH_KEYED) !== 0) {
+		if (context.state.options.dev && (flags & EACH_KEYED) !== 0) {
 			context.state.init.push(
 				b.stmt(b.call('$.validate_each_keys', b.thunk(collection), key_function))
 			);
@@ -2574,7 +2571,7 @@ export const template_visitors = {
 		/** @type {Expression[]} */
 		const args = [
 			context.state.node,
-			b.literal(each_type),
+			b.literal(flags),
 			each_node_meta.array_name ? each_node_meta.array_name : b.thunk(collection),
 			key_function,
 			b.arrow([b.id('$$anchor'), item, index], b.block(declarations.concat(block.body)))
diff --git a/packages/svelte/src/internal/client/dom/blocks/snippet.js b/packages/svelte/src/internal/client/dom/blocks/snippet.js
index 2df4487536..846fbd671a 100644
--- a/packages/svelte/src/internal/client/dom/blocks/snippet.js
+++ b/packages/svelte/src/internal/client/dom/blocks/snippet.js
@@ -10,6 +10,8 @@ import {
 import { hydrate_next, hydrate_node, hydrating } from '../hydration.js';
 import { create_fragment_from_html } from '../reconciler.js';
 import { assign_nodes } from '../template.js';
+import * as w from '../../warnings.js';
+import { DEV } from 'esm-env';
 
 /**
  * @template {(node: TemplateNode, ...args: any[]) => void} SnippetFn
@@ -88,6 +90,11 @@ export function createRawSnippet(fn) {
 			var html = snippet.render().trim();
 			var fragment = create_fragment_from_html(html);
 			element = /** @type {Element} */ (fragment.firstChild);
+
+			if (DEV && (element.nextSibling !== null || element.nodeType !== 3)) {
+				w.invalid_raw_snippet_render();
+			}
+
 			/** @type {TemplateNode} */ (/** @type {unknown} */ (anchor)).before(element);
 		}
 
diff --git a/packages/svelte/src/internal/client/warnings.js b/packages/svelte/src/internal/client/warnings.js
index e1a6aa4325..31f67a725a 100644
--- a/packages/svelte/src/internal/client/warnings.js
+++ b/packages/svelte/src/internal/client/warnings.js
@@ -60,6 +60,18 @@ export function hydration_mismatch(location) {
 	}
 }
 
+/**
+ * The `render` function passed to `createRawSnippet` should return HTML for a single element
+ */
+export function invalid_raw_snippet_render() {
+	if (DEV) {
+		console.warn(`%c[svelte] invalid_raw_snippet_render\n%cThe \`render\` function passed to \`createRawSnippet\` should return HTML for a single element`, bold, normal);
+	} else {
+		// TODO print a link to the documentation
+		console.warn("invalid_raw_snippet_render");
+	}
+}
+
 /**
  * Tried to unmount a component that was not mounted
  */
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 90457f42f6..b947c0ce3f 100644
--- a/packages/svelte/src/version.js
+++ b/packages/svelte/src/version.js
@@ -6,5 +6,5 @@
  * https://svelte.dev/docs/svelte-compiler#svelte-version
  * @type {string}
  */
-export const VERSION = '5.0.0-next.192';
+export const VERSION = '5.0.0-next.193';
 export const PUBLIC_VERSION = '5';
diff --git a/packages/svelte/tests/runtime-runes/samples/create-raw-snippet-invalid-render/_config.js b/packages/svelte/tests/runtime-runes/samples/create-raw-snippet-invalid-render/_config.js
new file mode 100644
index 0000000000..fb05b78e98
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/create-raw-snippet-invalid-render/_config.js
@@ -0,0 +1,13 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		dev: true
+	},
+
+	skip_mode: ['hydrate'],
+
+	warnings: [
+		'The `render` function passed to `createRawSnippet` should return HTML for a single element'
+	]
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/create-raw-snippet-invalid-render/main.svelte b/packages/svelte/tests/runtime-runes/samples/create-raw-snippet-invalid-render/main.svelte
new file mode 100644
index 0000000000..e35f01800d
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/create-raw-snippet-invalid-render/main.svelte
@@ -0,0 +1,11 @@
+<script>
+	import { createRawSnippet } from 'svelte';
+
+	const snippet = createRawSnippet(() => ({
+		render: () => `
+			<!-- --><div>123</div>
+		`
+	}));
+</script>
+
+{@render snippet()}
diff --git a/sites/svelte-5-preview/src/routes/docs/[slug]/+page.svelte b/sites/svelte-5-preview/src/routes/docs/[slug]/+page.svelte
index 7aa2ee78c6..bb5c166711 100644
--- a/sites/svelte-5-preview/src/routes/docs/[slug]/+page.svelte
+++ b/sites/svelte-5-preview/src/routes/docs/[slug]/+page.svelte
@@ -18,7 +18,7 @@
 
