diff --git a/.changeset/dirty-sloths-move.md b/.changeset/dirty-sloths-move.md
new file mode 100644
index 0000000000..07436a0b2e
--- /dev/null
+++ b/.changeset/dirty-sloths-move.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: consistently set value to blank string when value attribute is undefined
diff --git a/.changeset/large-islands-cover.md b/.changeset/large-islands-cover.md
new file mode 100644
index 0000000000..969d2fc254
--- /dev/null
+++ b/.changeset/large-islands-cover.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: optimise || expressions in template
diff --git a/.changeset/strange-hairs-trade.md b/.changeset/strange-hairs-trade.md
new file mode 100644
index 0000000000..192e5ef3d1
--- /dev/null
+++ b/.changeset/strange-hairs-trade.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: expand boolean attribute support
diff --git a/.changeset/two-doors-exercise.md b/.changeset/two-doors-exercise.md
new file mode 100644
index 0000000000..b41e582ae7
--- /dev/null
+++ b/.changeset/two-doors-exercise.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: add check for `is` attribute to correctly detect custom elements
diff --git a/.github/workflows/docs-preview-create-request.yml b/.github/workflows/docs-preview-create-request.yml
deleted file mode 100644
index f57766dc36..0000000000
--- a/.github/workflows/docs-preview-create-request.yml
+++ /dev/null
@@ -1,26 +0,0 @@
-# https://github.com/sveltejs/svelte.dev/blob/main/apps/svelte.dev/scripts/sync-docs/README.md
-name: Docs preview create request
-
-on:
-  pull_request_target:
-    branches:
-      - main
-
-jobs:
-  dispatch:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Repository Dispatch
-        uses: peter-evans/repository-dispatch@v3
-        with:
-          token: ${{ secrets.SYNC_REQUEST_TOKEN }}
-          repository: sveltejs/svelte.dev
-          event-type: docs-preview-create
-          client-payload: |-
-            {
-              "package": "svelte",
-              "repo": "${{ github.repository }}",
-              "owner": "${{ github.event.pull_request.head.repo.owner.login }}",
-              "branch": "${{ github.event.pull_request.head.ref }}",
-              "pr": ${{ github.event.pull_request.number }}
-            }
diff --git a/.github/workflows/docs-preview-delete-request.yml b/.github/workflows/docs-preview-delete-request.yml
deleted file mode 100644
index 4eb0e996a6..0000000000
--- a/.github/workflows/docs-preview-delete-request.yml
+++ /dev/null
@@ -1,27 +0,0 @@
-# https://github.com/sveltejs/svelte.dev/blob/main/apps/svelte.dev/scripts/sync-docs/README.md
-name: Docs preview delete request
-
-on:
-  pull_request_target:
-    branches:
-      - main
-    types: [closed]
-
-jobs:
-  dispatch:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Repository Dispatch
-        uses: peter-evans/repository-dispatch@v3
-        with:
-          token: ${{ secrets.SYNC_REQUEST_TOKEN }}
-          repository: sveltejs/svelte.dev
-          event-type: docs-preview-delete
-          client-payload: |-
-            {
-              "package": "svelte",
-              "repo": "${{ github.repository }}",
-              "owner": "${{ github.event.pull_request.head.repo.owner.login }}",
-              "branch": "${{ github.event.pull_request.head.ref }}",
-              "pr": ${{ github.event.pull_request.number }}
-            }
diff --git a/.github/workflows/sync-request.yml b/.github/workflows/sync-request.yml
deleted file mode 100644
index de2ce77692..0000000000
--- a/.github/workflows/sync-request.yml
+++ /dev/null
@@ -1,22 +0,0 @@
-# https://github.com/sveltejs/svelte.dev/blob/main/apps/svelte.dev/scripts/sync-docs/README.md
-name: Sync request
-
-on:
-  push:
-    branches:
-      - main
-
-jobs:
-  dispatch:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Repository Dispatch
-        uses: peter-evans/repository-dispatch@v3
-        with:
-          token: ${{ secrets.SYNC_REQUEST_TOKEN }}
-          repository: sveltejs/svelte.dev
-          event-type: sync-request
-          client-payload: |-
-            {
-              "package": "svelte"
-            }
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 7c22f3c7bc..2e61ca8abe 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
@@ -227,7 +227,7 @@ export function RegularElement(node, context) {
 			node_id,
 			attributes_id,
 			(node.metadata.svg || node.metadata.mathml || is_custom_element_node(node)) && b.true,
-			node.name.includes('-') && b.true,
+			is_custom_element_node(node) && b.true,
 			context.state
 		);
 
