diff --git a/.changeset/wise-tigers-happen.md b/.changeset/wise-tigers-happen.md
deleted file mode 100644
index 53cc671859..0000000000
--- a/.changeset/wise-tigers-happen.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': minor
----
-
-feat: attachments `fromAction` utility
diff --git a/documentation/docs/98-reference/.generated/client-warnings.md b/documentation/docs/98-reference/.generated/client-warnings.md
index 77d1df4cdd..fe90b0db38 100644
--- a/documentation/docs/98-reference/.generated/client-warnings.md
+++ b/documentation/docs/98-reference/.generated/client-warnings.md
@@ -200,6 +200,19 @@ Consider the following code:
 
 To fix it, either create callback props to communicate changes, or mark `person` as [`$bindable`]($bindable).
 
+### select_multiple_invalid_value
+
+```
+The `value` property of a `<select multiple>` element should be an array, but it received a non-array value. The selection will be kept as is.
+```
+
+When using `<select multiple value={...}>`, Svelte will mark all selected `<option>` elements as selected by iterating over the array passed to `value`. If `value` is not an array, Svelte will emit this warning and keep the selected options as they are.
+
+To silence the warning, ensure that `value`:
+
+- is an array for an explicit selection
+- is `null` or `undefined` to keep the selection as is
+
 ### state_proxy_equality_mismatch
 
 ```
diff --git a/documentation/docs/98-reference/.generated/compile-warnings.md b/documentation/docs/98-reference/.generated/compile-warnings.md
index 7069f90206..b579d38602 100644
--- a/documentation/docs/98-reference/.generated/compile-warnings.md
+++ b/documentation/docs/98-reference/.generated/compile-warnings.md
@@ -632,6 +632,25 @@ In some situations a selector may target an element that is not 'visible' to the
 </style>
 ```
 
+### element_implicitly_closed
+
+```
+This element is implicitly closed by the following `%tag%`, which can cause an unexpected DOM structure. Add an explicit `%closing%` to avoid surprises.
+```
+
+In HTML, some elements are implicitly closed by another element. For example, you cannot nest a `<p>` inside another `<p>`:
+
+```html
+<!-- this HTML... -->
+<p><p>hello</p>
+
+<!-- results in this DOM structure -->
+<p></p>
+<p>hello</p>
+```
+
+Similarly, a parent element's closing tag will implicitly close all child elements, even if the `</` was a typo and you meant to create a _new_ element. To avoid ambiguity, it's always a good idea to have an explicit closing tag.
+
 ### element_invalid_self_closing_tag
 
 ```
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 4508a9b054..3f7876144f 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,41 @@
 # svelte
 
+## 5.33.0
+
+### Minor Changes
+
+- feat: XHTML compliance ([#15538](https://github.com/sveltejs/svelte/pull/15538))
+
+- feat: add `fragments: 'html' | 'tree'` option for wider CSP compliance ([#15538](https://github.com/sveltejs/svelte/pull/15538))
+
+## 5.32.2
+
+### Patch Changes
+
+- chore: simplify `<pre>` cleaning ([#15980](https://github.com/sveltejs/svelte/pull/15980))
+
+- fix: attach `__svelte_meta` correctly to elements following a CSS wrapper ([#15982](https://github.com/sveltejs/svelte/pull/15982))
+
+- fix: import untrack directly from client in `svelte/attachments` ([#15974](https://github.com/sveltejs/svelte/pull/15974))
+
+## 5.32.1
+
+### Patch Changes
+
+- Warn when an invalid `<select multiple>` value is given ([#14816](https://github.com/sveltejs/svelte/pull/14816))
+
+## 5.32.0
+
+### Minor Changes
+
+- feat: warn on implicitly closed tags ([#15932](https://github.com/sveltejs/svelte/pull/15932))
+
+- feat: attachments `fromAction` utility ([#15933](https://github.com/sveltejs/svelte/pull/15933))
+
+### Patch Changes
+
+- fix: only re-run directly applied attachment if it changed ([#15962](https://github.com/sveltejs/svelte/pull/15962))
+
 ## 5.31.1
 
 ### Patch Changes
diff --git a/packages/svelte/messages/client-warnings/warnings.md b/packages/svelte/messages/client-warnings/warnings.md
index f8e9ebd8a0..f1901271d1 100644
--- a/packages/svelte/messages/client-warnings/warnings.md
+++ b/packages/svelte/messages/client-warnings/warnings.md
@@ -168,6 +168,17 @@ Consider the following code:
 
 To fix it, either create callback props to communicate changes, or mark `person` as [`$bindable`]($bindable).
 
+## select_multiple_invalid_value
+
+> The `value` property of a `<select multiple>` element should be an array, but it received a non-array value. The selection will be kept as is.
+
+When using `<select multiple value={...}>`, Svelte will mark all selected `<option>` elements as selected by iterating over the array passed to `value`. If `value` is not an array, Svelte will emit this warning and keep the selected options as they are.
+
+To silence the warning, ensure that `value`:
+
+- is an array for an explicit selection
+- is `null` or `undefined` to keep the selection as is
+
 ## state_proxy_equality_mismatch
 
 > Reactive `$state(...)` proxies and the values they proxy have different identities. Because of this, comparisons with `%operator%` will produce unexpected results
diff --git a/packages/svelte/messages/compile-warnings/template.md b/packages/svelte/messages/compile-warnings/template.md
index c1675e5995..d61a61d950 100644
--- a/packages/svelte/messages/compile-warnings/template.md
+++ b/packages/svelte/messages/compile-warnings/template.md
@@ -30,6 +30,23 @@
 
 > `<%name%>` will be treated as an HTML element unless it begins with a capital letter
 
+## element_implicitly_closed
+
+> This element is implicitly closed by the following `%tag%`, which can cause an unexpected DOM structure. Add an explicit `%closing%` to avoid surprises.
+
+In HTML, some elements are implicitly closed by another element. For example, you cannot nest a `<p>` inside another `<p>`:
+
+```html
+<!-- this HTML... -->
+<p><p>hello</p>
+
+<!-- results in this DOM structure -->
+<p></p>
+<p>hello</p>
+```
+
+Similarly, a parent element's closing tag will implicitly close all child elements, even if the `</` was a typo and you meant to create a _new_ element. To avoid ambiguity, it's always a good idea to have an explicit closing tag.
+
 ## element_invalid_self_closing_tag
 
 > Self-closing HTML tags for non-void elements are ambiguous — use `<%name% ...></%name%>` rather than `<%name% ... />`
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 45a875d19b..0a992d1901 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": "5.31.1",
+  "version": "5.33.0",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/attachments/index.js b/packages/svelte/src/attachments/index.js
index dc2f3e93d7..b9fde9b6d9 100644
--- a/packages/svelte/src/attachments/index.js
+++ b/packages/svelte/src/attachments/index.js
@@ -2,7 +2,7 @@
 /** @import { Attachment } from './public' */
 import { noop, render_effect } from 'svelte/internal/client';
 import { ATTACHMENT_KEY } from '../constants.js';
-import { untrack } from 'svelte';
+import { untrack } from '../index-client.js';
 import { teardown } from '../internal/client/reactivity/effects.js';
 
 /**
diff --git a/packages/svelte/src/compiler/phases/1-parse/state/element.js b/packages/svelte/src/compiler/phases/1-parse/state/element.js
index d20369b0d9..6b6c9160d8 100644
--- a/packages/svelte/src/compiler/phases/1-parse/state/element.js
+++ b/packages/svelte/src/compiler/phases/1-parse/state/element.js
@@ -93,7 +93,16 @@ export default function element(parser) {
 				}
 			}
 
-			if (parent.type !== 'RegularElement' && !parser.loose) {
+			if (parent.type === 'RegularElement') {
+				if (!parser.last_auto_closed_tag || parser.last_auto_closed_tag.tag !== name) {
+					const end = parent.fragment.nodes[0]?.start ?? start;
+					w.element_implicitly_closed(
+						{ start: parent.start, end },
+						`</${name}>`,
+						`</${parent.name}>`
+					);
+				}
+			} else if (!parser.loose) {
 				if (parser.last_auto_closed_tag && parser.last_auto_closed_tag.tag === name) {
 					e.element_invalid_closing_tag_autoclosed(start, name, parser.last_auto_closed_tag.reason);
 				} else {
@@ -186,6 +195,8 @@ export default function element(parser) {
 	parser.allow_whitespace();
 
 	if (parent.type === 'RegularElement' && closing_tag_omitted(parent.name, name)) {
+		const end = parent.fragment.nodes[0]?.start ?? start;
+		w.element_implicitly_closed({ start: parent.start, end }, `<${name}>`, `</${parent.name}>`);
 		parent.end = start;
 		parser.pop();
 		parser.last_auto_closed_tag = {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index f2eda3a7d2..e2e006c14b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -154,10 +154,6 @@ export function client_component(analysis, options) {
 		legacy_reactive_imports: [],
 		legacy_reactive_statements: new Map(),
 		metadata: {
-			context: {
-				template_needs_import_node: false,
-				template_contains_script_tag: false
-			},
 			namespace: options.namespace,
 			bound_contenteditable: false
 		},
@@ -174,8 +170,7 @@ export function client_component(analysis, options) {
 		update: /** @type {any} */ (null),
 		expressions: /** @type {any} */ (null),
 		after_update: /** @type {any} */ (null),
-		template: /** @type {any} */ (null),
-		locations: /** @type {any} */ (null)
+		template: /** @type {any} */ (null)
 	};
 
 	const module = /** @type {ESTree.Program} */ (
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-template/fix-attribute-casing.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/fix-attribute-casing.js
new file mode 100644
index 0000000000..ce56c43d7c
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/fix-attribute-casing.js
@@ -0,0 +1,18 @@
+const svg_attributes =
