diff --git a/packages/svelte/src/internal/client/dom/blocks/each.js b/packages/svelte/src/internal/client/dom/blocks/each.js
index 9b80aa2cea..afe2e403ce 100644
--- a/packages/svelte/src/internal/client/dom/blocks/each.js
+++ b/packages/svelte/src/internal/client/dom/blocks/each.js
@@ -15,14 +15,13 @@ import {
 } from '../../hydration.js';
 import { empty, map_get, map_set } from '../../operations.js';
 import { insert, remove } from '../../reconciler.js';
-import { set } from '../../runtime.js';
 import {
 	destroy_effect,
 	pause_effect,
 	render_effect,
 	resume_effect
 } from '../../reactivity/effects.js';
-import { source, mutable_source } from '../../reactivity/sources.js';
+import { source, mutable_source, set } from '../../reactivity/sources.js';
 import { is_array } from '../../utils.js';
 import { BRANCH_EFFECT } from '../../constants.js';
 
diff --git a/packages/svelte/src/internal/client/proxy.js b/packages/svelte/src/internal/client/proxy.js
index cbe981ef66..5fc57ae280 100644
--- a/packages/svelte/src/internal/client/proxy.js
+++ b/packages/svelte/src/internal/client/proxy.js
@@ -1,7 +1,6 @@
 import { DEV } from 'esm-env';
 import {
 	get,
-	set,
 	updating_derived,
 	batch_inspect,
 	current_component_context,
@@ -19,7 +18,7 @@ import {
 	object_prototype
 } from './utils.js';
 import { add_owner, check_ownership, strip_owner } from './dev/ownership.js';
-import { mutable_source, source } from './reactivity/sources.js';
+import { mutable_source, source, set } from './reactivity/sources.js';
 import { STATE_SYMBOL, UNINITIALIZED } from './constants.js';
 
 /**
diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index cc4b9e5b57..0afc654880 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -1,7 +1,26 @@
 import { DEV } from 'esm-env';
-import { current_component_context } from '../runtime.js';
+import {
+	current_component_context,
+	current_consumer,
+	current_dependencies,
+	current_effect,
+	current_untracked_writes,
+	current_untracking,
+	flushSync,
+	get,
+	ignore_mutation_validation,
+	is_batching_effect,
+	is_runes,
+	last_inspected_signal,
+	mark_signal_consumers,
+	schedule_effect,
+	set_current_untracked_writes,
+	set_last_inspected_signal,
+	set_signal_status,
+	untrack
+} from '../runtime.js';
 import { default_equals, safe_equal } from './equality.js';
-import { CLEAN, SOURCE } from '../constants.js';
+import { CLEAN, DERIVED, DIRTY, MANAGED, SOURCE } from '../constants.js';
 
 /**
  * @template V
@@ -44,3 +63,100 @@ export function mutable_source(initial_value) {
 