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 0b4ac87342..5bc3041ca4 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
@@ -4,6 +4,7 @@
 import { cannot_be_set_statically } from '../../../../../../utils.js';
 import { is_event_attribute, is_text_attribute } from '../../../../../utils/ast.js';
 import * as b from '../../../../../utils/builders.js';
+import { is_custom_element_node } from '../../../../nodes.js';
 import { build_template_chunk } from './utils.js';
 
 /**
@@ -128,7 +129,7 @@ export function process_children(nodes, initial, is_element, { visit, state }) {
 function is_static_element(node, state) {
 	if (node.type !== 'RegularElement') return false;
 	if (node.fragment.metadata.dynamic) return false;
-	if (node.name.includes('-')) return false; // we're setting all attributes on custom elements through properties
+	if (is_custom_element_node(node)) return false; // we're setting all attributes on custom elements through properties
 
 	for (const attribute of node.attributes) {
 		if (attribute.type !== 'Attribute') {
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
index 077ced10c2..8746143408 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
@@ -126,22 +126,22 @@ export function build_template_chunk(
 				// extra work in the template_effect (instead we do the work in set_text).
 				return { value, has_state };
 			} else {
-				let expression = value;
-				// only add nullish coallescence if it hasn't been added already
-				if (value.type === 'LogicalExpression' && value.operator === '??') {
-					const { right } = value;
-					// `undefined` isn't a Literal (due to pre-ES5 shenanigans), so the only nullish literal is `null`
-					// however, you _can_ make a variable called `undefined` in a Svelte component, so we can't just treat it the same way
-					if (right.type !== 'Literal') {
-						expression = b.logical('??', value, b.literal(''));
-					} else if (right.value === null) {
-						// if they do something weird like `stuff ?? null`, replace `null` with empty string
-						value.right = b.literal('');
+				// add `?? ''` where necessary (TODO optimise more cases)
+				if (
+					value.type === 'LogicalExpression' &&
+					value.right.type === 'Literal' &&
+					(value.operator === '??' || value.operator === '||')
+				) {
+					// `foo ?? null` -=> `foo ?? ''`
+					// otherwise leave the expression untouched
+					if (value.right.value === null) {
+						value = { ...value, right: b.literal('') };
 					}
 				} else {
-					expression = b.logical('??', value, b.literal(''));
+					value = b.logical('??', value, b.literal(''));
 				}
-				expressions.push(expression);
+
+				expressions.push(value);
 			}
 
 			quasi = b.quasi('', i + 1 === values.length);
diff --git a/packages/svelte/src/compiler/phases/nodes.js b/packages/svelte/src/compiler/phases/nodes.js
index b1e13e5cff..e92d2d0893 100644
--- a/packages/svelte/src/compiler/phases/nodes.js
+++ b/packages/svelte/src/compiler/phases/nodes.js
@@ -23,10 +23,14 @@ export function is_element_node(node) {
 
 /**
  * @param {AST.RegularElement | AST.SvelteElement} node
- * @returns {node is AST.RegularElement}
+ * @returns {boolean}
  */
 export function is_custom_element_node(node) {
-	return node.type === 'RegularElement' && node.name.includes('-');
+	return (
+		node.type === 'RegularElement' &&
+		(node.name.includes('-') ||
+			node.attributes.some((attr) => attr.type === 'Attribute' && attr.name === 'is'))
+	);
 }
 
 /**
diff --git a/packages/svelte/src/internal/client/dom/elements/attributes.js b/packages/svelte/src/internal/client/dom/elements/attributes.js
index a2fffe8696..eab27e6c02 100644
--- a/packages/svelte/src/internal/client/dom/elements/attributes.js
+++ b/packages/svelte/src/internal/client/dom/elements/attributes.js
@@ -68,14 +68,14 @@ export function set_value(element, value) {
 				// treat null and undefined the same for the initial value
 				value ?? undefined) ||
 		// @ts-expect-error
-		// `progress` elements always need their value set when its `0`
+		// `progress` elements always need their value set when it's `0`
 		(element.value === value && (value !== 0 || element.nodeName !== 'PROGRESS'))
 	) {
 		return;
 	}
 