+	'accent-height accumulate additive alignment-baseline allowReorder alphabetic amplitude arabic-form ascent attributeName attributeType autoReverse azimuth baseFrequency baseline-shift baseProfile bbox begin bias by calcMode cap-height class clip clipPathUnits clip-path clip-rule color color-interpolation color-interpolation-filters color-profile color-rendering contentScriptType contentStyleType cursor cx cy d decelerate descent diffuseConstant direction display divisor dominant-baseline dur dx dy edgeMode elevation enable-background end exponent externalResourcesRequired fill fill-opacity fill-rule filter filterRes filterUnits flood-color flood-opacity font-family font-size font-size-adjust font-stretch font-style font-variant font-weight format from fr fx fy g1 g2 glyph-name glyph-orientation-horizontal glyph-orientation-vertical glyphRef gradientTransform gradientUnits hanging height href horiz-adv-x horiz-origin-x id ideographic image-rendering in in2 intercept k k1 k2 k3 k4 kernelMatrix kernelUnitLength kerning keyPoints keySplines keyTimes lang lengthAdjust letter-spacing lighting-color limitingConeAngle local marker-end marker-mid marker-start markerHeight markerUnits markerWidth mask maskContentUnits maskUnits mathematical max media method min mode name numOctaves offset onabort onactivate onbegin onclick onend onerror onfocusin onfocusout onload onmousedown onmousemove onmouseout onmouseover onmouseup onrepeat onresize onscroll onunload opacity operator order orient orientation origin overflow overline-position overline-thickness panose-1 paint-order pathLength patternContentUnits patternTransform patternUnits pointer-events points pointsAtX pointsAtY pointsAtZ preserveAlpha preserveAspectRatio primitiveUnits r radius refX refY rendering-intent repeatCount repeatDur requiredExtensions requiredFeatures restart result rotate rx ry scale seed shape-rendering slope spacing specularConstant specularExponent speed spreadMethod startOffset stdDeviation stemh stemv stitchTiles stop-color stop-opacity strikethrough-position strikethrough-thickness string stroke stroke-dasharray stroke-dashoffset stroke-linecap stroke-linejoin stroke-miterlimit stroke-opacity stroke-width style surfaceScale systemLanguage tabindex tableValues target targetX targetY text-anchor text-decoration text-rendering textLength to transform type u1 u2 underline-position underline-thickness unicode unicode-bidi unicode-range units-per-em v-alphabetic v-hanging v-ideographic v-mathematical values version vert-adv-y vert-origin-x vert-origin-y viewBox viewTarget visibility width widths word-spacing writing-mode x x-height x1 x2 xChannelSelector xlink:actuate xlink:arcrole xlink:href xlink:role xlink:show xlink:title xlink:type xml:base xml:lang xml:space y y1 y2 yChannelSelector z zoomAndPan'.split(
+		' '
+	);
+
+const svg_attribute_lookup = new Map();
+
+svg_attributes.forEach((name) => {
+	svg_attribute_lookup.set(name.toLowerCase(), name);
+});
+
+/**
+ * @param {string} name
+ */
+export default function fix_attribute_casing(name) {
+	name = name.toLowerCase();
+	return svg_attribute_lookup.get(name) || name;
+}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-template/index.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/index.js
new file mode 100644
index 0000000000..d0327e702a
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/index.js
@@ -0,0 +1,68 @@
+/** @import { Location } from 'locate-character' */
+/** @import { Namespace } from '#compiler' */
+/** @import { ComponentClientTransformState } from '../types.js' */
+/** @import { Node } from './types.js' */
+import { TEMPLATE_USE_MATHML, TEMPLATE_USE_SVG } from '../../../../../constants.js';
+import { dev, locator } from '../../../../state.js';
+import * as b from '../../../../utils/builders.js';
+
+/**
+ * @param {Node[]} nodes
+ */
+function build_locations(nodes) {
+	const array = b.array([]);
+
+	for (const node of nodes) {
+		if (node.type !== 'element') continue;
+
+		const { line, column } = /** @type {Location} */ (locator(node.start));
+
+		const expression = b.array([b.literal(line), b.literal(column)]);
+		const children = build_locations(node.children);
+
+		if (children.elements.length > 0) {
+			expression.elements.push(children);
+		}
+
+		array.elements.push(expression);
+	}
+
+	return array;
+}
+
+/**
+ * @param {ComponentClientTransformState} state
+ * @param {Namespace} namespace
+ * @param {number} [flags]
+ */
+export function transform_template(state, namespace, flags = 0) {
+	const tree = state.options.fragments === 'tree';
+
+	const expression = tree ? state.template.as_tree() : state.template.as_html();
+
+	if (tree) {
+		if (namespace === 'svg') flags |= TEMPLATE_USE_SVG;
+		if (namespace === 'mathml') flags |= TEMPLATE_USE_MATHML;
+	}
+
+	let call = b.call(
+		tree ? `$.from_tree` : `$.from_${namespace}`,
+		expression,
+		flags ? b.literal(flags) : undefined
+	);
+
+	if (state.template.contains_script_tag) {
+		call = b.call(`$.with_script`, call);
+	}
+
+	if (dev) {
+		call = b.call(
+			'$.add_locations',
+			call,
+			b.member(b.id(state.analysis.name), '$.FILENAME', true),
+			build_locations(state.template.nodes)
+		);
+	}
+
+	return call;
+}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-template/template.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/template.js
new file mode 100644
index 0000000000..8f7f8a1f43
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/template.js
@@ -0,0 +1,162 @@
+/** @import { AST } from '#compiler' */
+/** @import { Node, Element } from './types'; */
+import { escape_html } from '../../../../../escaping.js';
+import { is_void } from '../../../../../utils.js';
+import * as b from '#compiler/builders';
+import fix_attribute_casing from './fix-attribute-casing.js';
+import { regex_starts_with_newline } from '../../../patterns.js';
+
+export class Template {
+	/**
+	 * `true` if HTML template contains a `<script>` tag. In this case we need to invoke a special
+	 * template instantiation function (see `create_fragment_with_script_from_html` for more info)
+	 */
+	contains_script_tag = false;
+
+	/** `true` if the HTML template needs to be instantiated with `importNode` */
+	needs_import_node = false;
+
+	/** @type {Node[]} */
+	nodes = [];
+
+	/** @type {Node[][]} */
+	#stack = [this.nodes];
+
+	/** @type {Element | undefined} */
+	#element;
+
+	#fragment = this.nodes;
+
+	/**
+	 * @param {string} name
+	 * @param {number} start
+	 */
+	push_element(name, start) {
+		this.#element = {
+			type: 'element',
+			name,
+			attributes: {},
+			children: [],
+			start
+		};
+
+		this.#fragment.push(this.#element);
+
+		this.#fragment = /** @type {Element} */ (this.#element).children;
+		this.#stack.push(this.#fragment);
+	}
+
+	/** @param {string} [data] */
+	push_comment(data) {
+		this.#fragment.push({ type: 'comment', data });
+	}
+
+	/** @param {AST.Text[]} nodes */
+	push_text(nodes) {
+		this.#fragment.push({ type: 'text', nodes });
+	}
+
+	pop_element() {
+		this.#stack.pop();
+		this.#fragment = /** @type {Node[]} */ (this.#stack.at(-1));
+	}
+
+	/**
+	 * @param {string} key
+	 * @param {string | undefined} value
+	 */
+	set_prop(key, value) {
+		/** @type {Element} */ (this.#element).attributes[key] = value;
+	}
+
+	as_html() {
+		return b.template([b.quasi(this.nodes.map(stringify).join(''), true)], []);
+	}
+
+	as_tree() {
+		// if the first item is a comment we need to add another comment for effect.start
+		if (this.nodes[0].type === 'comment') {
+			this.nodes.unshift({ type: 'comment', data: undefined });
+		}
+
+		return b.array(this.nodes.map(objectify));
+	}
+}
+
+/**
+ * @param {Node} item
+ */
+function stringify(item) {
+	if (item.type === 'text') {
+		return item.nodes.map((node) => node.raw).join('');
+	}
+
+	if (item.type === 'comment') {
+		return item.data ? `<!--${item.data}-->` : '<!>';
+	}
+
+	let str = `<${item.name}`;
+
+	for (const key in item.attributes) {
+		const value = item.attributes[key];
+
+		str += ` ${key}`;
+		if (value !== undefined) str += `="${escape_html(value, true)}"`;
+	}
+
+	if (is_void(item.name)) {
+		str += '/>'; // XHTML compliance
+	} else {
+		str += `>`;
+		str += item.children.map(stringify).join('');
+		str += `</${item.name}>`;
+	}
+
+	return str;
+}
+
+/** @param {Node} item */
+function objectify(item) {
+	if (item.type === 'text') {
+		return b.literal(item.nodes.map((node) => node.data).join(''));
+	}
+
+	if (item.type === 'comment') {
+		return item.data ? b.array([b.literal(`// ${item.data}`)]) : null;
+	}
+
+	const element = b.array([b.literal(item.name)]);
+
+	const attributes = b.object([]);
+
+	for (const key in item.attributes) {
+		const value = item.attributes[key];
+
+		attributes.properties.push(
+			b.prop(
+				'init',
+				b.key(fix_attribute_casing(key)),
+				value === undefined ? b.void0 : b.literal(value)
+			)
+		);
+	}
+
+	if (attributes.properties.length > 0 || item.children.length > 0) {
+		element.elements.push(attributes.properties.length > 0 ? attributes : b.null);
+	}
+
+	if (item.children.length > 0) {
+		const children = item.children.map(objectify);
+		element.elements.push(...children);
+
+		// special case — strip leading newline from `<pre>` and `<textarea>`
+		if (item.name === 'pre' || item.name === 'textarea') {
+			const first = children[0];
+			if (first?.type === 'Literal') {
+				first.value = /** @type {string} */ (first.value).replace(regex_starts_with_newline, '');
+			}
+		}
+	}
+
+	return element;
+}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-template/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/types.d.ts
new file mode 100644
index 0000000000..1555e10ef0
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-template/types.d.ts
@@ -0,0 +1,22 @@
+import type { AST } from '#compiler';
+
+export interface Element {
+	type: 'element';
+	name: string;
+	attributes: Record<string, string | undefined>;
+	children: Node[];
+	/** used for populating __svelte_meta */
+	start: number;
+}
+
+export interface Text {
+	type: 'text';
+	nodes: AST.Text[];
+}
+
+export interface Comment {
+	type: 'comment';
+	data: string | undefined;
+}
+
+export type Node = Element | Text | Comment;
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index 763b6773c7..2388ee1b00 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -3,16 +3,15 @@ import type {
 	Statement,
 	LabeledStatement,
 	Identifier,
-	PrivateIdentifier,
 	Expression,
 	AssignmentExpression,
 	UpdateExpression,
 	VariableDeclaration
 } from 'estree';
-import type { AST, Namespace, StateField, ValidatedCompileOptions } from '#compiler';
+import type { AST, Namespace, ValidatedCompileOptions } from '#compiler';
 import type { TransformState } from '../types.js';
 import type { ComponentAnalysis } from '../../types.js';
-import type { SourceLocation } from '#shared';
+import type { Template } from './transform-template/template.js';
 
 export interface ClientTransformState extends TransformState {
 	/**
@@ -53,26 +52,10 @@ export interface ComponentClientTransformState extends ClientTransformState {
 	/** Expressions used inside the render effect */
 	readonly expressions: Expression[];
 	/** The HTML template string */
-	readonly template: Array<string | Expression>;
-	readonly locations: SourceLocation[];
+	readonly template: Template;
 	readonly metadata: {
 		namespace: Namespace;
 		bound_contenteditable: boolean;
-		/**
-		 * Stuff that is set within the children of one `Fragment` visitor that is relevant
-		 * to said fragment. Shouldn't be destructured or otherwise spread unless inside the
-		 * `Fragment` visitor to keep the object reference intact (it's also nested
-		 * within `metadata` for this reason).