 	<meta name="twitter:title" content="{data.page.title} • Docs • Svelte 5 preview" />
 	<meta name="twitter:description" content="{data.page.title} • Svelte 5 preview documentation" />
-	<meta name="Description" content="{data.page.title} • Svelte 5 preview documentation" />
+	<meta name="description" content="{data.page.title} • Svelte 5 preview documentation" />
 </svelte:head>
 
 <div class="text" id="docs-content" use:copy_code_descendants>
diff --git a/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md b/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md
index 879e39e5f0..5f0ee7c0ea 100644
--- a/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md
+++ b/sites/svelte-5-preview/src/routes/docs/content/01-api/02-runes.md
@@ -556,17 +556,22 @@ let props = $props();
 
 If you're using TypeScript, you can declare the prop types:
 
+<!-- prettier-ignore -->
 ```ts
-type MyProps = any;
-// ---cut---
-let { a, b, c, ...everythingElse }: MyProps = $props();
+interface MyProps {
+	required: string;
+	optional?: number;
+	partOfEverythingElse?: boolean;
+};
+
+let { required, optional, ...everythingElse }: MyProps = $props();
 ```
 
 > In an earlier preview, `$props()` took a type argument. This caused bugs, since in a case like this...
 >
 > ```ts
 > // @errors: 2558
-> let { x = 42 } = $props<{ x: string }>();
+> let { x = 42 } = $props<{ x?: string }>();
 > ```
 >
 > ...TypeScript [widens the type](https://www.typescriptlang.org/play?#code/CYUwxgNghgTiAEAzArgOzAFwJYHtXwBIAHGHIgZwB4AVeAXnilQE8A+ACgEoAueagbgBQgiCAzwA3vAAe9eABYATPAC+c4qQqUp03uQwwsqAOaqOnIfCsB6a-AB6AfiA) of `x` to be `string | number`, instead of erroring.
diff --git a/sites/svelte.dev/src/routes/(authed)/repl/[id]/+page.svelte b/sites/svelte.dev/src/routes/(authed)/repl/[id]/+page.svelte
index c867ff332f..2e4413de48 100644
--- a/sites/svelte.dev/src/routes/(authed)/repl/[id]/+page.svelte
+++ b/sites/svelte.dev/src/routes/(authed)/repl/[id]/+page.svelte
@@ -70,7 +70,7 @@
 
 	<meta name="twitter:title" content="{data.gist.name} • REPL • Svelte" />
 	<meta name="twitter:description" content="Cybernetically enhanced web apps" />
-	<meta name="Description" content="Interactive Svelte playground" />
+	<meta name="description" content="Interactive Svelte playground" />
 </svelte:head>
 
 <div class="repl-outer {zen_mode ? 'zen-mode' : ''}">
diff --git a/sites/svelte.dev/src/routes/(authed)/repl/embed/+page.svelte b/sites/svelte.dev/src/routes/(authed)/repl/embed/+page.svelte
index 43fed8a1cb..2833ca007c 100644
--- a/sites/svelte.dev/src/routes/(authed)/repl/embed/+page.svelte
+++ b/sites/svelte.dev/src/routes/(authed)/repl/embed/+page.svelte
@@ -10,7 +10,7 @@
 
 	<meta name="twitter:title" content="Svelte REPL" />
 	<meta name="twitter:description" content="Cybernetically enhanced web apps" />
-	<meta name="Description" content="Interactive Svelte playground" />
+	<meta name="description" content="Interactive Svelte playground" />
 </svelte:head>
 
 <div class="repl-outer">
diff --git a/sites/svelte.dev/src/routes/+page.svelte b/sites/svelte.dev/src/routes/+page.svelte
index 3a3463f712..1b6a59c1d7 100644
--- a/sites/svelte.dev/src/routes/+page.svelte
+++ b/sites/svelte.dev/src/routes/+page.svelte
@@ -11,7 +11,7 @@
 