 	return s;
 }
+
+/**
+ * @template V
+ * @param {import('#client').Source<V>} signal
+ * @param {V} value
+ * @returns {V}
+ */
+export function set(signal, value) {
+	if (
+		!current_untracking &&
+		!ignore_mutation_validation &&
+		current_consumer !== null &&
+		is_runes(null) &&
+		(current_consumer.f & DERIVED) !== 0
+	) {
+		throw new Error(
+			'ERR_SVELTE_UNSAFE_MUTATION' +
+				(DEV
+					? ": Unsafe mutations during Svelte's render or derived phase are not permitted in runes mode. " +
+						'This can lead to unexpected errors and possibly cause infinite loops.\n\nIf this mutation is not meant ' +
+						'to be reactive do not use the "$state" rune for that declaration.'
+					: '')
+		);
+	}
+
+	if (!signal.eq(value, signal.v)) {
+		signal.v = value;
+
+		// Increment write version so that unowned signals can properly track dirtyness
+		signal.w++;
+
+		// If the current signal is running for the first time, it won't have any
+		// consumers as we only allocate and assign the consumers after the signal
+		// has fully executed. So in the case of ensuring it registers the consumer
+		// properly for itself, we need to ensure the current effect actually gets
+		// scheduled. i.e:
+		//
+		// $effect(() => x++)
+		//
+		// We additionally want to skip this logic for when ignore_mutation_validation is
+		// true, as stores write to source signal on initialization.
+		if (
+			is_runes(null) &&
+			!ignore_mutation_validation &&
+			current_effect !== null &&
+			(current_effect.f & CLEAN) !== 0 &&
+			(current_effect.f & MANAGED) === 0
+		) {
+			if (current_dependencies !== null && current_dependencies.includes(signal)) {
+				set_signal_status(current_effect, DIRTY);
+				schedule_effect(current_effect, false);
+			} else {
+				if (current_untracked_writes === null) {
+					set_current_untracked_writes([signal]);
+				} else {
+					current_untracked_writes.push(signal);
+				}
+			}
+		}
+
+		mark_signal_consumers(signal, DIRTY, true);
+
+		// @ts-expect-error
+		if (DEV && signal.inspect) {
+			if (is_batching_effect) {
+				set_last_inspected_signal(/** @type {import('#client').SourceDebug} */ (signal));
+			} else {
+				for (const fn of /** @type {import('#client').SourceDebug} */ (signal).inspect) fn();
+			}
+		}
+	}
+
+	return value;
+}
+
+/**
+ * @template V
+ * @param {import('#client').Source<V>} signal
+ * @param {V} value
+ * @returns {void}
+ */
+export function set_sync(signal, value) {
+	flushSync(() => set(signal, value));
+}
+
+/**
+ * @template V
+ * @param {import('#client').Source<V>} source
+ * @param {V} value
+ */
+export function mutate(source, value) {
+	set(
+		source,
+		untrack(() => get(source))
+	);
+	return value;
+}
diff --git a/packages/svelte/src/internal/client/reactivity/store.js b/packages/svelte/src/internal/client/reactivity/store.js
index 9e0999053b..44b25ce636 100644
--- a/packages/svelte/src/internal/client/reactivity/store.js
+++ b/packages/svelte/src/internal/client/reactivity/store.js
@@ -1,9 +1,9 @@
 import { subscribe_to_store } from '../../../store/utils.js';
 import { noop } from '../../common.js';
 import { UNINITIALIZED } from '../constants.js';
-import { get, set, set_ignore_mutation_validation, untrack } from '../runtime.js';
+import { get, set_ignore_mutation_validation, untrack } from '../runtime.js';
 import { user_effect } from './effects.js';
-import { mutable_source } from './sources.js';
+import { mutable_source, set } from './sources.js';
 
 /**
  * Gets the current value of a store. If the store isn't subscribed to yet, it will create a proxy
diff --git a/packages/svelte/src/internal/client/render.js b/packages/svelte/src/internal/client/render.js
index 707a642ea3..fee89913fd 100644
--- a/packages/svelte/src/internal/client/render.js
+++ b/packages/svelte/src/internal/client/render.js
@@ -35,7 +35,6 @@ import {
 	current_component_context,
 	deep_read,
 	get,
-	set,
 	is_signals_recorded,
 	inspect_fn,
 	current_effect
@@ -66,7 +65,7 @@ import {
 } from './utils.js';
 import { run } from '../common.js';
 import { bind_transition } from './transitions.js';
-import { mutable_source, source } from './reactivity/sources.js';
+import { mutable_source, source, set } from './reactivity/sources.js';
 import { safe_not_equal } from './reactivity/equality.js';
 import { derived, derived_safe_equal } from './reactivity/deriveds.js';
 
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 47b9dac584..ee303b2078 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -28,6 +28,7 @@ import {
 	BRANCH_EFFECT
 } from './constants.js';
 import { flush_tasks } from './dom/task.js';
+import { mutate, set } from './reactivity/sources.js';
 
 const IS_EFFECT = EFFECT | PRE_EFFECT | RENDER_EFFECT;
 