-		 */
-		context: {
-			/** `true` if the HTML template needs to be instantiated with `importNode` */
-			template_needs_import_node: boolean;
-			/**
-			 * `true` if HTML template contains a `<script>` tag. In this case we need to invoke a special
-			 * template instantiation function (see `create_fragment_with_script_from_html` for more info)
-			 */
-			template_contains_script_tag: boolean;
-		};
 	};
 	readonly preserve_whitespace: boolean;
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
index 96a4addb72..30e370327f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
@@ -11,7 +11,7 @@ import { get_value } from './shared/declarations.js';
  * @param {ComponentContext} context
  */
 export function AwaitBlock(node, context) {
-	context.state.template.push('<!>');
+	context.state.template.push_comment();
 
 	// Visit {#await <expression>} first to ensure that scopes are in the correct order
 	const expression = b.thunk(/** @type {Expression} */ (context.visit(node.expression)));
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Comment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Comment.js
index 24011e62aa..21d1619f8a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Comment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Comment.js
@@ -7,5 +7,5 @@
  */
 export function Comment(node, context) {
 	// We'll only get here if comments are not filtered out, which they are unless preserveComments is true
-	context.state.template.push(`<!--${node.data}-->`);
+	context.state.template.push_comment(node.data);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index e5aee24765..f80fa0e61e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -32,7 +32,7 @@ export function EachBlock(node, context) {
 	);
 
 	if (!each_node_meta.is_controlled) {
-		context.state.template.push('<!>');
+		context.state.template.push_comment();
 	}
 
 	let flags = 0;
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
index b6dca0779a..4825184d31 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
@@ -1,14 +1,13 @@
-/** @import { Expression, Identifier, Statement, TemplateElement } from 'estree' */
-/** @import { AST, Namespace } from '#compiler' */
-/** @import { SourceLocation } from '#shared' */
+/** @import { Expression, Statement } from 'estree' */
+/** @import { AST } from '#compiler' */
 /** @import { ComponentClientTransformState, ComponentContext } from '../types' */
 import { TEMPLATE_FRAGMENT, TEMPLATE_USE_IMPORT_NODE } from '../../../../../constants.js';
-import { dev } from '../../../../state.js';
 import * as b from '#compiler/builders';
-import { sanitize_template_string } from '../../../../utils/sanitize_template_string.js';
 import { clean_nodes, infer_namespace } from '../../utils.js';
+import { transform_template } from '../transform-template/index.js';
 import { process_children } from './shared/fragment.js';
 import { build_render_statement } from './shared/utils.js';
+import { Template } from '../transform-template/template.js';
 
 /**
  * @param {AST.Fragment} node
@@ -18,7 +17,7 @@ export function Fragment(node, context) {
 	// Creates a new block which looks roughly like this:
 	// ```js
 	// // hoisted:
-	// const block_name = $.template(`...`);
+	// const block_name = $.from_html(`...`);
 	//
 	// // for the main block:
 	// const id = block_name();
@@ -67,14 +66,9 @@ export function Fragment(node, context) {
 		update: [],
 		expressions: [],
 		after_update: [],
-		template: [],
-		locations: [],
+		template: new Template(),
 		transform: { ...context.state.transform },
 		metadata: {
-			context: {
-				template_needs_import_node: false,
-				template_contains_script_tag: false
-			},
 			namespace,
 			bound_contenteditable: context.state.metadata.bound_contenteditable
 		}
@@ -89,24 +83,6 @@ export function Fragment(node, context) {
 		body.push(b.stmt(b.call('$.next')));
 	}
 
-	/**
-	 * @param {Identifier} template_name
-	 * @param {Expression[]} args
-	 */
-	const add_template = (template_name, args) => {
-		let call = b.call(get_template_function(namespace, state), ...args);
-		if (dev) {
-			call = b.call(
-				'$.add_locations',
-				call,
-				b.member(b.id(context.state.analysis.name), '$.FILENAME', true),
-				build_locations(state.locations)
-			);
-		}
-
-		context.state.hoisted.push(b.var(template_name, call));
-	};
-
 	if (is_single_element) {
 		const element = /** @type {AST.RegularElement} */ (trimmed[0]);
 
@@ -117,14 +93,10 @@ export function Fragment(node, context) {
 			node: id
 		});
 
-		/** @type {Expression[]} */
-		const args = [join_template(state.template)];
+		let flags = state.template.needs_import_node ? TEMPLATE_USE_IMPORT_NODE : undefined;
 
-		if (state.metadata.context.template_needs_import_node) {
-			args.push(b.literal(TEMPLATE_USE_IMPORT_NODE));
-		}
-
-		add_template(template_name, args);
+		const template = transform_template(state, namespace, flags);
+		state.hoisted.push(b.var(template_name, template));
 
 		body.push(b.var(id, b.call(template_name)));
 		close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
@@ -164,15 +136,16 @@ export function Fragment(node, context) {
 
 				let flags = TEMPLATE_FRAGMENT;
 
-				if (state.metadata.context.template_needs_import_node) {
+				if (state.template.needs_import_node) {
 					flags |= TEMPLATE_USE_IMPORT_NODE;
 				}
 
-				if (state.template.length === 1 && state.template[0] === '<!>') {
+				if (state.template.nodes.length === 1 && state.template.nodes[0].type === 'comment') {
 					// special case — we can use `$.comment` instead of creating a unique template
 					body.push(b.var(id, b.call('$.comment')));
 				} else {
-					add_template(template_name, [join_template(state.template), b.literal(flags)]);
+					const template = transform_template(state, namespace, flags);
+					state.hoisted.push(b.var(template_name, template));
 
 					body.push(b.var(id, b.call(template_name)));
 				}
@@ -199,86 +172,3 @@ export function Fragment(node, context) {
 
 	return b.block(body);
 }
-
-/**
- * @param {Array<string | Expression>} items
- */
-function join_template(items) {
-	let quasi = b.quasi('');
-	const template = b.template([quasi], []);
-
-	/**
-	 * @param {Expression} expression
-	 */
-	function push(expression) {
-		if (expression.type === 'TemplateLiteral') {
-			for (let i = 0; i < expression.expressions.length; i += 1) {
-				const q = expression.quasis[i];
-				const e = expression.expressions[i];
-
-				quasi.value.cooked += /** @type {string} */ (q.value.cooked);
-				push(e);
-			}
-
-			const last = /** @type {TemplateElement} */ (expression.quasis.at(-1));
-			quasi.value.cooked += /** @type {string} */ (last.value.cooked);
-		} else if (expression.type === 'Literal') {
-			/** @type {string} */ (quasi.value.cooked) += expression.value;
-		} else {
-			template.expressions.push(expression);
-			template.quasis.push((quasi = b.quasi('')));
-		}
-	}
-
-	for (const item of items) {
-		if (typeof item === 'string') {
-			quasi.value.cooked += item;
-		} else {
-			push(item);
-		}
-	}
-
-	for (const quasi of template.quasis) {
-		quasi.value.raw = sanitize_template_string(/** @type {string} */ (quasi.value.cooked));
-	}
-
-	quasi.tail = true;
-
-	return template;
-}
-
-/**
- *
- * @param {Namespace} namespace
- * @param {ComponentClientTransformState} state
- * @returns
- */
-function get_template_function(namespace, state) {
-	const contains_script_tag = state.metadata.context.template_contains_script_tag;
-	return namespace === 'svg'
-		? contains_script_tag
-			? '$.svg_template_with_script'
-			: '$.ns_template'
-		: namespace === 'mathml'
-			? '$.mathml_template'
-			: contains_script_tag
-				? '$.template_with_script'
-				: '$.template';
-}
-
-/**
- * @param {SourceLocation[]} locations
- */
-function build_locations(locations) {
-	return b.array(
-		locations.map((loc) => {
-			const expression = b.array([b.literal(loc[0]), b.literal(loc[1])]);
-
-			if (loc.length === 3) {
-				expression.elements.push(build_locations(loc[2]));
-			}
-
-			return expression;
-		})
-	);
-}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
index a69b9cfe70..405b400b42 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
@@ -9,7 +9,7 @@ import * as b from '#compiler/builders';
  * @param {ComponentContext} context
  */
 export function HtmlTag(node, context) {
-	context.state.template.push('<!>');
+	context.state.template.push_comment();
 
 	const expression = /** @type {Expression} */ (context.visit(node.expression));
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js
index c650a1e15c..3702a47bc9 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js
@@ -8,7 +8,7 @@ import * as b from '#compiler/builders';
  * @param {ComponentContext} context
  */
 export function IfBlock(node, context) {
-	context.state.template.push('<!>');
+	context.state.template.push_comment();
 	const statements = [];
 
 	const consequent = /** @type {BlockStatement} */ (context.visit(node.consequent));
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js
index 7d6a8b0006..5e63f7e872 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js
@@ -8,7 +8,7 @@ import * as b from '#compiler/builders';
  * @param {ComponentContext} context
  */
 export function KeyBlock(node, context) {
-	context.state.template.push('<!>');
+	context.state.template.push_comment();
 
 	const key = /** @type {Expression} */ (context.visit(node.expression));
 	const body = /** @type {Expression} */ (context.visit(node.fragment));
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
index 1d39289f3d..c1806b5128 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
@@ -1,17 +1,14 @@
 /** @import { ArrayExpression, Expression, ExpressionStatement, Identifier, MemberExpression, ObjectExpression } from 'estree' */
 /** @import { AST } from '#compiler' */
-/** @import { SourceLocation } from '#shared' */
 /** @import { ComponentClientTransformState, ComponentContext } from '../types' */
 /** @import { Scope } from '../../../scope' */
 import {
 	cannot_be_set_statically,
 	is_boolean_attribute,
 	is_dom_property,
-	is_load_error_element,
-	is_void
+	is_load_error_element
 } from '../../../../../utils.js';
-import { escape_html } from '../../../../../escaping.js';
-import { dev, is_ignored, locator } from '../../../../state.js';
+import { is_ignored } from '../../../../state.js';
 import { is_event_attribute, is_text_attribute } from '../../../../utils/ast.js';
 import * as b from '#compiler/builders';
 import { is_custom_element_node } from '../../../nodes.js';
@@ -39,40 +36,24 @@ import { visit_event_attribute } from './shared/events.js';
  * @param {ComponentContext} context
  */
 export function RegularElement(node, context) {
-	/** @type {SourceLocation} */
-	let location = [-1, -1];
-
-	if (dev) {
-		const loc = locator(node.start);
-		if (loc) {
-			location[0] = loc.line;
-			location[1] = loc.column;
-			context.state.locations.push(location);
-		}
-	}
+	context.state.template.push_element(node.name, node.start);
 
 	if (node.name === 'noscript') {
-		context.state.template.push('<noscript></noscript>');
+		context.state.template.pop_element();
 		return;
 	}
 
 	const is_custom_element = is_custom_element_node(node);
 
-	if (node.name === 'video' || is_custom_element) {
-		// cloneNode is faster, but it does not instantiate the underlying class of the
-		// custom element until the template is connected to the dom, which would
-		// cause problems when setting properties on the custom element.
-		// Therefore we need to use importNode instead, which doesn't have this caveat.
-		// Additionally, Webkit browsers need importNode for video elements for autoplay
-		// to work correctly.
-		context.state.metadata.context.template_needs_import_node = true;
-	}
-
-	if (node.name === 'script') {
-		context.state.metadata.context.template_contains_script_tag = true;
-	}
+	// cloneNode is faster, but it does not instantiate the underlying class of the
+	// custom element until the template is connected to the dom, which would
+	// cause problems when setting properties on the custom element.
+	// Therefore we need to use importNode instead, which doesn't have this caveat.
+	// Additionally, Webkit browsers need importNode for video elements for autoplay
+	// to work correctly.
