diff --git a/packages/svelte/tests/runtime-runes/samples/async-commit-stale-reader-dropped-dep/_config.js b/packages/svelte/tests/runtime-runes/samples/async-commit-stale-reader-dropped-dep/_config.js
new file mode 100644
index 0000000000..89d42b5b96
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-commit-stale-reader-dropped-dep/_config.js
@@ -0,0 +1,37 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target, logs }) {
+		await tick();
+		const [x, y, shift] = target.querySelectorAll('button');
+
+		assert.deepEqual(logs, ['effect _ 0']);
+
+		// write x — the batch is pending on its async expression
+		x.click();
+		await tick();
+		assert.deepEqual(logs, ['effect _ 0']);
+
+		// the effect newly depends on `x` — it reads the held-back value (0)
+		// (at some point it read latest, but we decided against doing this)
+		y.click();
+		await tick();
+		assert.deepEqual(logs, ['effect _ 0', 'effect 0 1']);
+
+		// the effect re-runs and no longer depends on `x` at all
+		y.click();
+		await tick();
+		assert.deepEqual(logs, ['effect _ 0', 'effect 0 1', 'effect _ 2']);
+
+		// the pending batch settles and commits x = 1 — the effect no longer
+		// depends on `x`, so it should not re-run
+		shift.click();
+		await tick();
+		assert.deepEqual(logs, ['effect _ 0', 'effect 0 1', 'effect _ 2']);
+		assert.htmlEqual(
+			target.innerHTML,
+			'<p>1</p><button>x</button><button>y</button><button>shift</button>'
+		);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-commit-stale-reader-dropped-dep/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-commit-stale-reader-dropped-dep/main.svelte
new file mode 100644
index 0000000000..4d9d616293
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-commit-stale-reader-dropped-dep/main.svelte
@@ -0,0 +1,24 @@
+<script>
+	let x = $state(0);
+	let y = $state(0);
+
+	const deferred = [];
+
+	function delay(value) {
+		if (!value) return value;
+		return new Promise((resolve) => deferred.push(() => resolve(value)));
+	}
+
+	$effect(() => {
+		if (y === 1) {
+			console.log(`effect ${x} ${y}`);
+		} else {
+			console.log(`effect _ ${y}`);
+		}
+	});
+</script>
+
+<p>{await delay(x)}</p>
+<button onclick={() => x++}>x</button>
+<button onclick={() => y++}>y</button>
+<button onclick={() => deferred.shift()?.()}>shift</button>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-3/_config.js b/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-3/_config.js
index c9e7513b22..868ae1f54f 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-3/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-3/_config.js
@@ -2,7 +2,6 @@ import { tick } from 'svelte';
 import { test } from '../../test';
 
 export default test({
-	skip: true, // TODO works on https://github.com/sveltejs/svelte/pull/17971
 	async test({ assert, target }) {
 		await tick();
 		const [a_b, a_c, b_d, shift, pop] = target.querySelectorAll('button');
@@ -63,12 +62,12 @@ export default test({
 		`
 		);
 
-		pop.click(); // second b resolved, still pending: [b, a]
+		pop.click(); // second b resolved, still pending: [b, a] but b is now obsolete
 		await tick();
 		assert.htmlEqual(
 			target.innerHTML,
 			`
-			a 0 | b 0 | c 0 | d 0
+			a 1 | b 2 | c 0 | d 1
 			<button>a and b</button>
 			<button>a and c</button>
 			<button>b and d</button>
@@ -79,18 +78,6 @@ export default test({
 