@@ -66,20 +67,33 @@ export function set_current_effect(effect) {
 }
 
 /** @type {null | import('#client').ValueSignal[]} */
-let current_dependencies = null;
+export let current_dependencies = null;
 let current_dependencies_index = 0;
+
 /**
  * Tracks writes that the effect it's executed in doesn't listen to yet,
  * so that the dependency can be added to the effect later on if it then reads it
  * @type {null | import('#client').Source[]}
  */
-let current_untracked_writes = null;
+export let current_untracked_writes = null;
+
+/** @param {null | import('#client').Source[]} writes */
+export function set_current_untracked_writes(writes) {
+	current_untracked_writes = writes;
+}
+
 /** @type {null | import('#client').SourceDebug} */
-let last_inspected_signal = null;
+export let last_inspected_signal = null;
+
+/** @param {import('#client').SourceDebug} signal */
+export function set_last_inspected_signal(signal) {
+	last_inspected_signal = signal;
+}
+
 /** If `true`, `get`ting the signal should not register it as a dependency */
 export let current_untracking = false;
 /** Exists to opt out of the mutation validation for stores which may be set for the first time during a derivation */
-let ignore_mutation_validation = false;
+export let ignore_mutation_validation = false;
 /** @param {boolean} value */
 export function set_ignore_mutation_validation(value) {
 	ignore_mutation_validation = value;
@@ -113,7 +127,7 @@ export let updating_derived = false;
  * @param {null | import('#client').ComponentContext} context
  * @returns {boolean}
  */
-function is_runes(context) {
+export function is_runes(context) {
 	const component_context = context || current_component_context;
 	return component_context !== null && component_context.r;
 }
@@ -751,90 +765,6 @@ export function get(signal) {
 	return signal.v;
 }
 
-/**
- * @template V
- * @param {import('#client').Source<V>} signal
- * @param {V} value
- * @returns {V}
- */
-export function set(signal, value) {
-	if (
-		!current_untracking &&
-		!ignore_mutation_validation &&
-		current_consumer !== null &&
-		is_runes(null) &&
-		(current_consumer.f & DERIVED) !== 0
-	) {
-		throw new Error(
-			'ERR_SVELTE_UNSAFE_MUTATION' +
-				(DEV
-					? ": Unsafe mutations during Svelte's render or derived phase are not permitted in runes mode. " +
-						'This can lead to unexpected errors and possibly cause infinite loops.\n\nIf this mutation is not meant ' +
-						'to be reactive do not use the "$state" rune for that declaration.'
-					: '')
-		);
-	}
-
-	if (!signal.eq(value, signal.v)) {
-		signal.v = value;
-
-		// Increment write version so that unowned signals can properly track dirtyness
-		signal.w++;
-
-		// If the current signal is running for the first time, it won't have any
-		// consumers as we only allocate and assign the consumers after the signal
-		// has fully executed. So in the case of ensuring it registers the consumer
-		// properly for itself, we need to ensure the current effect actually gets
-		// scheduled. i.e:
-		//
-		// $effect(() => x++)
-		//
-		// We additionally want to skip this logic for when ignore_mutation_validation is
-		// true, as stores write to source signal on initialization.
-		if (
-			is_runes(null) &&
-			!ignore_mutation_validation &&
-			current_effect !== null &&
-			(current_effect.f & CLEAN) !== 0 &&
-			(current_effect.f & MANAGED) === 0
-		) {
-			if (current_dependencies !== null && current_dependencies.includes(signal)) {
-				set_signal_status(current_effect, DIRTY);
-				schedule_effect(current_effect, false);
-			} else {
-				if (current_untracked_writes === null) {
-					current_untracked_writes = [signal];
-				} else {
-					current_untracked_writes.push(signal);
-				}
-			}
-		}
-
-		mark_signal_consumers(signal, DIRTY, true);
-
-		// @ts-expect-error
-		if (DEV && signal.inspect) {
-			if (is_batching_effect) {
-				last_inspected_signal = /** @type {import('#client').SourceDebug} */ (signal);
-			} else {
-				for (const fn of /** @type {import('#client').SourceDebug} */ (signal).inspect) fn();
-			}
-		}
-	}
-
-	return value;
-}
-
-/**
- * @template V
- * @param {import('#client').Source<V>} signal
- * @param {V} value
- * @returns {void}
- */
-export function set_sync(signal, value) {
-	flushSync(() => set(signal, value));
-}
-
 /**
  * Invokes a function and captures all signals that are read during the invocation,
  * then invalidates them.
@@ -863,26 +793,13 @@ export function invalidate_inner_signals(fn) {
 	}
 }
 