+	context.state.template.needs_import_node ||= node.name === 'video' || is_custom_element;
 
-	context.state.template.push(`<${node.name}`);
+	context.state.template.contains_script_tag ||= node.name === 'script';
 
 	/** @type {Array<AST.Attribute | AST.SpreadAttribute>} */
 	const attributes = [];
@@ -110,7 +91,7 @@ export function RegularElement(node, context) {
 					const { value } = build_attribute_value(attribute.value, context);
 
 					if (value.type === 'Literal' && typeof value.value === 'string') {
-						context.state.template.push(` is="${escape_html(value.value, true)}"`);
+						context.state.template.set_prop('is', value.value);
 						continue;
 					}
 				}
@@ -290,12 +271,9 @@ export function RegularElement(node, context) {
 				}
 
 				if (name !== 'class' || value) {
-					context.state.template.push(
-						` ${attribute.name}${
-							is_boolean_attribute(name) && value === true
-								? ''
-								: `="${value === true ? '' : escape_html(value, true)}"`
-						}`
+					context.state.template.set_prop(
+						attribute.name,
+						is_boolean_attribute(name) && value === true ? undefined : value === true ? '' : value
 					);
 				}
 			} else if (name === 'autofocus') {
@@ -329,8 +307,6 @@ export function RegularElement(node, context) {
 		context.state.after_update.push(b.stmt(b.call('$.replay_events', node_id)));
 	}
 
-	context.state.template.push('>');
-
 	const metadata = {
 		...context.state.metadata,
 		namespace: determine_namespace_for_children(node, context.state.metadata.namespace)
@@ -352,7 +328,6 @@ export function RegularElement(node, context) {
 	const state = {
 		...context.state,
 		metadata,
-		locations: [],
 		scope: /** @type {Scope} */ (context.state.scopes.get(node.fragment)),
 		preserve_whitespace:
 			context.state.preserve_whitespace || node.name === 'pre' || node.name === 'textarea'
@@ -446,14 +421,7 @@ export function RegularElement(node, context) {
 		context.state.update.push(b.stmt(b.assignment('=', dir, dir)));
 	}
 
-	if (state.locations.length > 0) {
-		// @ts-expect-error
-		location.push(state.locations);
-	}
-
-	if (!is_void(node.name)) {
-		context.state.template.push(`</${node.name}>`);
-	}
+	context.state.template.pop_element();
 }
 
 /**
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js
index 6067c2562a..fec7b5762a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js
@@ -9,7 +9,7 @@ import * as b from '#compiler/builders';
  * @param {ComponentContext} context
  */
 export function RenderTag(node, context) {
-	context.state.template.push('<!>');
+	context.state.template.push_comment();
 
 	const expression = unwrap_optional(node.expression);
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SlotElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SlotElement.js
index ba9fcc7377..401cfde428 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SlotElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SlotElement.js
@@ -11,7 +11,7 @@ import { memoize_expression } from './shared/utils.js';
  */
 export function SlotElement(node, context) {
 	// <slot {a}>fallback</slot>  -->   $.slot($$slots.default, { get a() { .. } }, () => ...fallback);
-	context.state.template.push('<!>');
+	context.state.template.push_comment();
 
 	/** @type {Property[]} */
 	const props = [];
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
index b279b5badd..ec1c650814 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
@@ -88,7 +88,7 @@ export function SvelteBoundary(node, context) {
 		b.call('$.boundary', context.state.node, props, b.arrow([b.id('$$anchor')], block))
 	);
 
-	context.state.template.push('<!>');
+	context.state.template.push_comment();
 	context.state.init.push(
 		external_statements.length > 0 ? b.block([...external_statements, boundary]) : boundary
 	);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js
index ee597dd043..7e97035e00 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js
@@ -13,7 +13,7 @@ import { build_render_statement } from './shared/utils.js';
  * @param {ComponentContext} context
  */
 export function SvelteElement(node, context) {
-	context.state.template.push(`<!>`);
+	context.state.template.push_comment();
 
 	/** @type {Array<AST.Attribute | AST.SpreadAttribute>} */
 	const attributes = [];
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index 6d3d8a68e6..57402c2b4a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -440,11 +440,17 @@ export function build_component(node, component_name, context, anchor = context.
 	}
 
 	if (Object.keys(custom_css_props).length > 0) {
-		context.state.template.push(
-			context.state.metadata.namespace === 'svg'
-				? '<g><!></g>'
-				: '<svelte-css-wrapper style="display: contents"><!></svelte-css-wrapper>'
-		);
+		if (context.state.metadata.namespace === 'svg') {
+			// this boils down to <g><!></g>
+			context.state.template.push_element('g', node.start);
+		} else {
+			// this boils down to <svelte-css-wrapper style='display: contents'><!></svelte-css-wrapper>
+			context.state.template.push_element('svelte-css-wrapper', node.start);
+			context.state.template.set_prop('style', 'display: contents');
+		}
+
+		context.state.template.push_comment();
+		context.state.template.pop_element();
 
 		statements.push(
 			b.stmt(b.call('$.css_props', anchor, b.thunk(b.object(custom_css_props)))),
@@ -452,7 +458,7 @@ export function build_component(node, component_name, context, anchor = context.
 			b.stmt(b.call('$.reset', anchor))
 		);
 	} else {
-		context.state.template.push('<!>');
+		context.state.template.push_comment();
 		statements.push(b.stmt(fn(anchor)));
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/fragment.js
index c91e2b3b44..7af2c2d4aa 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/fragment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/fragment.js
@@ -64,11 +64,11 @@ export function process_children(nodes, initial, is_element, { visit, state }) {
 	function flush_sequence(sequence) {
 		if (sequence.every((node) => node.type === 'Text')) {
 			skipped += 1;
-			state.template.push(sequence.map((node) => node.raw).join(''));
+			state.template.push_text(sequence);
 			return;
 		}
 
-		state.template.push(' ');
+		state.template.push_text([{ type: 'Text', data: ' ', raw: ' ', start: -1, end: -1 }]);
 
 		const { has_state, value } = build_template_chunk(sequence, visit, state);
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js
index 5901cb4c50..2928ca9173 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js
@@ -24,9 +24,11 @@ export function RegularElement(node, context) {
 			context.state.preserve_whitespace || node.name === 'pre' || node.name === 'textarea'
 	};
 
+	const node_is_void = is_void(node.name);
+
 	context.state.template.push(b.literal(`<${node.name}`));
 	const body = build_element_attributes(node, { ...context, state });
-	context.state.template.push(b.literal('>'));
+	context.state.template.push(b.literal(node_is_void ? '/>' : '>')); // add `/>` for XHTML compliance
 
 	if ((node.name === 'script' || node.name === 'style') && node.fragment.nodes.length === 1) {
 		context.state.template.push(
@@ -94,7 +96,7 @@ export function RegularElement(node, context) {
 		);
 	}
 
-	if (!is_void(node.name)) {
+	if (!node_is_void) {
 		state.template.push(b.literal(`</${node.name}>`));
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/utils.js b/packages/svelte/src/compiler/phases/3-transform/utils.js
index 5aa40c8abb..1445ce3aa6 100644
--- a/packages/svelte/src/compiler/phases/3-transform/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/utils.js
@@ -271,19 +271,12 @@ export function clean_nodes(
 
 	var first = trimmed[0];
 
-	// initial newline inside a `<pre>` is disregarded, if not followed by another newline
+	// if first text node inside a <pre> is a single newline, discard it, because otherwise
+	// the browser will do it for us which could break hydration
 	if (parent.type === 'RegularElement' && parent.name === 'pre' && first?.type === 'Text') {
-		const text = first.data.replace(regex_starts_with_newline, '');
-		if (text !== first.data) {
-			const tmp = text.replace(regex_starts_with_newline, '');
-			if (text === tmp) {
-				first.data = text;
-				first.raw = first.raw.replace(regex_starts_with_newline, '');
-				if (first.data === '') {
-					trimmed.shift();
-					first = trimmed[0];
-				}
-			}
+		if (first.data === '\n' || first.data === '\r\n') {
+			trimmed.shift();
+			first = trimmed[0];
 		}
 	}
 
@@ -331,7 +324,7 @@ export function clean_nodes(
 }
 
 /**
- * Infers the namespace for the children of a node that should be used when creating the `$.template(...)`.
+ * Infers the namespace for the children of a node that should be used when creating the fragment
  * @param {Namespace} namespace
  * @param {AST.SvelteNode} parent
  * @param {AST.SvelteNode[]} nodes
diff --git a/packages/svelte/src/compiler/types/index.d.ts b/packages/svelte/src/compiler/types/index.d.ts
index ef52552a2e..a53a431cf1 100644
--- a/packages/svelte/src/compiler/types/index.d.ts
+++ b/packages/svelte/src/compiler/types/index.d.ts
@@ -122,6 +122,15 @@ export interface CompileOptions extends ModuleCompileOptions {
 	 * @default false
 	 */
 	preserveWhitespace?: boolean;
+	/**
+	 * Which strategy to use when cloning DOM fragments:
+	 *
+	 * - `html` populates a `<template>` with `innerHTML` and clones it. This is faster, but cannot be used if your app's [Content Security Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CSP) includes [`require-trusted-types-for 'script'`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Security-Policy/require-trusted-types-for)
+	 * - `tree` creates the fragment one element at a time and _then_ clones it. This is slower, but works everywhere
+	 *
+	 * @default 'html'
+	 */
+	fragments?: 'html' | 'tree';
 	/**
 	 * Set to `true` to force the compiler into runes mode, even if there are no indications of runes usage.
 	 * Set to `false` to force the compiler into ignoring runes, even if there are indications of runes usage.
diff --git a/packages/svelte/src/compiler/validate-options.js b/packages/svelte/src/compiler/validate-options.js
index ab932ed5bc..85305d7ce9 100644
--- a/packages/svelte/src/compiler/validate-options.js
+++ b/packages/svelte/src/compiler/validate-options.js
@@ -110,6 +110,8 @@ export const validate_component_options =
 
 			preserveComments: boolean(false),
 
+			fragments: list(['html', 'tree']),
+
 			preserveWhitespace: boolean(false),
 
 			runes: boolean(undefined),
diff --git a/packages/svelte/src/compiler/warnings.js b/packages/svelte/src/compiler/warnings.js
index c281433213..2a8316308c 100644
--- a/packages/svelte/src/compiler/warnings.js
+++ b/packages/svelte/src/compiler/warnings.js
@@ -114,6 +114,7 @@ export const codes = [
 	'bind_invalid_each_rest',
 	'block_empty',
 	'component_name_lowercase',
+	'element_implicitly_closed',
 	'element_invalid_self_closing_tag',
 	'event_directive_deprecated',
 	'node_invalid_placement_ssr',
@@ -746,6 +747,16 @@ export function component_name_lowercase(node, name) {
 	w(node, 'component_name_lowercase', `\`<${name}>\` will be treated as an HTML element unless it begins with a capital letter\nhttps://svelte.dev/e/component_name_lowercase`);
 }
 
+/**
+ * This element is implicitly closed by the following `%tag%`, which can cause an unexpected DOM structure. Add an explicit `%closing%` to avoid surprises.
