From 4866aa233359e8d307122e14cb56196beaa94b22 Mon Sep 17 00:00:00 2001
From: Simon Holthausen <simon.holthausen@vercel.com>
Date: Tue, 2 Jun 2026 13:26:53 +0200
Subject: [PATCH] don't bail self-invalidation in async mode + don't mark
 reactions on initial run

not marking without not bailing makes two tests fail, revealing that the "don't self-invalidate in async mode" change would actually be a subtle breaking change
---
 .../svelte/src/internal/client/reactivity/batch.js     | 10 ++++++----
 .../svelte/src/internal/client/reactivity/deriveds.js  |  8 +++-----
 packages/svelte/src/internal/client/runtime.js         |  1 -
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index bdc2bdae42..566adc5b03 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -287,18 +287,20 @@ export class Batch {
 		if (this.#committed) return;
 
 		current_batch = this;
-		this.#started = true;
 
 		if (flush_count++ > 1000) {
 			this.#unlink();
 			infinite_loop_guard();
 		}
 
-		// TODO we only need to do this for re-runs
-		for (const [source, snapshot] of this.current) {
-			mark_reactions(this, source, snapshot.wv, null);
+		if (this.#started) {
+			for (const [source, snapshot] of this.current) {
+				mark_reactions(this, source, snapshot.wv, null);
+			}
 		}
 
+		this.#started = true;
+
 		if (DEV) {
 			// track all the values that were updated during this flush,
 			// so that they can be reset afterwards
diff --git a/packages/svelte/src/internal/client/reactivity/deriveds.js b/packages/svelte/src/internal/client/reactivity/deriveds.js
index 6352c66b17..99a809dbaa 100644
--- a/packages/svelte/src/internal/client/reactivity/deriveds.js
+++ b/packages/svelte/src/internal/client/reactivity/deriveds.js
@@ -1,6 +1,5 @@
-/** @import { Derived, Effect, Reaction, Source, Value } from '#client' */
+/** @import { Derived, Effect, Source, Value } from '#client' */
 /** @import { Batch } from './batch.js'; */
-/** @import { Boundary } from '../dom/blocks/boundary.js'; */
 import { DEV } from 'esm-env';
 import {
 	ERROR_VALUE,
@@ -26,14 +25,13 @@ import {
 	write_version,
 	skipped_deps,
 	new_deps,
-	is_destroying_effect,
-	current_sources
+	is_destroying_effect
 } from '../runtime.js';
 import { equals, safe_equals } from './equality.js';
 import * as e from '../errors.js';
 import * as w from '../warnings.js';
 import { async_effect, destroy_effect, destroy_effect_children, teardown } from './effects.js';
-import { eager_effects, internal_set, set_eager_effects, source, state } from './sources.js';
+import { eager_effects, internal_set, set_eager_effects, state } from './sources.js';
 import { get_error } from '../../shared/dev.js';
 import { async_mode_flag, tracing_mode_flag } from '../../flags/index.js';
 import { component_context } from '../context.js';
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index b4dcc04b30..78f4179890 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -300,7 +300,6 @@ export function update_reaction(reaction) {
 		// ensure that if any of those untracked writes result in re-invalidation
 		// of the current effect, then that happens accordingly
 		if (
-			!async_mode_flag &&
 			is_runes() &&
 			untracked_writes !== null &&
 			!untracking &&