-/**
- * @template V
- * @param {import('#client').Source<V>} source
- * @param {V} value
- */
-export function mutate(source, value) {
-	set(
-		source,
-		untrack(() => get(source))
-	);
-	return value;
-}
-
 /**
  * @param {import('#client').ValueSignal} signal
  * @param {number} to_status
  * @param {boolean} force_schedule
  * @returns {void}
  */
-function mark_signal_consumers(signal, to_status, force_schedule) {
+export function mark_signal_consumers(signal, to_status, force_schedule) {
 	const runes = is_runes(null);
 	const consumers = signal.consumers;
 
@@ -974,7 +891,7 @@ const STATUS_MASK = ~(DIRTY | MAYBE_DIRTY | CLEAN);
  * @param {number} status
  * @returns {void}
  */
-function set_signal_status(signal, status) {
+export function set_signal_status(signal, status) {
 	signal.f = (signal.f & STATUS_MASK) | status;
 }
 
diff --git a/packages/svelte/src/internal/index.js b/packages/svelte/src/internal/index.js
index 67663e6cc2..a63b1bcf31 100644
--- a/packages/svelte/src/internal/index.js
+++ b/packages/svelte/src/internal/index.js
@@ -1,7 +1,5 @@
 export {
 	get,
-	set,
-	set_sync,
 	invalidate_inner_signals,
 	flushSync,
 	tick,
@@ -10,7 +8,6 @@ export {
 	update_prop,
 	update_pre,
 	update_pre_prop,
-	mutate,
 	value_or_fallback,
 	exclude_from_object,
 	pop,
diff --git a/packages/svelte/src/reactivity/index.js b/packages/svelte/src/reactivity/index.js
index b68cef7be3..f802121a2e 100644
--- a/packages/svelte/src/reactivity/index.js
+++ b/packages/svelte/src/reactivity/index.js
@@ -1,5 +1,5 @@
-import { source } from '../internal/client/reactivity/sources.js';
-import { get, set } from '../internal/client/runtime.js';
+import { source, set } from '../internal/client/reactivity/sources.js';
+import { get } from '../internal/client/runtime.js';
 
 /** @type {Array<keyof Date>} */
 const read = [
diff --git a/packages/svelte/tests/signals/test.ts b/packages/svelte/tests/signals/test.ts
index de5ca18fde..be93d77959 100644
--- a/packages/svelte/tests/signals/test.ts
+++ b/packages/svelte/tests/signals/test.ts
@@ -5,6 +5,7 @@ import { source } from '../../src/internal/client/reactivity/sources';
 import type { Derived } from '../../src/internal/client/reactivity/types';
 import { proxy } from '../../src/internal/client/proxy';
 import { derived } from '../../src/internal/client/reactivity/deriveds';
+import { set } from '../../src/internal/client/reactivity/sources';
 
 /**
  * @param runes runes mode
@@ -46,8 +47,8 @@ describe('signals', () => {
 		});
 
 		return () => {
-			$.flushSync(() => $.set(count, 1));
-			$.flushSync(() => $.set(count, 2));
+			$.flushSync(() => set(count, 1));
+			$.flushSync(() => set(count, 2));
 
 			assert.deepEqual(log, ['0:0', '1:2', '2:4']);
 		};
@@ -67,8 +68,8 @@ describe('signals', () => {
 		});
 
 		return () => {
-			$.flushSync(() => $.set(count, 1));
-			$.flushSync(() => $.set(count, 2));
+			$.flushSync(() => set(count, 1));
+			$.flushSync(() => set(count, 2));
 