+ * @param {null | NodeLike} node
+ * @param {string} tag
+ * @param {string} closing
+ */
+export function element_implicitly_closed(node, tag, closing) {
+	w(node, 'element_implicitly_closed', `This element is implicitly closed by the following \`${tag}\`, which can cause an unexpected DOM structure. Add an explicit \`${closing}\` to avoid surprises.\nhttps://svelte.dev/e/element_implicitly_closed`);
+}
+
 /**
  * Self-closing HTML tags for non-void elements are ambiguous — use `<%name% ...></%name%>` rather than `<%name% ... />`
  * @param {null | NodeLike} node
diff --git a/packages/svelte/src/constants.js b/packages/svelte/src/constants.js
index 2ecd4afee2..4e1785723c 100644
--- a/packages/svelte/src/constants.js
+++ b/packages/svelte/src/constants.js
@@ -17,6 +17,8 @@ export const TRANSITION_GLOBAL = 1 << 2;
 
 export const TEMPLATE_FRAGMENT = 1;
 export const TEMPLATE_USE_IMPORT_NODE = 1 << 1;
+export const TEMPLATE_USE_SVG = 1 << 2;
+export const TEMPLATE_USE_MATHML = 1 << 3;
 
 export const HYDRATION_START = '[';
 /** used to indicate that an `{:else}...` block was rendered */
diff --git a/packages/svelte/src/internal/client/dev/elements.js b/packages/svelte/src/internal/client/dev/elements.js
index bf75e6e5cc..62ac09d784 100644
--- a/packages/svelte/src/internal/client/dev/elements.js
+++ b/packages/svelte/src/internal/client/dev/elements.js
@@ -1,4 +1,4 @@
-/** @import { SourceLocation } from '#shared' */
+/** @import { SourceLocation } from '#client' */
 import { HYDRATION_END, HYDRATION_START, HYDRATION_START_ELSE } from '../../../constants.js';
 import { hydrating } from '../dom/hydration.js';
 
diff --git a/packages/svelte/src/internal/client/dom/elements/attachments.js b/packages/svelte/src/internal/client/dom/elements/attachments.js
index 6e3089a384..4fc1280138 100644
--- a/packages/svelte/src/internal/client/dom/elements/attachments.js
+++ b/packages/svelte/src/internal/client/dom/elements/attachments.js
@@ -1,15 +1,33 @@
-import { effect } from '../../reactivity/effects.js';
+/** @import { Effect } from '#client' */
+import { block, branch, effect, destroy_effect } from '../../reactivity/effects.js';
+
+// TODO in 6.0 or 7.0, when we remove legacy mode, we can simplify this by
+// getting rid of the block/branch stuff and just letting the effect rip.
+// see https://github.com/sveltejs/svelte/pull/15962
 
 /**
  * @param {Element} node
  * @param {() => (node: Element) => void} get_fn
  */
 export function attach(node, get_fn) {
-	effect(() => {
-		const fn = get_fn();
+	/** @type {false | undefined | ((node: Element) => void)} */
+	var fn = undefined;
+
+	/** @type {Effect | null} */
+	var e;
+
+	block(() => {
+		if (fn !== (fn = get_fn())) {
+			if (e) {
+				destroy_effect(e);
+				e = null;
+			}
 
-		// we use `&&` rather than `?.` so that things like
-		// `{@attach DEV && something_dev_only()}` work
-		return fn && fn(node);
+			if (fn) {
+				e = branch(() => {
+					effect(() => /** @type {(node: Element) => void} */ (fn)(node));
+				});
+			}
+		}
 	});
 }
diff --git a/packages/svelte/src/internal/client/dom/elements/bindings/select.js b/packages/svelte/src/internal/client/dom/elements/bindings/select.js
index 32cd160de2..20f95af5ec 100644
--- a/packages/svelte/src/internal/client/dom/elements/bindings/select.js
+++ b/packages/svelte/src/internal/client/dom/elements/bindings/select.js
@@ -2,6 +2,8 @@ import { effect } from '../../../reactivity/effects.js';
 import { listen_to_event_and_reset_event } from './shared.js';
 import { untrack } from '../../../runtime.js';
 import { is } from '../../../proxy.js';
+import { is_array } from '../../../../shared/utils.js';
+import * as w from '../../../warnings.js';
 
 /**
  * Selects the correct option(s) (depending on whether this is a multiple select)
@@ -12,6 +14,17 @@ import { is } from '../../../proxy.js';
  */
 export function select_option(select, value, mounting) {
 	if (select.multiple) {
+		// If value is null or undefined, keep the selection as is
+		if (value == undefined) {
+			return;
+		}
+
+		// If not an array, warn and keep the selection as is
+		if (!is_array(value)) {
+			return w.select_multiple_invalid_value();
+		}
+
+		// Otherwise, update the selection
 		return select_options(select, value);
 	}
 
@@ -124,14 +137,12 @@ export function bind_select_value(select, get, set = get) {
 }
 
 /**
- * @template V
  * @param {HTMLSelectElement} select
- * @param {V} value
+ * @param {unknown[]} value
  */
 function select_options(select, value) {
 	for (var option of select.options) {
-		// @ts-ignore
-		option.selected = ~value.indexOf(get_option_value(option));
+		option.selected = value.includes(get_option_value(option));
 	}
 }
 
diff --git a/packages/svelte/src/internal/client/dom/operations.js b/packages/svelte/src/internal/client/dom/operations.js
index aae44d4b39..97062f04e3 100644
--- a/packages/svelte/src/internal/client/dom/operations.js
+++ b/packages/svelte/src/internal/client/dom/operations.js
@@ -204,3 +204,44 @@ export function sibling(node, count = 1, is_text = false) {
 export function clear_text_content(node) {
 	node.textContent = '';
 }
+
+/**
+ *
+ * @param {string} tag
+ * @param {string} [namespace]
+ * @param {string} [is]
+ * @returns
+ */
+export function create_element(tag, namespace, is) {
+	let options = is ? { is } : undefined;
+	if (namespace) {
+		return document.createElementNS(namespace, tag, options);
+	}
+	return document.createElement(tag, options);
+}
+
+export function create_fragment() {
+	return document.createDocumentFragment();
+}
+
+/**
+ * @param {string} data
+ * @returns
+ */
+export function create_comment(data = '') {
+	return document.createComment(data);
+}
+
+/**
+ * @param {Element} element
+ * @param {string} key
+ * @param {string} value
+ * @returns
+ */
+export function set_attribute(element, key, value = '') {
+	if (key.startsWith('xlink:')) {
+		element.setAttributeNS('http://www.w3.org/1999/xlink', key, value);
+		return;
+	}
+	return element.setAttribute(key, value);
+}
diff --git a/packages/svelte/src/internal/client/dom/reconciler.js b/packages/svelte/src/internal/client/dom/reconciler.js
index 9897e08d53..8d3b5c0495 100644
--- a/packages/svelte/src/internal/client/dom/reconciler.js
+++ b/packages/svelte/src/internal/client/dom/reconciler.js
@@ -1,6 +1,6 @@
 /** @param {string} html */
 export function create_fragment_from_html(html) {
 	var elem = document.createElement('template');
-	elem.innerHTML = html;
+	elem.innerHTML = html.replaceAll('<!>', '<!---->'); // XHTML compliance
 	return elem.content;
 }
diff --git a/packages/svelte/src/internal/client/dom/template.js b/packages/svelte/src/internal/client/dom/template.js
index de2df62c92..0b77ab1396 100644
--- a/packages/svelte/src/internal/client/dom/template.js
+++ b/packages/svelte/src/internal/client/dom/template.js
@@ -1,9 +1,25 @@
 /** @import { Effect, TemplateNode } from '#client' */
+/** @import { TemplateStructure } from './types' */
 import { hydrate_next, hydrate_node, hydrating, set_hydrate_node } from './hydration.js';
-import { create_text, get_first_child, is_firefox } from './operations.js';
+import {
+	create_text,
+	get_first_child,
+	is_firefox,
+	create_element,
+	create_fragment,
+	create_comment,
+	set_attribute
+} from './operations.js';
 import { create_fragment_from_html } from './reconciler.js';
 import { active_effect } from '../runtime.js';
-import { TEMPLATE_FRAGMENT, TEMPLATE_USE_IMPORT_NODE } from '../../../constants.js';
+import {
+	NAMESPACE_MATHML,
+	NAMESPACE_SVG,
+	TEMPLATE_FRAGMENT,
+	TEMPLATE_USE_IMPORT_NODE,
+	TEMPLATE_USE_MATHML,
+	TEMPLATE_USE_SVG
+} from '../../../constants.js';
 
 /**
  * @param {TemplateNode} start
@@ -23,7 +39,7 @@ export function assign_nodes(start, end) {
  * @returns {() => Node | Node[]}
  */
 /*#__NO_SIDE_EFFECTS__*/
-export function template(content, flags) {
+export function from_html(content, flags) {
 	var is_fragment = (flags & TEMPLATE_FRAGMENT) !== 0;
 	var use_import_node = (flags & TEMPLATE_USE_IMPORT_NODE) !== 0;
 
@@ -64,17 +80,6 @@ export function template(content, flags) {
 	};
 }
 
-/**
- * @param {string} content
- * @param {number} flags
- * @returns {() => Node | Node[]}
- */
-/*#__NO_SIDE_EFFECTS__*/
-export function template_with_script(content, flags) {
-	var fn = template(content, flags);
-	return () => run_scripts(/** @type {Element | DocumentFragment} */ (fn()));
-}
-
 /**
  * @param {string} content
  * @param {number} flags
@@ -82,7 +87,7 @@ export function template_with_script(content, flags) {
  * @returns {() => Node | Node[]}
  */
 /*#__NO_SIDE_EFFECTS__*/
-export function ns_template(content, flags, ns = 'svg') {
+function from_namespace(content, flags, ns = 'svg') {
 	/**
 	 * Whether or not the first item is a text/element node. If not, we need to
 	 * create an additional comment node to act as `effect.nodes.start`
@@ -133,22 +138,120 @@ export function ns_template(content, flags, ns = 'svg') {
 /**
  * @param {string} content
  * @param {number} flags
- * @returns {() => Node | Node[]}
  */
 /*#__NO_SIDE_EFFECTS__*/
-export function svg_template_with_script(content, flags) {
-	var fn = ns_template(content, flags);
-	return () => run_scripts(/** @type {Element | DocumentFragment} */ (fn()));
+export function from_svg(content, flags) {
+	return from_namespace(content, flags, 'svg');
 }
 
 /**
  * @param {string} content
  * @param {number} flags
+ */
+/*#__NO_SIDE_EFFECTS__*/
+export function from_mathml(content, flags) {
+	return from_namespace(content, flags, 'math');
+}
+
+/**
+ * @param {TemplateStructure[]} structure
+ * @param {NAMESPACE_SVG | NAMESPACE_MATHML | undefined} [ns]
+ */
+function fragment_from_tree(structure, ns) {
+	var fragment = create_fragment();
+
+	for (var item of structure) {
+		if (typeof item === 'string') {
+			fragment.append(create_text(item));
+			continue;
+		}
+
+		// if `preserveComments === true`, comments are represented as `['// <data>']`
+		if (item === undefined || item[0][0] === '/') {
+			fragment.append(create_comment(item ? item[0].slice(3) : ''));
+			continue;
+		}
+
+		const [name, attributes, ...children] = item;
+
+		const namespace = name === 'svg' ? NAMESPACE_SVG : name === 'math' ? NAMESPACE_MATHML : ns;
+
+		var element = create_element(name, namespace, attributes?.is);
+
+		for (var key in attributes) {
+			set_attribute(element, key, attributes[key]);
+		}
+
+		if (children.length > 0) {
+			var target =
+				element.tagName === 'TEMPLATE'
+					? /** @type {HTMLTemplateElement} */ (element).content
+					: element;
+
+			target.append(
+				fragment_from_tree(children, element.tagName === 'foreignObject' ? undefined : namespace)
+			);
+		}
+
+		fragment.append(element);
+	}
+
+	return fragment;
+}
+
+/**
+ * @param {TemplateStructure[]} structure
+ * @param {number} flags
  * @returns {() => Node | Node[]}
  */
 /*#__NO_SIDE_EFFECTS__*/
-export function mathml_template(content, flags) {
-	return ns_template(content, flags, 'math');
+export function from_tree(structure, flags) {
+	var is_fragment = (flags & TEMPLATE_FRAGMENT) !== 0;
+	var use_import_node = (flags & TEMPLATE_USE_IMPORT_NODE) !== 0;
+
+	/** @type {Node} */
+	var node;
+
+	return () => {
+		if (hydrating) {
+			assign_nodes(hydrate_node, null);
+			return hydrate_node;
+		}
+
+		if (node === undefined) {
+			const ns =
+				(flags & TEMPLATE_USE_SVG) !== 0
+					? NAMESPACE_SVG
+					: (flags & TEMPLATE_USE_MATHML) !== 0
+						? NAMESPACE_MATHML
+						: undefined;
+
+			node = fragment_from_tree(structure, ns);
+			if (!is_fragment) node = /** @type {Node} */ (get_first_child(node));
+		}
+
+		var clone = /** @type {TemplateNode} */ (