 	// @ts-expect-error
-	element.value = value;
+	element.value = value ?? '';
 }
 
 /**
diff --git a/packages/svelte/src/utils.js b/packages/svelte/src/utils.js
index b16c0551f1..e8e1bc224c 100644
--- a/packages/svelte/src/utils.js
+++ b/packages/svelte/src/utils.js
@@ -170,7 +170,10 @@ const DOM_BOOLEAN_ATTRIBUTES = [
 	'reversed',
 	'seamless',
 	'selected',
-	'webkitdirectory'
+	'webkitdirectory',
+	'defer',
+	'disablepictureinpicture',
+	'disableremoteplayback'
 ];
 
 /**
@@ -197,7 +200,10 @@ const ATTRIBUTE_ALIASES = {
 	defaultvalue: 'defaultValue',
 	defaultchecked: 'defaultChecked',
 	srcobject: 'srcObject',
-	novalidate: 'noValidate'
+	novalidate: 'noValidate',
+	allowfullscreen: 'allowFullscreen',
+	disablepictureinpicture: 'disablePictureInPicture',
+	disableremoteplayback: 'disableRemotePlayback'
 };
 
 /**
@@ -219,7 +225,11 @@ const DOM_PROPERTIES = [
 	'volume',
 	'defaultValue',
 	'defaultChecked',
-	'srcObject'
+	'srcObject',
+	'noValidate',
+	'allowFullscreen',
+	'disablePictureInPicture',
+	'disableRemotePlayback'
 ];
 