 			assert.deepEqual(log, ['A:0:0', 'B:0', 'A:1:2', 'B:2', 'A:2:4', 'B:4']);
 		};
@@ -88,8 +89,8 @@ describe('signals', () => {
 		});
 
 		return () => {
-			$.flushSync(() => $.set(count, 1));
-			$.flushSync(() => $.set(count, 2));
+			$.flushSync(() => set(count, 1));
+			$.flushSync(() => set(count, 2));
 
 			assert.deepEqual(log, ['A:0', 'B:0:0', 'A:2', 'B:1:2', 'A:4', 'B:2:4']);
 		};
@@ -106,8 +107,8 @@ describe('signals', () => {
 		});
 
 		return () => {
-			$.flushSync(() => $.set(count, 1));
-			$.flushSync(() => $.set(count, 2));
+			$.flushSync(() => set(count, 1));
+			$.flushSync(() => set(count, 2));
 
 			assert.deepEqual(log, [0, 2, 4]);
 		};
@@ -125,8 +126,8 @@ describe('signals', () => {
 		});
 
 		return () => {
-			$.flushSync(() => $.set(count, 1));
-			$.flushSync(() => $.set(count, 2));
+			$.flushSync(() => set(count, 1));
+			$.flushSync(() => set(count, 2));
 
 			assert.deepEqual(log, [0, 4, 8]);
 		};
@@ -162,12 +163,12 @@ describe('signals', () => {
 			let i = 2;
 			while (--i) {
 				res.length = 0;
-				$.set(B, 1);
-				$.set(A, 1 + i * 2);
+				set(B, 1);
+				set(A, 1 + i * 2);
 				$.flushSync();
 
-				$.set(A, 2 + i * 2);
-				$.set(B, 2);
+				set(A, 2 + i * 2);
+				set(B, 2);
 				$.flushSync();
 
 				assert.equal(res.length, 4);
@@ -190,13 +191,13 @@ describe('signals', () => {
 		});
 
 		return () => {
-			$.flushSync(() => $.set(count, 1));
+			$.flushSync(() => set(count, 1));
 			// Ensure we're not leaking consumers
 			assert.deepEqual(count.consumers?.length, 1);
-			$.flushSync(() => $.set(count, 2));
+			$.flushSync(() => set(count, 2));
 			// Ensure we're not leaking consumers
 			assert.deepEqual(count.consumers?.length, 1);
-			$.flushSync(() => $.set(count, 3));
+			$.flushSync(() => set(count, 3));
 			// Ensure we're not leaking consumers
 			assert.deepEqual(count.consumers?.length, 1);
 			assert.deepEqual(log, [0, 1, 2, 3]);
@@ -219,11 +220,11 @@ describe('signals', () => {
 
 			$.get(c);
 
-			$.flushSync(() => $.set(a, 1));
+			$.flushSync(() => set(a, 1));
 
 			$.get(c);
 
-			$.flushSync(() => $.set(b, 1));
+			$.flushSync(() => set(b, 1));
 
 			$.get(c);
 
@@ -252,11 +253,11 @@ describe('signals', () => {
 		});
 
 		return () => {
-			$.flushSync(() => $.set(count, 1));
-			$.flushSync(() => $.set(count, 2));
-			$.flushSync(() => $.set(count, 3));
-			$.flushSync(() => $.set(count, 4));
-			$.flushSync(() => $.set(count, 0));
+			$.flushSync(() => set(count, 1));
+			$.flushSync(() => set(count, 2));
+			$.flushSync(() => set(count, 3));
+			$.flushSync(() => set(count, 4));
+			$.flushSync(() => set(count, 0));
 			// Ensure we're not leaking consumers
 			assert.deepEqual(count.consumers?.length, 1);
 			assert.deepEqual(log, [0, 2, 'limit', 0]);
@@ -314,7 +315,7 @@ describe('signals', () => {
 
 		const value = source({ count: 0 });
 		user_effect(() => {
-			$.set(value, { count: 0 });
+			set(value, { count: 0 });
 			$.get(value);
 		});