+			use_import_node || is_firefox ? document.importNode(node, true) : node.cloneNode(true)
+		);
+
+		if (is_fragment) {
+			var start = /** @type {TemplateNode} */ (get_first_child(clone));
+			var end = /** @type {TemplateNode} */ (clone.lastChild);
+
+			assign_nodes(start, end);
+		} else {
+			assign_nodes(clone, clone);
+		}
+
+		return clone;
+	};
+}
+
+/**
+ * @param {() => Element | DocumentFragment} fn
+ */
+export function with_script(fn) {
+	return () => run_scripts(fn());
 }
 
 /**
diff --git a/packages/svelte/src/internal/client/dom/types.d.ts b/packages/svelte/src/internal/client/dom/types.d.ts
new file mode 100644
index 0000000000..bc3525919b
--- /dev/null
+++ b/packages/svelte/src/internal/client/dom/types.d.ts
@@ -0,0 +1,4 @@
+export type TemplateStructure =
+	| string
+	| undefined
+	| [string, Record<string, string> | undefined, ...TemplateStructure[]];
diff --git a/packages/svelte/src/internal/client/index.js b/packages/svelte/src/internal/client/index.js
index b5f746b276..226d79a65f 100644
--- a/packages/svelte/src/internal/client/index.js
+++ b/packages/svelte/src/internal/client/index.js
@@ -88,13 +88,13 @@ export {
 export {
 	append,
 	comment,
-	ns_template,
-	svg_template_with_script,
-	mathml_template,
-	template,
-	template_with_script,
+	from_html,
+	from_mathml,
+	from_svg,
+	from_tree,
 	text,
-	props_id
+	props_id,
+	with_script
 } from './dom/template.js';
 export { user_derived as derived, derived_safe_equal } from './reactivity/deriveds.js';
 export {
diff --git a/packages/svelte/src/internal/client/types.d.ts b/packages/svelte/src/internal/client/types.d.ts
index b46bdf2013..9703c2aac1 100644
--- a/packages/svelte/src/internal/client/types.d.ts
+++ b/packages/svelte/src/internal/client/types.d.ts
@@ -183,4 +183,8 @@ export type ProxyStateObject<T = Record<string | symbol, any>> = T & {
 	[STATE_SYMBOL]: T;
 };
 
+export type SourceLocation =
+	| [line: number, column: number]
+	| [line: number, column: number, SourceLocation[]];
+
 export * from './reactivity/types';
diff --git a/packages/svelte/src/internal/client/warnings.js b/packages/svelte/src/internal/client/warnings.js
index c84b487e28..e07892a4b0 100644
--- a/packages/svelte/src/internal/client/warnings.js
+++ b/packages/svelte/src/internal/client/warnings.js
@@ -158,6 +158,17 @@ export function ownership_invalid_mutation(name, location, prop, parent) {
 	}
 }
 
+/**
+ * The `value` property of a `<select multiple>` element should be an array, but it received a non-array value. The selection will be kept as is.
+ */
+export function select_multiple_invalid_value() {
+	if (DEV) {
+		console.warn(`%c[svelte] select_multiple_invalid_value\n%cThe \`value\` property of a \`<select multiple>\` element should be an array, but it received a non-array value. The selection will be kept as is.\nhttps://svelte.dev/e/select_multiple_invalid_value`, bold, normal);
+	} else {
+		console.warn(`https://svelte.dev/e/select_multiple_invalid_value`);
+	}
+}
+
 /**
  * Reactive `$state(...)` proxies and the values they proxy have different identities. Because of this, comparisons with `%operator%` will produce unexpected results
  * @param {string} operator
diff --git a/packages/svelte/src/internal/shared/types.d.ts b/packages/svelte/src/internal/shared/types.d.ts
index a97a61af67..4deeb76b2f 100644
--- a/packages/svelte/src/internal/shared/types.d.ts
+++ b/packages/svelte/src/internal/shared/types.d.ts
@@ -3,10 +3,6 @@ export type Store<V> = {
 	set(value: V): void;
 };
 
-export type SourceLocation =
-	| [line: number, column: number]
-	| [line: number, column: number, SourceLocation[]];
-
 export type Getters<T> = {
 	[K in keyof T]: () => T[K];
 };
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index e42e6741bd..20c84d001e 100644
--- a/packages/svelte/src/version.js
+++ b/packages/svelte/src/version.js
@@ -4,5 +4,5 @@
  * The current version, as set in package.json.
  * @type {string}
  */
-export const VERSION = '5.31.1';
+export const VERSION = '5.33.0';
 export const PUBLIC_VERSION = '5';
diff --git a/packages/svelte/tests/helpers.js b/packages/svelte/tests/helpers.js
index f853d5873c..e62b662372 100644
--- a/packages/svelte/tests/helpers.js
+++ b/packages/svelte/tests/helpers.js
@@ -190,3 +190,5 @@ if (typeof window !== 'undefined') {
 		};
 	});
 }
+
+export const fragments = /** @type {'html' | 'tree'} */ (process.env.FRAGMENTS) ?? 'html';
diff --git a/packages/svelte/tests/hydration/test.ts b/packages/svelte/tests/hydration/test.ts
index 266ac07bff..70d5c5d072 100644
--- a/packages/svelte/tests/hydration/test.ts
+++ b/packages/svelte/tests/hydration/test.ts
@@ -4,6 +4,7 @@ import * as fs from 'node:fs';
 import { assert } from 'vitest';
 import { compile_directory } from '../helpers.js';
 import { assert_html_equal } from '../html_equal.js';
+import { fragments } from '../helpers.js';
 import { assert_ok, suite, type BaseTest } from '../suite.js';
 import { createClassComponent } from 'svelte/legacy';
 import { render } from 'svelte/server';
@@ -43,7 +44,12 @@ function read(path: string): string | void {
 
 const { test, run } = suite<HydrationTest>(async (config, cwd) => {
 	if (!config.load_compiled) {
-		await compile_directory(cwd, 'client', { accessors: true, ...config.compileOptions });
+		await compile_directory(cwd, 'client', {
+			accessors: true,
+			fragments,
+			...config.compileOptions
+		});
+
 		await compile_directory(cwd, 'server', config.compileOptions);
 	}
 
@@ -125,7 +131,8 @@ const { test, run } = suite<HydrationTest>(async (config, cwd) => {
 
 		flushSync();
 
-		const normalize = (string: string) => string.trim().replace(/\r\n/g, '\n');
+		const normalize = (string: string) =>
+			string.trim().replaceAll('\r\n', '\n').replaceAll('/>', '>');
 
 		const expected = read(`${cwd}/_expected.html`) ?? rendered.html;
 		assert.equal(normalize(target.innerHTML), normalize(expected));
diff --git a/packages/svelte/tests/runtime-browser/test.ts b/packages/svelte/tests/runtime-browser/test.ts
index 582a10edf7..63e601b115 100644
--- a/packages/svelte/tests/runtime-browser/test.ts
+++ b/packages/svelte/tests/runtime-browser/test.ts
@@ -5,7 +5,7 @@ import * as path from 'node:path';
 import { compile } from 'svelte/compiler';
 import { afterAll, assert, beforeAll, describe } from 'vitest';
 import { suite, suite_with_variants } from '../suite';
-import { write } from '../helpers';
+import { write, fragments } from '../helpers';
 import type { Warning } from '#compiler';
 
 const assert_file = path.resolve(__dirname, 'assert.js');
@@ -87,6 +87,7 @@ async function run_test(
 					build.onLoad({ filter: /\.svelte$/ }, (args) => {
 						const compiled = compile(fs.readFileSync(args.path, 'utf-8').replace(/\r/g, ''), {
 							generate: 'client',
+							fragments,
 							...config.compileOptions,
 							immutable: config.immutable,
 							customElement: test_dir.includes('custom-elements-samples'),
diff --git a/packages/svelte/tests/runtime-legacy/samples/attachment-in-mutated-state/_config.js b/packages/svelte/tests/runtime-legacy/samples/attachment-in-mutated-state/_config.js
new file mode 100644
index 0000000000..5d37252358
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/attachment-in-mutated-state/_config.js
@@ -0,0 +1,16 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	test({ assert, target, logs }) {
+		assert.deepEqual(logs, ['up']);
+
+		const button = target.querySelector('button');
+
+		flushSync(() => button?.click());
+		assert.deepEqual(logs, ['up']);
+
+		flushSync(() => button?.click());
+		assert.deepEqual(logs, ['up', 'down']);
+	}
+});
diff --git a/packages/svelte/tests/runtime-legacy/samples/attachment-in-mutated-state/main.svelte b/packages/svelte/tests/runtime-legacy/samples/attachment-in-mutated-state/main.svelte
new file mode 100644
index 0000000000..fbec108c7a
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/attachment-in-mutated-state/main.svelte
@@ -0,0 +1,15 @@
+<script>
+	let state = {
+		count: 0,
+		attachment(){
+			console.log('up');
+			return () => console.log('down');
+		}
+	};
+</script>
+
+<button onclick={() => state.count++}>{state.count}</button>
+
+{#if state.count < 2}
+	<div {@attach state.attachment}></div>
+{/if}
diff --git a/packages/svelte/tests/runtime-legacy/shared.ts b/packages/svelte/tests/runtime-legacy/shared.ts
index 14b6cff841..690a7e3d98 100644
--- a/packages/svelte/tests/runtime-legacy/shared.ts
+++ b/packages/svelte/tests/runtime-legacy/shared.ts
@@ -6,7 +6,7 @@ import { proxy } from 'svelte/internal/client';
 import { flushSync, hydrate, mount, unmount } from 'svelte';
 import { render } from 'svelte/server';
 import { afterAll, assert, beforeAll } from 'vitest';
-import { compile_directory } from '../helpers.js';
+import { compile_directory, fragments } from '../helpers.js';
 import { setup_html_equal } from '../html_equal.js';
 import { raf } from '../animation-helpers.js';
 import type { CompileOptions } from '#compiler';
@@ -158,6 +158,7 @@ async function common_setup(cwd: string, runes: boolean | undefined, config: Run
 		rootDir: cwd,
 		dev: force_hmr ? true : undefined,
 		hmr: force_hmr ? true : undefined,
+		fragments,
 		...config.compileOptions,
 		immutable: config.immutable,
 		accessors: 'accessors' in config ? config.accessors : true,
diff --git a/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/main.svelte b/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/main.svelte
index 4c98245e5b..82774f160d 100644
--- a/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/main.svelte
@@ -1,18 +1,20 @@
 <script module>
-    customElements.define('value-element', class extends HTMLElement {
+	if(!customElements.get('value-element')) {
+		customElements.define('value-element', class extends HTMLElement {
 
-        constructor() {
-            super();
-            this.attachShadow({ mode: 'open' });
-        }
+			constructor() {
+				super();
+				this.attachShadow({ mode: 'open' });
+			}
 
-        set value(v) {
-            if (this.__value !== v) {
-                this.__value = v;
-                this.shadowRoot.innerHTML = `<span>${v}</span>`;
-            }
-        }
-    });
+			set value(v) {
+				if (this.__value !== v) {
+					this.__value = v;
+					this.shadowRoot.innerHTML = `<span>${v}</span>`;
+				}
+			}
+		});
+	}
 </script>
 
 <my-element string="test" object={{ test: true }}></my-element>
diff --git a/packages/svelte/tests/runtime-runes/samples/functional-templating/_config.js b/packages/svelte/tests/runtime-runes/samples/functional-templating/_config.js
new file mode 100644
index 0000000000..5d36f2e969
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/functional-templating/_config.js
@@ -0,0 +1,9 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		fragments: 'tree'
+	},
+
+	html: `<p>hello</p>`
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/functional-templating/main.svelte b/packages/svelte/tests/runtime-runes/samples/functional-templating/main.svelte
new file mode 100644
index 0000000000..302a01f335
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/functional-templating/main.svelte
@@ -0,0 +1 @@
+<p>hello</p>
diff --git a/packages/svelte/tests/runtime-runes/samples/select-multiple-invalid-value/_config.js b/packages/svelte/tests/runtime-runes/samples/select-multiple-invalid-value/_config.js
new file mode 100644
index 0000000000..1f04f176af
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/select-multiple-invalid-value/_config.js
@@ -0,0 +1,7 @@
+import { test } from '../../test';
+
+export default test({
+	warnings: [
+		'The `value` property of a `<select multiple>` element should be an array, but it received a non-array value. The selection will be kept as is.'