 		shift.click(); // first b resolved, first + last batch settled, still pending: [a]
 		await tick();
-		assert.htmlEqual(
-			target.innerHTML,
-			`
-			a 1 | b 2 | c 0 | d 1
-			<button>a and b</button>
-			<button>a and c</button>
-			<button>b and d</button>
-			<button>shift</button>
-			<button>pop</button>
-		`
-		);
-
 		shift.click(); // all resolved
 		await tick();
 		assert.htmlEqual(
diff --git a/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-4/_config.js b/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-4/_config.js
index 472a3ebcaf..fff23f68ef 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-4/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-4/_config.js
@@ -2,7 +2,6 @@ import { tick } from 'svelte';
 import { test } from '../../test';
 
 export default test({
-	skip: true, // TODO works on https://github.com/sveltejs/svelte/pull/17971
 	async test({ assert, target }) {
 		await tick();
 		const [a_b, a_c, b_d, shift, pop] = target.querySelectorAll('button');
@@ -63,12 +62,12 @@ export default test({
 		`
 		);
 
-		pop.click(); // second b resolved, still pending: [b, a]
+		pop.click(); // second b resolved, still pending: [b, a] with b obsolete so can render some already
 		await tick();
 		assert.htmlEqual(
 			target.innerHTML,
 			`
-			a 0 | b 0 | c 0 | d 0
+			a 1 | b 2 | c 0 | d 1
 			<button>a and b</button>
 			<button>a and c</button>
 			<button>b and d</button>
@@ -78,22 +77,6 @@ export default test({
 		);
 
 		pop.click(); // second a resolved, first a/b now obsolete
-		// TODO would be nice to show final result here already, right now it doesn't because
-		// we have no handle on the already resolved first a anymore
-		await tick();
-		assert.htmlEqual(
-			target.innerHTML,
-			`
-			a 0 | b 0 | c 0 | d 0
-			<button>a and b</button>
-			<button>a and c</button>
-			<button>b and d</button>
-			<button>shift</button>
-			<button>pop</button>
-		`
-		);
-
-		shift.click(); // queue empty
 		await tick();
 		assert.htmlEqual(
 			target.innerHTML,
diff --git a/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-fork-3/_config.js b/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-fork-3/_config.js
index 61360d8dc9..fd7bc40eed 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-fork-3/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-overlap-multiple-fork-3/_config.js
@@ -2,7 +2,6 @@ import { tick } from 'svelte';
 import { test } from '../../test';
 
 export default test({
-	skip: true,
 	async test({ assert, target }) {
 		await tick();
 		const [a_b_fork, a_c, b_d, shift, pop, commit] = target.querySelectorAll('button');
diff --git a/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-5/_config.js b/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-5/_config.js
new file mode 100644
index 0000000000..c1acd5bce6
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-5/_config.js
@@ -0,0 +1,52 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const [x, y, resolve] = target.querySelectorAll('button');
+
+		x.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+			<button>x</button>
+			<button>y++</button>
+			<button>resolve</button>
+			<h1>WORLD</h1>
+		`
+		);
+
+		y.click();
+		await tick();
+		// the new branch reads `upper` — a derived of the source the pending batch
+		// wrote — as a new dependency. It renders with the pre-write value 'WORLD',
+		// as the pending batch's write is hidden from the batch that commits
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+			<button>x</button>
+			<button>y++</button>
+			<button>resolve</button>
+			<h1>WORLD</h1>
+			<p>WORLD</p>
+		`
+		);
+
+		resolve.click();
+		await tick();
+		// the pending batch discovers that the new branch depends on its write
+		// when it resumes, and commits it fully consistent
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+			<button>x</button>
+			<button>y++</button>
+			<button>resolve</button>
+			<h1>UNIVERSE</h1>
+			universe
+			<p>UNIVERSE</p>
+		`
+		);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-5/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-5/main.svelte
new file mode 100644
index 0000000000..aa95730425
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-5/main.svelte
@@ -0,0 +1,29 @@
+<script>
+	let x = $state({ x: 'world' });
+	let y = $state(0);
+	let deferred = [];
+
+	const upper = $derived(x.x.toUpperCase());
+
+	function delay(s) {
+		const d = Promise.withResolvers();
+		deferred.push(() => d.resolve(s));
+		return d.promise;
+	}
+</script>
+
+<button onclick={() => (x = { x: 'universe' })}>x</button>
+
+<button onclick={() => y++}>y++</button>
+
+<button onclick={() => deferred.shift()()}>resolve</button>
+
+<h1>{upper}</h1>
+
+{#if x.x === 'universe'}
+	{await delay(x.x)}
+{/if}
+
+{#if y > 0}
+	<p>{upper}</p>
+{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-fork-4/_config.js b/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-fork-4/_config.js
index 6a6399a19e..a20f8c0ba5 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-fork-4/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-state-new-branch-fork-4/_config.js
@@ -2,7 +2,6 @@ import { tick } from 'svelte';
 import { test } from '../../test';
 