 	<meta name="twitter:title" content="Svelte" />
 	<meta name="twitter:description" content="Cybernetically enhanced web apps" />
-	<meta name="Description" content="Cybernetically enhanced web apps" />
+	<meta name="description" content="Cybernetically enhanced web apps" />
 </svelte:head>
 
 <h1 class="visually-hidden">Svelte</h1>
diff --git a/sites/svelte.dev/src/routes/blog/+page.svelte b/sites/svelte.dev/src/routes/blog/+page.svelte
index 39bd289603..d19a49a7e4 100644
--- a/sites/svelte.dev/src/routes/blog/+page.svelte
+++ b/sites/svelte.dev/src/routes/blog/+page.svelte
@@ -13,7 +13,7 @@
 
 	<meta name="twitter:title" content="Svelte blog" />
 	<meta name="twitter:description" content="Articles about Svelte and UI development" />
-	<meta name="Description" content="Articles about Svelte and UI development" />
+	<meta name="description" content="Articles about Svelte and UI development" />
 </svelte:head>
 
 <h1 class="visually-hidden">Blog</h1>
diff --git a/sites/svelte.dev/src/routes/blog/[slug]/+page.svelte b/sites/svelte.dev/src/routes/blog/[slug]/+page.svelte
index 158973aebe..b1962b35c4 100644
--- a/sites/svelte.dev/src/routes/blog/[slug]/+page.svelte
+++ b/sites/svelte.dev/src/routes/blog/[slug]/+page.svelte
@@ -14,7 +14,7 @@
 	<meta name="twitter:card" content="summary_large_image" />
 	<meta name="twitter:title" content={data.post.title} />
 	<meta name="twitter:description" content={data.post.description} />
-	<meta name="Description" content={data.post.description} />
+	<meta name="description" content={data.post.description} />
 
 	<meta name="twitter:image" content="https://svelte.dev/blog/{$page.params.slug}/card.png" />
 	<meta name="og:image" content="https://svelte.dev/blog/{$page.params.slug}/card.png" />
diff --git a/sites/svelte.dev/src/routes/docs/[slug]/+page.svelte b/sites/svelte.dev/src/routes/docs/[slug]/+page.svelte
index ddcdadf144..6142ff8dbf 100644
--- a/sites/svelte.dev/src/routes/docs/[slug]/+page.svelte
+++ b/sites/svelte.dev/src/routes/docs/[slug]/+page.svelte
@@ -19,7 +19,7 @@
 
 	<meta name="twitter:title" content="{data.page.title} • Docs • Svelte" />
 	<meta name="twitter:description" content="{data.page.title} • Svelte documentation" />
-	<meta name="Description" content="{data.page.title} • Svelte documentation" />
+	<meta name="description" content="{data.page.title} • Svelte documentation" />
 </svelte:head>
 
 <div class="text" id="docs-content" use:copy_code_descendants>
diff --git a/sites/svelte.dev/src/routes/examples/[slug]/+page.svelte b/sites/svelte.dev/src/routes/examples/[slug]/+page.svelte
index 22c6d4f81a..07fc075350 100644
--- a/sites/svelte.dev/src/routes/examples/[slug]/+page.svelte
+++ b/sites/svelte.dev/src/routes/examples/[slug]/+page.svelte
@@ -34,7 +34,7 @@
 
 	<meta name="twitter:title" content="Svelte examples" />
 	<meta name="twitter:description" content="Cybernetically enhanced web apps" />
-	<meta name="Description" content="Interactive example Svelte apps" />
+	<meta name="description" content="Interactive example Svelte apps" />
 </svelte:head>
 
 <h1 class="visually-hidden">Examples</h1>
diff --git a/sites/svelte.dev/src/routes/tutorial/[slug]/+page.svelte b/sites/svelte.dev/src/routes/tutorial/[slug]/+page.svelte
index 2ec28418d4..5b8223b35b 100644
--- a/sites/svelte.dev/src/routes/tutorial/[slug]/+page.svelte
+++ b/sites/svelte.dev/src/routes/tutorial/[slug]/+page.svelte
@@ -102,7 +102,7 @@
 
 	<meta name="twitter:title" content="Svelte tutorial" />
 	<meta name="twitter:description" content="{selected.section.title} / {selected.chapter.title}" />
-	<meta name="Description" content="{selected.section.title} / {selected.chapter.title}" />
+	<meta name="description" content="{selected.section.title} / {selected.chapter.title}" />
 </svelte:head>
 
 <svelte:window bind:innerWidth={width} />