 /**
diff --git a/packages/svelte/tests/runtime-runes/samples/attribute-boolean-case-insensitivity/_config.js b/packages/svelte/tests/runtime-runes/samples/attribute-boolean-case-insensitivity/_config.js
new file mode 100644
index 0000000000..d0b8a421b3
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/attribute-boolean-case-insensitivity/_config.js
@@ -0,0 +1,60 @@
+import { test } from '../../test';
+
+export default test({
+	// JSDOM lacks support for some of these attributes, so we'll skip it for now.
+	//
+	// See:
+	//  - `async`: https://github.com/jsdom/jsdom/issues/1564
+	//  - `nomodule`: https://github.com/jsdom/jsdom/issues/2475
+	//  - `autofocus`: https://github.com/jsdom/jsdom/issues/3041
+	//  - `inert`: https://github.com/jsdom/jsdom/issues/3605
+	//  - etc...: https://github.com/jestjs/jest/issues/139#issuecomment-592673550
+	skip_mode: ['client'],
+
+	html: `
+	<script nomodule async defer></script>
+	<form novalidate></form>
+	<input readonly required checked webkitdirectory>
+	<select multiple disabled></select>
+	<button formnovalidate></button>
+	<img ismap>
+	<video autoplay controls loop muted playsinline disablepictureinpicture disableremoteplayback></video>
+	<audio disableremoteplayback></audio>
+	<track default>
+	<iframe allowfullscreen></iframe>
+	<details open></details>
+	<ol reversed></ol>
+	<div autofocus></div>
+	<span inert></span>
+
+	<script nomodule async defer></script>
+	<form novalidate></form>
+	<input readonly required checked webkitdirectory>
+	<select multiple disabled></select>
+	<button formnovalidate></button>
+	<img ismap>
+	<video autoplay controls loop muted playsinline disablepictureinpicture disableremoteplayback></video>
+	<audio disableremoteplayback></audio>
+	<track default>
+	<iframe allowfullscreen></iframe>
+	<details open></details>
+	<ol reversed></ol>
+	<div autofocus></div>
+	<span inert></span>
+
+	<script></script>
+	<form></form>
+	<input>
+	<select></select>
+	<button></button>
+	<img>
+	<video></video>
+	<audio></audio>
+	<track>
+	<iframe></iframe>
+	<details></details>
+	<ol></ol>
+	<div></div>
+	<span></span>
+`
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/attribute-boolean-case-insensitivity/main.svelte b/packages/svelte/tests/runtime-runes/samples/attribute-boolean-case-insensitivity/main.svelte
new file mode 100644
index 0000000000..e9e5a16168
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/attribute-boolean-case-insensitivity/main.svelte
@@ -0,0 +1,22 @@
+<script>
+	let runesMode = $state('using a rune so that we trigger runes mode');
+
+	const attributeValues = [true, 'test', false];
+</script>
+
+{#each attributeValues as val}
+	<script NOMODULE={val} ASYNC={val} DEFER={val}></script>
+	<form NOVALIDATE={val}></form>
+	<input READONLY={val} REQUIRED={val} CHECKED={val} WEBKITDIRECTORY={val} />
+	<select MULTIPLE={val} DISABLED={val}></select>
+	<button FORMNOVALIDATE={val}></button>
+	<img ISMAP={val} />
+	<video AUTOPLAY={val} CONTROLS={val} LOOP={val} MUTED={val} PLAYSINLINE={val} DISABLEPICTUREINPICTURE={val} DISABLEREMOTEPLAYBACK={val}></video>
+	<audio DISABLEREMOTEPLAYBACK={val}></audio>
+	<track DEFAULT={val} />
+	<iframe ALLOWFULLSCREEN={val}></iframe>
+	<details OPEN={val}></details>
+	<ol REVERSED={val}></ol>
+	<div AUTOFOCUS={val}></div>
+	<span INERT={val}></span>
+{/each}
diff --git a/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/_config.js b/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/_config.js
new file mode 100644
index 0000000000..118a51157e
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/_config.js
@@ -0,0 +1,19 @@
+import { test } from '../../test';
+
+export default test({
+	mode: ['client', 'server'],
+	async test({ assert, target }) {
+		const my_element = /** @type HTMLElement & { object: { test: true }; } */ (
+			target.querySelector('my-element')
+		);
+		const my_link = /** @type HTMLAnchorElement & { object: { test: true }; } */ (
+			target.querySelector('a')
+		);
+		assert.equal(my_element.getAttribute('string'), 'test');
+		assert.equal(my_element.hasAttribute('object'), false);
+		assert.deepEqual(my_element.object, { test: true });
+		assert.equal(my_link.getAttribute('string'), 'test');
+		assert.equal(my_link.hasAttribute('object'), false);
+		assert.deepEqual(my_link.object, { test: 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
new file mode 100644
index 0000000000..ff94a9484c
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/custom-element-attributes/main.svelte
@@ -0,0 +1,2 @@
+<my-element string="test" object={{ test: true }}></my-element>
+<a is="my-link" string="test" object={{ test: true }}></a>
diff --git a/packages/svelte/tests/runtime-runes/samples/value-attribute-null-undefined/_config.js b/packages/svelte/tests/runtime-runes/samples/value-attribute-null-undefined/_config.js
new file mode 100644
index 0000000000..08f0c5aec7
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/value-attribute-null-undefined/_config.js
@@ -0,0 +1,49 @@
+import { test, ok } from '../../test';
+import { flushSync } from 'svelte';
+
+export default test({
+	mode: ['client'],
+
+	async test({ assert, target }) {
+		/**
+		 * @type {HTMLInputElement | null}
+		 */
+		const input = target.querySelector('input[type=text]');
+		/**
+		 * @type {HTMLButtonElement | null}
+		 */
+		const setString = target.querySelector('#setString');
+		/**
+		 * @type {HTMLButtonElement | null}
+		 */
+		const setNull = target.querySelector('#setNull');
+		/**
+		 * @type {HTMLButtonElement | null}
+		 */
+		const setUndefined = target.querySelector('#setUndefined');
+
+		ok(input);
+		ok(setString);
+		ok(setNull);
+		ok(setUndefined);
+
+		// value should always be blank string when value attribute is set to null or undefined
+
+		assert.equal(input.value, '');
+		setString.click();
+		flushSync();
+		assert.equal(input.value, 'foo');
+
+		setNull.click();
+		flushSync();
+		assert.equal(input.value, '');
+
+		setString.click();
+		flushSync();
+		assert.equal(input.value, 'foo');
+
+		setUndefined.click();
+		flushSync();
+		assert.equal(input.value, '');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/value-attribute-null-undefined/main.svelte b/packages/svelte/tests/runtime-runes/samples/value-attribute-null-undefined/main.svelte
new file mode 100644
index 0000000000..9f944923c2
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/value-attribute-null-undefined/main.svelte
@@ -0,0 +1,9 @@
+<script>
+	let value = $state();
+</script>
+
+<input type="text" {value} />
+
+<button id="setString" onclick={() => {value = "foo";}}></button>
+<button id="setNull" onclick={() => {value = null;}}></button>
+<button id="setUndefined" onclick={() => {value = undefined;}}></button>