 export default test({
-	skip: true, // TODO works on https://github.com/sveltejs/svelte/pull/17971
 	async test({ assert, target }) {
 		const [x, y, resolve, commit] = target.querySelectorAll('button');
 
diff --git a/packages/svelte/tests/runtime-runes/samples/async-state-read-new-dependency/_config.js b/packages/svelte/tests/runtime-runes/samples/async-state-read-new-dependency/_config.js
new file mode 100644
index 0000000000..37c2f7e97c
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-state-read-new-dependency/_config.js
@@ -0,0 +1,30 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['client'],
+	async test({ assert, target }) {
+		await tick();
+		const [update, show, resolve] = target.querySelectorAll('button');
+
+		update.click();
+		await tick();
+
+		show.click();
+		await tick();
+
+		// the template effect newly depends on `value`, which the pending batch
+		// has written — it reads the pre-write value and crashes
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>update</button>
+				<button>show</button>
+				<button>resolve</button>
+				<p>crash</p>
+			`
+		);
+
+		resolve.click();
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-state-read-new-dependency/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-state-read-new-dependency/main.svelte
new file mode 100644
index 0000000000..05db2f78dd
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-state-read-new-dependency/main.svelte
@@ -0,0 +1,22 @@
+<script>
+	let value = $state();
+	let show = $state(false);
+	const deferred = Promise.withResolvers();
+
+	function wait(value) {
+		return value === undefined ? '' : deferred.promise;
+	}
+</script>
+
+<button onclick={() => (value = { x: 1 })}>update</button>
+<button onclick={() => (show = true)}>show</button>
+<button onclick={() => deferred.resolve('')}>resolve</button>
+
+{await wait(value)}
+
+<svelte:boundary>
+	<p>{show ? value.x + value.x : ''}</p>
+	{#snippet failed()}
+		<p>crash</p>
+	{/snippet}
+</svelte:boundary>
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-29/_config.js b/packages/svelte/tests/runtime-runes/samples/error-boundary-29/_config.js
new file mode 100644
index 0000000000..ef4e1203b1
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-29/_config.js
@@ -0,0 +1,14 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+// A render effect in a branch that is created during traversal doesn't run right away (in async mode,
+// it runs together with the other render effects of the batch), but its error is still caught by the boundary
+export default test({
+	mode: ['client'],
+	test({ assert, target }) {
+		const [show] = target.querySelectorAll('button');
+
+		flushSync(() => show.click());
+		assert.htmlEqual(target.innerHTML, '<button>show</button><p>crash</p>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-29/main.svelte b/packages/svelte/tests/runtime-runes/samples/error-boundary-29/main.svelte
new file mode 100644
index 0000000000..170bc308e3
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-29/main.svelte
@@ -0,0 +1,16 @@
+<script>
+	let value = $state();
+	let show = $state(false);
+</script>
+
+<button onclick={() => (show = true)}>show</button>
+
+{#if show}
+	<svelte:boundary>
+		<p>{value.x}</p>
+
+		{#snippet failed()}
+			<p>crash</p>
+		{/snippet}
+	</svelte:boundary>
+{/if}