+	]
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/select-multiple-invalid-value/main.svelte b/packages/svelte/tests/runtime-runes/samples/select-multiple-invalid-value/main.svelte
new file mode 100644
index 0000000000..f3dfedf0e9
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/select-multiple-invalid-value/main.svelte
@@ -0,0 +1,9 @@
+<select multiple value={null}>
+  <option>option</option>
+</select>
+<select multiple value={undefined}>
+  <option>option</option>
+</select>
+<select multiple value={123}>
+  <option>option</option>
+</select>
diff --git a/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/Component.svelte b/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/Component.svelte
new file mode 100644
index 0000000000..5668311b0e
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/Component.svelte
@@ -0,0 +1,7 @@
+<h2>hello from component</h2>
+
+<style>
+	h2 {
+		color: var(--color);
+	}
+</style>
diff --git a/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/_config.js b/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/_config.js
new file mode 100644
index 0000000000..1d76b0dd00
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/_config.js
@@ -0,0 +1,42 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		dev: true
+	},
+
+	html: `
+		<h1>hello</h1>
+		<svelte-css-wrapper style="display: contents; --color: red;">
+			<h2 class="svelte-13kae5a">hello from component</h2>
+		</svelte-css-wrapper>
+		<p>goodbye</p>
+	`,
+
+	async test({ target, assert }) {
+		const h1 = target.querySelector('h1');
+		const h2 = target.querySelector('h2');
+		const p = target.querySelector('p');
+
+		// @ts-expect-error
+		assert.deepEqual(h1.__svelte_meta.loc, {
+			file: 'main.svelte',
+			line: 5,
+			column: 0
+		});
+
+		// @ts-expect-error
+		assert.deepEqual(h2.__svelte_meta.loc, {
+			file: 'Component.svelte',
+			line: 1,
+			column: 0
+		});
+
+		// @ts-expect-error
+		assert.deepEqual(p.__svelte_meta.loc, {
+			file: 'main.svelte',
+			line: 7,
+			column: 0
+		});
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/main.svelte b/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/main.svelte
new file mode 100644
index 0000000000..f49a48fb52
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/svelte-meta-css-wrapper/main.svelte
@@ -0,0 +1,7 @@
+<script>
+	import Component from './Component.svelte';
+</script>
+
+<h1>hello</h1>
+<Component --color="red" />
+<p>goodbye</p>
diff --git a/packages/svelte/tests/snapshot/samples/await-block-scope/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/await-block-scope/_expected/client/index.svelte.js
index 3e5a12ed9d..9bb45ebf78 100644
--- a/packages/svelte/tests/snapshot/samples/await-block-scope/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/await-block-scope/_expected/client/index.svelte.js
@@ -5,7 +5,7 @@ function increment(_, counter) {
 	counter.count += 1;
 }
 
-var root = $.template(`<button> </button> <!> `, 1);
+var root = $.from_html(`<button> </button> <!> `, 1);
 
 export default function Await_block_scope($$anchor) {
 	let counter = $.proxy({ count: 0 });
diff --git a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js
index 390e86a351..ba3f4b155a 100644
--- a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js
@@ -10,7 +10,7 @@ const snippet = ($$anchor) => {
 	$.append($$anchor, text);
 };
 
-var root = $.template(`<!> `, 1);
+var root = $.from_html(`<!> `, 1);
 
 export default function Bind_component_snippet($$anchor) {
 	let value = $.state('');
diff --git a/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js b/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js
index 219db6ffd5..3a13fa7e15 100644
--- a/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js
@@ -1,7 +1,7 @@
 import 'svelte/internal/disclose-version';
 import * as $ from 'svelte/internal/client';
 
-var root = $.template(`<div></div> <svg></svg> <custom-element></custom-element> <div></div> <svg></svg> <custom-element></custom-element>`, 3);
+var root = $.from_html(`<div></div> <svg></svg> <custom-element></custom-element> <div></div> <svg></svg> <custom-element></custom-element>`, 3);
 
 export default function Main($$anchor) {
 	// needs to be a snapshot test because jsdom does auto-correct the attribute casing
diff --git a/packages/svelte/tests/snapshot/samples/each-index-non-null/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/each-index-non-null/_expected/client/index.svelte.js
index 3d46a679b8..804a7c26f1 100644
--- a/packages/svelte/tests/snapshot/samples/each-index-non-null/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/each-index-non-null/_expected/client/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/disclose-version';
 import 'svelte/internal/flags/legacy';
 import * as $ from 'svelte/internal/client';
 
-var root_1 = $.template(`<p></p>`);
+var root_1 = $.from_html(`<p></p>`);
 
 export default function Each_index_non_null($$anchor) {
 	var fragment = $.comment();
diff --git a/packages/svelte/tests/snapshot/samples/functional-templating/_config.js b/packages/svelte/tests/snapshot/samples/functional-templating/_config.js
new file mode 100644
index 0000000000..23231c969b
--- /dev/null
+++ b/packages/svelte/tests/snapshot/samples/functional-templating/_config.js
@@ -0,0 +1,7 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		fragments: 'tree'
+	}
+});
diff --git a/packages/svelte/tests/snapshot/samples/functional-templating/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/functional-templating/_expected/client/index.svelte.js
new file mode 100644
index 0000000000..792d5421e1
--- /dev/null
+++ b/packages/svelte/tests/snapshot/samples/functional-templating/_expected/client/index.svelte.js
@@ -0,0 +1,25 @@
+import 'svelte/internal/disclose-version';
+import 'svelte/internal/flags/legacy';
+import * as $ from 'svelte/internal/client';
+
+var root = $.from_tree(
+	[
+		['h1', null, 'hello'],
+		' ',
+		[
+			'div',
+			{ class: 'potato' },
+			['p', null, 'child element'],
+			' ',
+			['p', null, 'another child element']
+		]
+	],
+	1
+);
+
+export default function Functional_templating($$anchor) {
+	var fragment = root();
+
+	$.next(2);
+	$.append($$anchor, fragment);
+}
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/functional-templating/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/functional-templating/_expected/server/index.svelte.js
new file mode 100644
index 0000000000..dc49c0c213
--- /dev/null
+++ b/packages/svelte/tests/snapshot/samples/functional-templating/_expected/server/index.svelte.js
@@ -0,0 +1,5 @@
+import * as $ from 'svelte/internal/server';
+
+export default function Functional_templating($$payload) {
+	$$payload.out += `<h1>hello</h1> <div class="potato"><p>child element</p> <p>another child element</p></div>`;
+}
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/functional-templating/index.svelte b/packages/svelte/tests/snapshot/samples/functional-templating/index.svelte
new file mode 100644
index 0000000000..c0fe8965b8
--- /dev/null
+++ b/packages/svelte/tests/snapshot/samples/functional-templating/index.svelte
@@ -0,0 +1,6 @@
+<h1>hello</h1>
+
+<div class="potato">
+	<p>child element</p>
+	<p>another child element</p>
+</div>
diff --git a/packages/svelte/tests/snapshot/samples/hello-world/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/hello-world/_expected/client/index.svelte.js
index 899c126001..68fdaa4570 100644
--- a/packages/svelte/tests/snapshot/samples/hello-world/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/hello-world/_expected/client/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/disclose-version';
 import 'svelte/internal/flags/legacy';
 import * as $ from 'svelte/internal/client';
 
-var root = $.template(`<h1>hello world</h1>`);
+var root = $.from_html(`<h1>hello world</h1>`);
 
 export default function Hello_world($$anchor) {
 	var h1 = root();
diff --git a/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js
index 3c8322500b..1fac1338c5 100644
--- a/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/hmr/_expected/client/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/disclose-version';
 import 'svelte/internal/flags/legacy';
 import * as $ from 'svelte/internal/client';
 
-var root = $.template(`<h1>hello world</h1>`);
+var root = $.from_html(`<h1>hello world</h1>`);
 
 function Hmr($$anchor) {
 	var h1 = root();
diff --git a/packages/svelte/tests/snapshot/samples/nullish-coallescence-omittance/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/nullish-coallescence-omittance/_expected/client/index.svelte.js
index 21f6ed9680..b46acee82e 100644
--- a/packages/svelte/tests/snapshot/samples/nullish-coallescence-omittance/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/nullish-coallescence-omittance/_expected/client/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/disclose-version';
 import * as $ from 'svelte/internal/client';
 
 var on_click = (_, count) => $.update(count);
-var root = $.template(`<h1></h1> <b></b> <button> </button> <h1></h1>`, 1);
+var root = $.from_html(`<h1></h1> <b></b> <button> </button> <h1></h1>`, 1);
 
 export default function Nullish_coallescence_omittance($$anchor) {
 	let name = 'world';
diff --git a/packages/svelte/tests/snapshot/samples/purity/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/purity/_expected/client/index.svelte.js
index f661dbc01d..a351851875 100644
--- a/packages/svelte/tests/snapshot/samples/purity/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/purity/_expected/client/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/disclose-version';
 import 'svelte/internal/flags/legacy';
 import * as $ from 'svelte/internal/client';
 
-var root = $.template(`<p></p> <p></p> <!>`, 1);
+var root = $.from_html(`<p></p> <p></p> <!>`, 1);
 
 export default function Purity($$anchor) {
 	var fragment = root();
diff --git a/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js
index 541b56a407..78147659ff 100644
--- a/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/client/index.svelte.js
@@ -1,7 +1,7 @@
 import 'svelte/internal/disclose-version';
 import * as $ from 'svelte/internal/client';
 
-var root = $.template(`<header><nav><a href="/">Home</a> <a href="/away">Away</a></nav></header> <main><h1> </h1> <div class="static"><p>we don't need to traverse these nodes</p></div> <p>or</p> <p>these</p> <p>ones</p> <!> <p>these</p> <p>trailing</p> <p>nodes</p> <p>can</p> <p>be</p> <p>completely</p> <p>ignored</p></main> <cant-skip><custom-elements></custom-elements></cant-skip> <div><input></div> <div><source></div> <select><option>a</option></select> <img src="..." alt="" loading="lazy"> <div><img src="..." alt="" loading="lazy"></div>`, 3);
+var root = $.from_html(`<header><nav><a href="/">Home</a> <a href="/away">Away</a></nav></header> <main><h1> </h1> <div class="static"><p>we don't need to traverse these nodes</p></div> <p>or</p> <p>these</p> <p>ones</p> <!> <p>these</p> <p>trailing</p> <p>nodes</p> <p>can</p> <p>be</p> <p>completely</p> <p>ignored</p></main> <cant-skip><custom-elements></custom-elements></cant-skip> <div><input/></div> <div><source/></div> <select><option>a</option></select> <img src="..." alt="" loading="lazy"/> <div><img src="..." alt="" loading="lazy"/></div>`, 3);
 
 export default function Skip_static_subtree($$anchor, $$props) {
 	var fragment = root();
diff --git a/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/server/index.svelte.js
index e694c12647..a587c05e2c 100644
--- a/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/skip-static-subtree/_expected/server/index.svelte.js
@@ -3,5 +3,5 @@ import * as $ from 'svelte/internal/server';
 export default function Skip_static_subtree($$payload, $$props) {
 	let { title, content } = $$props;
 
-	$$payload.out += `<header><nav><a href="/">Home</a> <a href="/away">Away</a></nav></header> <main><h1>${$.escape(title)}</h1> <div class="static"><p>we don't need to traverse these nodes</p></div> <p>or</p> <p>these</p> <p>ones</p> ${$.html(content)} <p>these</p> <p>trailing</p> <p>nodes</p> <p>can</p> <p>be</p> <p>completely</p> <p>ignored</p></main> <cant-skip><custom-elements with="attributes"></custom-elements></cant-skip> <div><input autofocus></div> <div><source muted></div> <select><option value="a">a</option></select> <img src="..." alt="" loading="lazy"> <div><img src="..." alt="" loading="lazy"></div>`;
+	$$payload.out += `<header><nav><a href="/">Home</a> <a href="/away">Away</a></nav></header> <main><h1>${$.escape(title)}</h1> <div class="static"><p>we don't need to traverse these nodes</p></div> <p>or</p> <p>these</p> <p>ones</p> ${$.html(content)} <p>these</p> <p>trailing</p> <p>nodes</p> <p>can</p> <p>be</p> <p>completely</p> <p>ignored</p></main> <cant-skip><custom-elements with="attributes"></custom-elements></cant-skip> <div><input autofocus/></div> <div><source muted/></div> <select><option value="a">a</option></select> <img src="..." alt="" loading="lazy"/> <div><img src="..." alt="" loading="lazy"/></div>`;
 }
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/client/index.svelte.js
index a67210e541..c446b3d3ef 100644
--- a/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/client/index.svelte.js
@@ -8,7 +8,7 @@ function reset(_, str, tpl) {
 	$.set(tpl, ``);
 }
 
-var root = $.template(`<input> <input> <button>reset</button>`, 1);
+var root = $.from_html(`<input/> <input/> <button>reset</button>`, 1);
 
 export default function State_proxy_literal($$anchor) {
 	let str = $.state('');
diff --git a/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/server/index.svelte.js
index 7b2a884d70..f814dd4f84 100644
--- a/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/state-proxy-literal/_expected/server/index.svelte.js
@@ -11,5 +11,5 @@ export default function State_proxy_literal($$payload) {
 		tpl = ``;
 	}
 
-	$$payload.out += `<input${$.attr('value', str)}> <input${$.attr('value', tpl)}> <button>reset</button>`;
+	$$payload.out += `<input${$.attr('value', str)}/> <input${$.attr('value', tpl)}/> <button>reset</button>`;
 }
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/text-nodes-deriveds/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/text-nodes-deriveds/_expected/client/index.svelte.js
index d520d1ef24..464435cb0a 100644
--- a/packages/svelte/tests/snapshot/samples/text-nodes-deriveds/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/text-nodes-deriveds/_expected/client/index.svelte.js
@@ -1,7 +1,7 @@
 import 'svelte/internal/disclose-version';
 import * as $ from 'svelte/internal/client';
 
-var root = $.template(`<p> </p>`);
+var root = $.from_html(`<p> </p>`);
 
 export default function Text_nodes_deriveds($$anchor) {
 	let count1 = 0;
diff --git a/packages/svelte/tests/validator/samples/implicitly-closed-by-parent/input.svelte b/packages/svelte/tests/validator/samples/implicitly-closed-by-parent/input.svelte
new file mode 100644
index 0000000000..f67eba18b8
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/implicitly-closed-by-parent/input.svelte
@@ -0,0 +1,6 @@
+<main><div class="hello"></main>
+
+<main>
+	<div class="hello">
+		<p>hello</p>
+</main>
diff --git a/packages/svelte/tests/validator/samples/implicitly-closed-by-parent/warnings.json b/packages/svelte/tests/validator/samples/implicitly-closed-by-parent/warnings.json
new file mode 100644
index 0000000000..1316a2b65b
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/implicitly-closed-by-parent/warnings.json
@@ -0,0 +1,26 @@
+[
+	{
+		"code": "element_implicitly_closed",
+		"message": "This element is implicitly closed by the following `</main>`, which can cause an unexpected DOM structure. Add an explicit `</div>` to avoid surprises.",
+		"start": {
+			"line": 1,
+			"column": 6
+		},
+		"end": {
+			"line": 1,
+			"column": 25
+		}
+	},
+	{
+		"code": "element_implicitly_closed",
+		"message": "This element is implicitly closed by the following `</main>`, which can cause an unexpected DOM structure. Add an explicit `</div>` to avoid surprises.",
+		"start": {
+			"line": 4,
+			"column": 1
+		},
+		"end": {
+			"line": 4,
+			"column": 20
+		}
+	}
+]
diff --git a/packages/svelte/tests/validator/samples/implicitly-closed-by-sibling/input.svelte b/packages/svelte/tests/validator/samples/implicitly-closed-by-sibling/input.svelte
new file mode 100644
index 0000000000..7721f2f380
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/implicitly-closed-by-sibling/input.svelte
@@ -0,0 +1,9 @@
+<div>
+	<p class="hello">
+		<span></span>
+		<p></p>
+</div>
+
+<div>
+	<p class="hello"><p></p>
+</div>
diff --git a/packages/svelte/tests/validator/samples/implicitly-closed-by-sibling/warnings.json b/packages/svelte/tests/validator/samples/implicitly-closed-by-sibling/warnings.json
new file mode 100644
index 0000000000..6ea36c5a50
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/implicitly-closed-by-sibling/warnings.json
@@ -0,0 +1,26 @@
+[
+	{
+		"code": "element_implicitly_closed",
+		"message": "This element is implicitly closed by the following `<p>`, which can cause an unexpected DOM structure. Add an explicit `</p>` to avoid surprises.",
+		"start": {
+			"line": 2,
+			"column": 1
+		},
+		"end": {
+			"line": 2,
+			"column": 18
+		}
+	},
+	{
+		"code": "element_implicitly_closed",
+		"message": "This element is implicitly closed by the following `<p>`, which can cause an unexpected DOM structure. Add an explicit `</p>` to avoid surprises.",
+		"start": {
+			"line": 8,
+			"column": 1
+		},
+		"end": {
+			"line": 8,
+			"column": 18
+		}
+	}
+]
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index fcc1ec315c..201dbed9aa 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -985,6 +985,15 @@ declare module 'svelte/compiler' {
 		 * @default false
 		 */
 		preserveWhitespace?: boolean;
+		/**
+		 * Which strategy to use when cloning DOM fragments:
+		 *
+		 * - `html` populates a `<template>` with `innerHTML` and clones it. This is faster, but cannot be used if your app's [Content Security Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CSP) includes [`require-trusted-types-for 'script'`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Security-Policy/require-trusted-types-for)
+		 * - `tree` creates the fragment one element at a time and _then_ clones it. This is slower, but works everywhere
+		 *
+		 * @default 'html'
+		 */
+		fragments?: 'html' | 'tree';
 		/**
 		 * Set to `true` to force the compiler into runes mode, even if there are no indications of runes usage.
 		 * Set to `false` to force the compiler into ignoring runes, even if there are indications of runes usage.
@@ -2872,6 +2881,15 @@ declare module 'svelte/types/compiler/interfaces' {
 		 * @default false
 		 */
 		preserveWhitespace?: boolean;
+		/**
+		 * Which strategy to use when cloning DOM fragments:
+		 *
+		 * - `html` populates a `<template>` with `innerHTML` and clones it. This is faster, but cannot be used if your app's [Content Security Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CSP) includes [`require-trusted-types-for 'script'`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Content-Security-Policy/require-trusted-types-for)
+		 * - `tree` creates the fragment one element at a time and _then_ clones it. This is slower, but works everywhere
+		 *
+		 * @default 'html'
+		 */
+		fragments?: 'html' | 'tree';
 		/**
 		 * Set to `true` to force the compiler into runes mode, even if there are no indications of runes usage.
 		 * Set to `false` to force the compiler into ignoring runes, even if there are indications of runes usage.
diff --git a/playgrounds/sandbox/run.js b/playgrounds/sandbox/run.js
index 3a62286b24..93d01a4b10 100644
--- a/playgrounds/sandbox/run.js
+++ b/playgrounds/sandbox/run.js
@@ -85,9 +85,25 @@ for (const generate of /** @type {const} */ (['client', 'server'])) {
 		}
 
 		write(output_js, compiled.js.code + '\n//# sourceMappingURL=' + path.basename(output_map));
-
 		write(output_map, compiled.js.map.toString());
 
+		// generate with fragments: 'tree'
+		if (generate === 'client') {
+			const compiled = compile(source, {
+				dev: true,
+				filename: input,
+				generate,
+				runes: argv.values.runes,
+				fragments: 'tree'
+			});
+
+			const output_js = `${cwd}/output/${generate}/${file}.tree.js`;
+			const output_map = `${cwd}/output/${generate}/${file}.tree.js.map`;
+
+			write(output_js, compiled.js.code + '\n//# sourceMappingURL=' + path.basename(output_map));
+			write(output_map, compiled.js.map.toString());
+		}
+
 		if (compiled.css) {
 			write(output_css, compiled.css.code);
 		}